毕业设计英文翻译Programmable_logic
PLC毕业设计外文翻译3
学校名称外文翻译专业：班级学号：学生姓名：指导教师：二〇一一年六月学校名称本科生毕业设计原文1：Programmable logic controllers 译文1：可编程逻辑控制器原文2：Foundation of PLC译文2：PLC基础专业班级：学生姓名：指导教师：学院：2011年6月原文1：Programmable logic controllersProgrammable logic controller(PLC) is eight 10- Year on behalf new generation industry that develop the control equip, and is an automatic control, calculator with the thing that the correspondence technique combine together, and is a the spot equipments for exclusively used foring the industry production line controling. Make the PLC there is characteristics of obvious oneself on the design with the long- term and continuous that circulate because of the special of the complexity, usage environment of the control object: The dependable is high, and the adaptability is wide, and have to correspond by letter the function, and weave the the convenience, construction mold piece . Gather the the control in the modern in the system, the PLC have already become a kind of importance of basic control unit, control the realm the inside in the industry applied the foreground is very and extensive.A programmable logic controller(PLC) is a solid-state devide used to control machine motion or process operation by means of a stored program. The PLC sends output control signals and receives input signals through input/output (I/O) devices.A PLC controls outputs in response to stimuli at the inputs according to the logic prescribed by the stored program.The inputs are made up of limit switches,pushbuttons,thumbwheels, switches,pulses,analog signals,ASCII serial data,and binary or BCD data from absolute position encoders.The outputs are voltage or current levers to drive end devices such as lolenids,motor staters,relays,lights,and so on.Other output devices such include analog devices,digital BCD displays,ASCII compatible devices,servo variable-speed drives,and even computers.Programmable controllers were developed(circa in 1968) when General Motors Corp,and other automobile manufacturers were experimenting to see if there might be an alterantive to scrapping all their hardwired control panels of machine tools and other production equipment during a model changeover.This annual tradition was necessary because rewiring of the panels was more expensive than buying new oens.The automotive companies approached a number of control equipment manufacturers and asked them to develop a control system that would have a longer productive life without major rewiring,but would still be understandable to and repairable by plant personnel.The new product wa namd a“programmable controller”．The processor part of the PLC contains a central processing unit and memory.The central proce ssing unit(CPU) is the“trafficdirector”of the processor,the memory stores ing into the processor are the electrical signals from the input devices，as conditioned by the input module to voltage levels acceptable to processor logic．The processor scans the state of I／O and updates outputs based on instructions stored in the memory of the PLC．For example，the processor may be programmed so that if an input connected to a limit switch is true(1imit switch closed),then a corresponding output wired to an output module is to be energized．This output might be asolenoid for example．The processor remembers this command through its memory and compares on each scan to see if that limit is, in fact ,closed. If it is closed, the processor energizes the solenoid by turning on the output module.The output device, such as a solenoid or motor stater,is wired to an output mofule’s terminal,and itreceives its shift signal from the processor, in effect the peocessor is performing a long and complicated series of logic decisions. The PLC performs such decisions sequentially and in accordance with the stored program.similarly, analog I/O allows the processor to make decisions based on the magnitude of a signal, rather than just if is on or off.For example,the processor may be programmes toencrease or decrease the steam flow to a boiler(analog output) based on a comparison of the actual temperature in the boiler(analog input) to the desired temperature. this is often performed by utilizing the built-in PID(proportional,integral,derivative) capabilities of the processor.Proper power to the programmable controller is critical. Today’s systems are available in a wide variety of electrical configurations. Virtually all are designed for use in single-phase power systems, and most are now beginning to be offered with the optional ability to operate in a DC supply environment. AC designs are offered in either single voltage supplies, such as 115 or 230V AC; while some can be configured as either through a selection made on the power supply. Proper grounding of the power supply connection is required for a safe installation. Some programmable controller designs have individual grounding connections from rack to face- plates and other system components, so care must be taken to follow well electrical practice in system grounding during electricalinstallation. In certain applications, a 24 or 120 V DC power supply is required. This is common for installations that axe made where no AC power is available, such as remote electrical generation stations. It is also found where AC power is unreliable and where loss of control is considered an unacceptable situationEven the best of today' s well-designed and manufactured programmable controllers require occasional preventative maintenance and repair. This section looks at some of the tools provided by the manufacturer and techniques for general maintenance.Most of the medium- and large-sized programmable controller systems available today are designed to be maintained by individuals with a wide variety of skills, without the benefit of in-depth formal training of this piece of equipment. This is accomplished in the design by providing individual modules of functionality installed in a chassis serviced from the front (all module types including power supplies). Front access is critical to proper maintenance. This allows easy inspection and replacement of the suspected bad module. Module health is determined by inspecting the LED indicators normally provided on the front of each module. Typical indicators will be on or off depending on the design and individual condition of the module in question. Various CPU and I/O modules will have indicators showing I/O control communications status, memory integrity, power supply tolerance check, scan integrity, and others. On future controller designs, and even today on a few systems, it is likely that English language messages will be displayed on the controller advising the user or maintenance personnel that a particular failure has occurred and recommended actions to take.The modular design and diagnostic indicators are, of course, important, but would be quite useless without well designed documentation provided by the manufacturer for the programmable controller system in question. Proper documentation will have sections dedicated to each major subsystem including CPU, I/O, and programming device. Each should explain in depth the stop-by-stop inspection of the system. All possible combinations of failure mode should be listed, along with suggested actions for repair. This will most often involve only the substitution of a re- placement board for the suspected failed unit. The user is urged to purchase a set of spare modules for the system in question as recommended by the manufacturer. This is normally, at a minimum, a single replacement module for each CPU and programming device serviceable module, and spare I/O modules equal to 10% of the number in the system.Because a PLC is “software based”,its control logic functions can be changed byreprogramming its memory. Keyboard programming devices facilitate entry of the revised program, which can be designed to cause an existing machine or process to operate in a different sequence or to respond to different levels of, or combinations of stimuli .Hardware modifications are needed only if additional, changed, or relocated input/output devices are involved.Programmable controller memory is formatted into bits, bytes, and words of memory.A bit is a single storage element for either a zero or a one. A byte consists of eight bits, and a word (normally) consists of 16 bits, or two bytes. Some systems still use a word length of eight bits, but most have adopted a 16 bit word, even though they may use an 8 bit microprocessor.Depending on the specific design of the programmable controller, it will have a stated memory capacity. This is an indication, although not the only one, of the capability and power of the system. Medium and large controllers are normally expandable from one memory size to their maximum size. Small controllers are normally fixed in their memory size. Size of the memory capacity must be examined relative to the word size ( 8 bit or 16 bit) and utilization. While it is clear that twice the information can be stored in a 16 bit word than in an 8 bit word, it may not be immediately clear that some controllers utilize memory more efficiently than others. For example, a normally open contact and its associated reference address (e.g. Input 1), may use in 8 bit byte each for storage. Combined, they consume one 16 bit word. Some controllers may use more memory than this for these instructions or others. In a large program, these inefficiencies can build on each other to cause a poor utilization of the system memory. A careful analysis of the various programmable controller models is required to assess utilization efficiency. Normal practice calls for an additional 20% - 40% of memory size to be specified to allow for modifications and later expansion. This analysis, combined with knowledge of the application needs, will allow for an intelligent choice of programmable controller.In fine, PLC conduct and actions the spot control equipments, can dependable，accurately complete the control the operation, and can pass with upper grade work machine correspondence, constitute the distribute type the system to complete to control the industry equip. system control request, is a modern industry control the inside compare forerunner’s control project, and apply the foreground to is extensive.译文1：可编程逻辑控制器可编程逻辑控制器（PLC）是八十年代发展起来的新一代工业控制装置，是自动控制、计算机和通信技术相结合的产物，是一种专门用于工业生产过程控制的现场设备。
机电一体化毕业设计PLCS(可编程逻辑控制器)毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：PLC文献、资料英文题目：文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14PLC1 .About Programmable Logic Controllers (PLCs)PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options.Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels. Number of points is the sum of the inputs and the outputs. PLCs may be specified by any possible combination of these values. Expandable units may be stacked or linked together to increase total control capacity. Maximum number of channels refers to the maximum total number of input and output channels in an expanded system. PLC system specifications to consider include scan time, number of instructions, data memory, and program memory. Scan time is the time required by the PLC to check the states of its inputs and outputs. Instructions are standard operations (such as math functions) available to PLC software. Data memory is the capacity for data storage. Program memory is the capacity for control software.Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs. Outputs for PLCs include DC, AC, relay, analog, frequency or pulse, Programming options for PLCs include front panel, hand held, and computer.Programmable logic controllers use a variety of software programming languages for control. These include IEC 61131-3, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD), structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic. The IEC 61131-3 programming environment provides support for five languages specified by the global standard: Sequential Function Chart, Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multi-vendor compatibility and multi-languageprogramming. SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallel sequences. FBD uses a broad function library to build complex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable communication and interface functions. LD is a graphic language for discrete control and interlocking logic. It is completely compatible with FBD for discrete function control. ST is a text language used for complex mathematical procedures and calculations less well suited to graphical languages. IL is a low-level language similar to assembly code. It is used in relatively simple logic instructions. Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLCs). Ladder logic programming is a graphical representation of the program designed to look like relay logic. Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries. C is a high level programming language suited to handle the most complex computation, sequential, and data logging tasks. It is typically developed and debugged on a PC. BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions.Programmable logic controllers can also be specified with a number of computer interface options, network specifications and features. PLC power options, mounting options and environmental operating conditions are all also important to consider.2. PLC hardwarePLC hardware mainly has the central processing unit (CPU), memory, input unit, output unit, the communication interface, expansion interface power components. Among them, the CPU is the core, input unit of PLC with output unit is connected site input/output devices to the CPU, interface circuit between the communication interface used with programmer, connecting peripherals such as the PC.2.1 The central processing unit (CPU)The same sort of microcomputer is same, the CPU is the core of PLC. PLC deployed by the CPU in different and different, with models used into three categories: general microprocessor (such as 8086, Z80, 80286, etc.), single chip microprocessor (such as 8031, etc) and a piece 8096 microprocessors (such as AMD29W, etc.). Small PLC is used mostly eight general microprocessor and single chip microprocessor; Medium PLC is used mostly 16 general microprocessor or single chip microprocessor; Large PLC mostly by using high-speed a piece microprocessors.2.2 memoryMemory basically has two kinds: one kind is read/write operation of random access memory RAM, another kind is read only memory (ROM, PROM, an EPROM and EEPROM. In PLC, memory is mainly used for storage system programming, the user program and job data.System programming is written by PLC manufacturer, and PLC hardware related, complete system diagnosis, command interpretation, function subroutine calling, management, logic operations, communications and various parameters, and other functions, provide PLC operation platform. System programming related to the performance, but also in PLC PLC in use process fluctuant, so is not directly by manufacturer in read-only memory ROM, curing PROM or an EPROM, users can't access and modification.The user program with PLC control object is determined by users, according to the object of production process control requirements and prepare application. In orderto facilitate read, check and modification, the user program generally exist in CMOS static RAM, use of lithium battery as backup power, to ensure off when power is not lost information. In order to prevent interference in the destruction of RAM, when the user program after operating normally, not program, but will need to change its curable in read-only memory an EPROM. Now there are many PLC directly used as a user EEPROM memory.2.3 Input/output unitInput/output unit usually also say I/O unit or an I/O modules, PLC and industrial production site is the connection between the components. PLC via input interface can detect various controlled object data to these data to be controlled object as PLC to control the basis; Meanwhile PLC and through the output interface will deal with the results gave controlled object, in order to realize the control purpose.Due to external input device, and output equipment required the signal level is varied, and internal CPU processing of PLC information is only standard level, so I/O interface to realize the conversion. The I/O interface generally have photoelectric isolation and filter function, in order to improve the PLC anti-jamming ability. In addition, I/O interface usually a state instructions, working condition, intuitive, and easy to maintain. PLC offers a variety of operation level and drive ability of I/O interface, there are various functions of I/O interface for customers to choose. The I/O interface is the main type of: the digital quantity (the switch quantity) input, the digital quantity (the switch quantity) output, analogue inputs, analog output, etc.2.4 Communication interfacePLC with various communication interface, the communication interface with communications processor commonly. PLC through these communication interface can and monitors, printers, and other PLC, computers and other devices communicate. PLC and printer connections, but will process information, system parameters, such as output print; And monitor connection, but will control process image display; Connect with other PLC, can form a multiple machine system or network, realize the more massive joined control. And computer connections, can form a multistage distributed controlsystem, the realization control and management combined. Remote I/O system must also equipped with corresponding communication interface module.2.5. Intelligence interface moduleIntelligent interface module is an independent computer system, it has its own CPU, system program, storage and PLC system bus connected interface. It as a module, PLC system by bus and PLC is linked together, exchange data, and the coordinated management in PLC under work independently. PLC intelligent interface module is a lot of motion, such as: high-speed counting module, closed-loop control module, motion control module, interrupt control module, etc.2.6. Programming deviceProgramming device's role is to edit, commissioning, input user program, and also can be online monitoring PLC internal state and parameters, and PLC man-machine dialogue. It is the development, application and maintenance PLC indispensable tools. Programming device can be special programmer, also can be equipped with a special programming packages general computer system. Special programmer is by PLC specializes in this factory, some manufacturers use PLC, and it mainly consists of product keyboard, a display and external storage etc. Parts. Pick up socket Special programming implement have simple programmer and intelligent programmer two kinds.Simple type programmer can only online programming, and cannot directly enter and edit ladder-diagram program, should be ladder-diagram program into instruction table program can input. Simple programmer small volume, price cheap, it can directly interpolated in PLC programming socket, or use special cables and PLC is linked together, to facilitate the programming and debugging. Some simple programming device used to with storage box, store the user program, such as mitsubishi FX - 20P - E simple programming device.2.7. PowerPLC is equipped with switch power, for internal circuit use. Compared with ordinary power, PLC power good stability, strong anti-jamming capability. The powersupply provided for grid stability requirement is not high, average allowed in the power supply voltage rating the range of the plus or minus 15%. Many PLC also provide outward, used in dc 24V external sensor power supply.2. 8.Other external equipmentIn addition to the above mentioned components and equipment outside, PLC and many external devices, such as an EPROM writing implement, external storage,man/machine interface device etc. An EPROM writing implement user program can be used to cure to an EPROM memory of a PLC external equipment. In order to make the debugging good user program with an EPROM not easily lost, often written within the RAM save to an EPROM PLC.3. INTRODUCTIONFor simple programming the relay model of the PLC is sufficient. As more complex functions are used the more complex VonNeuman model of the PLC must be used. A VonNeuman computer processes one instruction at a time. Most computers operate this way, although they appear to be doing many things at once. Input is obtained from the keyboard and mouse, output is sent to the screen, and the disk and memory are used for both input and output for storage. (Note: the directions of these arrows are very important to engineers, always pay attention to indicate where information is flowing.)In this figure the data enters the left side through the inputs. (Note: most engineering diagrams have inputs on the left and outputs on the right.) It travels through buffering circuits before it enters the CPU. The CPU outputs data through other circuits. Memory and disks are used for storage of data that is not destined for output. If we look at a personal computer as a controller, it is controlling the user by outputting stimuli on the screen, and inputting responses from the mouse and the keyboard.4. OPERATION SEQUENCEAll PLCs have four basic stages of operations that are repeated many times per second. Initially when turned on the first time it will check it’s own hardware and software for faults. If there are no problems it will copy all the input and copy their values into memory, this is called the input scan. Using only the memory copy of the inputs the ladder logic program will be solved once, this is called the logic scan. While solving the ladder logic the output values are only changed in temporary memory. When the ladder scan is done the outputs will be updated using the temporary values in memory, this is called the output scan. The PLC now restarts the process by starting a self check for faults. This process typically repeats 10 to 100 times per second as is shown in Figure 3.SELF TEST - Checks to see if all cards error free, reset watch-dog timer, etc. (A watchdog timer will cause an error, and shut down the PLC if not reset withina short period of time - this would indicate that the ladder logic is not beingscanned normally).INPUT SCAN - Reads input values from the chips in the input cards, and copies their values to memory. This makes the PLC operation faster, and avoids caseswhere an input changes from the start to the end of the program (e.g., anemergency stop). There are special PLC functions that read the inputs directly,and avoid the input tables.LOGIC SOLVE/SCAN - Based on the input table in memory, the program is executed 1 step at a time, and outputs are updated. This is the focus of the latersections.OUTPUT SCAN - The output table is copied from memory to the output chips.These chips then drive the output devices.The input and output scans often confuse the beginner, but they are important.The input scan takes a snapshot of the inputs, and solves the logic. This prevents potential problems that might occur if an input that is used in multiple places in the ladder logic program changed while half way through a ladder scan. Thus changing the behaviors of half of the ladder logic program. This problem could have severe effects on complex programs that are developed later in the book. One side effect of the input scan is that if a change in input is too short in duration, it might fall between input scans and be missed.When the PLC is initially turned on the normal outputs will be turned off. This does not affect the values of the inputs.4.1 The Input and Output ScansWhen the inputs to the PLC are scanned the physical input values are copied into memory. When the outputs to a PLC are scanned they are copied from memory to the physical outputs. When the ladder logic is scanned it uses the values in memory, not the actual input or output values. The primary reason for doing this is so that if a program uses an input value in multiple places, a change in the input value will not invalidate the logic. Also, if output bits were changed as each bit was changed, instead of all at once at the end of the scan the PLC would operate much slower.4.2 The Logic ScanLadder logic programs are after relay logic. In relay logic each element in the ladder will switch as quickly as possible. But in a program elements can only be examines one at a time in a fixed sequence. Consider the ladder logic in Figure 4, the ladder logic will be interpreted left-to-right, top-to-bottom. In the figure the ladder logic scan begins at the top rung. At the end of the rung it interprets the top output first, then the output branched below it. On the second rung it solves branches, before moving along the ladder logic rung.Ladder Logic Execution SequenceThe logic scan sequence become important when solving ladder logic programs which use outputs as inputs. It also becomes important when considering output usage. Consider Figure 5, the first line of ladder logic will examine input A and set output X to have the same value. The second line will examine input B and set the output X to have the opposite value. So the value of X was only equal to A until the second line of ladder logic was scanned. Recall that during the logic scan the outputs are only changed in memory, the actual outputs are only updated when the ladder logic scan is complete. Therefore the output scan would update the real outputs based upon the second line of ladder logic, and the first line of ladder logic would be ineffective.A Duplicated Output ErrorPLC1．PLC介绍PLCS（可编程逻辑控制器）是用于各种自动控制系统和过程的可控网络集线器。
可编程控制器外文翻译、中英文翻译、外文文献翻译
毕业设计中英文翻译院系专业班级姓名学号指导教师20**年 4 月Programmable Logic Controllers (PLC)1、MotivationProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating [Moody and Morley, 1999, p. 110]:`If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC basedsoftware design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than SO0/a of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs [Rockwell, 1999].In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options.Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels. Number of points is the sum of the inputs and the outputs. PLCs may be specified by any possible combination of these values. Expandable units may be stacked or linked together to increase total control capacity. Maximum number of channels refers to the maximum total number of input and output channels in an expanded system. PLC system specifications to consider include scan time, number of instructions, data memory, and program memory. Scan time is the time required by the PLC to check the states of its inputs and outputs. Instructions are standard operations (such as math functions) available to PLC software. Data memory is the capacity for data storage. Program memory is the capacity for control software.Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs. Outputs for PLCs include DC, AC, relay, analog, frequency or pulse, transistor, and triac. Programming options for PLCs include front panel, hand held, and computer.Programmable logic controllers use a variety of software programming languages for control. These include IEC 61131-3, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD), structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic. The IEC 61131-3 programming environment provides support for five languages specified by the global standard: Sequential Function Chart,Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multi-vendor compatibility and multi-language programming. SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallel sequences. FBD uses a broad function library to build complex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable communication and interface functions. LD is a graphic language for discrete control and interlocking logic. It is completely compatible with FBD for discrete function control. ST is a text language used for complex mathematical procedures and calculations less well suited to graphical languages. IL is a low-level language similar to assembly code. It is used in relatively simple logic instructions. Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLCs). Ladder logic programming is a graphical representation of the program designed to look like relay logic. Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries. C is a high level programming language suited to handle the most complex computation, sequential, and data logging tasks. It is typically developed and debugged on a PC. BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions.Programmable logic controllers can also be specified with a number of computer interface options, network specifications and features. PLC power options, mounting options and environmental operating conditions are all also important to consider.2、ResumeA PLC (programmable Logic Controller) is a device that was invented to replace the necessary sequential relay circuits for control.The PLC works by looking at its input and depending upon their state, turning on/off its outputs. The user enters a program, usually via software or programmer, which gives the desired results.PLC is used in many "real world" applications. If there is industry present, chance are good that there is a PLC present. If you are involved in machining, packing, material handling, automated assembly or countless other industries, you are probably already using them. If you are not, you are wasting money and time. Almost any application that needs some type of electrical control has a need for a PLC.For example, let's assume that when a switch turns on we want to turn a solenoid on for 5second and then turn it off regardless of how long the switch is on for. We can do this with a simple external timer. But what if the process included 10 switches and solenoids? We should need 10 external times. What if the process also needed to count how many times the switch individually turned on? We need a lot of external counters.As you can see the bigger the process the more of a need we have for a PLC. We can simply program the PLC to count its input and turn the solenoids on for the specified time.We will take a look at what is considered to be the "top 20" PLC instructions. It can be safely estimated that with a firm understanding of these instructions one can solve more than 80% of the applications in existence.Of course we will learn more than just these instruction to help you solve almost ALL potential PLC applications.The PLC mainly consists of a CPU, memory areas, and appropriate circuits to receive input/output data. We can actually consider the PLC to be a box full of hundreds or thousands of separate relay, counters, times and data storage locations,Do these counters,timers, etc. really exist? No,they don't "physically" exist but rather they simulated and be considered software counters, timers, etc. . These internal relays are simulated through bit locations in registers.What does each part do? Let me tell you.Input RelaysThese are connected to the outside world.They physically exsit and receive signals from switches,sensors,ect..Typically they are not relays but rather they are transistors.Internal Utility RelaysThese do not receive signals from the outside world nor do they physically exist.they are simulated relays and are what enables a PLC to eliminate external relays.There are also some special relays that are dedicated to performing only one task.Some are always on while some are always off.Some are on only once during power-on and are typically used for initializing data that was stored.CountersThese again do not physically exist. They are simulated counters and they can be programmed to count pulses.Typically these counters can count up,down or both up anddown.Since they are simulated,they are limited in their counting speed.Some manufacturers also include high-speed counters that are hardware based.We think of these as physically existing.Most times these counters can count up,down or up and down.TimersThese also do not physically exist.They come in many varieties and increments.The most common type is an on-delay type.Others include off-delays and both retentive and non-retentive types.Increments vary from 1ms through 1s.Output RelaysThere are connected to the outside world.They physically exist and send on/off signals to solenoids,lights,etc..They can be transistors,relays,or triacs depending upon the model chosen Data StorageTypically there are registers assigned to simply store data.They are usually used as temporary storage for math or data manipulation.They can also typically be used to store data when power is removed form the PLC.Upon power-up they will still have the same contents as before power was moved.Very convenient and necessary!A PLC works by continually scanning a program.We can think of this scan cycle as consisting of 3 important steps.There are typically more than 3 but we can focus on the important parts and not worry about the others,Typically the others are checking the system and updating the current internal counter and timer values,Step 1 is to check input status,First the PLC takes a look at each input to determine if it is on off.In other words,is the sensor connected to the first input on?How about the third...It records this data into its memory to be used during the next step.Step 2 is to execute program.Next the PLC executes your program one instruction at a time.Maybe your program said that if the first input was on then it should turn on the first output.Since it already knows which inputs are on/off from the previous step,it will be able to decide whether the first output should be turned on based on the state of the first input.It will store the execution results for use later during the next step.Step 3 is to update output status.Finally the PLC updates the status the outputs.It updates the outputs based on which inputs were on during the first step and the results executing your program during the second step.Based on the example in step 2 it would now turn on the firstoutput because the first input was on and your program said to turn on the first output when this condition is true.After the third step the PLC goes back to step one repeats the steps continuously.One scan time is defined as the time it takes to execute the 3 steps continuously.One scan time is defined as the time it takes to execute the 3 steps listed above.Thus a practical system is controlled to perform specified operations as desired.3、PLC StatusThe lack of keyboard, and other input-output devices is very noticeable on a PLC. On the front of the PLC there are normally limited status lights. Common lights indicate;power on - this will be on whenever the PLC has powerprogram running - this will often indicate if a program is running, or if no program is runningfault - this will indicate when the PLC has experienced a major hardware or software problemThese lights are normally used for debugging. Limited buttons will also be provided for PLC hardware. The most common will be a run/program switch that will be switched to program when maintenance is being conducted, and back to run when in production. This switch normally requires a key to keep unauthorized personnel from altering the PLC program or stopping execution. A PLC will almost never have an on-off switch or reset button on the front. This needs to be designed into the remainder of the system.The status of the PLC can be detected by ladder logic also. It is common for programs to check to see if they are being executed for the first time, as shown in Figure 1. The ’first scan’ input will be true on the very first time the ladder logic is scanned, but false on every other scan. In this case the address for ’first scan’ in a PLC-5 is ’S2:1/14’. With the logic in the example the first scan will seal on ’light’, until ’clear’ is turned on. So the light will turn on after the PLC has been turned on, but it will turn off and stay off after ’clear’ is turned on. The ’first scan’ bit is also referred to at the ’first pass’ bit.Figure 1 An program that checks for the first scan of the PLC4、Memory TypesThere are a few basic types of computer memory that are in use today.RAM (Random Access Memory) - this memory is fast, but it will lose its contents when power is lost, this is known as volatile memory. Every PLC uses this memory for the central CPU when running the PLC.ROM (Read Only Memory) - this memory is permanent and cannot be erased. It is often used for storing the operating system for the PLC.EPROM (Erasable Programmable Read Only Memory) - this is memory that can be programmed to behave like ROM, but it can be erased with ultraviolet light and reprogrammed.EEPROM (Electronically Erasable Programmable Read Only Memory) – This memory can store programs like ROM. It can be programmed and erased using a voltage, so it is becoming more popular than EPROMs.All PLCs use RAM for the CPU and ROM to store the basic operating system for the PLC. When the power is on the contents of the RAM will be kept, but the issue is what happens when power to the memory is lost. Originally PLC vendors used RAM with a battery so that the memory contents would not be lost if the power was lost. This method is still in use, but is losing favor. EPROMs have also been a popular choice for programming PLCs. The EPROM is programmed out of the PLC, and then placed in the PLC. When the PLC is turned on the ladder logic program on the EPROM is loaded into the PLC and run. This method can be very reliable, but the erasing and programming technique can be time consuming. EEPROM memories are a permanent part of the PLC, and programs can be stored in them like EPROM. Memory costs continue to drop, and newer types (such as flash memory) are becoming available, and these changes will continue to impact PLCs.5、Objective and Significance of the ThesisThe objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of theautomation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspect Customer-Driven ManufacturingIn modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements.A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice.Higher Degree of Design Automation and Software QualityStudies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999] have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancingthe knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.System ComplexityThe software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs [Simmons et al., 1998].Design Theory DevelopmentToday, the primary focus of most design research is based on mechanical or electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design. A system design theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system modeling, can advance future development in engineering design.Application in Logical Hardware DesignFrom a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely complex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.可编程控制器1、前言可编程序的逻辑控制器（PLC），是由Richard E.Morley 于1968年发明的，如今已经被广泛的应用于生产、运输、化学等工业中。
外文文献及翻译：Programmable Logic Controller PLC
本科毕业设计英文参考资料题目Programmable LogicController PLC院系专业姓名学号学习年限指导教师申请学位2012年05月20日英文原文：Programmable Logic Controller PLC1 PLC IntroducePLC Introduction Programmable controller is the first in the late 1960s in the United States, then called PLC programmable logic controller (Programmable Logic Controller) is used to replace relays. For the implementation of the logical judgment, timing, sequence number, and other control functions. The concept is presented PLC General Motors Coroperation.PLC and the basic design is the computer functional improvements, flexible, generic and other advantages and relay control system simple and easy to operate, such as the advantages of cheap prices combined controller hardware is standard and overall. According to the practical application of target software in order to control the content of the user procedures memory controller, the controller and connecting the accused convenient target. In the mid-1970s, the PLC has been widely used as a central processing unit microprocessor, import export module and the external circuits are used, large-scale integrated circuits even when the PLC is no longer the only logical (IC) judgment functions also have data processing, PID conditioning and data communications functions. International Electro technical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definition: programmable controller is a digital electronic computers operating system, specifically for applications in the industrial design environment. It used programmable memory, used to implement logic in their internal storage operations, sequence control, timing, counting and arithmetic operations, such as operating instructions, and through digital and analog input and output, the control of various types of machinery or production processes. Programmable controller and related peripherals, and industrial control systems easily linked to form a whole, to expand its functional design. Programmable controller for the user, is non-contact equipment, the procedures can be changed to change production processes. The programmable controller has become a powerful tool for factory automation, widely popular replication. Programmable controller is user-oriented industries dedicated control computer, with many distinctive features.①high reliability, anti-interference capability;②programming visual, simple;③adaptability good;④functional improvements, strong functional interface.Programmable Logic Controllers (PLC), a computing device invented by Richard E. Morley, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days.Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan, an increase of the annual sales volume to 15 million PLC per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLC are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating: “If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLC are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLC can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PLC-programming requires a simultaneous consideration ofhardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than 50% of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs.In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigure ability of manufacturing systems.PLC is well-adapted to a range of automation tasks. These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation, and where changes to the system would be expected during its operational life. PLC contains input and output devices compatible with industrial pilot devices and controls; little electrical design is required, and the design problem centers on expressing the desired sequence of operations. PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design. On the other hand, in the case of mass-produced goods, customized control systems are economic due to the lower cost of the components, which can be optimally chosen instead of a "generic" solution, and where the non-recurring engineering charges are spread over thousands or millions of units.For high volume or very simple fixed automation tasks, different techniques are used. For example, a consumer dishwasher would be controlled by an electromechanical cam timer costing only a few dollars in production quantities.A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies, input/output hardware and necessary testing and certification) can be spread over many sales, and where the end-user would not need to alter the control. Automotive applications are an example; millions of units are built each year, and very few end-users alter the programming of these controllers. However, some specialty vehicles such as transit busses economically use PLC instead of custom-designed controls, because the volumes are low and the development cost would be uneconomic.Very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLC. Very high-speed or precision controls may also require customized solutions; for example,aircraft flight controls.Programmable controllers are widely used in motion control, positioning control and torque control. Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements.PLC may include logic for single-variable feedback analog control loop, a "proportional, integral, derivative" or "PID controller". A PID loop could be used to control the temperature of a manufacturing process, for example. Historically PLC was usually configured with only a few analog control loops; where processes required hundreds or thousands of loops, a distributed control system (DCS) would instead be used. As PLC has become more powerful, the boundary between DCS and PLC applications has become less distinct.PLC has similar functionality as Remote Terminal Units. An RTU, however, usually does not support control algorithms or control loops. As hardware rapidly becomes more powerful and cheaper, RTU, PLC and DCS are increasingly beginning to overlap in responsibilities, and many vendors sell RTU with PLC-like features and vice versa. The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTU and PLC, although nearly all vendors also offer proprietary alternatives and associated development environments.2 The structure of PLC systemStructurally divides, PLC divides into the stationary type and the combined type (module type) two kinds. Stationary PLC including the CPU board, the I/O board, demonstrated the kneading board, the memory block, the power source and so on; these elements combine not a dismountable whole. Module type PLC including the CPU module, the I/O module, the memory, the power source module, the ledger wall or the rack, these modules may defer to certain rule combination disposition.1、CPU constitutionCPU is the PLC core, plays nerve center's role, wraps PLC to have CPU at least every time, it the function which entrusts with according to the PLC system program receives and stores the user program and the data, with scanning way gathering the condition or the data which sends by the scene input device, coexisting enters the stipulation in the register,simultaneously, diagnoses the power source and in the PLC internal circuit active status and the programming process grammatical error and so on. After enters the movement, one by one reads the instruction from the user program memory, the duty which stipulated according to the instruction produces the corresponding control signal again after the analysis, directs the related control circuit.CPU mainly by the operator, controller, register and implementation of data link between them, control and state BUS, CPU unit also includes peripheral chips, bus interface and related circuitry. Memory is mainly used for storing programs and data, is an integral unit PLC.In the user view, unnecessarily detailed analysis of the CPU's internal circuitry, but the working mechanism of the various parts, or should have sufficient understanding. CPU and the control work, which will read the instructions, directives and executive orders to explain. However, the pace of work from the vibration signals. Computing devices used for digital or logic operation, under the command of the controller work.CPU speed and memory capacity are important parameters for PLC, which determines the pace of work PLC, I/O number and software capacity, etc., thereby limiting the control of the scale.2、I/O modulesPLC interface with the electrical circuit is through the input and output section (I/O) completion. I/O module integrates the PLC's I/O circuits; the input register reflecting the input signal status, output point reflects the state of the output latch. Input module will transform electrical signals into digital signals into the PLC system, the output module opposite. I/O into digital input (DI), digital outputs (DO), analog input (AI), analog output (AO) modules.3、Common I/O as followSwitching capacity: voltage level by points, with 220V AC, 110V AC, 24VDC, by Way of isolation, there is isolation and transistor isolation relays.Analog: by type of signal, a current type (4-20mA ,0-20mA), voltage (0-10V ,0-5V,-10-10V) and so on, by the precision points are 12bit, 14bit, 16bit, etc. .In addition to these general-purpose IO, there are special IO modules, such as thermal resistance, thermocouple, pulse and other modules.By I/O module specifications and to determine the number of points, I/O modules can be more or less, but the maximum number of CPU can be the basic configuration management capabilities, which by the largest floor or rack slot limit.Power ModulesPLC power supply modules for the PLC to provide the power supply integrated circuits. Meanwhile, some of them for the work input circuit to provide 24V power supply. Power input types are: AC power (220V AC or 110V AC), DC power supply (commonly used to 24VDC).Most modular PLC to use floor or rack, its role is to: electrical, the realization of the modules, so that the CPU can access all the modules on the floor, machinery and realize the connection between each module, so that each module constitutes a overall.3 Installation and debugging Of PLC control systemProgramming device: development and application programmer is the PLC to monitor the operation, inspection, maintenance indispensable device for programming, some system settings, monitor the PLC and the PLC control system working conditions, but it is not directly involved in field control run. PLC programmers are generally small hand-held programmer, the current general by the computer (running programming software) as programmer. That is, our system PC.Human Machine Interface is the simplest indicators and buttons, the current LCD screen (or touch screen) type-one operator terminal has been widely applied by the computer (running the configuration software) as a very popular man-machine interface.PLC communication network rely on advanced industrial network technology can quickly and efficiently collect, transfer of production and management of data. Therefore, the network automation system integration projects in the importance of more and more significant, even been suggested that the network is the controller's point of view argument.PLC is a service specifically for the industrial production control device, usually do not need to take measures, it can be directly used in industrial environments. However, when the production environment is too harsh, especially strong electromagnetic interference, or improper installation, can not guarantee the normal operation of PLC, and therefore should pay attention to the following questions using the.First, the working environment1. PLC required temperature in the temperature 0 ~ 55 ℃, heating installation, large components can not be placed below the space around the ventilation and cooling should be large enough, the basic unit and expansion unit interval between the need for more than 30mm; switch cabinet, the lower should be a ventilation shutters, to prevent too much direct sunlight; if the surrounding Stresses above 55 ℃, to install electric fan forced ventilation.2. PLC humidity in order to ensure the insulation performance, air relative humidity should be less than 85% (no condensation).3. PLC should be made from a strong shock vibration source, to prevent the vibration frequency of 10 ~ 55Hz frequent or continuous vibration. When the environment is inevitable when using vibration, shock absorption to take measures, such as glue, such as using shock absorption.4. Air to avoid corrosion and flammable gases, such as hydrogen chloride, hydrogen sulfide, etc.. The more the air of dust or corrosive gas environment can be installed in a closed PLC good control room or control cabinet, and install air cleaning devices.5. Power PLC power supply is 50Hz, 220 (1 ± 10%) V AC, for the power cord to the interference, PLC itself has sufficient capacity to resist. Reliability requirements for high power interference is particularly serious situation or environment, you can install a shield with variable ratio of 1:1 isolation transformer to reduce the interference between the equipment and land. Power input can also be cascaded LC filter circuitSecond, installation and wiring1. Power lines, control lines and power lines and PLC I/O lines should be split wiring, isolation transformer and PLC and I/O should be used between the cable connections.2. PLC should stay away from strong interference sources such as welding, high-power silicon rectifier devices and large power equipment, not with the high-voltage electrical switch installed in the same cabinet.3. PLC input and output separately from the best alignment, switch and analog should be laid separately. The transmission of analog signals should be shielded cable, one end or both ends of the shield should be grounding resistance should be less than the shielding layer 1 / 10.4. PLC basic unit and expansion modules and functional modules, connecting cablesshould be installed separately, to prevent interference from outside signals.5. AC output line and DC output lines do not use the same cable, the output line should be far from power lines and power lines, to avoid parallel.Third, I/O wiring terminal1. Input Connection(1) Input connection generally should not exceed 30 meters. But if the environment interfere with small, small voltage drop, the input terminalLonger be appropriate.(2) Input / output lines can not be used with a cable, input / output lines should be separated.(3) The extent possible, normally open contact form connected to the input in the establishment of the ladder and relay the same schematic2. Output connection(1) Output terminal is divided into separate output and public output. In different groups, using different types and voltage levels of output voltage. However, output in the same group can only use the same type, the same voltage level of power.(2) Since the PLC's output devices are packaged in printed circuit board and connected to the terminal board that if the load short-circuits connecting the output components, printed circuit boards will be burned, thus, applied fuse protected output devices.(3) The relay output, inductive load borne by the size, will affect the life of the relay, therefore, choose to use the relay inductive load longer working life.(4) PLC may interfere with the output load, so to take measures to control, such as the DC output of the continued flow of control protection, exchange of the output RC snubbed circuit, transistors and resistors Triad output bypass the protection.Third, the external safety circuitIn order to ensure that the entire system to work reliably in a safe condition to avoid failure due to external power supply, PLC abnormalities, misuse, and the output error caused major economic losses and human casualties, PLC necessary protection should be installed outside the circuit.(1) Emergency stop circuit. The user can load the risk of harm, in addition to be taken into account in the control program, it should design external emergency stop circuit, PLCfailure, the load can cause injury and reliable power supply cut off.(2) Protection circuit. Reversible operation such as forward and reverse operation of the control system, to set an external electrical interlock protection; reciprocating and down movement of the control system, to set the outer limit protection circuits.(3) Programmable controller self-test features such as watchdog timer check out the unusual, the output all closed. But when the PLC CPU can not control when the output fault, therefore, can damage the danger of the user load, to ensure that the equipment in a safe condition to run, need to design the external circuit to be protective.(4) Power supply overload protection. If the PLC power supply failure, interruption time of less than 10 seconds, PLC work will not be affected, if the power failure or power down more than 10 seconds exceeded allowable value, then the PLC to stop working, all the output points are also broken; when power restored If the RUN input connected, the operation automatically. Therefore, some easy to overload the input device should be set to the necessary limit protection circuits.(5) Major fault alarm and protection. Major accident-prone places, in order to ensure that the control system in a major accident is still reliable alarm and protection，should be associated with major fault signal output through the external circuit to the control system to run in the security situation.4 Digital and analog signalsDigital or discrete signals behave as binary switches, yielding simply an on or off signal (1 or 0, True or False, respectively). Push buttons, limit switches, and photoelectric sensors are examples of devices providing a discrete signal. Discrete signals are sent using voltage or current, where a specific range is designated as on and another as off. For example, a PLC might use 24 V DC I/O, with values above 22 V DC representing on, values below 2VDC representing off, and intermediate values undefined. Initially, PLC had only discrete I/O.Analog signals are like volume controls, with a range of values between zero and full-scale. These are typically interpreted as integer values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of bits available to store the data. As PLC typically use 16-bit signed binary processors, the integer values are limitedbetween -32,768 and +32,767. Pressure, temperature, flow, and weight are often represented by analog signals. Analog signals can use voltage or current with a magnitude proportional to the value of the process signal. For example, an analog 0 - 10 V input or 4-20 mA would be converted into an integer value of 0 - 32767.Atonally, along with the development of the ages, the people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc., well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The research target of the artificial intelligence makes use of the calculator exactly to carry out, imitate these intelligences behavior, moderating the work through person's brain and calculators, with the mode that person's machine combine, for resolve the very complicated problem to look for the best path.中文译文：可编程控制器PLC1 PLC简介可编程控制器是60年代末在美国首先出现的，当时叫可编程逻辑控制器PLC （Programmable Logic Controller），目的是用来取代继电器。
毕业设计中英文翻译
Integrated circuitAn integrated circuit or monolithic integrated circuit (also referred to as IC, chip, or microchip) is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material. Additional materials are deposited and patterned to form interconnections between semiconductor devices.Integrated circuits are used in virtually all electronic equipment today and have revolutionized the world of electronics. Computers, mobile phones, and other digital appliances are now inextricable parts of the structure of modern societies, made possible by the low cost of production of integrated circuits.IntroductionICs were made possible by experimental discoveries showing that semiconductor devices could perform the functions of vacuum tubes and by mid-20th-century technology advancements in semiconductor device fabrication. The integration of large numbers of tiny transistors into a small chip was an enormous improvement over the manual assembly of circuits using discrete electronic components. The integrated circuit's mass production capability, reliability, and building-block approach tocircuit design ensured the rapid adoption of standardized ICs in place of designs using discrete transistors.There are two main advantages of ICs over discrete circuits: cost and performance. Cost is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, much less material is used to construct a packaged IC than to construct a discrete circuit. Performance is high because the components switch quickly and consume little power (compared to their discrete counterparts) as a result of the small size and close proximity of the components. As of 2006, typical chip areas range from a few square millimeters to around 350 mm2, with up to 1 million transistors per mm2.TerminologyIntegrated circuit originally referred to a miniaturized electronic circuit consisting of semiconductor devices, as well as passive components bonded to a substrate or circuit board.[1] This configuration is now commonly referred to as a hybrid integrated circuit. Integrated circuit has since come to refer to the single-piece circuit construction originally known as a monolithic integrated circuit.[2]InventionEarly developments of the integrated circuit go back to 1949, when the German engineer Werner Jacobi (Siemens AG) filed a patent for an integrated-circuit-like semiconductor amplifying device showing five transistors on a common substrate arranged in a 2-stage amplifier arrangement. Jacobi disclosed small and cheap hearing aids as typical industrial applications of his patent. A commercial use of his patent has not been reported.The idea of the integrated circuit was conceived by a radar scientist working for the Royal Radar Establishment of the British Ministry of Defence, Geoffrey W.A. Dummer (1909–2002). Dummer presented the idea to the public at the Symposium on Progress in Quality Electronic Components in Washington, D.C. on May 7, 1952.[4] He gave many sympodia publicly to propagate his ideas, and unsuccessfully attempted to build such a circuit in 1956.A precursor idea to the IC was to create small ceramic squares (wafers), each one containing a single miniaturized component. Components could then be integrated and wired into a tridimensional or tridimensional compact grid. This idea, which looked very promising in 1957, was proposed to the US Army by Jack Kilby, and led to the short-lived Micro module Program. However, as the project was gaining momentum, Jack Kilby came up with a new, revolutionary design: the IC.Newly employed by Texas Instruments, Jack Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working integrated example on September 12, 1958.In his patent application of February 6, 1959, Jack Kilby described his new device as ―a body of semiconductor material ... wherein all the components of the electronic circuit are completely integrated.‖Jack Kilby won the 2000 Nobel Prize in Physics for his part of the invention of the integrated circuit.Jack Kilby's work was named an IEEE Milestone in 2009.Noyce also came up with his own idea of an integrated circuit half a year later than Jack Kilby. His chip solved many practical problems that Jack Kilby's had not. Produced at Fairchild Semiconductor, it was made of silicon, whereas Jack Kilby chip was made of germanium. GenerationsIn the early days of integrated circuits, only a few transistors could be placed on a chip, as the scale used was large because of the contemporary technology, and manufacturing yields were low by today's standards. As the degree of integration was small, the design was done easily. Over time, millions, and today billions of transistors could be placed on one chip, and to make a good design became a task to be planned thoroughly. This gave rise to new design methods.SSI, MSI and LSIThe first integrated circuits contained only a few transistors. Called "small-scale integration" (SSI), digital circuits containing transistors numbering in the tens for example, while early linear ICs such as the Plessey SL201 or the Philips TAA320 had as few as two transistors. The term Large Scale Integration was first used by IBM scientist Rolf Landauer when describing the theoretical concept, from there came the terms for SSI, MSI, VLSI, and ULSI.SSI circuits were crucial to early aerospace projects, and aerospace projects helped inspire development of the technology. Both the Minuteman missile and Apollo program needed lightweight digital computers for their inertial guidance systems; the Apollo guidance computer led and motivated the integrated-circuit technology,while the Minuteman missile forced it into mass-production. The Minuteman missile program and various other Navy programs accounted for the total $4 million integrated circuit market in 1962, and by 1968, U.S. Government space and defense spending still accounted for 37% of the $312 million total production. The demand by the U.S. Government supported the nascent integrated circuit market until costs fell enough to allow firms to penetrate the industrial and eventually the consumer markets. The average price per integrated circuit dropped from $50.00 in1962 to $2.33 in 1968.[13] Integrated circuits began to appear in consumer products by the turn of the decade, a typical application being FMinter-carrier sound processing in television receivers.The next step in the development of integrated circuits, taken in the late 1960s, introduced devices which contained hundreds of transistors on each chip, called "medium-scale integration" (MSI).They were attractive economically because while they cost little more to produce than SSI devices, they allowed more complex systems to be produced using smaller circuit boards, less assembly work (because of fewer separate components), and a number of other advantages.Further development, driven by the same economic factors, led to "large-scale integration" (LSI) in the mid 1970s, with tens of thousands of transistors per chip.Integrated circuits such as 1K-bit RAMs, calculator chips, and the first microprocessors, that began to be manufactured in moderate quantities in the early 1970s, had under 4000 transistors. True LSI circuits, approaching 10,000 transistors, began to be produced around 1974, for computer main memories and second-generation microprocessors.VLSIThe final step in the development process, starting in the 1980s and continuing through the present, was "very large-scale integration" (VLSI). The development started with hundreds of thousands of transistors in the early 1980s, and continues beyond several billion transistors as of 2009. Multiple developments were required to achieve this increased density. Manufacturers moved to smaller design rules and cleaner fabrication facilities, so that they could make chips with more transistors and maintain adequate yield. The path of process improvements was summarized by the International Technology Roadmap for Semiconductors (ITRS). Design tools improved enough to make it practical to finish these designs in a reasonable time. The more energy efficient CMOS replaced NMOS and PMOS, avoiding a prohibitive increase in power consumption. Better texts such as the landmark textbook by Mead and Conway helped schools educate more designers, among other factors.In 1986 the first one megabit RAM chips were introduced, which contained more than one million transistors. Microprocessor chips passed the million transistor mark in 1989 and the billion transistor mark in 2005.[14] The trend continues largely unabated, with chips introduced in 2007 containing tens of billions of memory transistors.[15]ULSI, WSI, SOC and 3D-ICTo reflect further growth of the complexity, the term ULSI that stands for "ultra-large-scale integration" was proposed for chips of complexityof more than 1 million transistors.Wafer-scale integration (WSI) is a system of building very-large integrated circuits that uses an entire silicon wafer to produce a single "super-chip". Through a combination of large size and reduced packaging, WSI could lead to dramatically reduced costs for some systems, notably massively parallel supercomputers. The name is taken from the term Very-Large-Scale Integration, the current state of the art when WSI was being developed.A system-on-a-chip (SoC or SOC) is an integrated circuit in which all the components needed for a computer or other system are included on a single chip. The design of such a device can be complex and costly, and building disparate components on a single piece of silicon may compromise the efficiency of some elements. However, these drawbacks are offset by lower manufacturing and assembly costs and by a greatly reduced power budget: because signals among the components are kept on-die, much less power is required (see Packaging).A three-dimensional integrated circuit (3D-IC) has two or more layers of active electronic components that are integrated both vertically and horizontally into a single circuit. Communication between layers useson-die signaling, so power consumption is much lower than in equivalent separate circuits. Judicious use of short vertical wires can substantially reduce overall wire length for faster operation.Advances in integrated circuitsAmong the most advanced integrated circuits are the microprocessors or "cores", which control everything from computers and cellular phones to digital microwave ovens. Digital memory chips and ASICs are examples of other families of integrated circuits that are important to the modern information society. While the cost of designing and developing a complex integrated circuit is quite high, when spread across typically millions of production units the individual IC cost is minimized. The performance of ICs is high because the small size allows short traces which in turn allows low power logic (such as CMOS) to be used at fast switching speeds.ICs have consistently migrated to smaller feature sizes over the years, allowing more circuitry to be packed on each chip. This increased capacity per unit area can be used to decrease cost and/or increase functionality—see Moore's law which, in its modern interpretation, states that the number of transistors in an integrated circuit doubles every two years. In general, as the feature size shrinks, almost everything improves—the cost per unit and the switching power consumption godown, and the speed goes up. However, ICs with nanometer-scale devices are not without their problems, principal among which is leakage current (see subthreshold leakage for a discussion of this), although these problems are not insurmountable and will likely be solved or at least ameliorated by the introduction of high-k dielectrics. Since these speed and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. This process, and the expected progress over the next few years, is well described by the International Technology Roadmap for Semiconductors (ITRS).In current research projects, integrated circuits are also developed for sensoric applications in medical implants or other bioelectronic devices. Particular sealing strategies have to be taken in such biogenic environments to avoid corrosion or biodegradation of the exposed semiconductor materials.[16] As one of the few materials well established in CMOS technology, titanium nitride (TiN) turned out as exceptionally stable and well suited for electrode applications in medical implants.[17][18] ClassificationIntegrated circuits can be classified into analog, digital and mixed signal (both analog and digital on the same chip).Digital integrated circuits can contain anything from one to millions of logic gates, flip-flops, multiplexers, and other circuits in a few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration. These digital ICs, typically microprocessors, DSPs, and micro controllers, work using binary mathematics to process "one" and "zero" signals.Analog ICs, such as sensors, power management circuits, and operational amplifiers, work by processing continuous signals. They perform functions like amplification, active filtering, demodulation, and mixing. Analog ICs ease the burden on circuit designers by having expertly designed analog circuits available instead of designing a difficult analog circuit from scratch.ICs can also combine analog and digital circuits on a single chip to create functions such as A/D converters and D/A converters. Such circuits offer smaller size and lower cost, but must carefully account for signal interference.ManufacturingFabricationRendering of a small standard cell with three metal layers (dielectric has been removed). The sand-colored structures are metal interconnect, with the vertical pillars being contacts, typically plugs of tungsten. The reddish structures are poly-silicon gates, and the solid at the bottom is the crystalline silicon bulk.Schematic structure of a CMOS chip, as built in the early 2000s. The graphic shows LDD-Misfit's on an SOI substrate with five materialization layers and solder bump for flip-chip bonding. It also shows the section for FEOL (front-end of line), BEOL (back-end of line) and first parts of back-end process.The semiconductors of the periodic table of the chemical elements were identified as the most likely materials for a solid-state vacuum tube. Starting with copper oxide, proceeding to germanium, then silicon, the materials were systematically studied in the 1940s and 1950s. Today, silicon monocrystals are the main substrate used for ICs although someIII-V compounds of the periodic table such as gallium arsenide are used for specialized applications like LEDs, lasers, solar cells and the highest-speed integrated circuits. It took decades to perfect methods of creating crystals without defects in the crystalline structure of the semiconducting material.Semiconductor ICs are fabricated in a layer process which includes these key process steps:∙Imaging∙Deposition∙EtchingThe main process steps are supplemented by doping and cleaning.∙Integrated circuits are composed of many overlapping layers, each defined by photolithography, and normally shown in different colors.Some layers mark where various dopants are diffused into thesubstrate (called diffusion layers), some define where additional ions are implanted (implant layers), some define the conductors(poly-silicon or metal layers), and some define the connectionsbetween the conducting layers (via or contact layers). All components are constructed from a specific combination of these layers.∙In a self-aligned CMOS process, a transistor is formed wherever the gate layer (poly-silicon or metal) crosses a diffusion layer.∙Capacitive structures, in form very much like the parallel conducting plates of a traditional electrical capacitor, are formedaccording to the area of the "plates", with insulating material between the plates. Capacitors of a wide range of sizes are common on ICs.∙Meandering stripes of varying lengths are sometimes used to form on-chip resistors, though most logic circuits do not need any resistors.The ratio of the length of the resistive structure to its width, combined with its sheet resistivity, determines the resistance.∙More rarely, inductive structures can be built as tiny on-chip coils, or simulated by gyrators.Since a CMOS device only draws current on the transition between logic states, CMOS devices consume much less current than bipolar devices.A random access memory is the most regular type of integrated circuit; the highest density devices are thus memories; but even a microprocessor will have memory on the chip. (See the regular array structure at the bottom of the first image.) Although the structures are intricate – with widths which have been shrinking for decades – the layers remain much thinner than the device widths. The layers of material are fabricated much like a photographic process, although light waves in the visible spectrum cannot be used to "expose" a layer of material, as they would be too large for the features. Thus photons of higher frequencies (typically ultraviolet) are used to create the patterns for each layer. Because each feature is so small, electron microscopes are essential tools for a process engineer who might be debugging a fabrication process.Each device is tested before packaging using automated test equipment (ATE), in a process known as wafer testing, or wafer probing. The wafer is then cut into rectangular blocks, each of which is called a die. Each good die (plural dice, dies, or die) is then connected into a package using aluminum (or gold) bond wires which are welded and/or thermosonic bonded to pads, usually found around the edge of the die. After packaging, the devices go through final testing on the same or similar ATE used during wafer probing. Industrial CT scanning can also be used. Test cost can account for over 25% of the cost of fabrication on lower cost products, but can be negligible on low yielding, larger, and/or higher cost devices.As of 2005, a fabrication facility (commonly known as a semiconductor fab) costs over $1 billion to construct,[19] because much of the operation is automated. Today, the most advanced processes employ the following techniques:∙The wafers are up to 300 mm in diameter (wider than a common dinner plate).∙Use of 32 nanometer or smaller chip manufacturing process. Intel, IBM, NEC, and AMD are using ~32 nanometers for their CPU chips.IBM and AMD introduced immersion lithography for their 45 nmprocesses[20]∙Copper interconnects where copper wiring replaces aluminium for interconnects.∙Low-K dielectric insulators.∙Silicon on insulator (SOI)∙Strained silicon in a process used by IBM known as strained silicon directly on insulator (SSDOI)∙Multigate devices such as trin-gate transistors being manufactured by Intel from 2011 in their 22 nim process.PackagingIn the late 1990s, plastic quad flat pack (PQFP) and thin small-outline package (TSOP) packages became the most common for high pin count devices, though PGA packages are still often used for high-end microprocessors. Intel and AMD are currently transitioning from PGA packages on high-end microprocessors to land grid array (LGA) packages.Ball grid array (BGA) packages have existed since the 1970s. Flip-chip Ball Grid Array packages, which allow for much higher pin count than other package types, were developed in the 1990s. In an FCBGA package the die is mounted upside-down (flipped) and connects to the packageballs via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array of input-output signals (called Area-I/O) to be distributed over the entire die rather than being confined to the die periphery.Traces out of the die, through the package, and into the printed circuit board have very different electrical properties, compared to on-chip signals. They require special design techniques and need much more electric power than signals confined to the chip itself.When multiple dies are put in one package, it is called SiP, for System In Package. When multiple dies are combined on a small substrate, often ceramic, it's called an MCM, or Multi-Chip Module. The boundary between a big MCM and a small printed circuit board is sometimes fuzzy. Chip labeling and manufacture dateMost integrated circuits large enough to include identifying information include four common sections: the manufacturer's name or logo, the part number, a part production batch number and/or serial number, and a four-digit code that identifies when the chip was manufactured. Extremely small surface mount technology parts often bear only a number used in a manufacturer's lookup table to find the chip characteristics.The manufacturing date is commonly represented as a two-digit year followed by a two-digit week code, such that a part bearing the code 8341 was manufactured in week 41 of 1983, or approximately in October 1983. Legal protection of semiconductor chip layoutsLike most of the other forms of intellectual property, IC layout designs are creations of the human mind. They are usually the result of an enormous investment, both in terms of the time of highly qualified experts, and financially. There is a continuing need for the creation of new layout-designs which reduce the dimensions of existing integrated circuits and simultaneously increase their functions. The smaller an integrated circuit, the less the material needed for its manufacture, and the smaller the space needed to accommodate it. Integrated circuits are utilized in a large range of products, including articles of everyday use, such as watches, television sets, washing machines, automobiles, etc., as well as sophisticated data processing equipment.The possibility of copying by photographing each layer of an integrated circuit and preparing photomasks for its production on the basis of the photographs obtained is the main reason for the introduction of legislation for the protection of layout-designs.A diplomatic conference was held at Washington, D.C., in 1989, which adopted a Treaty on Intellectual Property in Respect of Integrated Circuits (IPIC Treaty). The Treaty on Intellectual Property in respect of Integrated Circuits, also called Washington Treaty or IPIC Treaty (signed at Washington on May 26, 1989) is currently not in force, but was partially integrated into the TRIPs agreement.National laws protecting IC layout designs have been adopted in a number of countries.Other developmentsIn the 1980s, programmable logic devices were developed. These devices contain circuits whose logical function and connectivity can be programmed by the user, rather than being fixed by the integrated circuit manufacturer. This allows a single chip to be programmed to implement different LSI-type functions such as logic gates, adders and registers. Current devices called field-programmable gate arrays can now implement tens of thousands of LSI circuits in parallel and operate up to 1.5 GHz (Anachronism holding the speed record).The techniques perfected by the integrated circuits industry over the last three decades have been used to create very small mechanical devices driven by electricity using a technology known asmicroelectromechanical systems. These devices are used in a variety of commercial and military applications. Example commercial applications include DLP projectors, inkjet printers, and accelerometers used to deploy automobile airbags.In the past, radios could not be fabricated in the same low-cost processes as microprocessors. But since 1998, a large number of radio chips have been developed using CMOS processes. Examples include Intel's DECT cordless phone, or Atheros's 802.11 card.Future developments seem to follow the multi-coremulti-microprocessor paradigm, already used by the Intel and AMD dual-core processors. Intel recently unveiled a prototype, "not for commercial sale" chip that bears 80 microprocessors. Each core is capable of handling its own task independently of the others. This is in response to the heat-versus-speed limit that is about to be reached using existing transistor technology. This design provides a new challenge to chip programming. Parallel programming languages such as theopen-source X10 programming language are designed to assist with this task.集成电路集成电路或单片集成电子电路（也称为IC、集成电路片或微型集成电路片）是一种电子电路制作的图案扩散微量元素分析在基体表面形成一层薄的半导体材料。
计算机毕业设计专业英语翻译
本文摘自《计算机英语》（第二版）机械工业出版社出版的第五单元Unit 5 Software DevelopmentSection AComputer Program1>IntroductionA computer program is a set of instructions that directs a computer to perform some processing function or combination of functions. For the instructions to be carried out ,a computer must execute a program , that is , the computer reads the program , and then follows the steps encoded in the program in a precise order until completion . A program can be executed many different times , with each execution yielding a potentially different result depending upon the options and data that the user gives the computer .Programs fall into two major classes : application programs and operating systems . An application program is one that carries out some function directly for a user , such as word processing or game playing . An operating system is program that manages the computer and the various resources and devices connected to it , such as RAM ( random access memory ) , hard drives , monitors , keyboards , printers , and modems , so that they may be used by other programs . Examples of operating systems are DOS , Windows 95 , OS/2 , and UNIX.2>Program DevelopmentSoftware designers create new programs by using special applications programs , often called utility programs or development programs . A programmer uses another type of program called a text editor to write the new program in a special notation called a programmer creates a text file , which is an ordered list of instructions , also called the program source file . The individual instructions that make up the program source file are calledsource code . At this point , a special applications program translates the source code into machine language , or object code---a format that the operating system will recognize as a proper program and be able to execute .Three types of applications programs translate from source code to object code : compilers , interpreters , and assemblers . The three operate differently and on different types of programming languages , but they serve the same purpose of translating from a programming language into machine language .A compiler translates text files written in a high-level programming language---such as FORTRAN , C, or Pascal---from the source code to the object code all at once . This differs from the approach taken by interpreted languages such as BASIC , in which a program is translated into object code statement by statement as each instruction is executed . The advantage to interpreted languages is that they can begin executing the program immediately instead of having to wait for all of the source code to be compiled . Changes can also be made to the program fairly quickly without having to wait for it to be compiled again . The disadvantage of interpreted languages is that they are slow to execute , since the entire program must be translated one instruction at a time , each time the program is run . On the other hand , compiled languages are compiled only once and thus can be executed by the computer much more quickly than interpreted languages . For this reason , compiled languages are more common and are almost always used in professional and scientific applications .Another type of translator is the assembler , which is used for programs or parts of programs written in assembly language . Assembly language is another programming language , but it is much more similar to machine language than other types of high-level languages . In assembly language , a single statement can usually be translated into a single instruction ofmachine language . Today , assembly language is rarely used to write an entire program , but is instead most often used when the programmer needs to directly control some aspect of the computer’s function .Programs are often written as a set of smaller pieces , with each piece representing some aspect of the overall application program . After each piece has been compiled separately , a program called a linker combines all of the translated pieces into a single executable program .Programs seldom work correctly the first time , so a program callec a debugger is often used to help find problems called bugs . Debugging programs usually detect an event in the executing program and point the programmer back to the origin of the event in the program code .Recent programming systems , such as Java , use a combination of approaches to create and execute programs . A compiler takes a Java source program and translates it into an intermediate form . Such intermediate programs are then transferred over the Internet into computers where an interpreter program then executes the intermediate form as an application program .3>Program ElementsMost programs are built from just a few kinds of steps that are repeated many times in different contexts and in different combinations throughout the program . The most common step performs some computation , and then proceeds to the next step in the program , in the order specified by the programmer .Programs often need to repeat a short series of steps many times , for instance in looking through a list of game scores and finding the highest score . Such repetitive sequences of code are called loops .One of the capabilities that make computers so useful is their ability to make conditional decisions and perform different instructions based on the values of data being processed . IF-then-else statements implement this function by testing some piece of data and then selecting one of twosequences of instructions on the basis of the result . One of the instructions in these alternatives may be a goto statement that directs the computer to select its next instruction from a different part of the program . For example , a program might compare two numbers and branch to a different part of the program depending on the result of the comparision: Programs often use a specific sequence of steps more than once . Such a sequence of steps can be grouped together into a subroutine , which can then be called , or accdssed , as needed in different parts of the main program . Each time a subroutine is called , the computer remembers where it was in the program when the call was made , so that it can return there upon completion of the subroutine . Preceding each call , a program can specify that different data be used by the subroutine , allowing a very general piece of code to be written once and used in multiple ways .Most programs use several varieties of subroutines . The most common of these are functions , procedures , library routines , system routines , and device drivers . Functions are short subroutines that compute some value , such as computations of angles , which the computer cannot compute with a single basic instruction . Procedures perform a more complex function , such as sorting a set of names . Library routines are subroutines that are written for use by many different programs . System routines are similar to library routines but are actually found in the operating system . They provide some service for the application programs , such as printing a line of text . Device drivers are system routines that are added to an operating system to allow the computer to communicate with a new device , such as a scanner , modem , or printer . Device drivers often have features that can be executed directly as applications programs . This allows the user to directly control the device , which is useful if , for instance , a color printer needs to be realigned to attain the best printing quality after changing an ink cartridge .4>Program FunctionModern computers ususlly store programs on some form of magnetic storage media that can be accessed randomly by the computer , such as the hard drive disk permanently located in the computer , or a portable floppy disk . Additional information on such disks , called directories , indicates the names of the various programs on the disk , when they were written to the disk , and where the program begins on the disk media . When a user directs the computer to execute a particular application program , the operating system looks through these directories , locates the program , and reads a copy into RAM . The operating system then directs the CPU ( central processing unit ) to start executing the instructions at the beginning of the program . Instructions at the beginning of the program prepare the computer to process information by locating free memory locations in RAM to hold working data , retrieving copies of the standard options and defaults the user has indicated from a disk , and drawing initial displays on the monitor .The application program requests a copy of any information the user enters by making a call to a system routine . The operating system converts any data so entered into a standard internal form . The application then uses this information to decide what to do next---for example , perform some desired processing function such as reformatting a page of text , or obtain some additional information from another file on a disk . In either case , calls to other system routines are used to actually carry out the display of the results or the accessing of the file from the disk .When the application reaches completion or is prompted to quit , it makes further system calls to make sure that all data that needs to be saved has been written back to disk . It then makes a final system call to the operating system indicating that it is finished . The operating system then frees up the RAM and any devices that the application was using and awaits a command from the user to start another program .5>HistoryPeople have been storing sequences of instructions in the form of a program for several centuries . Music boxes of the 18th century and player pianos of the late 19th and early 20th centuries played musical programs stored as series of metal pins , or holes in paper , with each line ( of pins or holes ) representing when a note was to be played , and the pin or hole indicating what note was to be played at that time . More elaborate control of physical devices became common in the early 1800s with French inventor Joseph Marie Jacquard’s invention of the punch-card controlled weaving loom . In the process of weaving a particular pattern , various parts of the loom had to be mechanically positioned . To automate this process , Jacquard used a single paper card to represent each positioning of the loom , with holes in the card to indicate which loom actions should be done . An entire tapestry could be encoded onto a deck of such cards , with the same deck yielding the same tapestry design each time it was used . Programs of over 24000 cards were developed and used .The world’s first programmable machine was designed---although never fully built---by the English mathematician and inventor , Charles Babbage . This machine , called the Analytical Engine , used punch cards similar to those used in the Jacquard loom to select the specific arithmetic operation to apply at each step . Inserting a different set of cards changed the computations the machine performed . This machine had counterparts for almost everything found in modern computers , although it was mechanical rather than electrical . Construction of the Analutical Engine was never completed because the technology required to build it did not exist at the time .The first card deck programs for the Analutical Engine were developed by British mathemstician Augusta Ada Byron , daughter of the poet Lord Byron . For this reason she is recognized as the world’s first programmer .The modern concept of an internally stored computer program was first proposed by Hungarian-American mathematician John von Neumann in1945 . V on Neumann’s idea was to use the computer’s memory to store th e program as well as the data . In this way , programs can be viewed as data and can be processed like data by other programs . This idea greatly simplifies the role of program storage and execution in computers .6>The FutureThe field of computer science has grown rapidly since the 1950s due to the increase in their use . Computer programs have undergone many changes during this time in response to user need and advances in technology . Newer ideas in computing such as parallel computing , distributed computing , and artificial intelligence , have radically altered the traditional concepts that once determined program form and function .Computer scientists working in the field of patallel computing , in which multiple CPUs cooperate on the same problem at the same time , have introduced a number of new program models . In parallel computing parts of a problem are worked on simultaneously by different processors , and this speeds up the solution of the problem . Many challenges face scientists and engineers who design programs for parallel processing computers , because of the extreme complexity of the systems and the difficulty involved in making them operate as effectively as possible . Another type of parallel computing called distributed computing uses CPUs from many interconnected computers to solve problems , Often the computers used to process information in a distributed computing application are connected over the Internet . Internet applications are becoming a particularly useful form of distributed computing , especially with programming languages such as Java . In such applications , a user logs on to a Web site and downloads a Java program onto their computer . When the Java program is run , it communicate with other programs at its home Web site , and may also communicate with other programs running on different computers or Web sites .Research into artificial intelligence ( AI ) has led to several other newstyles of programming . Logic programs , for example , do not consist of individual instructions for the computer to follow blindly , but instead consist of sets of rules : if x happens then do y . A special program called an inference engine uses these rules to “ reason” its way to a conclusion when presented with a new problem . Applications of logic programs include automatic monitoring of complex systems , and proving mathematical theorems .A radically different approach to computing in which there is no program in the conventional sense is called a neural network . A neural network is a group of highly interconnected simple processing elements , disigned to music the brain . Instead of having a program direct the information processing in the way that a traditional computer does , a neural network processes information depending upon the way that its processing elements are connected . Programming a neural network is accomplished by presenting it with known patterns of input data and adjusting the relative importance of the interconnections between the processing elements until the desired pattern matching is accomplished . Neural networks are usually simulated on traditional computers , but unlike traditional computer programs , neural networks are able to learn from their experience .译文部分如下：计算机程序1.引言一个计算机程序是一系列的指示说明用来指挥电脑的进程功能或者排列组合功能。
可编程控制器本科毕业论文中英文翻译材料关于PLC外文翻译
可编程控制器本科毕业论文中英文翻译材料关于PLC外文翻译中文翻译可编程控制器技术可编程序控制器(Programmable Logic Controller，习惯上简称为PLC)是以微处理器为核心的通用工业自动化装置。
是20世纪60年代末在继电器控制系统的基础上开发出来的，它将传统的继电器控制技术与计算机技术和通信技术融为一体，具有结构简单、性能优越、可靠性高、灵活通用、易于编程、使用方便等优点。
具体来说，PLC的特点表现为以下几个方面:?硬件的可靠性高。
PLC专业在工业环境的恶劣条件下应用而设计。
一个设计良好的PLC能置于有很强电噪声、电磁干扰、机械振动、极端温度和湿度很大的环境中。
在硬件设计方面，首先是选用优质器件，再就是采用合理的系统结构，加固、简化安装，使它易于抗振冲击，对印刷电路板的设计、加工和焊接都采取了极为严格的工艺措施，而在电路、结构及工艺上采取了一些独特的方式。
由于PLC 本身具有很高的可靠性，所以在发生故障的部位大多集中在输入/输出的部位以及如传感器件、限位开关、光电开关、电磁阀、电机等外围装置上。
?编程简单，使用方便。
用微机实现自动控制，常使用汇编语言编程，难于掌握，要求使用者具有一定水平的计算机硬件和软件知识。
PLC采用面向控制过程、面向问题的编程方式，与目前微机控制常用的汇编语言相比，虽然在PLC内部增加了解释程序，增加了程序的执行时间，但对大多数的机电控制设备来说，这种损耗是微不足道的。
?接线简单，通用性好。
在电信号匹配的情况下，PLC的接线只需将输入信号的设备(按钮、开关等)与PLC输入端子连接，将接受输出信号执行控制任务的执行元件(接触器、电磁阀)与PLC输出端子连接。
接线简单、工作量少，省去了传统的继电器控制系统的接线和拆线的麻烦。
PLC的编程逻辑提供了能随要求而改变的逻辑关系，这样生产线的自动化过程就能随意改变。
这种性能使PLC具有很高的经济效益。
用于连接现场设备的硬件接口实际上已经设计成为PLC的组成部分，模块化的自诊断接口电路能指出故障，并易于排除故障与替换故障部件，这样的软硬件设计就使现场电气人员与技术人员易于使用。
关于PLC的毕业设计外文及翻译
PLCs --Past, Present and FutureEveryone knows there's only one constant in the technology world, and that's change. This is especially evident in the evolution of Programmable Logic Controllers (PLC) and their varied applications. From their introduction more than 30 years ago, PLCs have become the cornerstone of hundreds of thousands of control systems in a wide range of industries.At heart, the PLC is an industrialized computer programmed with highly specialized languages, and it continues to benefit from technological advances in the computer and information technology worlds. The most prominent of which is miniaturization and communications.The Shrinking PLCWhen the PLC was first introduced, its size was a major improvement - relative to the hundreds of hard-wired relays and timers it replaced. A typical unit housing a CPU and I/O was roughly the size of a 19 television set. Through the 1980s and early 1990s, modular PLCs continued to shrink in footprint while increasing in capabilities and performance (see Diagram 1 for typical modular PLC configuration).In recent years, smaller PLCs have been introduced in the nano and micro classes that offer features previously found only in larger PLCs. This has made specifying a larger PLC just for additional features or performance, and not increased I/O count, unnecessary, as even those in the nano class are capable of Ethernet communication, motion control, on-board PID with autotune, remote connectivity and more.PLCs are also now well-equipped to replace stand-alone process controllers in many applications, due to their ability to perform functions of motion control, data acquisition, RTU (remote telemetry unit) and even some integrated HMI (human machine interface) functions. Previously, these functions often required their own purpose-built controllers and software, plus a separate PLC for the discrete control and interlocking.The Great CommunicatorPossibly the most significant change in recent years lies in the communications arena. In the 1970s Modicon introduction of Modbus communications protocol allowed PLCs to communicate over standard cabling. This translates to an ability to place PLCs in closer proximity to real world devices and communicate back to other system controls in a main panel.In the past 30 years we have seen literally hundreds of proprietary and standard protocols developed, each with their own unique advantages.Today's PLCs have to bedata compilers and information gateways. They have to interface with bar code scanners and printers, as well as temperature and analog sensors. They need multiple protocol support to be able to connect with other devices in the process. And furthermore, they need all these capabilities while remaining cost-effective and simple to program.Another primary development that has literally revolutionized the way PLCs are programmed, communicate with each other and interface with PCs for HMI, SCADA or DCS applications, came from the computing world.Use of Ethernet communications on the plant floor has doubled in the past five years. While serial communications remain popular and reliable, Ethernet is fast becoming the communications media of choice with advantages that simply can't be ignored, such as: * Network speed. * Ease of use when it comes to the setup and wiring. * Availability of off-the-shelf networking components. * Built-in communications setups.Integrated Motion ControlAnother responsibility the PLC has been tasked with is motion control. From simple open-loop to multi-axis applications, the trend has been to integrate this feature into PLC hardware and software.There are many applications that require accurate control at a fast pace, but not exact precision at blazing speeds. These are applications where the stand-alone PLC works well. Many nano and micro PLCs are available with high-speed counting capabilities and high-frequency pulse outputs built into the controller, making them a viable solution for open-loop control.The one caveat is that the controller does not know the position of the output device during the control sequence. On the other hand, its main advantage is cost. Even simple motion control had previously required an expensive option module, and at times was restricted to more sophisticated control platforms in order to meet system requirements.More sophisticated motion applications require higher-precision positioning hardware and software, and many PLCs offer high-speed option modules that interface with servo drives. Most drives today can accept traditional commands from host (PLC or PC) controls, or provide their own internal motion control. The trend here is to integrate the motion control configuration into the logic controller programming software package.Programming LanguagesA facet of the PLC that reflects both the past and the future is programming language. The IEC 61131-3 standard deals with programming languages and defines two graphical and two textual PLC programming language standards: * Ladder logic (graphical). * Function block diagram (graphical). * Structured text(textual).Instruction list (textual).This standard also defines graphical and textual sequential function chart elements to organize programs for sequential and parallel control processing. Based on the standard, many manufacturers offer at least two of these languages as options for programming their PLCs. Ironically, approximately 96 percent of PLC users recently still use ladder diagrams to construct their PLC code. It seems that ladder logic continues to be a top choice given it's performed so well for so long.Hardware PlatformsThe modern PLC has incorporated many types of Commercial off the Shelf (COTS) technology in its CPU. This latest technology gives the PLC a faster, more powerful processor with more memory at less cost. These advances have also allowed the PLC to expand its portfolio and take on new tasks like communications, data manipulation and high-speed motion without giving up the rugged and reliable performance expected from industrial control equipment.New technology has also created a category of controllers called Programmable Automation Controllers, or PACs. PACs differ from traditional PLCs in that they typically utilize open, modular architectures for both hardware and software, using de facto standards for network interfaces, languages and protocols. They could be viewed as a PC in an industrial PLC-like package.The FutureA 2005 PLC Product Focus Study from Reed Research Group pointed out factors increasingly important to users, machine builders and those making the purchasing decisions. The top picks for features of importance were.* The ability to network, and do so easily. Ethernet communications is leading the charge in this realm. Not only are new protocols surfacing, but many of the industry de facto standard serial protocols that have been used for many years are being ported to Ethernet platforms. These include Modbus (ModbusTCP), DeviceNet (Ethernet/IP) and Profibus (Profinet). Ethernet communication modules for PLCs are readily available with high-speed performance and flexible protocols. Also, many PLC CPUs are now available with Ethernet ports on board, saving I/O slot space. PLCs will continue to develop more sophisticated connectivity to report information to other PLCs, system control systems, data acquisition (SCADA) systems and enterprise resource planning (ERP) systems. Additionally, wireless communications will continue to gain popularity.* The ability to network PLC I/O connections with a PC. The same trends that have benefited PLC networking have migrated to the I/O level. Many PLC manufacturers are supporting the most accepted fieldbus networks, allowing PLC I/O to be distributed over large physical distances, or located where it was previously considered nearly impossible. This has opened the door for personal computers to interface with standard PLC I/O subsystems by using interface cards, typically supplied by the PLC manufacturer or a third party developer. Now these challenging locations can be monitored with today a PC. Where industrial-grade control engines are not required, the user can take advantage of more advanced software packages and hardware flexibility at a lower cost.* The ability to use universal programming software for multipletargets/platforms. In the past it was expected that an intelligent controller would be complex to program. That is no longer the case. Users are no longer just trained programmers, such as design engineers or systems integrators, but end-users who expect easier-to-use software in more familiar formats. The Windows-based look and feel that users are familiar with on their personal computers have become the most accepted graphical user interface. What began as simple relay logic emulation for programming PLCs has evolved into languages that use higher level function blocks that are much more intuitive to configure. PLC manufacturers are also beginning to integrate the programming of diverse functions that allow you to learn only one package in configuring logic, HMI, motion control and other specialized capabilities. Possibly the ultimate wish of the end-user would be for a software package that could seamlessly program many manufacturers PLCs and sub-systems. After all, Microsoft Windows operating system and applications work similarly whether installed on a Dell, HP or IBM computer, which makes it easier for the user.Overall, PLC users are satisfied with the products currently available, while keeping their eye on new trends and implementing them where the benefits are obvious. Typically, new installations take advantage of advancing technologies, helping them become more accepted in the industrial world.PLC的过去、现在与未来众所周知，科技世界里只有一个永恒真理，那就是变化。
毕业设计用英语怎么说
毕业设计用英语怎么说毕业设计是教学过程的最后阶段采用的一种总结性的实践教学环节。
仅对大专以上学校要求在毕业前根据专业的不同进行毕业设计，对中等专业学校的学生不作要求。
那么你知道毕业设计用英语怎么说吗?下面店铺为大家带来毕业设计的英语说法，欢迎各位同学们学习!毕业设计的英语说法：graduation project毕业设计相关英语表达：毕业设计大赛 Graduation Design Competition毕业设计作品 Graduation Design Works毕业设计指导 graduation-project guidance毕业设计论文质量 qualities of graduation design毕业设计模式 graduate design modes毕业设计的英语例句：1. This article introduced the customer system management system realization method.本文介绍了客户管理毕业设计的实现方法.2. Andworked at an insurance company my graduation field work.我在家保险公司进行我毕业设计.3. This project is my graduation design. a sub - item of my tutor's.此项目为本人的毕业设计. 是导师项目下的子项目.4. This graduation design is about project management's new critical chain method. "本毕业设计是对项目进度管理新技术关键链法的研究.5. This graduation project's topic is on - line auto sale management system management system.本次毕业设计的题目就是网上汽车销售管理系统.6. The traveling website construction is faces the realistic demand an utility system.旅游网站建设是面向现实需求的一个实用毕业设计.7. The whole design procedure consists of the architectural and the structural design.此次毕业设计包括两部分:建筑设计,结构设计.8. This graduation project's topic is on - line books management system management system.本次毕业设计的题目就是网络订餐系统.9. During a metalworking and machine tool plant internships, courses and graduate design.其间进行了金工及机床厂实习, 课程及毕业设计.10. This project belongs to reseachful new task, and is of a assignment.本毕业设计是一个属于研究型的新课题, 工程浩大.11. The study are the design of the logistics and transport systems.本毕业设计的研究内容是物流运输的系统.12. My graduation project is about the origin and regulation of stem cells.我的毕业设计是关于干细胞调节的起源的.13. After the graduation project and found a lot of accumulated several more.毕业设计做完了,发现好多,积累了好更.14. Ninety percent of my class is already working on the final project.我们班百分之九十的同学都已经开始做毕业设计了.15. This paper analyzes the Web - based e - commerce platform -- Automobile Sales Management System.本文研究分析了基于的电子商务的平台开发汽车销售管理毕业设计.。
自动化毕业英文翻译
Programmable Logic Control (CPLD / FPGA)In our design, we selected CPLD / FPGA, as compared with the traditional MCU has many advantages, mainly in the following areas:①advanced programming very easy. CPLD / FPGA products, part of the daisy chain in-system programming mode. This advanced method of programming has become the world's development trend of various types of programmable devices. Because it obviates the expensive and inconvenient operation dedicated programmer, just need to download a very simple programming circuit and a PC, printer communication cable on the line. It is not programmed pressure, the TTL level line can be programmed at any time, and the so-called multi-chip daisy chain serial programming. Its programming up to 1 million times, such as Lattice's isles and AMD's MACH family. In addition, programming can easily achieve infrared, ultrasonic or radio programming programmer, or through the telephone line remote online programming. These features are in communication devices and military special purpose devices.② high speed. CPLD / FPGA clock delay of up to ns level, combined with the parallel work, in the ultra high-speed real-time monitoring and control applications and has a very broad application prospects. If you use the FLEX10K50 ALTERA development network image through USB interface, real-time encryption / decryption ASIC system, carried out in FLEX10K50 up to 56-bit parallel binary arithmetic, each encryption / decryption cycle of only a few μs, and the MCU takes nearly 1 minute . Another example is in the mold manufacturing EDM processing, motor control, the effective operation of the processing parts from only a few μs, which is required for the control of sensitive and high-speed circuit feeding service, not a short circuit or arcing is less than the breakdown . Obviously, this work, MCU is difficult to directly participate. If direct feeding by ispLSI1032 service control, feeding on the closed-loop motor speed service, the use of sampling ispLSI direct control of the AD1674, 8-bit accuracy using a maximum speed of 8μs / each, in order to achieve a good closed-loop speed control of synchronous and .③ high reliability. In high reliability applications, MCU’s shortcomings as a CPLD / FPGA application left a lot of useless. Although the function of this group developed the device is achieved through the EDA software. But the physical mechanism like a 74LS164 as purely a hardware circuit is very reliable. Through the rational design of most applications, no need to consider the complex reset and initialization. Design using a simple statement just idle initialentry into the same, we can effectively prevent any possible "death" phenomenon. Because it is working in parallel, it can be used as either input pin interrupt monitoring is similar to pin MCU, and the reaction rate is only satisfied wonderful class. CPLD / FPGA, high reliability is also reflected in almost the entire system can be downloaded on the same chip, thus greatly reducing the volume, easy to manage and shielding.④powerful, applications are broad. Currently, CPLD / FPGA to select a large range, according to different applications use different capacity chips, such as Lattice's ispLSI and AMD's MACH, the smallest chip for the 1000 equivalent logic gates, the largest of several one hundred thousand . ALTERA and XILINX gate introduced millions of CPLD / FPGA can achieve almost any form of digital circuits or digital systems design. With the wide application of such devices and the cost dropped significantly, and the market rate increase, CPLD / FPGA in the system rate is almost equal to the direct application of ASIC development.⑤easy to use, develop convenient. The design of SCM experts in application system is very simple. However, for beginners, such as the CPU's work, many of the usage of special registers, interrupt concepts, etc., really is not an easy task. In contrast, CPLD / FPGA application does not require too much preparation to learn the knowledge, as long as a little bit of design of digital circuits and computer software basics, you can in the short term to handle basic design and development skills. And in turn, to learn to use SCM, it appeared hundreds of times more. This is undoubtedly high for us to provide a shortcut to learning, standing on the shoulders of giants, of course faster to be successful. It can be predicted, the study of EDA technology boom and the CPLD / FPGA application boom never inferior to boom over the past 10 years, single chip.⑥short development cycle. EDA software features as the corresponding sound and powerful, convenient and real-time simulation capabilities, and intuitive image of the development process, and the hardware factors involved very little, it can be very complicated in a very short time the system design, which is the product to market quickly the most valuable features. Some EDA experts predict, the future of large-scale systems of CPLD / FPGA design is just all kinds of logic and then apply the IP core (CORE) of the assembly, the design cycle, only hour. TI company that eighty percent of an ASIC IP core features available such as ready-made logic synthesis.1.Development of language VHDLVHDL (Very High Speed Integrated Circuit Hardware Description Language) is a very high speed integrated circuit hardware description language, it can describe the function of the hardware circuitry, signal connectivity and the time between languages. It can be more effective than the circuit diagram to express the characteristics of the hardware circuit. Using the VHDL language, you can proceed to the general requirements of the system, since the detailed content will be designed to come down to earth, and finally to complete the overall design of the system hardware. IEEE VHDL language has been the industry standard as a design to facilitate reuse and sharing the results. At present, it can not be applied analog circuit design, but has been put into research. VHDL program structure, including: entity (Entity), structure (Architecture), configure (Configuration), Package Collection (Package) and the Library (Library). Among them, the entity is the basic unit of a VHDL program, by entity and the structure of two parts: the physical design system that is used to describe the external interface signal; structure used to describe the behavior of the system, the system processes or system data structure form. Configuration select the required language from the library system design unit to form different versions of different specifications, so that the function is designed to change the system. Collection of records of the design module package to share the data types, constants, subroutines and so on. Database used to store the compiled entities, the body structure, including the collection and configuration: one is the development of engineering software user, the other is the manufacturer's database.VHDL, the main features are:① powerful, high flexibility: VHDL language is a powerful language structure, clear and concise code can be used to design complex control logic. VHDL language also supports hierarchical design, support design databases and build reusable components. Currently, VHDL language has become a design, simulation, synthesis of standard hardware description language.② Device independence: VHDL language allows designers to generate a design do not need to first select a specific device. For the same design description, you can use a variety of different device structures to achieve its function. So the design description stage, able to focus on design ideas. When the design, simulation, after the adoption of a specific device specified integrated, adapter can be.③ Portability: VHDL language is a standard language, so the use of VHDL design can be carried out by different EDA tool support. Transplanted from one to another simulation tools, synthesis tools from a port to another integrated tool, from a working platform into another working platform. EDA tools used in a technical skills, in other tools can also be used.④top-down design methods: the traditional design approach is bottom-up design or flat design. Bottom-up design methodology is to start the bottom of the module design, the gradual formation of the functional modules of complex circuits. Advantage of this design is obvious because it is a hierarchical circuit design, the general circuit sub-module are in accordance with the structure or function of division, so the circuit level clear, clear structure, easy people to develop, while the design archive file is easy, easy communication. Bottom-up design is also very obvious shortcomings, the overall design concept is often not leaving because the cost of months of low-level design in vain. Flat design is a module containing only the circuit, the circuit design is straightforward and, with no division structure and function, it is not hierarchical circuit design. Advantages of small circuit design can save time and effort, but with the increasing complexity of the circuit, this design highlights the shortcomings of the abnormal changes. Top-down design approach is to design top-level circuit description (top model), and then the top-level simulation using EDA software, if the top-level design of the simulation results meet the requirements, you can continue to lower the top-level module by the division level and simulation, design of such a level will eventually complete the entire circuit. Top-down design method compared with the first two are obvious advantages.⑤rich data types: as a hardware description language VHDL data types are very rich language, in addition to VHDL language itself dozens of predefined data types, in the VHDL language programming also can be user-defined data types. Std_logic data types in particular the use of VHDL language can make the most realistic complex signals in analog circuits.⑥ modeling convenience: the VHDL language can be integrated in the statement and the statement are available for simulation, behavior description ability, therefore particularly suitable for signal modeling language VHDL. The current VHDL synthesizer to complex arithmetic comprehensive descriptions (such as: Quartus Ⅱ 2.0 and above versions of std_logic_vector type of data can add, subtract, multiply, divide), so the circuit modeling for complex simulation of VHDL language, whether or comprehensive description of the language are very appropriate.⑦ rich runtime and packages: The current package supports VHDL, very rich, mostly in the form of libraries stored in a specific directory, the user can at any time. Such as the IEEE library collection std_logic_1164, std_logic_arith, std_logic_unsigned other package. In the CPLD / FPGA synthesis, EDA software vendors can also use the various libraries and provide package. VHDL language and the user using a variety of results can be stored in a library, in the design of the follow-up can continue to use.⑧VHDL language is a modeling hardware description language, so with ordinary computer languages are very different, common computer language is the CPU clock according to the beat, after an instruction to perform the next instruction, so instruction is a sequential, that is the order of execution, and execution of each instruction takes a specific time. VHDL language to describe the results with the corresponding hardware circuit, which follows the characteristics of hardware, there is no order of execution of the statement is executed concurrently; and statements that do not like ordinary software, take some time each instruction, just follow their own hardware delay.可编程逻辑控件（CPLD／FPGA）在设计中我们之所以选用CPLD/FPGA，因为它与传统的MCU相比有着许多优点。
自动化专业毕业设计外文翻译1
外文资料Programmable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic orso-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLC per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCare widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating:“If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLC are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLC can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects,more than SO0/a of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs [Rockwell, 1999].In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurebility of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.The objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of the automation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspects.In modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice.Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLC still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancing the knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.The software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs中文翻译1968年，Richard E. Morley创造出了新一代工业控制装置可编程逻辑控制器(PLC),现在，PLC已经被广泛应用于工业领域，包括机械制造也、运输系统、化学过程设备、等许多其他领域。
PLC毕业设计外文翻译--基于模块化 S7-200 培训设备的 PLC 开放实验设计
S7-200 based modular training facilities opento experimental designPLCPLC (programmable logic controller) is a micro-controller core, the computer technology, automatic control technology; communication network together network technology is an advanced automatic control device. The current PLC has become the three major branch of modern industrial automation Column (PLC, robotics, CAD / CAM), widely used in various fields of automation and control systems, various types of enterprises Industry require a certain amount of practical experience with such talent. Thus, PLC application technology has become the industrial automation technology relevant professional technical personnel and university students to learn important lessons.Siemens SIMATIC S7-200 series are small PLC, its high price in the domestic market large market share, because of its flexible and powerful communication features and other special advanced features are increasingly the more widely used in automatic control systems [1]. Siemens Automation and Drives Group is currently actively cooperate with colleges and universities Siemens to build the establishment of training center for small-scale automation, Qingdao University is one of them. Siemens to provide similar training center S7-200 training-related equipment and software development. Teachers take advantage of this favorable experimental conditions, based on the design of these devices to open .Made a number of pilot projects PLC open, so that school has spare capacity, "enough" to further strengthen the PLC application technology student learning, Understand and operate the most advanced automation equipment, the initial grasp of advanced control technologies of industrial automation and control system design technology patients, improve their practical ability to achieve training objectives applicable talents to meet community needs for such technical personnel requirements.1 Modular S7-200 training equipmentPrinciple and Application of PLC technology tolearn and master the necessary hardware and softwaretest platform to support. Siemens automatic in myschool Group set up jointly with the driver of a smallautomated training centers, equipped with 10 sets oftraining equipment S7-200, diagram at right .Figure(painted on some of the expansion module) below. Thedevice is modular in design, the main module in additionto superior performance, cost-effective .Higher CPU224XP host, but also comes with text display TD400C,with special PT100 temperature transmitter, Heaters, fans,and other physical control object, basic literacy trainingto achieve most of experiments, people could beconducted. Siemens products for the rich functionmodule, consider the cost and other factors, with acertain number of functional modules, including EM231RTD temperature measurement module, EM253 positioncontrol module, EM241 Modem communication module, CP243-1 Ethernet communication module, EM277 Prefabs-DP module, SP series weighing Siwarex MS weighing module sensors and extension of six modules, connected by bus expansion unit to achieve the function of switch-free wiring, training, experiments can be used interchangeably. Also comes with HMI (Human Machine Interface) devices TP177B, OP177B, MP277, etc. A total of 10 touch-screens, hanging in the equipment rack can also be supported by a separate operation. Using the standard package of equipment S7-300 rail card installed, so that reliable and stable module is installed, and when necessary S7-300 modules can be very easy to experiment with the addition of any module S7-300, the S7-200 and S7-300 the installation of a common platform. This experimental equipment for teaching, training and scientific research has provided teachers, good hardware conditions.2 PLC open to experimental designPLC courses each semester due to class a lot, by the laboratory equipment, space and curriculum hours restrictions, generally Principle and Application of PLC programs created in the experiment mainly supporting the basic instruction to practice, sequential control, a simple digital V olume control system design, such as the marquee design, automatic round trip transportation movement control, intersection traffic lights model control, Three-tier model of control of the elevator, the part of the experiment content is based, compulsory. For the S7-200 special high-level utility function Energy-rich extension module and field communication function widely used implementation is rarely involved. Taking into account students Ability to accept differences and experimental conditions, this part of the experiment for the content best suited to open experiment [2] , That is, relative to teachers Laboratory equipment and related information, made experimental mission requirements, prepared by the students to self test program to determine the effective efficiency measurement experiment Ifthe method of thinking so that students have more room to stimulate the students enthusiasm and initiative, ability of students to engineering practice, Ability to innovate, analyze and solve problems Ability of great importance [3] . Therefore, the use of existing experimental design Equipment, and taking into account the students learn to master the knowledge structure, design and development of some pilot projects open.2.1 The main module design based on the opening experimentUse of the main module, in addition to the completion of some basic PLC programming experiment, we can also perform some special functions [4] Experiment, Also practiced Micro / Win programming environment integrated with a variety of programming guide, are:(1) The main module includes TD400C, it is a highly cost-effective dedicated S7-200 PLC's new generation of text Display, is a simple man-machine interface device, no special configuration of HMI software, the use of Micro / WIN V4.0 SP4 to On the version of Chinese language interface in the configuration wizard to TD [5] . The configuration opening in TD400C experiments, show the user through the configuration Menu, the alarm menu, and interact with S7-200 CPU, CPU storage area for data access and editing, enabling small Type of human-computer interaction function with the control system, such as basic experiments with automatic round trip transportation control program can be realized Through the control panel to control the car motion state, and in position to reach both ends of the alarm screen limit, while TD400C modify the car to stay at the ends of time, so that the experimental effect is more rich and vivid, but also to enable students to understand the master Production site using the actual control equipment.(2) High-speed counter, high-speed output, internal and external interrupts and other useful special features, through an open experiment Learn and master, such as the first high-speed output by PTO (pulse train) output, and achieve the high-speed counter High-speed output of the PTO HSC0 count, the interrupt function by repeated HSC0 count, a programming Adjust the PWM (pulse width modulation) high-speed output, the timer interrupt to implement a second counter, and the current count value, PWM output duty cycle and other related content displayed on the TD 400C.(3) The main module with the PT100 temperature transmitter will be converted from 0 to 100 degrees C 0 ~ 10V analog input received as Into the CPU, the heater, fan and other physical control objects connected to the digital output on the CPU can be realized on analog Data transformation, manual PID control programming, using the configuration wizard to complete the PID, PID parameter self-tuning function of the experiment, so that Students deeply understand and master the industrial field of analog PID control knowledge and implementation.(4)Two S7-200 series PLC via RS232 communication cable, you can use the PPI protocol to form a Single master station communication network, can be PPI point to point communication experiment, to achieve data exchange between the two PLC, such as the I0.0 ~ I0.7 master map to the slave state of the Q0.0 ~ Q0.7, from the station I0.0 ~ I0.7 of the state map to the main station Q0.0 ~ Q0.7, the network will allow students to experience the simple wizard to use reading and writing instruction, and extended through the formation of PPI networks can be implemented Control functions are more complex.(5) S7-200 CPU's communications port supports a free-port communication mode; you can use user-defined communication protocol implementation now with the computer or other device with a serial communication interface for communication. Here, simple and easy for students to use Visual Basic (VB) language PC program to realize S7-200 CPU PC with the free port communication mode between the experimental [6], Completed by the PLC field switching, analog control of processing, the host computer realization of the process parameters of the monitoring, analysis, Statistics and revision, to provide a good interface for easy monitoring.2.2 CP243-1 Ethernet module based on the open design of experimentsSiemens SIMATIC NET Industrial Ethernet is an open communication system on top, can manage and control network Integration, and even can be integrated into the Internet, for remote control and provides the conditions for global networking. S7-200 PLC with a CP243-1 Ethernet module or Internet CP243-1 IT module S7-200 can be connected to the Ethernet. In this, select are CP243-1 expansion module some experiments, through the Micro / WIN configuration of the Ethernet Wizard to complete the simple model Block configuration. Computer by installing the Ethernet card and Micro / WIN, can be realized via Ethernet S7-200 CPU Remote programming, configuration and diagnostics. In addition, the two are equipped with CP243-1 module S7-200 PLC, through the software programming and download the configuration program, can be realized through the network cable to connect two S7-200 PLC Ethernet-based data exchange. By This experiment allows students to commonly used industrial site between the S7-200 Ethernet communications have a clear understanding.2.3 touch screen design based on the opening experimentTD400C can only display text information, and requirements of many industrial control systems controlled object has a strong human-machine interface function can, through the meaning and message with a clear picture to the operator and control systems to achieve dialogue and interaction between Uses. Man-machine interface touch screen is the direction of development. Touch-screen devices using existing open experiment designed to allow students to learn as He through the configuration software WinCC Flexible configuration of the touch screen and transfer procedures [7] And the HMI and PLC data Exchange and data structures, such as students in the HMI configuration of traffic light system is running on a monitor screen or inside the elevator car operation For interface, combined with the preparation of the experiment based on the S7-200 signal-controlled crossroads of three elevator control procedures or procedures, Testing procedures can be performed correctly, but also to enable students to operate advanced equipment, and learn its configuration methods. In addition, to learn Students design a running effect of the controlled object interface, such as the movement of car transport materials, machinery and hand movement, etc., can make up for lab Less than the actual controlled object in the defect, this can greatly help students in the ability to innovate, improve and control system features a rich, Stimulate enthusiasm for learning and enthusiasm.Given above, S7-200 using the modular design of the part of the training facilitiesopens to experimental projects. Specialized courses as students learn The deepening of learning, knowledge, and plenty of time to increase reserves under the circumstances, but also in the graduation project will combine multiple modules Together to achieve a relatively complex system, such as the S7-300 CPU access system, with the S7-200 to achieve the Prefabs, MPI communications, the use of EM253 motion control position control module, servo motor and stepper motor control knowledge and understanding And control and so on.3 ConclusionsFull use of existing modular laboratory S7-200 training equipment, a large number of open research and development pilot project to enrich the real Test content, broaden the horizons of students, for students to learn deeply felt PLC interesting, learning PLC useful, while students mastered Industrial field is currently producing more with the typical products and the latest Siemens technology development and application of a comprehensive understanding of PLC control Technology, computer industry configuration control, touch screen control, networking, and automation control systems in real mutual penetration And added that practical ability of students to analyze and solve problems in the comprehensive capabilities have been greatly improved, more confident To face the fierce competition for jobs, it was widely welcomed by students.外文资料翻译基于模块化 S7-200 培训设备的 PLC 开放实验设计PLC（可编程序控制器）是以微控制器为核心，把计算机技术、自动控制技术、通信网络技术融合在一起的一种先进的自动控制装置。
PLC外文翻译 初稿
《Programmable logic controller》1）Author:Hacene Habbi,Mimoun Zelmat Belkaem Ould2）Abstact:Operation of the mechanical control of a programmable controller is used in electrical and mechanical process automation of the digital computer, and used in many industrial and machine. If the factory assembly line, entertainment and recreation facilities and lighting device. Different from the general computer, programmable controller is designed for a plurality of input and output design, such as: extended temperature range, immunity to electrical noise, and resistance to vibration and impact. Control machine operation programs are usually stored in a battery backup or non volatile memory, programmable controller is an example. In a real-time system, because the output results must be bounded time response to input conditions, otherwise it will lead to accidents.3）PLC programmingCan programming controller is usually written in the special application program on PC, then through direct connection cable or network connected to the programmable controller. The program is stored in the programmable logic controller (PLC) battery backed ram or some other non-volatile flash memory. Usually, a can controller programming can be used to replace thousands of relays.IEC61131-3 standard is adopted based on PLC programming language standards program. A graphical programming notation sequential function chart can be in a certain extent, reduce the workload. Initially most can use ladder diagram programming a model, simulation of relay control panel equipment (such as relay contacts and coils), PLC to replace the relay. This model in today remains widespread. IEC 61131-3 currently defines five programming languages for programmable control systems: FBD (Function block diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming language), IL (Instruction list, similar to assembly language) and SFC (Sequential function chart). These techniques emphasize logical organization of operations.Although the basic concept can be programmable controller programming is common to all manufacturers, in the input / output address, memory organization and instruction set difference means, programming controller program is never perfect between each manufacturer terchangeable. even in the same product line of single manufacturer, different models may not directly compatible.4) ConclusionPLC can adapt to a variety of task automation. PLC since the advent of since, electrical engineering personnel because of its easy programming for secondary development, even than the general microcontroller programming is simpler, so it is very popular. It in to a large extent the industrial automation design from a professional design institute into the factories, mines and other enterprises, coupled with the small size, high reliability, strong anti-interference ability adaptability, installation and wiring is simple and many other advantages, which is widely used in industry. Known as the three pillars of modern industrial production automation (PLC, robot robot and computer aided design / manufacturing CAD / CAM one. Can be pre Material: in the field of industrial control in the future, the application of PLC control technology will form the trend of the world.PLC control input / output devices, compatible with industrial test device and control system, meet the requirement of electrical design, and the design problem expressed as a sequence of operations of the center. The application of programmable logic controller (PLC) is usually highly customized systems, so mass production, manufacturing cost is relatively low, and in line with the current growing automation equipment green energy-saving requirements.《可编程逻辑控制器》1）作者：哈车尼·蓝尔·米蒙会2）摘要：可编程控制器，是一种用于机电过程自动化的数字计算机，并应用在许多工业和机器上。
【机械专业文献翻译】可编程控制器
机械专业中英文文献翻译毕业设计中英文翻译院系专业班级姓名学号指导教师20**年 4 月Programmable Logic Controllers (PLC)1、MotivationProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating [Moody and Morley, 1999, p. 110]:`If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC basedsoftware design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than SO0/a of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs [Rockwell, 1999].In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options.Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels. Number of points is the sum of the inputs and the outputs. PLCs may be specified by any possible combination of these values. Expandable units may be stacked or linked together to increase total control capacity. Maximum number of channels refers to the maximum total number of input and output channels in an expanded system. PLC system specifications to consider include scan time, number of instructions, data memory, and program memory. Scan time is the time required by the PLC to check the states of its inputs and outputs. Instructions are standard operations (such as math functions) available to PLC software. Data memory is the capacity for data storage. Program memory is the capacity for control software.Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs. Outputs for PLCs include DC, AC, relay, analog, frequency or pulse, transistor, and triac. Programming options for PLCs include front panel, hand held, and computer.Programmable logic controllers use a variety of software programming languages for control. These include IEC 61131-3, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD), structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic. The IEC 61131-3 programming environment provides support for five languages specified by the global standard: Sequential Function Chart,Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multi-vendor compatibility and multi-language programming. SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallel sequences. FBD uses a broad function library to build complex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable communication and interface functions. LD is a graphic language for discrete control and interlocking logic. It is completely compatible with FBD for discrete function control. ST is a text language used for complex mathematical procedures and calculations less well suited to graphical languages. IL is a low-level language similar to assembly code. It is used in relatively simple logic instructions. Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLCs). Ladder logic programming is a graphical representation of the program designed to look like relay logic. Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries. C is a high level programming language suited to handle the most complex computation, sequential, and data logging tasks. It is typically developed and debugged on a PC. BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions.Programmable logic controllers can also be specified with a number of computer interface options, network specifications and features. PLC power options, mounting options and environmental operating conditions are all also important to consider.2、ResumeA PLC (programmable Logic Controller) is a device that was invented to replace the necessary sequential relay circuits for control.The PLC works by looking at its input and depending upon their state, turning on/off its outputs. The user enters a program, usually via software or programmer, which gives the desired results.PLC is used in many "real world" applications. If there is industry present, chance are good that there is a PLC present. If you are involved in machining, packing, material handling, automated assembly or countless other industries, you are probably already using them. If you are not, you are wasting money and time. Almost any application that needs some type of electrical control has a need for a PLC.For example, let's assume that when a switch turns on we want to turn a solenoid on for 5second and then turn it off regardless of how long the switch is on for. We can do this with a simple external timer. But what if the process included 10 switches and solenoids? We should need 10 external times. What if the process also needed to count how many times the switch individually turned on? We need a lot of external counters.As you can see the bigger the process the more of a need we have for a PLC. We can simply program the PLC to count its input and turn the solenoids on for the specified time.We will take a look at what is considered to be the "top 20" PLC instructions. It can be safely estimated that with a firm understanding of these instructions one can solve more than 80% of the applications in existence.Of course we will learn more than just these instruction to help you solve almost ALL potential PLC applications.The PLC mainly consists of a CPU, memory areas, and appropriate circuits to receive input/output data. We can actually consider the PLC to be a box full of hundreds or thousands of separate relay, counters, times and data storage locations,Do these counters,timers, etc. really exist? No,they don't "physically" exist but rather they simulated and be considered software counters, timers, etc. . These internal relays are simulated through bit locations in registers.What does each part do? Let me tell you.Input RelaysThese are connected to the outside world.They physically exsit and receive signals from switches,sensors,ect..Typically they are not relays but rather they are transistors.Internal Utility RelaysThese do not receive signals from the outside world nor do they physically exist.they are simulated relays and are what enables a PLC to eliminate external relays.There are also some special relays that are dedicated to performing only one task.Some are always on while some are always off.Some are on only once during power-on and are typically used for initializing data that was stored.CountersThese again do not physically exist. They are simulated counters and they can be programmed to count pulses.Typically these counters can count up,down or both up anddown.Since they are simulated,they are limited in their counting speed.Some manufacturers also include high-speed counters that are hardware based.We think of these as physically existing.Most times these counters can count up,down or up and down.TimersThese also do not physically exist.They come in many varieties and increments.The most common type is an on-delay type.Others include off-delays and both retentive and non-retentive types.Increments vary from 1ms through 1s.Output RelaysThere are connected to the outside world.They physically exist and send on/off signals to solenoids,lights,etc..They can be transistors,relays,or triacs depending upon the model chosen Data StorageTypically there are registers assigned to simply store data.They are usually used as temporary storage for math or data manipulation.They can also typically be used to store data when power is removed form the PLC.Upon power-up they will still have the same contents as before power was moved.Very convenient and necessary!A PLC works by continually scanning a program.We can think of this scan cycle as consisting of 3 important steps.There are typically more than 3 but we can focus on the important parts and not worry about the others,Typically the others are checking the system and updating the current internal counter and timer values,Step 1 is to check input status,First the PLC takes a look at each input to determine if it is on off.In other words,is the sensor connected to the first input on?How about the third...It records this data into its memory to be used during the next step.Step 2 is to execute program.Next the PLC executes your program one instruction at a time.Maybe your program said that if the first input was on then it should turn on the first output.Since it already knows which inputs are on/off from the previous step,it will be able to decide whether the first output should be turned on based on the state of the first input.It will store the execution results for use later during the next step.Step 3 is to update output status.Finally the PLC updates the status the outputs.It updates the outputs based on which inputs were on during the first step and the results executing your program during the second step.Based on the example in step 2 it would now turn on the firstoutput because the first input was on and your program said to turn on the first output when this condition is true.After the third step the PLC goes back to step one repeats the steps continuously.One scan time is defined as the time it takes to execute the 3 steps continuously.One scan time is defined as the time it takes to execute the 3 steps listed above.Thus a practical system is controlled to perform specified operations as desired.3、PLC StatusThe lack of keyboard, and other input-output devices is very noticeable on a PLC. On the front of the PLC there are normally limited status lights. Common lights indicate;power on - this will be on whenever the PLC has powerprogram running - this will often indicate if a program is running, or if no program is runningfault - this will indicate when the PLC has experienced a major hardware or software problemThese lights are normally used for debugging. Limited buttons will also be provided for PLC hardware. The most common will be a run/program switch that will be switched to program when maintenance is being conducted, and back to run when in production. This switch normally requires a key to keep unauthorized personnel from altering the PLC program or stopping execution. A PLC will almost never have an on-off switch or reset button on the front. This needs to be designed into the remainder of the system.The status of the PLC can be detected by ladder logic also. It is common for programs to check to see if they are being executed for the first time, as shown in Figure 1. The ’first scan’ input will be true on the very first time the ladder logic is scanned, but false on every other scan. In this case the address for ’first scan’ in a PLC-5 is ’S2:1/14’. With the logic in the example the first scan will seal on ’light’, until ’clear’ is turned on. So the light will turn on after the PLC has been turned on, but it will turn off and stay off after ’clear’ is turned on. The ’first scan’ bit is also referred to at the ’first pass’ bit.Figure 1 An program that checks for the first scan of the PLC4、Memory TypesThere are a few basic types of computer memory that are in use today.RAM (Random Access Memory) - this memory is fast, but it will lose its contents when power is lost, this is known as volatile memory. Every PLC uses this memory for the central CPU when running the PLC.ROM (Read Only Memory) - this memory is permanent and cannot be erased. It is often used for storing the operating system for the PLC.EPROM (Erasable Programmable Read Only Memory) - this is memory that can be programmed to behave like ROM, but it can be erased with ultraviolet light and reprogrammed.EEPROM (Electronically Erasable Programmable Read Only Memory) – This memory can store programs like ROM. It can be programmed and erased using a voltage, so it is becoming more popular than EPROMs.All PLCs use RAM for the CPU and ROM to store the basic operating system for the PLC. When the power is on the contents of the RAM will be kept, but the issue is what happens when power to the memory is lost. Originally PLC vendors used RAM with a battery so that the memory contents would not be lost if the power was lost. This method is still in use, but is losing favor. EPROMs have also been a popular choice for programming PLCs. The EPROM is programmed out of the PLC, and then placed in the PLC. When the PLC is turned on the ladder logic program on the EPROM is loaded into the PLC and run. This method can be very reliable, but the erasing and programming technique can be time consuming. EEPROM memories are a permanent part of the PLC, and programs can be stored in them like EPROM. Memory costs continue to drop, and newer types (such as flash memory) are becoming available, and these changes will continue to impact PLCs.5、Objective and Significance of the ThesisThe objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of theautomation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspect Customer-Driven ManufacturingIn modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements.A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice.Higher Degree of Design Automation and Software QualityStudies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999] have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancingthe knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.System ComplexityThe software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs [Simmons et al., 1998].Design Theory DevelopmentToday, the primary focus of most design research is based on mechanical or electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design. A system design theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system modeling, can advance future development in engineering design.Application in Logical Hardware DesignFrom a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely complex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.可编程控制器1、前言可编程序的逻辑控制器（PLC），是由Richard E.Morley 于1968年发明的，如今已经被广泛的应用于生产、运输、化学等工业中。
机电专业中英文文献翻译-可编程逻辑控制器外文资料
PLCProgrammable Logic Controllers (PLCs), also referred to as programmable controllers, are in the computer family. They are used in commercial and industrial applications. A PLC monitors inputs, make decisions based on its program, and controls outputs to automate a process or machine. This course is meant to supply you with basic information on the functions and configurations of PLCs.In the 1960s, electromechanical devices were the order of the day as far as control was concerned. These devices commonly known as relays, were being used by the thousands to control many Sequential-type manufacturing processes and Stand-alone machines. Many of these relays were in use in the transportation industry, more specifically, the automothve industry. These relays used hundreds of wires and their interconnections to affect a control solution. The performance of a relay was basically reliable at least as a single device. But the common applications for relay panels called for 300 to 500 or more relays, and the reliability and maintenance issues associated with supposting these penels became a very great challenge. Cost became anther issue, for in spite of the low cost of the relay itself, the installed cost of the panel could be quite high. The total cost indueling purchased parts, wiring, and installation labor, could range from $30-$50 per relay. To make matters worse, the constantly changing needs of a process called for recurring modifications of a constantly changing needs of a process called for recurring modifications of a control panel. With relays, this was a costly prospect, as it was accomplished by a major rewiring effort on the panel. In addition, these changes were sometimes poorly documented, causing a second shift maintencance nightmare months later. In light of this, it was not uncommon to discard an entire control panel in favor of a new one with the appropriate components wired in a manner suited for the new process. Add to this the unpredictable, and potentially hight, cost of maintaining these systems as on high-volume motor vehide production lines, and it became clear that something was needed to improne the control process to make it more reliable, easier to troubleshoot, and more adaptable to changing control needs.That something, in the late 1960s, was the first programmable controller. This first “revollutionary” system was developed as a specific response to the needs of the major automotine manufacturers in the United States. these early controllers, or programmable logic controllers ( PLC ) , represented the first systems that (1) could be used on the factory floor, (2) could have there “ logic ” change without extensiverewiring or component changes, and (3) were easy to diagnost and repair when problems occurred. It is interesting to observe the progress that has been made in the past 15 years in the late 1960s must have been confusing and frightening to a great number of people. For example, what happened to the hardwired and eletromechanical devices that maintenance personnel were used to repairing with hard tools? They were replaced with “computers ” disquised as electromics designed to replace relays. Even the programming tools were designed to appear as relay equivalent presentations. We have the opportunity now to examine the promise, in retrospect, what the programmable controller brought manufacturing?All programmale controllers consist of the basic functional blocks. We will examine each block to understand the relathonship to the control system. First we looked at the center, as it is the heard of the system. It consists of a microprocessor, logic memory for the storage of the actual control logic, storage or variable memory for use with data that will ordimarily change as a function of the control propram execution, and a power supply to provide electrical power for the processor and memory. Next comes the I/O block. This function takes the conrtol level signals for the CPU and converts them to voltage and current levels suitable. The I/O type can range from digital, analog, or a variety of special purpose “smart ”I/O which are dedicated to a certain application task. The programming is normally used only to initially configure and program a system and is not required for the system to operate. It is also used in troubleshooting a system, and can prove to be a valuable tool in pinpointing the exact cause of a problem. The field devices shown here represent the various sensors and actuators connected to the I/O. These are the arms, legs, eyes, and ears of the system, including pushbuttons, limit switches, proximity suitches, photosensors, thermocouple, position sensing devices, and bar code reader as input; and pildt light, display devices, motor starters, DC and AC drivers, solenlids, and printers as outputs.1. Basic PLC OperationPLCs consist of input modules, a Central Processing Unit (CPU), and output modules or points. An input accepts a variety of digital or analog signals from various field devices (sensors) and converts them into a logic signal that can be used by the CPU. The CPU makes decisions and executes control instructions based on program instructions in memory. Output modules convert control instructions from the CPU into a digital or analog signal that can be used to control various field devices(actuators). A programming device is used to input the desired instructions. These instructions determine what the PLC will do for a specific input. An operator interface device allows process information to be displayed and new control parameters to be entered. Pushbuttons (sensors), in this simple example, connected to PLC inputs, can be used to start and stop a motor connected to a PLC through a motor starter (actuator).2. Hard-Wired ControlPrior to PLCs, many of these control tasks were solved by contactors or relay controls. This is often referred to as hardwired control. Circuit diagrams had to be designed, electrical components specified and installed, and wiring lists created. Electrical components necessary to perform a specific task. If an error was made the wires had to be reconnected correctly. A change in function or system expansion required extensive component changes and rewiring.3. Advantages of PLCsThe same, as well as more complex tasks, can be done with a PLC. Wiring between devices and relay contacts is done in the PLC program. Hard-wiring, though still required to connect field devices, is less intensive. Modifying the application and correcting errors are easier to handle. It is easier to create and change a program in a PLC than it is to wire and rewire a circuit.Following are just a few of the advantages of PLCs:(1) Smaller physical size than hard-wire solutions.(2) Easier and faster to make changes.(3) PLCs have integrated diagnostics and override functions.(4) Applications can be immediately documented.(5) Applications can be duplicated faster and less expensively.4. Siemens PLCsSiemens makes several PLC product lines in the SIMATIC S7 family. They are: S7-200, S7-300, and S7-400.(1)S7-200The S7-200 is referred to as a micro-PLC because of its small size. The S7-200 has a brick design which means that the power supply and I/O terminal are on-board. The S7-200 can be used on smaller, stand-alone applications such as elevators, carwashes, or mixing machines. It can also be used on more complex industrial applications such as bottling and packaging machines.(2) S7-300 and S7-400The S7-300 and S7-400 PLCs are used in more complex applications that support a greater of I/O points. Both PLCs are modular and expandable. The power supply and I/O consist of separate modules connected to the CPU. Choosing either the S7-300 or S7-400 depends on the complexity of the task and possible future expansion. Your Siemens sales representative can provide you with additional information on any of the Siemens PLCs.5. CPUCPU is a microprocessor system that contains the system memory and is the PLC decision-making unit. The CPU monitors the inputs and makes decisions based on instructions held in the program memory. The CPU performs relay, counting timing ,data comparison, and sequential operations.6. Programming DevicesThe program is created in a programming device (PG) and then transferred to the PLC. The program for the S7-200 can be created using a dedicated Siemens SIMATIC S7 programming device, such as a PG 720 or PG 740, if STEP 7 Micro/WIN software is installed.A personal computer (PC), with STEP 7 Micro/WIN installed, can also be used as a programming device with the S7-200.7. SoftwareA software program is required in order to tell the PLC what instructions it must follow. Programming software is typically PLC specific. A software package for one PLC, or one family of PLCs, such as the S7 family, would not be useful on other PLCs. The S7-200 uses a Windows-based software program called STEP 7-Micro/WIN32. The PG 720 and PG 740 have STEP 7-Micro/WIN32 software pre-installed. Micro/WIN32 is installed on a personal computer in a similar manner to any other computer software.8. Connector Cables PPI (Point-to-Point Interface)Connector cables are required to transfer data from the programming device tothe PLC. Communication can only take place when the two devices speak the same language or protocol. Communication between a Siemens programming device and the S7-200 is referred to as PPI protocol. An appropriate cable is required for a programming device such as a PG 720 or PG 740. The S7-200 uses a 9-pin, D-connector, This is a straight-through serial device that is compatible with Simens programming devices (MPI port) and is a standard connector for other serial interfaces.A special cable, referred to as a PC/PPI cable, is needed when a personal computer is used as a programming device. This cable allows the serial interface of the PLC to communicate with the RS-232 serial interface of a personal computer. DIP switches on the PC/PPI cable are used to select an appropriate speed (bit rate) at which information is passed between the PLC and the computer.可编程逻辑控制器可编程逻辑控制器（PLC），也就是可编程控制器，是计算机家族的一员。
毕业设计的英文翻译----开放式控制器体系结构 - 过去,现在和未来
Open Controller Architecture - Past, Present and FutureGunter Pritschow (Co-ordinator), Yusuf Altintas, Francesco Jovane, Yoram Koren, Mamoru Mitsuishi, Shozo Takata, Hendrik van Brussel, Manfred Weck, Kazuo YamazakiAbstractOpen Control Systems are the key enabler for the realization of modular and re-configurable manufacturing systems. The large number of special purpose machines and the high level of automation have led to an increasing importance of open control systems based on vendor neutral standards. This paper gives an overview on the past, present and future of Open Controller Architecture. After reflecting on the different criteria, categories and characteristics of open controllers in general, the CNC products in the market are evaluated and an overview on the world-wide research activities in Europe, North America and Japan is given. Subsequently the efforts to harmonize the different results are described in order to establish a common world-wide standard in the future. Due to the “mix-and-match’’ nature of open controllers concentrated attention must be paid to testing mechanisms in the form of conformance and interoperability tests.Keywords: Open architecture control, CNC, Machine tool1 INTRODUCTIONOpen Architecture Control (OAC) is a well known term in the field of machine control. Since the early nineties several initiatives world-wide have worked on concepts for enabling control vendors, machine tool builders and end-users to benefit more from flexible and agile production facilities. The main aim was the easy implementation and integration of customer-specific controls by means of open interfaces and configuration methods in a vendor-neutral, standardized environment [13][19].The availability and broad acceptance of such systems result in reduced costs and increased flexibility. Software can be reused and user-specific algorithms or applications can be integrated. Users can design their controls according to a given configuration. This trend was forced both by the increasing number of special purpose machines with a high level of automation and the increasing development costs for software (Figure 1).Figure 1: CNC Hardware and software -Actual trend existingIn the past the CNC market was dominated by heterogeneous, device-oriented systems with proprietary hardware and software components. The tight coupling of application software, system software and hardware led to very complex and inflexible systems. Great efforts were made to maintain and further develop the products according to new market requirements. Modern CNC approaches, which comprise extensive functionality to achieve a high quality and flexibility of machining results combined with a reduced processing time, favor PC- based solutions with a homogenous, standardized environment (Figure 2). The structure is software- oriented and configurable due to defined interfaces and software platforms. Open control interfaces are necessary for continuously integrating new advanced functionality into control systems and are important for creating re-configurable manufacturing units [17]. Unbundling hardware and software allows profiting from the short innovation cycles of the semiconductor industry and information technology. With the possibility for reusing software components, the performance of the overall system increases simply by upgrading the hardware platform.Figure 2: PC-based, software-oriented Control SystemsThere are a lot of benefits for suppliers and users of open control systems (Figure 3) [7]. CNC designers and academics benefit from a high degree of openness coveringalso the internal interfaces of the CNC. For CNC users the external openness is much more important. It provides the methods and utilities for integrating user-specific applications into existing controls and for adapting to user-specific requirements, e.g. adaptable user interfaces or collection of machine and production data. The external openness is mainly based on the internal openness but has functional or performance Iimitations .2 STATE OF THE ART2.1 Control Systems and their interfacesControls are highly sophisticated systems due to very strict requirements regarding real-time and reliability. For controlling the complexity of these systems hardware and software interfaces are an essential means. The interfaces of control systems can be divided into two groups-external and internal interfaces (Figure4).External InterfacesThese interfaces connect the control system to superior units, to subordinate units and to the user. They can be divided into programming interfaces and communication interfaces. NC and PLC programming interfaces are harmonized by national or international standards, such as RS-274, DIN 66025 or IEC 61131-3. Communication interfaces are also strongly influenced by standards. Fieldbus systems like SERCOS, Profibus or DeviceNet are used as the interface to drives and 110s. LAN (Local Area Network) networks mainly based on Ethernet and TCP/lP do reflect the interfaces to superior systems.Internal InterfacesInternal interfaces are used for interaction and data- exchange between components that build up the control- system core. An important criterion in this area is the support of real-time mechanisms. To achieve a re-configurable and adaptable control the internal architecture of the control system is based on a platform concept. The main aims are to hide the hardware-specific details from the software components and to establish a defined but flexible way of communication between the software components. An application programming interface(API) ensures these requirements. The whole functionality of a control system is subdivided into several encapsulated, modular software components interacting via the defined API.2.2 Hardware and software structure of control systemsFigure 5 shows different variants for the hardware structures of control systems. Variant a) shows an analog drives interface with position controller in the control system core. Each module of this structure uses its own processor which leads to a large variety of vendor-specific hardware. Combining modules leads to a significant reduction of the number of processors. Variant b) shows intelligent digital drives with integrated control functionality, which result from higher capacity, miniaturization and higher performance of the processors. Variant c) shows a PC-based single processor solution with a real-time extension of the operating system. All control-functions run as software tasks in the PC-based real-time environment.2.3 Market overviewThe controls available in the market provide different levels of openness according to the criteria shown in Figure 6. An important criterion is the use of a standardized computing platform (i.e. hardware, operating system and middleware) as an environment to execute the HMI and CNC software. Besides this, the connectivity of the CNC to upper and lower factory levels must be guaranteed. Application Programming Interfaces (API) are used to integrate third party software in the CNC products. Al though most of today’s controls offer openness concerning the operator-related control functions (Human-Machine Interface, HMI) only few controls allow users to modify their low-level control algorithms to influence the machine-related control functions.Figure 7 gives an overview of the characteristics of today’s control s ystems regarding the degree of openness.Although many control systems provide open interfaces for software integration (e.g. OPC) there is still no common definition of data which is passed back and forth via the programming interface. Therefore, the control systems available on the market today do not implicitly support “plug-and-play” features. To improve this situation, the fieldbus systems can serve as a role model (see Figure 8). The variety of different fieldbus systems has led to the broad consensus that harmonizing the application-oriented interfaces is desirable in order to hide the plurality and the complexity of the systems from the user. Most fieldbus organizations are already using so-called device profiles in order to support the interchangeability of the devices of different vendors.For example, the SERCOS interface standard (IEC61491) for the cyclic and deterministic communication between CNC and drives has defined the semantics forapprox. 400 parameters describing drive and control functions which are used by the devices of different vendors.3 DEFINITIONS AND CATEGORIES OF OPENNESS3.1 DefinitionsThe “Technical Committee of Open Systems” of IEEE defines an open system as follows: “An open system provides capabilities that enable properly implemented applications to run on a variety of platforms from multiple vendors, interoperate with other system applications and present a consistent style of interaction with the user” (IEEE 1003.0).To estimate the openness of a controller the following criteria can be applied (Figure 9):Portability. Application modules (AM) can be used on different platforms without any changes, while maintaining their capabilities.Extendibility. A varying number of AM can run on a platform without any conflicts.Inferoperability. AM work together in a consistent manner and can interchange data in a defined way.Scalability. Depending on the requirements of the user, functionality of the AM and performance and size of the hardware can be adapted.To fulfill the requirements of the IEEE-definition and these criteria of openness, an open control system must be:vendor neutral. This guarantees independence of single proprietary interests.consensus-driven. It is controlled by a group of vendors and users (usually in the form of a user group or an interested group).standards-based. This ensures a wide distribution in the form of standards (national/international standards or de-facto standards).freely available. It is free of charge to any interested party.3.2 Categories of Open Control SystemsIf we speak of openness in control systems, the following categories can be identified (Figure 10):Open HMl: The openness is restricted to the non-real-time part of the control system. Adaptations can be made in user oriented applications.Kernel with restricted openness: The control kernel has a fixed topology, but offers interfaces to insert user-specific filters even for real-time functions.Open Control System: The topology of the control kernel depends on the process. It offers interchangeability, scalability, portability and interoperability.Open control systems that are available today mostly offer the possibility for modifications in the non-real-time part in a fixed software topology. They lack the necessary flexibility and are not based on vendor-neutral standards.3.3 RequirementsA vendor-neutral open control system can only be realized if the control functionality is subdivided in functional units and if well-defined interfaces between these units are specified (Figure 11). Therefore modularity can be identified as the key for an open system architecture. In determining the module complexity there is an obvious trade-off between the degree of openness and the cost of integration [6]. Smaller modules provide a higher level of openness and more options, but increase the complexity and integration costs. Furthermore such a low level of granularity can lead to much higher demands for resources and it may even deteriorate the real-time performance of the overall system.Combining modules in the manner of “mix-and-match’’ requires a comprehensive set of standard Application Programming Interfaces (APIs). For vendor-neutral open control systems the interfaces need to be standardized and broadly accepted. Due to the complexity of such modular systems the definition of a system architecture is recommendable and helpful. This leads to the introduction of so-called system platforms (Figure 12). These platforms encapsulate the specifics of a computing system by absorbing the characteristics of hardware, operating system and communication. The availability of such middleware systems facilitates the easy porting of application software and also the interoperability of application modules even in distributed heterogeneous environments.Due to the possibility to “mix-and-match’’ modules via standardized interfaces the quality of the overall system is determined by the degree of the interoperability between the single modules (see Section 5).4 SYSTEMS ON THE WAY TO THE MARKET4.1 Major international activitiesOSEC (Japan)The OSE (Open System Environment for Manufacturing) consortium was established in December 1994. Three project phases were carried out until March 1999 [1][2][3]. The OSEC Architecture was intended to provide end users, machine makers, control vendors, software vendors, system integrators, etc. a standard platform for industrial machine controllers, with which they can add their own unique values to the industrial machines, and hence promote the technical and commercial development of the industrial machines. The OSEC API is defined in the form of an interface protocol, which is used to exchange messages among controller software components representing the functionality and the real- time cycle. Each functional block can be encapsulated as an object so it is not necessary to deal with how a functional block processes messages to it at architecture level (Figure 13). Although the structure of functional blocks can be defined uniquely by the OSEC architecture from a logical point of view, the system is neither determined nor limited at its implementation phase because there are so many options for implementations. These options may include system contrivances such as device driver, interprocess communication, installation mechanisms such as static library and DLL, hardware factors like selection of controller card, and implementations of software modules added for execution control and/or monitoring of various software. In other words, the implementation model to realize the architecture model is not limited to a particular model. In this way, it is assured to incorporate various ideas in the implementation model depending on the system size or its hardware implementation and/or utilization.JOP (Japan)In parallel to the OSE consortium activities, MSTC formed the Open-Controller Technical Committee (OC- TC) from 1996 to 2000, under the umbrella of JOP (Japanese Open Promotion Group). The objectives of OC-TC were to provide the opportunities for various companies to discuss and work together on the standardization of open controller technologies. The OC- TC was also expected to act as liaison between domestic and international activities in this field. OC-TC was participated by approximately 50 members, which included major Japanese controller vendors, machine tool builders, integrators, users, and academics. Some of the members represented the other groups concerning open controllers such as the OSE consortium and the FA Intranet Promotion Group .One of the working groups was engaged in developing a standard API for interfacing between NC and PC-based HMI. It should be also effective for the communication between NC and an upper level management controller. The work was carried out based on the proposals from the major controller vendors and that from the OSE consortium. The developed specifications were named PAPI and released July, 1999 [4] [5]. PAPI was approved as a JIS (Japan Industrial Standard) technical report and published in October, 2000. To demonstrate the effectiveness of the specifications developed by OC-TC, in Nagoya in October 1999, two CNCs manufactured by different vendors were connected to a Windows NT machine in which the same HMI systems developed by the University of Tokyo were implemented (Figure 14). Since any specific controller architecture is not assumed, PAPI can be implemented in various types of existing CNC systems, such as PC + proprietary NC, PC + NC board, and Software NC on PC+110 board. The HMI system communicates with the CNCs via PAPI which is a function-oriented software library in the programming language C. The PAPI interface is neutralizing the vendor-specific interface by mapping the PAPI calls to the vendor-specific API and protocol.OMAC (USA)The Open Modular Architecture Controllers (OMAC) Users Group is an industry forum to advance the state of controller technology [l0]. An effort was undertaken within OMAC to define API specification for eventual submittal to an established standards body. The OMAC API adopted a component-based approach to achieve plug-and-play modularization, using interface classes to specify the API [11]. For distributed communication, component-based technology uses proxy agents to handle method invocations that cross process boundaries. OMAC API contains diffe rent “sizes” and “types” of reusab le plug-and-play components - component, module, and task - each with a unique Finite State Machine (FSM) model so that component collaboration is performed in a known manner. The term component applies to reusable pieces of software that serves as a building block within an application while the term module refers to a container of components. Tasks are components used to encapsulate programmable functional behavior consisting of a series of steps that run to completion, including support for starting, stopping, restarting, halting, and resuming, and may be run multiple times while a controller is running. Tasks can be used to build controller programs consisting of a series of Transient Tasks, with ability to restart and navigate, or as standalone Resident Tasks to handle specialized controller requirements, (e.g., axis homing or ESTOP).To integrate components, a framework is necessary to formalize the collaborations and other life cycle aspects in which components operate. The OMAC API uses Microsoft Component Object Model (COM) as the initial framework in which to develop components, with the expected benefit that control vendors could then concentrate on application-specific improvements that define their strategic market-share - as opposed to spending valuable programming resources reinventing and maintaining software “plumbing.”The primary problem with COM framework, specifically under the Windows 2000 operating system, is the lack of hard, real-time preemptive scheduling, but third party extensions to Windows 2000 can be used to overcome this requirement.Figure 15 illustrates a sketch of OMAC API controller functionality. The HMI module is responsible for human interaction with a controller including presenting data, handing commands, and monitoring events and in the OMAC API “mirrors” the actual controller with references to all the major modules and components via proxy agents. The Task Coordinator module is responsible for sequencing operations and coordinating the various modules in the system based on programmable Tasks. The Task Coordinator can be considered the highest level Finite State Machine in the controller. A Task Generator module translates an application-specific control program (e.g., RS 274 part program) into a series of application-neutral Transient Tasks. The Axis Group module is responsible for coordinating the motions of individual axes, transforming an incoming motion segment specification into a sequence of equi-time- spaced setpoints for the coordinated axes. The Axis module is responsible for servo control of axis motion, transforming incoming motion setpoints into setpoints for the corresponding actuators 10 points. The Control Law component is responsible for servo control loop calculations to reach specified setpoints. OSACA (Europe)In Europe the ESPRIT project OSACA (Open System Architecture for Controls within Automation Systems) was initiated in 1992 with the aim to unite European interests and to create a vendor-neutral standard for open control systems[9][16].It was supported by major European control vendor and machine tool builders. OSACA reached a mature state already in April 1996 having at its disposal a stable set of specifications and a tested pool for system software. Based on these results, several application-oriented projects were carried out. In 1988 two pilot demonstrators in the automotive industry proved the interoperability of OSACA-compliant controllers and applications. The OSACA association eth currently 35 members from all over the word is the lasting organization to keep and maintain the OSACA-related specifications.The basic technical approach of the OSACA architecture is the hierarchical decomposition of control functionality into so-called functional units (Figure 16).For each of these functional units (e.g. motion control, motion control manager, axescontrol, logic control, etc.) the interfaces are specified by applying object-oriented information models. This technique is similar to the approach of MAP/MMS but with a limited and manageable number of object classes.The data interface consists of several variable objects that support the read and/or write access to data structure(data flow).The data can be of a simple type or of a complex type(array, structure, union).By using formal templates(Figure17) all the characteristics of a single interface object are specified. These elements cover the name (e.g, “mc-active-feed-override”), the type (e.g. UNS32: 32-bit unsigned value), the scaling (e.g. 0.l%),the range and the access rights (read only, to all the major modules and components via proxy write only, read/write) of the data. An additional description is to avoid misinterpretations of the use of the data. The process interface consists of several process objects that are used to describe the dynamic behavior (control flow) of the application modules by means of finite state machine (FSM). The state machines are described by static states, dynamic states and transitions to change the states of a given state-machine. The transitions can handle input and output parameters to pass data between application modules via the communication platform. The formal template for such process interfaces consists of an unambiguous description and the following attributes: list of static states (identifier, list of possible transitions), list of dynamic states (identifier) and a list of transitions (input parameters, output parameters, return codes). The process interface can also be used to activate application-specific functions in form of procedure calls. The interoperability of distributed application modules is supported by an infrastructure (so-called OSACA platform) which comprises client-server principles, synchronous and asynchronous calls and event handling via any underlying communication protocol and media (e.g. by using the TCP/lP protocol). A dedicated configuration runtime system is handling the system’s startup and shutdown. Besides, it also allows an easy reconfiguration of the system.开放式控制器体系结构- 过去，现在和未来摘要开放式控制系统是用于模块化和可重新配置制造系统实现的关键推动者。
控制类毕业设计中英文翻译资料--模煳逻辑
模糊逻辑-分析和控制复杂系统的新途径--托马斯索沃尔欢迎进入模糊逻辑的精彩世界，你可以用新科学有力地实现一些东西。
在你的技术与管理技能的领域中，增加了基于模糊逻辑分析和控制的能力，你就可以实现除此之外的其他人与物无法做到的事情。
以下就是模糊逻辑的基础知识：随着系统复杂性的增加，对系统精确的阐述变得越来越难，最终变得无法阐述。
于是，终于到达了一个只有靠人类发明的模糊逻辑才能解决的复杂程度。
模糊逻辑用于系统的分析和控制设计，因为它可以缩短工程发展的时间；有时，在一些高度复杂的系统中，这是唯一可以解决问题的方法。
虽然，我们经常认为控制是和控制一个物理系统有关系的，但是，扎德博士最初设计这个概念的时候本意并非如此。
实际上，模糊逻辑适用于生物，经济，市场营销和其他大而复杂的系统。
模糊这个词最早出现在扎德博士于1962年在一个工程学权威刊物上发表论文中。
1963年，扎德博士成为加州大学伯克利分校电气工程学院院长。
那就意味着达到了电气工程领域的顶尖。
扎德博士认为模糊控制是那时的热点，不是以后的热点，更不应该受到轻视。
目前已经有了成千上万基于模糊逻辑的产品，从聚焦照相机到可以根据衣服脏度自我控制洗涤方式的洗衣机等。
如果你在美国，你会很容易找到基于模糊的系统。
想一想，当通用汽车告诉大众，她生产的汽车其反刹车是根据模糊逻辑而造成的时候，那会对其销售造成多么大的影响。
以下的章节包括：1)介绍处于商业等各个领域的人们他们如果从模糊逻辑演变而来的利益中得到好处，以及帮助大家理解模糊逻辑是怎么工作的。
2)提供模糊逻辑是怎么工作的一种指导，只有人们知道了这一点，才能运用它用于做一些对自己有利的事情。
这本书就是一个指导，因此尽管你不是电气领域的专家，你也可以运用模糊逻辑。
需要指出的是有一些针对模糊逻辑的相反观点和批评。
一个人应该学会观察反面的各个观点，从而得出自己的观点。
我个人认为，身为被表扬以及因写关于模糊逻辑论文而受到赞赏的作者，他会认为，在这个领域中的这种批评有点过激。
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Programmable logic controllerCynthia CooperFrom Wikipedia, the free encyclopediaA programmable logic controller or simply programmable controller is a digital computer used for automation of industrial processes, such as control of machinery on factory assembly lines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result.FeaturesControl panel with PLC (grey elements in the center). The unit consists of separate elements, from left to right; power supply, controller, relay units for input and output.The main difference from other computers is that PLCs are armored for severe condition (dust, moisture, heat, cold, etc) and have the facility for extensive input/output (I/O) arrangements. These connect the PLC to sensors and actuators. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. Someeven use machine vision. On the actuator side, PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic relays or solenoids, or analog outputs. The input/output arrangements may be built into a simple PLC, or the PLC may have external I/O modules attached to a computer network that plugs into the PLC.PLCs were invented as replacements for automated systems that would use hundreds or thousands of relays, cam timers, and drum sequencers. Often, a single PLC can be programmed to replace thousands of relays. Programmable controllers were initially adopted by the automotive manufacturing industry, where software revision replaced the re-wiring of hard-wired control panels when production models changed.Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams. The electricians were quite able to trace out circuit problems with schematic diagrams using ladder logic. This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.The functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers. PLC-like programming combined with remote I/O hardware, allow ageneral-purpose desktop computer to overlap some PLCs in certain applications.Under the IEC 61131-3 standard, PLCs can be programmed using standards-based programming languages. A graphical programming notation called Sequential Function Charts is available on certain programmable controllers.PLC compared with other control systemsPLCs are well-adapted to a range of automation tasks. These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation.PLCs contain input and output devices compatible with industrial pilot devices and controls.PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design. On the other hand, in the case of mass-produced goods, customized control systems are economic due to the lower cost of the components, which can be optimally chosen instead of a "generic" solution。
For high volume or very simple fixed automation tasks, different techniques are used. For example, a consumer dishwasher would be controlled by an electromechanical cam timer costing only a few dollars in production quantities.A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and input/outputhardware) can be spread over many sales, and where the end-user would not need to alter the control. Automotive applications are an example; millions of units are built each year, and very few end-users alter the programming of these controllers. However, some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls, because the volumes are low and the development cost would be uneconomic.Very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed or precision controls may also require customized solutions; for example, aircraft flight controls.PLCs may include logic for single-variable feedback analog control loop, a "proportional, integral, derivative" or "PID controller." A PID loop could be used to control the temperature of a manufacturing process, for example. Historically PLCs were usually configured with only a few analog control loops; where processes required hundreds or thousands of loops, a distributed control system (DCS) would instead be used. However, as PLCs have become more powerful, the boundary between DCS and PLC applications has become less clear-cut.Digital and analog signalsDigital or discrete signals behave as binary switches, yielding simply an On or Off signal (1 or 0, True or False, respectively). Push buttons, limit switches, and photoelectric sensors areexamples of devices providing a discrete signal. Discrete signals are sent using either voltage or current, where a specific range is designated as On and another as Off. For example, a PLC might use 24 V DC I/O, with values above 22 V DC representing On, values below 2VDC representing Off, and intermediate values undefined. Initially, PLCs had only discrete I/O.Analog signals are like volume controls, with a range of values between zero and full-scale. These are typically interpreted as integer values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of bits available to store the data. As PLCs typically use 16-bit signed binary processors, the integer values are limited between -32,768 and +32,767. Pressure, temperature, flow, and weight are often represented by analog signals. Analog signals can use voltage or current with a magnitude proportional to the value of the process signal. For example, an analog 4-20 mA or 0 - 10 V input would be converted into an integer value of 0 - 32767.ExampleAs an example, say a facility needs to store water in a tank. The water is drawn from the tank by another system, as needed, and our example system must manage the water level in the tank.Using only digital signals, the PLC has two digital inputs from float switches (tank empty and tank full). The PLC uses a digital output to open and close the inlet valve into the tank.When the water level drops enough so that the tank empty float switch is off (down), the PLC will open the valve to let more water in. Once the water level raises enough so that the tank full switch is on (up), the PLC will shut the inlet to stop the water from overflowing.An analog system might use a water pressure sensor or a load cell, and an adjustable (throttling)dripping out of the tank, the valve adjusts to slowly drip water back into the tank.In this system, to avoid 'flutter' adjustments that can wear out the valve, many PLCs incorporate "hysteresis" which essentially creates a "deadband" of activity. A technician adjusts this deadband so the valve moves only for a significant change in rate. This will in turn minimize the motion of the valve, and reduce its wear.A real system might combine both approaches, using float switches and simple valves to prevent spills, and a rate sensor and rate valve to optimize refill rates and prevent water hammer. Backup and maintenance methods can make a real system very complicated.System scaleA small PLC will have a fixed number of connections built in for inputs and outputs. Typically, expansions are available if the base model does not have enough I/O.PLCs used in larger I/O systems may have peer-to-peer (P2P) communication between processors. This allows separate parts of a complex process to have individual control while allowing thesubsystems to co-ordinate over the communication link. These communication links are also often used for HMI (Human-Machine Interface) devices such as keypads or PC-type workstations. Some of today's PLCs can communicate over a wide range of media including RS-485, Coaxial, and even Ethernet for I/O control at network speeds up to 100 Mbit/s.ProgrammingEarly PLCs, up to the mid-1980s, were programmed using proprietary programming panels or special-purpose programming terminals. they were designed to replace relay logic systems. These PLCs were programmed in "ladder logic", which strongly resembles a schematic diagram of relay logic. Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a Very High Level Programming Language designed to program PLCs based on State Transition Diagrams.Recently, the International standard IEC 61131-3 has become popular. IEC 61131-3 currently defines five programming languages for programmable control systems: FBD (Function block diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming language), IL (Instruction list, similar to assembly language) and SFC (Sequential function chart). These techniques emphasize logical organization of operations.While the fundamental concepts of PLC programming are common to all manufacturers, differences in I/O addressing, memoryorganization and instruction sets mean that PLC programs are never perfectly interchangeable between different makers. Even within the same product line of a single manufacturer, different models may not be directly compatible.User interfacePLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday control. AHuman-Machine Interface (HMI) is employed for this purpose. HMI's are also referred to as MMI's (Man Machine Interface) and GUI (Graphical User Interface).A simple system may use buttons and lights to interact with the user. Text displays are available as well as graphical touch screens. Most modern PLCs can communicate over a network to some other system, such as a computer running a SCADA (Supervisory Control And Data Acquisition) system or web browser.CommunicationsPLCs usually have built in communications ports usually 9-Pin RS232, and optionally for RS485 and Ethernet. Modbus or DF1 is usually included as one of the communications protocols. Others' options include various fieldbuses such as DeviceNet or Profibus.HistoryThe PLC was invented in response to the needs of the American automotive industry. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using relays, timers and dedicated closed-loopcontrollers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as the relay systems needed to be rewired by skilled electricians. In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems.The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquired by German Company AEG and then by French Schneider Electric, the current owner.The automotive industry is still one of the largest users of PLCs, and Modicon still numbers some of its controller models. PLCs are used in many different industries and machines such as packaging and semiconductor machines. Well known PLC brands are Toshiba, Siemens, Allen-Bradley, ABB, Mitsubishi, Omron, and General Electric.PLC编程在升降机控制运用附录B 中文翻译可编程逻辑控制器辛西娅.库珀维基自由百科全书可编程逻辑控制器或者简易可编程控制器是一种数字化的计算机，它应用于工业自动化的生产过程中，比如工厂装配生产线中机械的控制。