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RelaysThe Programmable Logic ControllerEarly machines were controlled by mechanical means using cams, gears, levers and other basic mechanical devices. As the complexity grew, so did the need for a more sophisticated control system. This system contained wired relay and switch control elements. These elements were wired as required to provide the control logic necessary for the particular type of machine operation. This was acceptable for a machine that never needed to be changed or modified, but as manufacturing techniques improved and plant changeover to new products became more desirable and necessary, a more versatile means of controlling this equipment had to be developed. Hardwired relay and switch logic was cumbersome and time consuming to modify. Wiring had to be removed and replaced to provide for the new control scheme required. This modification was difficult and time consuming to design and install and any small "bug" in the design could be a major problem to correct since that also required rewiring of the system. A new means to modify control circuitry was needed. The development and testing ground for this new means was the U.S. auto industry. The time period was the late 1960's and early 1970's and the result was the programmable logic controller, or PLC. Automotive plants were confronted with a change in manufacturing techniques every time a model changed and, in some cases, for changes on the same model if improvements had to be made during the model year. The PLC provided an easy way to reprogram the wiring rather than actually rewiring the control system.The PLC that was developed during this time was not very easy to program. The language was cumbersome to write and required highly trained programmers. These early devices were merely relay replacements and could do very little else. The PLC has at first gradually, and in recent years rapidly developed into a sophisticated and highly versatile control system component. Units today are capable of performing complex math functions including numerical integration and differentiation and operate at the fast microprocessor speeds now available. Older PLCs were capable of only handling discrete inputs and outputs (that is, on-off type signals), while today's systems can accept and generate analog voltagesand currents as well as a wide range of voltage levels and pulsed signals. PLCs are also designed to be rugged. Unlike their personal computer cousin, they can typically withstand vibration, shock, elevated temperatures, and electrical noise to which manufacturing equipment is exposed.As more manufacturers become involved in PLC production and development, and PLC capabilities expand, the programming language is also expanding. This is necessary to allow the programming of these advanced capabilities. Also, manufacturers tend to develop their own versions of ladder logic language (the language used to program PLCs). This complicates learning to program PLC's in general since one language cannot be learned that is applicable to all types. However, as with other computer languages, once the basics of PLC operation and programming in ladder logic are learned, adapting to the various manufacturers’ devices is not a complicated process. Most system designers eventually settle on one particular manufacturer that produces a PLC that is personally comfortable to program and has the capabilities suited to his or her area of applications.It should be noted that in usage, a programmable logic controller is generally referred to as a “PLC” or “programmable controller”. Although the term “programmable controller” is generally accepted, it is not abbreviated “PC” because the abbreviation “PC” is usually used in reference to a personal computer. As we will see in this chapter, a PLC is by no means a personal computer.Programmable controllers (the shortened name used for programmable logic controllers) are much like personal computers in that the user can be overwhelmed by the vast array of options and configurations available. Also, like personal computers, the best teacher of which one to select is experience. As one gains experience with the various options and configurations available, it becomes less confusing to be able to select the unit that will best perform in a particular application.The typical system components for a modularized PLC are:1. Processor.The processor (sometimes call a CPU), as in the self contained units, is generally specified according to memory required for the program to beimplemented. In themodularized versions, capability can also be a factor. This includes features such as higher math functions, PID control loops and optional programming commands. The processor consists of the microprocessor, system memory, serial communication ports for printer, PLC LAN link and external programming device and, in some cases, the system power supply to power the processor and I/O modules.2. Mounting rack.3. Input and output modules.Input and output (I/O) modules are specified according to the input and output signals associated with the particular application. These modules fall into the categories of discrete, analog, high speed counter or register types.Discrete I/O modules are generally capable of handling 8 or 16 and, in some cases 32, on-off type inputs or outputs per module. Modules are specified as input or output but generally not both although some manufacturers now offer modules that can be configured with both input and output points in the same unit. The module can be specified as AC only, DC only or AC/DC along with the voltage values for which it is designed.Analog input and output modules are available and are specified according to the desired resolution and voltage or current range. As with discrete modules, these are generally input or output; however some manufacturers provide analog input and output in the same module. Analog modules are also available which can directly accept thermocouple inputs for temperature measurement and monitoring by the PLC.Pulsed inputs to the PLC can be accepted using a high speed countermodule. This module can be capable of measuring the frequency of an inputsignal from a tachometer or other frequency generating device. These modules can also count the incoming pulses if desired. Generally, both frequency and count are available from the same module at the same time if both are required in the application.Register input and output modules transfer 8 or 16 bit words of information to and from the PLC. These words are generally numbers (BCD or Binary) which are generated from thumbwheel switches or encoder systems for input or data to be output to a display device by the PLC.Other types of modules may be available depending upon the manufacturer of the PLC and it's capabilities. These include specialized communication modules to allow for the transfer of information from one controller to another. One new development is an I/O Module which allows the serial transfer of information to remote I/O units that can be as far as 12,000 feet away.4. Power supply.The power supply specified depends upon the manufacturer's PLC being utilized in the application. As stated above, in some cases a power supply capable of delivering all required power for the system is furnished as part of the processor module. If the power supply is a separate module, it must be capable of delivering a current greater than the sum of all the currents needed by the other modules. For systems with the power supply inside the CPU module, there may be some modules in the system which require excessive power not available from the processor either because of voltage or current requirements that can only be achieved through the addition of a second power source. This is generally true if analog or external communication modules are present since these require ± DC supplies which, in the case of analog modules, must be well regulated.5. Programming unit.The programming unit allows the engineer or technician to enter and edit the program to be executed. In it's simplest form it can be a hand held device with a keypad for program entry and a display device (LED or LCD) for viewing program steps or functions, as shown. More advanced systems employ a separate personal computer which allows the programmer to write, view, edit and download the program to the PLC. This is accomplished with proprietary software available from the PLC manufacturer. This software also allows the programmer or engineer to monitor the PLC as it is running the program. With this monitoring system, such things as internal coils, registers, timers and other items not visible externally can be monitored to determine proper operation. Also, internal register data can be altered if required to fine tune program operation. This can be advantageous when debugging the program. Communication with the programmable controller with this system is via a cable connected to a special programming port on the controller. Connection to the personalcomputer can be through a serial port or from a dedicated card installed in the computer.A Programmable Controller is a specialized computer. Since it is a computer, it has all the basic component parts that any other computer has; a Central Processing Unit, Memory, Input Interfacing and Output Interfacing.The Central Processing Unit (CPU) is the control portion of the PLC. It interprets the program commands retrieved from memory and acts on those commands. In present day PLC's this unit is a microprocessor based system. The CPU is housed in the processor module of modularized systems.Memory in the system is generally of two types; ROM and RAM. The ROM memory contains the program information that allows the CPU to interpret and act on the Ladder Logic program stored in the RAM memory. RAM memory is generally kept alive with an on-board battery so that ladder programming is not lost when the system power is removed. This battery can be a standard dry cell or rechargeable nickel-cadmium type. Newer PLC units are now available with Electrically Erasable Programmable Read Only Memory (EEPROM) which does not require a battery. Memory is also housed in the processor module in modular systems.Input units can be any of several different types depending on input signals expected as described above. The input section can accept discrete or analog signals of various voltage and current levels. Present day controllers offer discrete signal inputs of both AC and DC voltages from TTL to 250 VDC and from 5 to 250 V AC. Analog input units can accept input levels such as ±10 VDC, ±5 VDC and 4-20 ma. current loop values. Discrete input units present each input to the CPU as a single 1 or 0 while analog input units contain analog to digital conversion circuitry and present the input voltage to the CPU as binary number normalized to the maximum count available from the unit. The number of bits representing the input voltage or current depends upon the resolution of the unit. This number generally contains a defined number of magnitude bits and a sign bit. Register input units present the word input to the CPU as it is received (Binary or BCD).Output units operate much the same as the input units with the exception that the unit is either sinking (supplying a ground) or sourcing (providing a voltage) discrete voltages orsourcing analog voltage or current. These output signals are presented as directed by the CPU. The output circuit of discrete units can be transistors for TTL and higher DC voltage or Triacs for AC voltage outputs. For higher current applications and situations where a physical contact closure is required, mechanical relay contacts are available. These higher currents, however, are generally limited to about 2-3 amperes. The analog output units have internal circuitry which performs the digital to analog conversion and generates the variable voltage or current output.The first thing the PLC does when it begins to function is update I/O. This means that all discrete input states are recorded from the input unit and all discrete states to be output are transferred to the output unit. Register data generally has specific addresses associated with it for both input and output data referred to as input and output registers. These registers are available to the input and output modules requiring them and are updated with the discrete data. Since this is input/output updating, it is referred to as I/O Update. The updating of discrete input and output information is accomplished with the use of input and output image registers set aside in the PLC memory. Each discrete input point has associated with it one bit of an input image register. Likewise, each discrete output point has one bit of an output image register associated with it. When I/O updating occurs, each input point that is ON at that time will cause a 1 to be set at the bit address associated with that particular input. If the input is off, a 0 will be set into the bit address. Memory in today's PLC's is generally configured in 16 bit words. This means that one word of memory can store the states of 16 discrete input points. Therefore, there may be a number of words of memory set aside as the input and output image registers. At I/O update, the status of the input image register is set according to the state of all discrete inputs and the status of the output image register is transferred to the output unit. This transfer of information typically only occurs at I/O update. It may be forced to occur at other times in PLC's which have an Immediate I/O Update command. This command will force the PLC to update the I/O at other times although this would be a special case.Before a study of PLC programming can begin, it is important to gain a fundamental understanding of the various types of PLCs available, the advantages and disadvantages ofeach, and the way in which a PLC executes a program. The open frame, shoebox, and modular PLCs are each best suited to specific types of applications based on the environmental conditions, number of inputs and outputs, ease of expansion, and method of entering and monitoring the program. Additionally, programming requires a prior knowledge of the manner in which a PLC receives input information, executes a program, and sends output information. With this information, we are now prepared to begin a study of PLC programming techniques.When writing programs for PLCs, it is beneficial to have a background in ladder diagramming for machine controls. This is basically the material that was covered in Chapter 1 of this text. The reason for this is that at a fundamental level, ladder logic programs for PLCs are very similar to electrical ladder diagrams. This is no coincidence.The engineers that developed the PLC programming language were sensitive to the fact that most engineers, technicians and electricians who work with electrical machines on a day-to-day basis will be familiar with this method of representing control logic. This would allow someone new to PLCs, but familiar with control diagrams, to be able to adapt very quickly to the programming language. It is likely that PLC programming language is one of the easiest programming languages to learn.可编程序控制器早期的机器用机械的方法采用凸轮控制、齿轮、杠杆和其他基本机械设备。

关于plc的外文文献翻译中英文翻译外文翻译

外文资料译文PLC technique discussion and future developmentAlong with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise.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 pathPLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipments, the people havealready no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot of problems for face on sweep but light, do you understand the HMI? Says the HMI here you basically not clear what it is, also have no interest understanding, change one inside text explains it into the touch to hold or man-machine interface you knew, and it combines with the PLC to our larger space.When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.The PLC still has the function that the high class counts the machine, being us while accept some dates of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class.You heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in the inner part of PLC, wecan establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the procedure exceeds WDT constitution time, the CPU turn but the WDT reset the appearance. The procedure restarts the movement, but will not carry on the breakage to the interruption.The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O card planks to carry on the share easily. A state software can pass all se hardwires link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat is to adopt this kind of way to make airship go up the sky.The development of the higher layer needs our continuous effort to obtain. The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.Knowing the available PLC network options and their best applications will ensure an efficient and flexible control system design.The programmable logic controller's (PLC's) ability to support a range of communication methods makes it an ideal control and data acquisition device for a wide variety of industrial automation and facility control applications. However, there is some confusion because so many possibilities exist. To help eliminate this confusion, let's list what communications are available and when they would be best applied.To understand the PLC's communications versatility, let's first define the terms used in describing the various systems.ASCII: This stands for "American Standard Code for Information Interchange." As shown in Fig. 1, when the letter "A" is transmitted, forinstance, it's automatically coded as "65" by the sending equipment. The receiving equipment translates the "65" back to the letter "A." Thus, different devices can communicate with each other as long as both use ASCII code.ASCII module: This intelligent PLC module is used for connecting PLCs to other devices also capable of communicating using ASCII code as a vehicle.Bus topology: This is a linear local area network (LAN) arrangement, as shown in Fig. 2A, in which individual nodes are tapped into a main communications cable at a single point and broadcast messages. These messages travel in both directions on the bus from the point of connection until they are dissipated by terminators at each end of the bus.CPU: This stands for "central processing unit," which actually is that part of a computer, PLC, or other intelligent device where arithmetic and logical operations are performed and instructions are decoded and executed.Daisy chain: This is a description of the connection of individual devices in a PLC network, where, as shown in Fig. 3, each device is connected to the next and communications signals pass from one unit to the next in a sequential fashion.Distributed control: This is an automation concept in which portions of an automated system are controlled by separate controllers, which are located in close proximity to their area of direct control (control is decentralized and spread out over the system).Host computer: This is a computer that's used to transfer data to, or receive data from, a PLC in a PLC/computer network.Intelligent device: This term describes any device equipped with its own CPU.I/O: This stands for "inputs and outputs," which are modules that handle data to the PLC (inputs) or signals from the PLC (outputs) to an external device.Kbps: This stands for "thousand bits per second," which is a rate of measure for electronic data transfer.Mbps: This stands for "million bits per second."Node: This term is applied to any one of the positions or stations in a network. Each node incorporates a device that can communicate with all other devices on the network.Protocol: The definition of how data is arranged and coded for transmission on a network.Ring topology. This is a LAN arrangement, as shown in Fig. 2C, in which each node is connected to two other nodes, resulting in a continuous, closed, circular path or loop for messages to circulate, usually in one direction. Some ring topologies have a special "loop back" feature that allows them to continue functioning even if the main cable is severed.RS232. This is an IEEE standard for serial communications that describes specific wiring connections, voltage levels, and other operating parameters for electronic data communications. There also are several other RS standards defined.Serial: This is an electronic data transfer scheme in which information is transmitted one bit at a time.Serial port: This the communications access point on a device that is set up for serial communications.Star topology. This is a LAN arrangement in which, as shown in Fig. 2B, nodes are connected to one another through a central hub, which can be active or passive. An active hub performs network duties such as message routing and maintenance. A passive central hub simply passes the message along to all the nodes connected to it.Topology: This relates to a specific arrangement of nodes in a LAN in relation to one another.Transparent: This term describes automatic events or processes built into a system that require no special programming or prompting from an operator.Now that we're familiar with these terms, let's see how they are used in describing the available PLC network options.PLC network optionsPLC networks provide you with a variety of networking options to meet specific control and communications requirements. Typical options include remote I/O, peer-to-peer, and host computer communications, as well as LANs. These networks can provide reliable and cost-effective communications between as few as two or as many as several hundred PLCs, computers, and other intelligent devices.Many PLC vendors offer proprietary networking systems that are unique and will not communicate with another make of PLC. This is because of the different communications protocols, command sequences, error-checking schemes, and communications media used by each manufacturer.However, it is possible to make different PLCs "talk" to one another; what's required is an ASCII interface for the connection(s), along with considerable work with software.Remote I/0 systemsA remote I/O configuration, as shown in Fig. 4A, has the actual inputs and outputs at some distance from the controller and CPU. This type of system, which can be described as a "master-and-slave" configuration, allows many distant digital and analog points to be controlled by a single PLC. Typically, remote I/Os are connected to the CPU via twisted pair or fiber optic cables.Remote I/O configurations can be extremely cost-effective control solutions where only a few I/O points are needed in widely separated areas. In this situation, it's not always necessary, or practical for that matter, to have a controller at each site. Nor is it practical to individually hard wire each I/O point over long distances back to the CPU. For example, remote I/O systems can be used in acquiring data from remote plant or facility locations. Information such as cycle times, counts, duration or events, etc. then can be sent back to the PLC for maintenance and management reporting.In a remote I/O configuration, the master controller polls the slaved I/O for its current I/O status. The remote I/O system responds, and the master PLCthen signals the remote I/O to change the state of outputs as dictated by the control program in the PLC's memory. This entire cycle occurs hundreds of times per second.Peer-to-peer networksPeer-to-peer networks, as shown in Fig. 4B, enhance reliability by decentralizing the control functions without sacrificing coordinated control. In this type of network, numerous PLCs are connected to one another in a daisy-chain fashion, and a common memory table is duplicated in the memory of each. In this way, when any PLC writes data to this memory area, the information is automatically transferred to all other PLCs in the network. They then can use this information in their own operating programs.With peer-to-peer networks, each PLC in the network is responsible for its own control site and only needs to be programmed for its own area of responsibility. This aspect of the network significantly reduces programming and debugging complexity; because all communications occur transparently to the user, communications programming is reduced to simple read-and-write statements.In a peer-to-peer system, there's no master PLC. However, it's possible to designate one of the PLCs as a master for use as a type of group controller. This PLC then can be used to accept input information from an operator input terminal, for example, sending all the necessary parameters to other PLCs and coordinating the sequencing of various events.Host computer linksPLCs also can be connected with computers or other intelligent devices. In fact, most PLCs, from the small to the very large, can be directly connected to a computer or part of a multi drop host computer network via RS232C or RS422 ports. This combination of computer and controller maximizes the capabilities of the PLC, for control and data acquisition, as well as the computer, for data processing, documentation, and operator interface.In a PLC/computer network, as shown in Fig. 4C, all communications areinitiated by the host computer, which is connected to all the PLCs in a daisy-chain fashion. This computer individually addresses each of its networked PLCs and asks for specific information. The addressed PLC then sends this information to the computer for storage and further analysis. This cycle occurs hundreds of times per second.Host computers also can aid in programming PLCs; powerful programming and documentation software is available for program development. Programs then can be written on the computer in relay ladder logic and downloaded into the PLC. In this way, you can create, modify, debug, and monitor PLC programs via a computer terminal.In addition to host computers, PLCs often must interface with other devices, such as operator interface terminals for large security and building management systems. Although many intelligent devices can communicate directly with PLCs via conventional RS232C ports and serial ASCII code, some don't have the software ability to interface with individual PLC models. Instead, they typically send and receive data in fixed formats. It's the PLC programmer's responsibility to provide the necessary software interface.The easiest way to provide such an interface to fixed-format intelligent devices is to use an ASCII/BASIC module on the PLC. This module is essentially a small computer that plugs into the bus of the PLC. Equipped with RS232 ports and programmed in BASIC, the module easily can handle ASCII communications with peripheral devices, data acquisition functions, programming sequences, "number crunching," report and display generation, and other requirements.Access, protocol, and modulation functions of LANsBy using standard interfaces and protocols, LANs allow a mix of devices (PLCs, PCs, mainframe computers, operator interface terminals, etc.) from many different vendors to communicate with others on the network.Access: A LAN's access method prevents the occurrence of more than one message on the network at a time. There are two common access methods.Collision detection is where the nodes "listen" to the network and transmit only if there are no other messages on the network. If two nodes transmit simultaneously, the collision is detected and both nodes retransmit until their messages get through properly.Token passing allows each node to transmit only if it's in possession of a special electronic message called a token. The token is passed from node to node, allowing each an opportunity to transmit without interference. Tokens usually have a time limit to prevent a single node from tying up the token for a long period of time.Protocol: Network protocols define the way messages are arranged and coded for transmission on the LAN. The following are two common types.Proprietary protocols are unique message arrangements and coding developed by a specific vendor for use with that vendor's product only.Open protocols are based on industry standards such as TCP/IP or ISO/OSI models and are openly published.Modulation: Network modulation refers to the way messages are encoded for transmission over a cable. The two most common types are broadband and baseband.Network transmission interfacesThe vast majority of PLC communications is done via RS232C and twisted pair cables. Most PLCs have an RS232 port and are capable of handling communications with host computers, printers, terminals, and other devices. Maximum transmission speed is Kbps.The distance and data transmission rates are standards for the various interfaces. Their actual performance is a function of the driving devices and varies significantly between manufacturers. As such, you should consult the manufacturer's specifications for actual distance and data transmission rate capabilities.The only real limitation on RS232C is the 50-ft recommended distance between devices. While RS232C installations often can achieve cablingdistances greater than this, the "unbalanced" design of the interface results in a greater susceptibility to surrounding electrical noise and reduced data integrity. This is particularly true where electromagnetic interference (EMI) and radio-frequency interference (RFI) are known to exist.When longer transmission distances are needed, RS422 is a better choice. Unlike the RS232C interface, RS422 is "balanced." Each of its primary signals consists of two wires that are always at opposite logic levels, with respect to signal ground. As a result, the interface can achieve longer transmission distance (4000 ft) and higher data transmission rates (up to 90 Kbps). In shorter runs (less than 50 ft), data transfer can reach 10 Mbps.Fiber optic communications are gaining greater acceptance and are being used in more and more installations. Fiber optic cable is virtually impervious to harsh environmental conditions and electrical noise. Also, these links can span extremely long distances and transmit data at very high speeds. For example, in some LAN systems, these links can transmit at relatively high speeds and span long distances before requiring a repeater. When repeaters are used, virtually unlimited distances can be achieved.可编程操纵器技术讨论与以后进展随着时期的进展,现今的技术也日趋完善、竞争愈演愈烈;单靠人工的操作已不能知足于目前的制造业前景,也无法保证更高质量的要求和高新技术企业的形象.人们在生产实践中看到,自动化给人们带来了极大的便利和产品质量上的保证,同时也减轻了人员的劳动强度,减少了人员上的编制.在许多复杂的生产进程中难以实现的目标操纵、整体优化、最正确决策等,熟练的操作工、技术人员或专家、治理者却能够容易判定和操作,能够取得中意的成效.人工智能的研究目标正是利用运算机来实现、模拟这些智能行为,通过人脑与运算机和谐工作,以人机结合的模式,为解决十分复杂的问题寻觅最正确的途径PLC的语言并非是咱们所想象的汇编语言或C语言来进行编程，而是采纳原有的继电器操纵的梯形图，使得电气工程师在编写程序时很容易就明白得了PLC的语言，而且很多的非电气专业人士也对PLC专门快熟悉并深切。

(完整版)PLC英文文献+翻译

自动化专业本科毕业设计英文翻译学院(部)：专业班级：学生姓名：指导教师：年月日Programmable Logic ControllerONE：PLC overviewProgrammable 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 Corporation. 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 a 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.First, high reliability, anti-interference capability;Second，programming visual, simple;Third, adaptability good;Fourth functional improvements, strong functional interface. TWO：History of PLCProgrammable 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 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 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 indicatingIf houses were built like software projects, a single woodpecker could d estroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladderlogic 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 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 reconfigurability 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. Three：now of PLCFrom the structure is divided into fixed PLC and Module PLC, the two kinds of PLC including CPU board, I/O board, display panel, memory block, power, these elements into a do not remove overall. Module type PLC including CPU module, I/O modules, memory, thepower modules, bottom or a frame, these modules can be according to certain rules combination configuration.In the user view, a detailed analysis of the CPU's internal unnecessary, but working mechanism of every part of the circuit. The CPU control works, by it reads CPU instruction, interprets the instruction and executes instructions. But the pace of work by shock signal control.Unit work under the controller command used in a digital or logic operations.In computing and storage register of computation result, it is also among the controller command and work. CPU speed and memory capacity is the important parameters fot PLC . its determines the PLC speed of work, IO PLC number and software capacity, so limits to control size.Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output.System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated foram ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development.User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory.PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time to time whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established communication networks which regularly check programs in PLC controllers to ensure execution only of good programs).Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines), program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that come up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions.Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220V AC. On some PLC controllers you’ll find electrical supply as a separatemodule. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current.This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC.Four：PLC design criteriaA 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 inreal-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 [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 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.Today, 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.From 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.可编程控制器一、PLC概述可编程控制器是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。

plc单片机毕业论文文献翻译中英文对照

外文翻译：The monolithic In order to prevent without authorization the visit or the copy monolithic integrated circuit machine in the procedure, the majority of monolithic integrated circuits all has the encryption to lock the localization or the encryption byte, by protects the internal procedure. If in programming time encrypts locks the localization to enable (locking), is unable with the ordinary programming directly reading in the monolithic integrated circuit the procedure, this is the so-called copy protection or says the fixed function. In fact, such protective measures are very frail, is very easily explained. The monolithic integrated circuit aggressor with the aid of the special purpose equipment or the self-made equipment, using the monolithic integrated circuit chip design in loophole or the software flaw, through the many kinds of technical method, may withdraw the essential information from the chip, gains in the monolithic integrated circuit the procedure. Therefore, has the newest technology extremely as electronic products project engineer which the essential understanding current monolithic integrated circuit attacks, achieves knows oneself and the other side, knows fairly well, can effectively prevent oneself spends the product which the massive moneys and the time laboriously designs the matter occurrence which is counterfeited by a others night between.monolithic integrated circuits attacks technology：At present, attacks the monolithic integrated circuit mainly to have four kind of technologies, respectively is:This technical usual use processor correspondence connection and in the use agreement, the encryption algorithm or these algorithm security loophole carries on the attack. The software attack obtains the success a case in point is to early A T M E L A the T 89 C series monolithic integrated circuit attack. The aggressor has used in this series monolithic integrated circuit cleaning operation succession design loophole, uses from arranges the procedure to lock the localization after the cleaning encryption, stops the next step of cleaning internal program memory data the operation, thus makes to add the dense monolithic integrated circuit not to turn the encryption monolithic integrated circuit, then use programming read-out internal procedure.This technology usually monitors the processor by the high time resolution when the normal operation all power sources and the connection connection simulation characteristic, and through monitors its electromagnetic radiation characteristic to implement the attack. Because the monolithic integrated circuit is an active electronic device, when it carries out the different instruction, the corresponding mains input consumption also correspondingly changes. Like this analyzes and examines these changes through the use special electronic surveying instrument and mathematics statistical method, then gains in the monolithic integrated circuit the specific essential information.the mistake has the technology This technical use exceptionally working condition causes the processor to make a mistake, then provides the extra visit to carry on the attack. Uses the most widespread mistake to have the attack method including the voltage impact and the clock impact. The low voltage and the high voltage attack may usefor to forbid the protection circuit work or to fortected the information. The power source and the clock transient state jump may affect the single scroll instruction in certain processors the decoding and the ece the processor to carry out the misoperation. Perhaps the clock transient state jump can reposition the protection circuit but not to be able to destroy is proxecution.This technology is the direct exposed chip interior segment, then the observation, holds controls, disturbs the monolithic integrated circuit by to achieve the attack goal.In order to facilitate in order to, the people divide into above four kind of attacks technology two kinds, a kind is the invasion attack (physical attack), this kind of attack needs to destroy the seal, then with the aid of the semiconductor test facility, the microscope and the micro locator, several hours even several week time can complete on the special laboratory flower. All micro probes technology all belongs to the invasion attack. Moreover three methods belong to the non- invasion attack, the monolithic integrated circuit which attacks cannot by the physical damage. In certain situation non- invasion attacks is specially dangerous, this is because the non- invasion attack needs the equipment usually to be possible the self-restraint and the promotion, therefore is extremely inexpensive.The majority of non- invasions attack needs the aggressor to have the good processor knowledge and the software knowledge. Is opposite with it, the invasion probe attack then does not need too many initial knowledge,moreover usually may use the one whole set similar technology to cope with the width scope the product. Therefore, the attack often starts to the monolithic integrated circuit from the invasion reverse engineering, the accumulation experience is helpful to the development more inexpensive and the fast non- invasion attack technology.Last step will be seeks the protection melt silk the position and protects the melt silk to expose under the ultraviolet ray. With enlargement factor at least 100 time of microscopes, inputs the foot from the programming voltage the segment to track generally, seeks the protection melt silk.This technical use exceptionally working condition causes the processor to make a mistake, then provides the extra visit to carry on the attack. Uses the most widespread mistake to have the attack method including the voltage impact and the clock impact. The low voltage and the high voltage attack may use for to forbid the protection circuit work or to force the processor to carry out the misoperation. Perhaps the clock transient state jump can reposition the protection circuit but not to be able to destroy is protected the information. The power source and the clock transient state jump may affect the single scroll instruction in certain processors the decoding and the execution.(4) probe technologyThis technology is the direct exposed chip interior segment, then the observation, holds controls, disturbs the monolithic integrated circuit by to achieve the attack goal.In order to facilitate in order to, the people divide into above four kindof attacks technology two kinds, a kind is the invasion attack (physical attack), this kind of attack needs to destroy the seal, then with the aid of the semiconductor test facility, the microscope and the micro locator, several hours even several week time can complete on the special laboratory flower. All micro probes technology all belongs to the invasion attack. Moreover three methods belong to the non- invasion attack, the monolithic integrated circuit which attacks cannot by the physical damage. In certain situation non- invasion attacks is specially dangerous, this is because the non- invasion attack needs the equipment usually to be possible the self-restraint and the promotion, therefore is extremely inexpensive.The majority of non- invasions attack needs the aggressor to have the good processor knowledge and the software knowledge. Is opposite with it, the invasion probe attack then does not need too many initial knowledge,moreover usually may use the one whole set similar technology to cope with the width scope the product. Therefore, the attack often starts to the monolithic integrated circuit from the invasion reverse engineering, the accumulation experience is helpful to the development more inexpensive and the fast non- invasion attack technology.3 invasions attacks general process：The invasion attack first step uncovers the chip seal. Some two methods may achieve this goal: The first kind is dissolves the chip seal completely, the exposed metal segment. The second kind is only moves above the silicon nucleus plastic seal. The first method needs the chip to tests on the jig, with the aid of Taiwan to operate. The second method except needs to have the aggressor certain knowledge and Wants outside skill, but also needs individual wisdom and the patience, but operates relatively quite is convenient.Above the chip plastic may use the knife to open, around the chip epoxy resin may use the aqua fortis perish. The hot aqua fortis can dissolve the chip seal but not to be able to affect the chip and the segment. This process carries on generally under the extremely dry condition, because the water existence possibly can corrode already the aluminum wire connection which exposes.Then first uses the acetone in the supersonic pond to clean this chip by except the remaining nitric acid, then cleans with the clear water by and is dry except the salinity. Not the supersonic pond, jumps over generally this step. In this kind of situation, the chip surface can a little dirty, but not too affects the ultraviolet ray to the chip operation effect.Last step will be seeks the protection melt silk the position and protects the melt silk to expose under the ultraviolet ray. With enlargement factor at least 100 time of microscopes, inputs the foot from the programming voltage the segment to track generally, seeks the protection melt silk.If does not have the microscope, then uses the chip different partially exposes to the ultraviolet ray under and the observed result way carries on the simple search. When operation applies not the opaque slip of paper cover chipby to protect the program memory not by the ultraviolet ray cleaning. Will protect the melt silk to expose in the ultraviolet ray next 5 ~ 10 minutes can broken the protection position protective function, afterwards, will use the simple programming to be possible the direct readout program memory content.Regarding used the protective layer to protect E E P R O the M unit the monolithic integrated circuit to say that, the use ultraviolet ray repositioned the protection circuit is not feasible. Regarding this kind of type monolithic integrated circuit, uses the micro probe technology reading the memory content generally. Opens after the chip seal, puts in the chip under the microscope to be able very easy finding中文翻译单片机为了防止未经授权访问或拷贝单片机的机内程序，大部分单片机都带有加密锁定位或者加密字节，以保护片内程序。

PLC的发展方向外文文献翻译、中英文翻译

外文资料The development direction of PLC:One is the development of the PLC operation in the direction of simplification.At present, one of the difficulties of PLC popularization is that the complicated programming makes the user prohibitive, and all programming languages of PLC are not the same in different manufacturers. Users often need to master more programming languages, which are difficult to control. Pid control, network communication, and so on. The programming and application of high speed counter, position control, data recording, formula and text display are also the difficulties in PLC programming. When programming them with common methods, we need to be familiar with the meaning of the special memory. They are assigned values at programming time and are accessed by the runtime to achieve corresponding functions. These programs also tend to have to do with interruptions. The process is cumbersome and error-prone, which hinders the further application of PLC. The development of PLC is bound to simplify the programming of complex tasks. At this point, Siemens acts as the forerunner, and only needs to input some parameters in the dialog box. Automatic generation of user programs, including interrupt programs, greatly facilitate the use of users.Second, PLC to high performance miniaturization direction development.PLC's function is getting richer and richer, and the volume is getting smaller and smaller. For example, Mitsubishi's FX-IS series PLC, the smallest type of machine, is only 60 × 90 × 75mm in volume, equivalent to a relay, but it has the ability to count at high speed, slope, alternate output and 16-bit four-bit operation, etc. It also has the adjustable potentiometer time setting function. PLC is no longer the early product that can only perform the logic operation of the switch quantity, but it has more and more powerful analog processing ability. And other advanced processing capabilities that used to be available only on computers, such as floating-point operations such as pid control, temperature control, precision Positioning, step drive, report statistics and so on. In this sense, the difference between PLC system and DCS (distributed Controlsystem) is becoming smaller and smaller. A process control system can also be constructed by using PLC.Third, the development of PLC network technology.There are two trends: on the one hand, the PLC network system is no longer a self-contained system, but is rapidly developing to an open system. In addition to forming its own characteristic PLC network system, the major brand PLC can also connect with the upper computer management system to achieve information communication and become a whole. Part of the information management system; on the other hand, field bus technology is widely used, PLC and other intelligent equipment installed on the site, such as intelligent instruments, sensors, intelligent solenoid valves, intelligent drive actuators, and so on, through a transmission medium (like twisted pair) Wires, coaxial cables, optical cables) link together and transmit information to each other according to the same communication protocol, thus forming a field network, which is more flexible in configuration, more convenient in expansion, and cheaper in cost than the simple PLC remote network. Performance price ratio is better, also more open meaning.Fourth, embedded PLC has a great space for development.The development of embedded PLC is diversified and has good performance at home and abroad: the netPLC, which combines fieldbus technology and PLC technology, introduced by Heuxun, Germany, has its own characteristics; A few years ago in China, Huazhong University of Science and Technology loaded embedded PLC system software into the EASYCORE1.00 core chipset as a hardware platform. The embedded PLC with multi-mode human channel is developed, and another development path is to develop the hardware / software integration of PLC and man-machine interface, which makes full use of case tools. Combined with the development platform and input of all kinds of embedded chips The hardware circuit library of the output channel is specially designed for developing customized PLC with ODM property for electromechanical equipment.The development space of embedded PLC in our country lies in the fact that it is very helpful to bring into full play the two characteristics of the development of automation industry in our country: there is a very strong market foundation for supporting electromechanical equipment, and it has enough, The best design and development team in the world. We can replace the universal PLC with the lowest cost, higher quality and custom-made design and production of embedded PLC.At the same time, the hardware, software, man-machine interface, communication and other aspects of embedded PLC function design is flexible, easy to cut, more close to the requirements of various grades of mechanical and electrical equipment. Embedded PLC is completely based on the technical foundation of embedded system. It can be used as .SOC chip, embedded operating system and programming environment that accords with EC61131-3 programming language standard, which makes it easy to find in the market.中文译文PLC的发展方向：一是PLC操作向简易化方向发展。

(完整版)PLC毕业设计的外文文献(及翻译)

PLC technique discussion and future developmentT.J.byersElectronic Test Equipment-principles and ApplicationsPrinceton University .AmericaAlong with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise.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.We come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only; And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide.The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipmentsdirect conjunction of the small power can.PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine; The saving machine can deposit the data that the I/ O input in the saving machine, and in work adjusting to become tired to add the machine and I/ Os to connect, saving machine separately saving machine RAM of the procedure saving machine ROM and dates, the ROM can do deposit of the data permanence in the saving machine, but RAM only for the CPU computes the temporary calculation usage of hour of buffer space.The PLC anti- interference is very and excellent, our root need not concern its service life and the work situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of the equipments for us, make our equipments more gentle.PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipments, the people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot of problems for face on sweep but light, do you understand the HMI? Says the HMI here you basically not clear what it is, also have no interest understanding, change one inside text explains it into the touch to hold orman-machine interface you knew, it combines with the PLC to our larger space.HMI the control not only is reduced the control press button, increase the vivid of the control, more main of it is can sequence of, and at can the change data input to output the feedback with data, control in the temperature curve of imitate but also can keep the manifestation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies in one's power, the one who make operate reduces the otiose error. Currently the HMI factory is also more and more, the function is also more and more strong, the price is also more and more low, and the noodles of the usage are wide more and more. The HMI foreground can say that think to be good.At a lot of situations, the list is a smooth movement that can't guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, becoming a total body, the match of your that thus make is more close, at each other attain to reflect the result that mutually flick.The PLC correspondence has already come more body now its value, at the PLC and correspondence between Places, can pass the communication of the information and the share of the data’s to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver.The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data; But take data in the watch for an instruction procedure that controls the PLC, that had the difficulty very much, for example you have to control one pedestal robot to pressthe action work that you imagine, you will draw up for it the form that a procedure combine with the data sends out to pass by.The form that information transport contain single work, the half a work and the difference of a workers .The meaning of the single work also is to say both, a can send out only, but a can receive only, for example a spy he can receive the designation of the superior only, but can't give the superior reply; A work of half is also 2 and can send out similar to accept the data, but can't send out and accept at the same time, for example when you make a phone call is to can't answer the phone, the other party also; But whole pair works is both can send out and accept the data, and can send out and accept at the same time. Be like the Internet is a typical example.The process that information transport also has synchronous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the data, is also the data signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick, but correspond work time of take up the CPU and also want to be long oppositely, at the same time the technique difficulty also very big. Its request lies in canting have an error margins in a dates deliver, otherwise the whole piece according to compare the occurrence mistake, this on the hardware is a bigger difficulty. Applied more and more extensive in some appropriative equipments, be like the appropriative medical treatment equipments, the numerical signal equipments...etc., in compare the one data deliver, its result is very good.And the different step is an application the most extensive, this receive benefit in it of technique difficulty is opposite and want to be small, at the same time not need to prepare the specialized clock signal, its characteristics to lie in, its data is partition, the long-lost send out and accept, be the CPU is too busy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, the data throw to lose at the same time opposite want to be little, we can pass the examination of the data to observe whether the data that we send out has the mistake or not, be like strange accidentally the method, tired addition and eight efficacies method etc, can use to helps whether the data that we examine to send out have or not themistake occurrence, pass the feedback to carry on the discriminator.A line of transmission of the information contains a string of and combines the cent of: The usual PLC is 8 machines, certainly also having 16 machines. We can be at the time of sending out the data a send out to the other party, also can be 88 send out the data to the other party, and 8 differentiations are also the as that we say to send out the data and combine sends out the data. A speed is more and slowly, but as long as 2 or three lines can solve problem, and can use the telephone line to carry on the long range control. But combine the ocular transmission speed is very quick of, it is a string of ocular of 25600%, occupy the advantage in the short distance, the in view of the fact TTL electricity is even, being limited by the scope of one meter generally, it combine unwell used for the data transmission of the long pull, thus the cost is too expensive.Under a lot of circumstances we are total to like to adopt the string to combine the conversion chip to carry on deliver, under this kind of circumstance not need us to carry on to deposited the machine to establish too and complicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the correspondence, because the PLC of the other party must has been wait for your data exportation at the time of sending out the data, it can't do other works.When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and combine to continue with the one who knock on door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo come together knock on door to have a conversation, after dialogue complete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authority, also having sex of have the initiative, the PLC had such function .Its characteristics lie in us and may meet the urgently abrupt affairs in the operation process of the equipments, we want to stop to start immediately up of work, the whereabouts manages the more important affair, this kind of circumstance is we usually meet of, PLC while carry out urgent mission, total will keep the current appearance first, for example the address of the procedure, CPU of tired add the machine data etc., be like to stick down which the book that we see is when we open the door the page or simply make a mark, because we treat and would still need to continue immediately after book of see the behind.The CPU always does the affair that should do according to our will, but your mistake of give it an affair, it also would be same to do, this we must notice.The interruption is not only a, sometimes existing jointly with the hour several inside break, break off to have the preferred Class, they will carry out the interruption of the higher Class according to person's request. This kind of breaks off the medium interruption to also became to break off the set. The Class that certainly breaks off is relevant according to various resources of CPU with internal PLC; also following a heap of capacity size of also relevant fasten.The contents that break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept the interruption and settle and the clock that count break off, still have the WDT to reset the interruption etc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can't comprehend the internal structure and operation orders of the interruption completely also, we do a very small example to explain.Each equipment always will not forget a button, it also is at we meet the urgent circumstance use of that is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait for processing the over surprised empress recover the operation again. Nasty stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CPU, the CPU carries on to the I/ O to examine again, being to confirm to have the exterior to trigger the signal, CPU protection the spot breaks off procedure counts the machine turn the homologous exterior I/ O automatically in the procedure to go to also, be exterior interruption procedure processing complete, the procedure counts the machine to return the main procedure to continue to work. Have 1:00 can what to explain is we generally would nasty stop the button of exterior break off to rise to the tallest Class, thus guarantee the safety.When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.The PLC still has the function that the high class counts the machine, being us while accept some dates of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class.You heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in the inner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the procedure exceeds WDT constitution time, the CPU turn but the WDT reset the appearance. The procedure restarts the movement, but will not carry on the breakage to the interruption.The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O card planks to carry on the share easily. A state software can pass all se hardwires link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat No.5 is to adopt this kind of way to make airship go up the sky.The development of the higher layer needs our continuous effort to obtain. The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.可编程控制器技术讨论与未来发展T.J.拜尔斯（电子测试设备原理及应用普林斯顿大学）随着时代的发展，当今的技术也日趋完善、竞争愈演愈烈；单靠人工的操作已不能满足于目前的制造业前景，也无法保证更高质量的要求和高新技术企业的形象。

PLC的应用外文文献翻译、中英文翻译、外文翻译

Application of PLCPLC is one kind specially for the digital operation operation electronic installation which applies under the industry environment designs. It uses may the coding memory, uses for in its internal memory operation and so on actuating logic operation, sequence operation, time, counting and arithmetic operation instructions, and can through digital or the simulation-like input and the output, controls each type the machinery or the production process. PLC and the related auxiliary equipment should according to form a whole easy with the industrial control system, easy to expand its function the principle to design.”In the 1970s the last stage, the programmable controller entered the practical application development phase, the computer technology has introduced in comprehensively the programmable controller, causes its function to have the leap. The higher operating speed, the subminiature volume, the more reliable industry antijamming design, the simulation quantity operation, the PID function and the extremely high performance-to-price ratio has established it in the modern industry status. In the early-1980s, the programmable controller has obtained the widespread application in the advanced industrial nation. This time programmable controller develops the characteristic is large-scale, the high velocity, the high performance, the product seriation. This stage's another characteristic is in the world produces the programmable controller's country to increase day by day, the output rises day by day. This symbolizes that the programmable controller marched into the mature stage.The 20th century last stage, the programmable controller's development characteristic was even more adapts in the modern industry need. From the control scale, this time has developed the large-scale machinery and subminiature machine; From the control, was born various special function unit, used in the pressure, the temperature, the rotational speed, the displacement and so on all kinds of control situation; From product necessary ability, has produced each kind of man-machine contact surface unit, the correspondence unit, caused to apply the programmable controller's industrial control equipment necessary to be easier. At present, the programmable controller in domain and so on machine manufacture, petroleum chemical industry, metallurgy steel and iron, automobile, light industry applications obtained the considerable development.Our country programmable controller's introduction, applies, the development, the production to follow the reform and open policy to start. At first has used the programmable controller massively in the introduction equipment. Then expanded the PLC application unceasingly in each kind of enterprise's production equipment and the product. At present, our country have been possible to produce the middle and small scale programmable controller. East Shanghai the room electricity Limited company produces the CF series, Hangzhou engine bed electrical equipment factory production's DKK and D series, Dalian Aggregate machine-tool Research institute produces S series, the Suzhou Electronic accounting machine Factory production's YZ series and so on many kinds of products have had certain scale and have obtained the application in the manufactured products. In addition, the non-flowers of tin light company, Chinese-foreign joint ventures and so on Shanghai Township Island Company are also our country quite famous PLC Manufacturers. May anticipate that along with our country modernization process's thorough, PLC will have the broader application world in our country.Uses the manual operation in view of the YNL draw die machine electric control system, the existence operation is complex, the operation requests high, needs specially shortcomings and so on operators, has designed PLC the control system. Has given the electrical machinery main return route, the PLC periphery wiring diagram; Has established the systems operation trapezoidal chart and the instruction list; And to this system key element shaping. After the improvement control system has realized the entire system board process automation, not only raised the production efficiency, but also has saved the labor force, reduced the production cost, may obtain a greater economic efficiency.PLC的应用PLC是一种专门为在工业环境下应用而设计的数字运算操作的电子装置。

PLC概述外文文献翻译、中英文翻译、外文翻译

外文原文：ONE、PLC overviewProgrammable 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 Corporation. 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 a 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.First, high reliability, anti-interference capability;Second，programming visual, simple;Third, adaptability good;Fourth functional improvements, strong functional interface.TWO、History of PLCProgrammable 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`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 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 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 reconfigurability of manufacturing systems. A further problem, impelling the need for asystematic 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.Three、now of PLCFrom the structure is divided into fixed PLC and Module PLC, the two kinds of PLC including CPU board, I/O board, display panel, memory block, power, these elements into a do not remove overall. Module type PLC including CPU module, I/O modules, memory, the power modules, bottom or a frame, these modules can be according to certain rules combination configuration.In the user view, a detailed analysis of the CPU's internal unnecessary, but working mechanism of every part of the circuit. The CPU control works, by it reads CPU instruction, interprets the instruction and executes instructions. But the pace of work by shock signal control.Unit work under the controller command used in a digital or logic operations.In computing and storage register of computation result, it is also among the controller command and work. CPU speed and memory capacity is the important parameters fot PLC . its determines the PLC speed of work, IO PLC number and software capacity, so limits to control size. Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output.System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating systemit also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development.User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/ each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory.PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time to time whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established communication networks which regularly check programs in PLC controllers to ensure execution only of good programs).Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines), program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that come up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions.Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 VAC. On some PLC controllers you’ll find electrical supply as a separatemodule. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current.This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC.Four、PLC design criteriaA 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 inreal-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 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 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.Today, 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.From 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 isimpossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.Five、AK 1703 ACPFollowing the principle of our product development, AK 1703 ACP has high functionality and flexibility, through the implementation of innovative and reliable technologies, on the stable basis of a reliable product platform.For this, the system concept ACP (Automation, Control and Protection) creates the technological preconditions. Balanced functionality permits the flexible combination of automation, telecontrol and communication tasks. Complemented with the scalable performance and various redundancy configurations, an optimal adaptation to the respective requirements of the process is achieved.AK 1703 ACP is thus perfectly suitable for automation with integrated telecontrol technology as:• Telecontrol substation or central device• Auto mation unit with autonomous functional groups• Data node, station control device, front-end or gateway• With local or remote peripherals• For rear panel installation or 19 inch assembly• Branch-neutral product, therefore versatile fields of application and high productstability• Versatile communication• Easy engineering• Plug & play for spare parts• Open system architecture• Scalable redundancy• The intelligent terminal - TM 1703The Base Unit AK 1703 ACP with Peripheral Elements has one basic system element CP-2010/CPC25 (Master control element) and CP-2012/PCCE25 (Processing and communication element) ,one bus line with max. 16 peripheral elements can be connected.CP-2010/CPC25 Features and FunctionsSystem Functions:• Central element,coordinating all system servicesCentral hub function for all connected basic system elements• Time managementCentral clock of the automation unitSetting anf keeping the own clock`s time with a resolution of 10ms Synchronization via serid communication via LAN or local• RedundancyVoting and change-over for redundant processing and communication elements of the own automation unitSupports voting and change-over by an external SCA-RS redundancy switchSupports applicational voting and change-over by an exterual system,e.g.a control system• SAT TOLLBOX|| connectionStoring firmware and parameters on a Flash CardCommunication:• Communication via installable protocol elements to any superior or subordinate automation unit• Automatic data flow routing• Priority based data transmission (priority control)•Own circular buffer and process image for each connected station(data keeping)• Redundant communication routesCommunication with redundant remote stations• Special application specific functions for dial-up trafficTest if stations are reachableProcess Peripherals:• Tansmission of spontaneous information objects from and to peripheral elements, via the serial Ax 1703 peripheral bus Functions for Automatoin:• Open-/closed-loop control function for the execution of freely definable user programs which are created with CAEX plus according to IEC 61131-3,ing function diagram technology512KB for user programApprox 50.000 variables and signals,2.000 of them retainedCycle of 10ms or a multiphe thereofOnline testLoadable without service interruption• Redundant open-/closed-loop control functionsSynchronization via redundancy linkTransmission of periodic process information between theopen-/closed-loop control function and the peripheral elements,via the serial Ax 1703 peripheral busSIX、SIEMENS PLCSIMATIC S7-300 series PLC applied to all walks of life and various occasions in the detection, monitoring and control of automation, its power to both the independent operation of, or connected to a network able to achieve complex control.The photoelectric products with isolation, high electromagnetic compatibility; have high industrial applicability, allowing the ambient temperature of 60 ℃; has strong anti-jamming and anti-vibration and impact resistance, so in a harsh working environment has been widely Applications.I also mean freedom of communication S7-300 type PLC' s a very unique feature, which allows S7-300-PLC can deal openly with any other communications equipment, communications controller, or PLC S7-300 type can be defined by the user's own Communications protocol (of the agreement ASCII), the baud rate to 1.5 Mbit / s (adjustable). So that can greatly increase the scope of communications so that the control system configuration more flexible and convenient. Of any kind with a serial interface peripherals, such as: printers or bar code readers, Drives, a modem (Modem), the top PC-connected, and so can be used. Users can program to develop communication protocols, the exchange of data (for example: ASCII character code), RS232 interfaces with the equipment can also be used PC / PPI cable linking the free communication communications.When the PC offline, under the control of the next crew, the whole system can operate normally.PC that is by control centre, mainly by the PC and laser printer components, using SIMATIC WINCC software platform, the all-Chinese interface, friendly man-machine dialogue. Managers and operators can be observed through a PC, shown in the various kinds of information to understand the present and past the ice-storage operation of the automatic control system and all the parameters, and through the mouse to print equipment management and implementation tasks.WINCC software in the field of automation can be used for all the operators’ control and monitoring tasks. Can be controlled in the process of the events clearly show, and shows the current status and order records, the recorded data can show all or select summary form, or may be required for editing, printing and output statements and trends .WINCC able to control the critical situation in the early stages of the report, and the signal can be displayed on the screen, can also use sound to be felt. It supported by online help and operational guidelines to eliminate failure. WINCC a workstation can be devoted to the process control to the process so that important information not is shielded. Software-assisted operation strategy ensures that the process was not illegal to visit and to provide for non-industrial environment in the wrong operation.WINCC is MICRSOFT WINDOWS98 or WINDOWS NT4.0 operating system, running on a PC object-oriented class 32-bit applications, OLE through the window and ODBC standard mechanism, as an ideal partner to enter the communications world WINDOWS, it can be easily WINCC To integrate a company-wide data processing system.Seven、CommunicationsCommunications are vital to an individual automation cell and to the automated factory as a whole. We've heard a lot about MAP in the last few years, and a lot of companies have jumped on the band wagon. Many, however were disappointed when a fully-defined and completed MAP specification didn’t appear immediately. Says Larry Kumara:”Right now , MAP is still a moving target for the manufacturers specification that is not final. Presently, for example, people are introducing products to meet the MAP 2.1standard.Yet 2.1-based products will be obsolete when the new standard for MAP,3.0is introduced.”Because of this, many PLC vendors are holding off on full MAP implementations. Omron, for example , has an ongoing MAP-compatibility program, but Frank Newborn, vice president of Omron’s Industrial Division, reports that because of the lack of a firm definition, Omron's PLCs don't yet talk to MAP.Since it’s unlikely that an individual PLC would talk to broadband MAP anyway, makers are concentrating n proprietary networks. According to Sal Provanzano, users fear that if they do get on board and vendors withdraw from MAP, they ‘ll pulse width modulation control system be the ones left holding a communications structure that’s not supported.译文：一、PLC概述可编程控制器是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。

PLC-外文文献+翻译

Programmable logic controllerA programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides， or lighting fixtures. PLCs are used in many industries and machines。

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。

1。

HistoryThe PLC was invented in response to the needs of the American automotive manufacturing industry。

PLC基础知识简介外文文献翻译、中英文翻译、外文翻译

附录：外文资料译文PLC elementary knowledge synopsisIn the automated control domain, PLC is one kind of important control device. At present, in the world has more than 200 factories to produce more than 300 varieties PLC product, applies in the automobile (23%), the grain processing (16.4%), chemistry/drugs manufacture (14.6%), the metal/mine (11.5%), the paper pulp/papermaking (11.3%) and so on the profession. In order to make fellow beginners conveniently to understand PLC, this article to the PLC development, the basic structure, the disposition, using and so on the elementary knowledge makes a synopsis.First, PLC development courseIn the industrial production process, the massive switches quantity sequential control, it carries on the smooth movement according to the logical condition, and defers to the logical relations to carry on the chain-like protection movement the control, and massive data acquisition. In the tradition, these functions are realize through air operated or the electricity control system. In 1968 American GM (general automobile) the company proposed the substitution continues the electricity control device the request, the second year, the American numeral company developed based on the integrated circuit and the electronic technology control device, used sequenced the method to apply for the first time to the electrical control, this was the first generation of programmable foreword controller, calledProgrammable Controller (PC).After the personal computer (is called PC) to develop, in order to be convenient, also in order to reflect the programmable controller the function characteristic, the programmable foreword controller chooses a name is Programmable Logic Controller (PLC), now, still frequently was called PLC PC.The PLC definition has many kinds. The international electrician committee (IEC) to PLC the definition is: The programmable controller is one kind of digital operation operation electronic system, specially for applies under the industry environment designs. It uses the programmable foreword the memory, uses for to carry out the logic operation, the sequential control in its internal storage, fixed time, counts with operation the and so on arithmetic operation instruction, and through digital, the simulation input and the output, controls each kind of type the machinery or the production process. The programmable foreword controller and its the related equipment, all should according to easy form a whole with the industry control system, is easy to expand its function the principle design.On the century 80's to the 90's intermediate stages, are PLC develop the quickest time, the yearly rate continuously maintenance are 30-40%. In this time, PLC in the processing simulation quantity ability, the digital operation ability, the man-machine connection ability and the networking capability obtains the large scale enhancement, PLC gradually enters the process control domain, substituted in certain applications has been at the dominant position in the process control domain the DCS system.PLC has the versatility strongly, the easy to operate,the adaption surface broad, the reliability high, the antijamming ability strong, the programming is simple and so on the characteristic. PLC in the industrial automation control specially is in the sequential control status, in future which may foresee, is unable to substitute.Second, PLC constitutionFrom the structure the minute, 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 element groups synthesize a not dismantable 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 the certain rule combination disposition. Second, PLC constitution.Third, CPU constitutionCPU is the PLC core, plays nerve center's role, every time wraps PLC at least to have CPU, it function receive and storage user program and data which entrusts with according to the PLC system program, with scanning way gathering the condition or the data which sends by the scene input device, and stores 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, reads from the user program memory by the strip takes the instruction, 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 logic unit, the controller, theregister and realizes the data, the control and the condition main line constitution which between them relates, the CPU unit also includes the periphery chip, the main line connection and the related electric circuit. The memory mainly uses in the stored routine and the data, is the PLC essential composition unit.Looked like in the user, nonessential multianalysis CPU internal circuit, but or should have the enough understanding to each part of work mechanism. The CPU controller controls the CPU work, reads by it takes the instruction, the interpretive order and carries out the instruction. But the work rhythm by shakes the signal control. The logic unit uses in to carry on the numeral or the logic operation, works under the controller direction. The register participation operation, coexists stores the operation the intermediate result, it also is works under the controller direction.The CPU speed and the memory capacity are the PLC important parameter, they are deciding the PLC working speed, the IO quantity and the software capacity and so on, therefore is limiting the control scale.Fourth, I/O modulePLC and the electrical return route connection, is (I/O) completes through the input output unit. The I/O module integrated the PLC I/O electric circuit, its input temporary storage device reflection input signal condition, output point reflection output latch condition. The load module transforms the electrical signal the digital signal to enter the PLC system, the output module is opposite. I/O divides into the switch quantity input (DI), switch quantity output (DO), simulation quantity input (AI), simulation quantity output (AO) and so on module.The switch quantity is refers has and closes (or 1 and 0) two kind of conditions signals, the simulation quantity is only a quantity which refers continuously changes. Commonly used I/O classifies as follows:Switch quantity: Divides equally according to the voltage water, has 220VAC, 110VAC, 24VDC, divides according to the isolation way, has the relay isolation and the transistor isolation.Simulation quantity: Divides according to the signal type, has the electric current (4-20mA,0-20mA), the voltage (0-10V,0-5V, -10-10V) and so on, divides according to the precision, has 12bit,14bit,16bit and so on.Besides above general I/O, but also has the special I/O module, like module and so on thermal resistance, thermo-element, pulse.According to the I/O points determination module specification and the quantity, the I/O module may be many may be few, but its biggest number the basic disposition ability which can manage CPU, namely biggest ledger wall or rack Key slot number limit.Fifth, power source moduleThe PLC power source uses in is the PLC various modules integrated circuit provides the work power source. At the same time, some also provides 24V for the input circuit the work power source. The mains input type includes: (What the alternating current supply (220VAC or 110VAC), the direct-current power supply is commonly used is 24VAC).Sixth, PLC system other equipment1st, programs the equipment: The programming is the PLC development application, the monitor movement, the inspection maintains the essential component, uses in toprogram, makes some hypotheses to the system, monitors the system working condition which PLC and PLC controls, but it not directly participates in the scene control movement. Small programming PLC generally has the grasping programming, at present generally (movement programming software) acts as the programming by the computer.2nd, man-machine contact surface: The simplest man-machine contact surface is the indicating lamp and the button, at present the liquid crystal screen (or touches screen) a formula writing style operator terminal application to be more and more widespread, (movement configuration software) acts as the man-machine contact surface by the computer extremely to popularize.3rd, input-output device: Uses in permanently the memory user data, like EPROM, EEPROM reading in, bar code microreader, input simulation quantity potentiometer, printer and so on.PLC基础知识简介在自动化控制领域，PLC是一种重要的控制设备。

电气工程与其自动化专业_外文文献_英文文献_外文翻译_plc方面

1、外文原文A: Fundamentals of Single-chip MicrocomputerTh e si ng le -c hi p mic ro co mput er i s t he c ul mi na ti on of both t h e de ve lo pmen t o f t he d ig it al co m pu te r an d th e i n te gr at ed c i rc ui t a rg ua bl y t h e to w mos t s ig ni f ic an t i nv en ti on s of t he 20th c e nt ur y [1].Th es e t ow ty pe s of ar ch it ec tu re a re fo un d i n s in gle -ch i p m i cr oc ompu te r. So me em pl oy t he spl i t pr og ra m/da ta memory o f th e Ha rv ar d ar ch it ect ure , sh own in Fi g.3-5A-1, o th ers fo ll ow t he ph il os op hy , wi del y a da pt ed f or ge ner al -pur po se co m pu te rs a nd m i cr op ro ce ss or s, o f maki ng n o log i ca l di st in ct ion be tw ee n pr og ra m an d d at a memory a s i n t he P r in ce to n ar ch ite c tu re , sh own i n F ig.3-5A-2.In g en er al te r ms a s in gl e -chi p m ic ro co mput er i sc h ar ac te ri zed by t he i nc or po ra ti on of a ll t he un it s of a co mputer i n to a s in gl e d ev i ce , as s ho wn in Fi g3-5A-3.Fig.3-5A-1 A Harvard typeProgrammemory DatamemoryCPU Input&Outputunitmemory CPU Input&OutputunitFig.3-5A-2. A conventional Princeton computerReset Interrupts PowerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).R OM i s us ua ll y f or th e p erm an ent, no n-vo la ti le s tor age o f an a pp lic ati on s pr og ra m .Man ym i cr oc ompu te rs an d m ar e in te nd e d f or hi gh -v ol ume a ppl ic at ions an d he nc e t he eco nomic al m an uf act ure o f th e de vic es re qu ir es t h at t he co nt en t s of t he pr og ra m mem or y b e co mm it t ed pe rm ane ntly du ri ng t he m an ufa c tu re o f ch ip s .Cl ea rl y, t hi s i mpl ie s a r i go ro us a pp ro ach to R OM c od e de ve l op ment s in ce ch ang es c an not be mad e af te r manu f ac tu re .Th is d ev elo pmen t pr oc ess ma y in vo lv e emul at io n us in g a so ph is ti ca te d d eve lo pmen t sy ste m w it h a ha rd ware e mula tio n c ap ab il it y as wel l as t he u se o f po werf ul s o ft ware t oo ls.Some m an uf act ure rs p ro vi de ad d it io na l ROM opt i on s byi n cl ud in g i n th eir r ange d ev ic es wi t h (or i nt en de d f or u se wit h)us er p ro gr ammable memory. Th e sim ple st o f th es e i s u su al lyde vi ce w hi ch c an o per at e in a mi cro pro ce ss or mod e b y u si ng s ome of t he i np ut /o utp ut li ne s as a n a ddr es s an d da ta b us f or ac ce ss in g ex te rna l m emor y. T hi s t y pe o f de vi ce ca n b eh av eExternalTimingcomponents System clock Timer/ CounterSerial I/OPrarallelI/ORAMROMCPUf u nc ti on al ly a s t he si ng le ch ip mi cr oc ompu te r fro m w hi ch it is de ri ve d al be it wi t h re st ri ct ed I/O a nd a m od if ied ex te rn alc i rc ui t. Th e u se o f th es e dev ic es i s c ommon e ve n i n pr od uc ti on c i rc ui ts wh ere t he vo lu me do es no t j us tif y t h e dev el opmen t costsof c us to m o n-ch i p ROM[2];t he re c a n s ti ll be a s ig nif i ca nt sa vingi n I/O an d o th er c hip s c ompa re d t o a co nv en ti on al mi c ro pr oc es sor ba se d ci rc ui t. Mo r e ex ac t re pl ace m en t fo r RO M dev i ce s ca n be ob ta in ed i n th e f orm o f va ri an ts wit h 'p ig gy-b ack'EPRO M(Er as ab le pr o gr ammabl e RO M )s oc ke ts o r d ev ic e s wi th EP ROM i n st ea d of ROM 。

plc外文论文及其翻译

摘自《可编程控制器在过程自动化中的应用》PROGRAMMABLE LOGIC CONTROLLERS INPROCESS AUTOMATIONAhti Mikkor, Lembit RoosimölderAbstract: Nowadays, control problems are solved using operating components from a wide variety of technologies: electronics, hydraulics, pneumatics and mechanics. Functio-nality, reliability and price of the controlled system are deter-mined by the quality of the solution made. The paper concentrates on practical use of programmable logic controllers (PLC) that is based on the five years project development experience in this area. Successful solutions and problems are under focus.Specific hardware, controller programming problems, data/signals exchange and human machine interfaces are considered. As a result the method for selecting programmable controllers according to specific needs is developed. Practical suggestions, possible hazards and warnings are proposed that could help to avoid mistakes.Key words: programmable controllers, PLC, automation, automation systems, process automation.1. INTRODUCTIONModern machinery consists of both mechanical and electronic parts. Overall functionality is determined by “balance”between these components. Initial planning and solution selection plays critical role in final result.In control methods the selection has to be made between relay-based circuits, special devices, programmable logic controllers (PLC) and new development electronics. This article is concentrated on PLC-s and experience that has collected over 5-year practical work with PLC-s. Strong and weak sides, positive and negative practices are discussed. Suggestions weather to use programmable controllers or not have been formed to help decision making.The most important decision in planning PLC-based system is selecting processor type. Mistakes mean extra costs for modifications or even need for completely new devices. The most common error is overestimating programming possibilities of small-sized processors. There are several methods for selecting PLC. Unfortunately most of them focus on electrical side of PLC-s and maximum count of signals allowed. They don’t involve analysis to determine possible special needs for user program or communications.Based on several existing methods, practical experience and future trends a new method for selecting PLC was developed. Ahti Mikkor has gainedhis experience by taking part in more than 15 big-scale automation projects. These projects include development of power consumption monitoring system in AS Kunda Nordic Cement factory, renewing testing rig for flowmeters, building Ahtme powerplant turbine safety systems, water treatment plants in towns Rakvere and Põlva, waste water treatment plant in town Jõgeva and development of monitoring system for central heating network in Tartu.2. PROS AND CONS IN USING PROGRAMMABLE LOGIC CONTROLLERS2.1 Positive argumentsThe main advantage that programmable controllers provide is flexibility (Jack, 2003). Behaviour of the system can be easily changed via program without any other alterations. Special devices for example make any changes in control algorithm very hard to implement. Flexibility makes PLC-s well suitable for frequently changed applications, for example in robotics.In PLC-s the relations between inputs and outputs are determined by user program. By using advanced programming technologies it is much easier to implement complex control algorithms than in any hard-wired solutions. It makes PLC-s very competitive for complex tasks, for example in controlling chemical processes.Special modules allow vast amount of different signals to be connected to the PLC system. Use of PLC-s should be considered in applications that require some “special” input or output signals. Typical example would be positioning using reference data from high-speed input.Typically PC visualization software packages are made for PLC-s. Some special devices have also PC software packages. Wide range of communication options between PLC-s makes it possible to gather all information from field devices into one central control point.Communication lines between PLC-s allow using information collected from other parts of the system in local process control. Modern communication technologies enable remote diagnostics and configuration (Jack, 2003). These two significantly reduce overall maintenance costs of the system.2.2 Negative argumentsProgrammable controllers are not equipped with enough memory to store big amounts of data. Although future trends show growth in PLC memory sizes, special devices (recorders) are still better suited for standalone datalogging applications. For networked solutions there is possibility to use visualization software packages together with PLC-s to archive collected data in any database format necessary. If logged data amounts are small or there are also control functions included, it’s reasonable to still use PLC-s. About visualization software packages it’s good to know that in standard versions most of them do not support offline recording so that after communication breakdown it is not possible toacquire data backwards from PLC.Modern communication options for PLC-s include standard protocols for example Ethernet. It is tempting to use existing office networks also as data carrier for automation system communications. Time has shown that it is better practice to keep these two separated if there is a need for constant online communication. Hardly traceable temporal network overloads can cause problems also in automation system communications All PLC-s need be programmed. All programming works include risk for accidental errors in control algorithm. Special devices are well tested and generally free of this kind of problems. If available, it’s economically thoughtful to use special devices.Safety applications that require highest degree of reliability should contain simplest devices and circuits possible. There is a rule that every new link in chain decreases overall reliability.In small applications it’s often cost saving to use relay-based circuits instead of PLC-s.3. FUTURE TRENDSProgress in process automation systems is aiming at so called complete automation when all the human has to do is to enter the parameters of the product wanted and everything else is carried out by machines (Rosin, 2000). Although the destination lies far ahead, trends indicate movement in that direction.Firstly, systems become more and more standardized. Big manufacturers organize their products into families. The aim is to reduce amount of knowledge needed for configuration and maintenance works of different devices from same company. It’s also important that this way built applications are easily expandable.Secondly, importance of communication is rising (Hughes, 2000). There are many reasons, some of more essentials are:• Better collaboration of different parts of the system.•Cutting costs on cabling. Less cabling results fall in fault probability, but also increases severity of ones that occur.• Sensors and actuators can be at longer distances from the processor module than if using conventional methods.• Increased scalability of the systems. New devices can be added at minimal costs.• At some cases it is better to make architecture of many small independent modules and network them. This solution enables system to keep working although some parts have failed.• Communication networks ease fault diagnostics and provide remote management possibilities. Central operating stations can be formed relatively easy.• Possibility to connect devices form different manufacturers (OPCFoundation, 2003).Third important tendency is spreading use of so called software controllers or Soft PLC-s (Siemens AG, 2003). These are PC software-based solutions that relate with field devices via communication networks. There is no need for processor module, resources of PC are used. Some Soft PLC-s are still formed as processor cards for PC (figure 1). Reliable communication networks are essential. Soft PLC-s are well suited for data acquisition applications because of data storage possibilities of PC-s.Figure 1. Siemens Simatic WinAC Slot PLC 412Fourthly, combo-devices (figure 2) that contain both operator panel and medium size processor module gain popularity (Siemens AG, 2002). In this solution possibility of disturbances is low and reuse of some components make whole package cheaper.Figure 2. Combo device Siemens Simatic C7-613Fifthly, processor software takes over properties from PC software. Data collected from production can be easily transferred into office applications (Siemens AG, 2000).4. METHOD FOR SELECTING PROGRAMMABLE CONTROLLERA method for forming an application specific list of required properties for selecting programmable controller was developed. There are nine criterions and the results are presented in Table 1. Selection is made by comparing results table with controller’s technical data. Following is short description of every criteria involved.Nature of solution determines weather it is expanding of old system or completely new development. In first case the architecture of system and hardware requirements are limited by already existing solution. Using hardware from same company makes servicing easier and avoids integration problems that would occur when using products form different manufacturers. For example many hardware producers integrate their own specific communication interfaces directly into processor module and for every universal protocol a special module is needed (Siemens AG, 2003). It is also possible to reduce spare part stock amounts when using same type hardware all over the system.Maximum number of electrical inputs-outputs allowed is classical criteria to determine processor class. If complex control algorithms and non-standard functions are needed, it’s not the most important parameter any more. Generally it is money saving to use one bigger processor module for input-output signals that originate from nearby locations than several smaller ones. In this case there will be no need for communication network and programming will be easier too.Special signals and modules are usually available for medium and large controller families only. Many microcontrollers do not even have possibility to add analogue output (Siemens AG, 2003). In some cases using special modules is the only way, in other ones (positioning) it is just an opportunity to save money.Layouts of sensors and actuators can be very different, sometimes the sensors are located several kilometres away from the actuator (pumping liquids in long pipes). In this case special communication network (Profibus, AS-inteface) might be the only solution. If not, it can at least save costs by reducing cabling works. Not all programmable controllers have interfaces for communication protocols.Properties of processor have important role in complex applications. Most common problem is lack of programming memory, sometimes also data memory. Memory requirements can be estimated by number of input and output signals. But in practice 100 digital input-output points system often has 3 times smaller program than 10 digital input-output points system. The only way to estimate program size exactly is using previous experience.Program specialities include special program functions needed. Different areas of applications have some typically used functions, for example temperature control in building automation. Programming is much simpler if these functions are already built into system software of processor. In process automation 2 digital output (up-down) closed loopPID regulation is quite often used. It might be a surprise but it’s not included in most of the microcontrollers (Siemens AG, 2003) and for average programmer it’s too complicated task to create his own regulator using standard functions. Basically there are 2 solutions: either to avoid this construction or to use applicable controller.Table 1. Table for method resultsCommunication is becoming more important in nowadays automation systems. In some cases non-standardised devices as barcode readers or electronic weights have to be included into the system. Then it’s vital to have functions for protocol programming (freeport programming). Standardised protocols demand existence of specific modules. Working conditions can usually be overcome by using special cabinets, but there are also specific series of programmable controllers that have improved resistance for electromagnetic disturbances, humidity and vibrations. In very dusty environments all cooling ventilators have to be equipped withfilters.5. CONCLUSIONSMain benefits of programmable controllers are:• flexibility• communication possibilities• realisation of complex control algorithms• reliabilityAlternative solutions should be considered if:• system is very simple• special devices are available• data recording is necessaryInitial selection of appropriate solution and hardware has great influence on final result. Mistakes in this step significantly increase overall budget of project as some programs might have to be changed and some hardware replaced.Based on his practical experience the author has formed a method for selecting programmable controller. It has 9 criteria’s: • nature of solution (new or existing)•maximum number of electrical inputs-outputs allowed (digital, analogue, inputs, outputs)• need for special modules (high-speed digital outputs)• layout of sensors and actuators (local or periphery)• properties of processor (program and data memory)• program specialities (special functions)• communication needs (Profibus, ASCII)• working conditions (humidity, temperature, vibration, dust) Method is not guaranteed to always point out the best selection, but using it certainly avoids mistakes.6. REFERENCESHughes, T. A. Programmable Controllers, Third Edition. ISA –The Instrumentation, Systems, and Automation Society, 2000, 334 p.Jack, H. Automating Manufacturing Systems with PLC-s, 828 p.,Available:/~jackh/books/plcs/pdf/plcbook4_2.pdf, Accessed:3.10.2003LOGO! Manual. Siemens AG, 2003, 312 p.OPC Foundation homepage: /, Accessed: 9.11.2003Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. [Master Thesis] – in Estonian.Berger, H. Automating with SIMATIC. Siemens AG, 2003, 214 p.SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p.SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p.SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG 2000, 468 p.参考文献[1] Hughes, T. A. Programmable Controllers, Third Edition. ISA – The Instrumentation, Systems, and Automation Society, 2000, 334 p.[2] Jack, H. Automating Manufacturing Systems with PLC-s, 828 p., Available:[3]/~jackh/books/plcs/pdf/plcbook4_2.pd f,Accessed:3.10.2003[4] LOGO! Manual. Siemens AG, 2003, 312 p.[5] OPC Foundation homepage: /, Accessed: 9.11.2003[6] Rosin, A. Programmable Controllers Simatic S7. Tallinn, TTU, 2000, 120 p. [Master Thesis] – in Estonian.[7] Berger, H. Automating with SIMATIC. Siemens AG, 2003, 214 p.[8] SIMATIC Programming with STEP 7 V 5.2: Manual. Siemens AG, 2002, 610 p.[9] SIMATIC S7-200 Programmable Controller System Manual. Siemens AG, 2003, 474 p.[10] SIMATIC HMI WinCC Configuration Manual. Volume 1, 2, 3. Siemens AG2000, 468 p.翻译：摘自《可编程控制器在过程自动化中的应用》摘要：目前，控制问题解决了各种各样的技术操作部分：电子，液压，气动和机械。

PLC控制系统英文文献+翻译

PLC控制系统英文文献+翻译PLC控制系统英文文献+翻译Beer filling, Gland machine PLC control system 1.Intorduction Malt beer production process is divided into manufacturing, manufacturing wort, before fermentation, after fermentation, filtration sterilization, packaging, and so few procedures. Beer filling, Gland part of a packaging machine processes. The membrane filtration of beer after the pipeline into the rotary Jiugang, then the valve into the bottle of wine, Gland, was bottled beer. Beer filling, Gland machine's efficiency and degree of automation direct impact on the level of beer production.China's beer industry to meet the increasing scale of production and the demand for beer modern high-speed filling machinery filling the requirements of domestic beer manufacturers are actively seeking to transform the unit or the filling of beer production equipment, making it a good use Performance, advanced technology and high production efficiency and operating a safe and secure, low maintenance costs of the modernization of beer filling machine. 2. Filling beer, Gland principle and control aircraft partsLiquid filling machine by filling principle can be divided into atmospheric filler,filling machines and vacuum pressure on the filling machine. Beer filling,Gland-filling method used pressure is higher than the atmospheric pressure under the filling, storage of the cylinder pressure than the pressure of the bottle, beer bottle into the liquid on pressure.Technology at home and abroad to achieve the filling line is basically: The Rotary Jiugang the rotating movement, placed in Jiugang slots on the empty bottles through the machinery will befixed at the upper Jiugang vacuum valve to open, closed Vacuum bottles for good treatment, Bozhuan stem from operating, open the valve of the bottle filling CO2 gases, vacuum convex .Round to open the vacuum valve, the bottle will air mixed with CO2 out of gas, open the valve again, the CO2 gas bottle filling, the filling valve on the pressure valve in the bottle close to back-pressure gas pressure at the open-Jiuye Pingbi into the bottle, through pneumatic or electrical control filling valve to achieve the filling of beer.Today's advanced international beer filling, Gland machine control system mainly by the photoelectric switch position detection part and take the bottles with, Jiugang speed part, dominated by the PLC, touch screen and other components. Filling, Gland of the mechanical structure and PLC programmable control devices, frequency stepless speed regulation, human-computer interface, and other modern means of complete automatic control technology, the combination of a mechanical and electrical integration.3. Controlled part of the programmeMany domestic beer manufacturers are now using the filling, Gland of the control system of uneven degree of automation; button and all the manual switch technology have set up operations in a box on the panel, PLC controller for the majority of Japanese companies or OMRON Mitsubishi's early products, equipment chain of control, less protection settings, plus the beer filling the scene poor environment, humidity, such as contact with the switch contacts serious corrosion, the system's signal detection of the high failure rate, resulting in equipment control system Operation of low reliability, the normal operation of equipment, such as short-cycle phenomenon.To the actual transformation of the Dandong Yalu River Brewery Co., Ltd. of filling, Gland machine control system as an example, the transformation of methods to clarify the control of such equipment thinking and ideas, according to the scene of the actual process conditions, to prepare the operation of the PLC Procedures. For beer filling, Gland control system of the actual situation and in accordance with the actual process conditions at the scene, re-design of the equipment of the PLC control system. This transformation of the same methods and ideas can be applied to other liquids and the transformation of filling equipment. 3.1 system hardware configurationJapan's Mitsubishi Corporation to use the FX2N128MRPLC use the system to replace the original 2-OMRON's C60P PLC, the original system of the PLC is due to old models, and computer on-line communications need to configure special converters, the system need to increase the external I / O input points , The extension of spare parts more difficult to find. FX2N128MRPLC is an integrated 128-point I / O controller of the box, a computing speed, command rich, high-cost performance, on-line programming simple and easy extension of the advantages of the Mitsubishi FX series, features the strongest small controller .(1) by the Mitsubishi 900 series of 970 GOT human-computer touch screen system to replace the original use of the button panel display equipment and monitor the operation of operating parameters. 970GOT HMI for the 16-color high-brightness significantly, through the convergence of connectivity and FX2N128MRPLC directly connected to the CPU, achieving rapid response. Has many maintenance features, such as the list-editing features, ladder monitoring (troubleshooting) function, the system monitoring functions to find fault and maintenanceof PLC Systems.(2) filling, Gland of the frequency converter in the transformation of no replacement, on-site detection signal means-testing is still used switch, switch for detecting long-term work in the humidity of the great occasions, the choice of capacitive proximity switches, according to PLC I / O terminal of the connection mode, select the type of close PNP switch, the control system of Figure 1. 3.2 Systems Programming PLC controller programming focus and the core is around Jiugang the rotation speed control and Jiugang on 60 bottles of detecting the location of the displaced, broken bottles, empty bottles at the location of testing and related displacement filling Such as control valves. The bottles displacement of testing procedures, using a Mitsubishi PLC in the left command.Figure 1 control system structure diagram .Bottles displacement of detection, using the left-PLC command, which commands the whole of one of the core control procedures, the main electrical switch detection and bottles at the bottle simultaneously detect mobile, the main motor to every week, just to the corresponding Jiugang Have a bottle of, PLC unit within the internal correspondence that 60 bottles of the unit for the M500 ~ M559, the number of units by the first letter K is set to K60, with each change in a second letter K is set to K1, M50 Reaction of the empty bottles in the short position, and detect the location of the motor speed to go on the frequency shift in the corresponding unit within the built-in "1" or "0", control valves and the corresponding mixing caps The motor stopped and opened. Continuous detection system in place after the 90 empty bottles, stop stirring caps the motor running, testing the number of bottles in accordance with the user's requirements canbe arbitrary.A bottle of detection. Rotary Jiugang through pressure to back pressure with the bottle of liquor in the process of empty bottles in the back-pressure, because the bottle itself may crack and other reasons leading to a sudden burst bottles, which need to detect the location of unexploded bottle bottle, in this bottle - The position opened purge solenoid valves, compressed air out, broken bottles at the bottle-blowing from the position in a row after the purge and several bottles of the electromagnetic valve open jet, a high-pressure spray Shuizhu, in the break Bottle position around a few bottles of spray bottles in a row.Detection of broken bottles and bottle-detection switch simultaneously detect movement of breaking bottles, to the main motor of each week, precisely corresponding Jiugang passed a bottle of, PLC unit within the internal correspondence that 20 broken bottles at the unit for the M600 ~ M619, unit With the number of the first letter K is set to K20, with each change in a second letter K is set to K1, M52 response to the location of the broken bottles and detected the location of the motor speed to the frequency shift continue, In the corresponding unit within the built-in "1" or "0", control and the corresponding jet purge solenoid valve opened and stopped. Continuous Spray and purge solenoid valve open to listen, time stopped in accordance with technological requirements can be arbitrary.System security is to control access to the caps simultaneously tracking, not only accurately detect the electrical switching speed detection, the broken bottles into the bottle and detection switch detection switch three conditions.970GOT human-computer touch-screen terminals operated by the software company's Mitsubishi GT WORKS package, whichis a GT Designer with the entire GOT9000 series of graphics software packages. The package is simple, prior to a personal computer simulation on the configuration and debug, after the man-machine operators to download terminals. At the same time, because the man-machine interface and a touch-screen role, will set common switch on the screen to facilitate the operation. And also to increase the number of features, such as setting alarm information. 4.After transformation control systemSystem at the normal operation of the machine for automatic control, in accordance with bottles into and out of the bottle for lack or slow pace set by running into the bottle stall bottles, no less than a bottle cap, automatic washing bottles burst, filling automatic back-pressure position , Covered under the system automatically lose covered a stop and safety protection, such as the coordination of action interlock. All the original button after the operation of the touch screen on. 5.Detection of the state control system monitoringDetection switch into the bottle and break bottles detection switch bottles of pressure by testing each part of the small metal plates above the location of a photoelectric pulse output, a further PLC acquisition, as each bottle of the pressure above the small metal plates is the location of activities , In the machine running after some time, some pressure above the small bottles of iron tablets and detection switch in the location of displacement, resulting in detection switch mistaken judgement, if not for the judgement of bottles of bottles, bottle explosion Lou Jian, misuse, such as the seizure of output errors So that the PLC have mistaken action, such as a back-pressure, unexploded bottle blowing, washing, stirring cap control system malfunction, such as failure phenomenon.Before the transformation of the daily production process, encountered this phenomenon, the operatives could only switch to the various functional or manual control buttons reach the stall so that the equipment work in the absence of monitoring state, the machine lost control function. Caused a lot of production of raw materials such as gas, water, wine waste. Only in the production of intermittent, can be fitter and maintenance electrician in accordance with the detection of small switch on the light-emitting diodes and anti-displacement by adjusting the distance only 5 ~ 8 mm detection switch installation location, and switch to fix detection of small metal plates Gap. This means of detection is very backward, after adjustment reaction to the results, timely response can not be adjusted results.In view of this testing situation, after the transformation of the filling, Gland control system configuration, this part of a new detection and integration in human-computer touch screen, complete bottle of detection.In human-computer touch screen interface on the page display, respectively, at customs, such as electromagnetic motor mixing valve switch state are in different colors to show, very intuitive.Increase the system's functions is to ensure the irrigation of the machine-Gland normal operation of automated control system specifically designed to. 6 Concluding remarks After the transformation of the control system will greatly simplify the complicated mechanical structure, the running and control of inspection, the degree of automation systems meet the design requirements, greatly reducing the operational strength of the labor so that the shrub-like beer output than in the past Raising more than 30 percent, greatly reduce the failure rate.Embodies the modern equipment of automatic control technology. In the digestion and absorption of today's industrial control on the basis of advanced technology innovation, development of domestic technology from the most advanced filling control system.啤酒灌装、压盖机PLC控制系统1、引言啤酒生产过程分为麦芽制造、麦芽汁制造、前发酵、后发酵、过滤灭菌、包装等几道工序。

PLC的发展方向外文文献翻译、中英文翻译

关于PLC的外文及翻译

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 multiple targets/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。

电气工程及其自动化专业_外文文献_英文文献_外文翻译_plc方面

1、外文原文A: Fundamentals of Single-chip MicrocomputerTh e si ng le-c hi p m ic ro co mp ut er i s t he c ul mi na ti on of b oth t h e de ve lo pm en t o f t he d ig it al co m pu te r an d th e i n te gr at edc i rc ui t a rg ua bl y t h e to w m os t s ig ni f ic an t i nv en ti on s o f t he20th c e nt ur y [1].Th es e t ow ty pe s of ar ch it ec tu re a re fo un d i n s in g le-c hip m i cr oc om pu te r. So m e em pl oy t he spl i t pr og ra m/da ta m e mo ry o f th e H a rv ar d ar ch it ect u re, sh ow n in Fi g.3-5A-1, o th ers fo ll ow t he p h il os op hy, wi del y a da pt ed f or ge n er al-p ur po se co m pu te rs a nd m i cr op ro ce ss o r s, o f ma ki ng n o log i ca l di st in ct ion be tw ee np r og ra m an d d at a m e mo ry a s i n t he P r in ce to n ar ch ite c tu re, sh ow n i n F ig.3-5A-2.In g en er al te r ms a s in gl e-chi p m ic ro co mp ut er i sc h ar ac te ri zed b y t he i nc or po ra ti on of a ll t he un it s of a co mp ut er i n to a s in gl e d ev i ce, as s ho wn in Fi g3-5A-3.Fig.3-5A-1 A Harvard typeFig.3-5A-2. A conventional Princeton computerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).R OM i s us ua ll y f or th e p e rm an en t,n o n-vo la ti le s tor a ge o f an a pp lic a ti on s pr og ra m .M an ym i cr oc om pu te rs an d m ar e in te nd e d f or hi gh-v ol um e a p pl ic at io ns a n d he nc e t h e eco n om ic al m an uf act u re o f th e de vic e s re qu ir es t h at t he co nt en t s o f t he pr og ra m me m or y b e co mm it t ed pe rm a ne nt ly d u ri ng t he m an ufa c tu re o f ch ip s .Cl ea rl y, t hi s i m pl ie s ar i go ro us a pp ro ach to R OM c od e de ve l op me nt s in ce ch a ng es c an no t b e m ad e af te r m anu f a c tu re .Th is d ev e lo pm en t pr oc ess ma y in vo lv e e m ul at io n us in g a so ph is ti ca te d d e ve lo pm en t sy ste m w it h ah a rd wa re e mu la tio n c ap ab il it y as w el l as t he u se o f po we rf ul s o ft wa re t oo ls.So me m an uf act u re rs p ro vi de ad d it io na l RO M opt i on s byi n cl ud in g i n th eir r a n ge d ev ic es wi t h (or i nt en de d f o r u se w it h) u s er p ro gr am ma ble me mo ry. Th e sim p le st o f th es e i s u su al lyd e vi ce w hi ch c an o p er at e in a mi cro p ro ce ss or m od e b y u si ng s om e o f t he i np ut/o utp u t li ne s as a n a d dr es s an d da ta b us f ora c ce ss in g ex te rna l m em or y. T hi s t y pe o f de vi ce ca nb eh av ef u nc ti on al ly a s t h e si ng le ch ip mi cr oc om pu te r fro m w hi ch it is d e ri ve d al be it wi t h re st ri ct ed I/O a nd a m od if ied ex te rn alc i rc ui t. Th e u se o f th es ed ev ic es i s c om mo ne ve n i n pr od uc ti on c i rc ui ts wh er e t he vo lu me do es no t j us tif y t h e d ev el o pm en t c os ts o f c us to m o n-ch i p R OM[2];t he re c a n s ti ll be a s ig nif i ca nt sa vi ng i n I/O an d o th er c h ip s c om pa re d t o a co nv en ti on al mi c ro pr oc es so r b a se d ci rc ui t. Mo r e ex ac t re pl ace m en t fo r RO M dev i ce s ca n be o b ta in ed i n th e f o rm o f va ri an ts w it h 'p ig gy-b ack'E P RO M(Er as ab le pr o gr am ma bl e RO M )s oc ke ts o r d ev ic e s wi th EP RO M i n st ea d o f RO M 。

关于PLC的中英文献翻译工业控制系统

INDUSTRIAL AND COLLABORATIVECONTROL SYSTEMS 之迟辟智美创作- A COMPLEMENTARY SYMBIOSIS –-Looking at today’s control system one can find a wide variety of implementations. From pure industrial to collaborative control system (CCS) tool kits to home grown systems and any variation in-between. Decisions on the type of implementation should be driven by technical arguments Reality shows that financial and sociological reasons form the complete picture. Any decision has it’s advantages and it’s drawbacks. Reliability, good documentation and support are arguments for industrial controls. Financial arguments drive decisions towards collaborative tools. Keeping the hands on the source code and being able to solve problems on your own and faster than industry are the argument for home grown solutions or open source solutions. The experience of many years of operations shows that which solution is the primary one does not matter, there are always areas where at least part of the other implementations exist. As a result heterogeneous systems have to be maintained. The support for different protocols is essential. This paper describes our experience with industrial control systems, PLC controlled turn key systems, the CCS tool kit EPICS and the operability between all of them.-INTRODUCTIONProcess controls in general started at DESY in the early 80th with the installation of the cryogenic control system for the accelerator HERA (Hadron-Elektron-Ring-Anlage). A new technology was necessary because the existing hardware was not capable to handle standard process controls signals like 4 to 20mA input and output signals and the software was not designed to run PID control loops at a stable repetition rate of 0.1 seconds. In addition sequence programs were necessary to implement startup and shutdown procedures for the complex cryogenic processes like cold boxes and compete compressor streets.Soon it was necessary to add interfaces to field buses and to add computing power to cryogenic controls. Since the installed D/3 system[1] only provided an documented serialconnection on a multibus board, the decision was made to implement a DMA connection to VME and to emulate the multibus board’s functionality. The necessary computing power for temperature conversions came from a Motorola MVME 167 CPU and the field bus adapter to the in house SEDAC field bus was running on an additional MVME 162.The operating system was VxWorks and the application was the EPICS toolkit.Since this implementation was successful it was also implemented for the utility controls which were looking for a generic solution to supervise their distributed PLC’s.A SELECTION OF PROCESS CONTROL SYSTEMS AT DESYDCS (D/3)As a result of a market survey the D/3 system from GSE was selected for the HERA cryogenic plant. The decision was fortunate because of the DCS character of the D/3. The possibility to expand the system on the display- and on the I/O side helped to solve the increasing control demands for HERA. The limiting factor for the size of the system is not the total number of I/O but the traffic on the communication network. This traffic is determined by the total amount of archived data not by the data configured in the alarm system.The technical background of this limitation is the fact that archived data are polled from the display servers whereas the alarms are pushed to configured destinations like alarm-files, (printer) queues or displays.SCADA Systems with DCS Features (Cube)The fact that the D/3 system mentioned above had some hard coded limitations with respect to the Y2K problem was forcing us to look for an upgrade or a WordStrment of the existing system. As a result of a call for tender the company Orsi with their product Cube came into play [2]. The project included a complete WordStrment of the installed functionality. This included the D/3 as well as the integration of the DESY field bus SEDAC and the temperature conversion in VME. The project started promising. But soon technical and organizational problemswere pushing the schedule to it’s limits wh ich were determined by the HERA shutdown scheduled at that time.The final acceptance test at the vendors site showed dramatic performance problems. Two factors could be identified as the cause of these problems. The first one was related to the under estimated CPU load of the 6th grade polynomial temperature conversion running at 1 Hz. The second one was the additional CPU load caused by the complex functionality of the existing D/3 system. Here it was underestimated that each digital and analog input and output channel had it’s own alarm limits in the D/3 system.In a SCADA like system as Cube the base functionality of a channel is to read the value and make it available to the system. Any additional functionality must be added. Last not least the load on the network for polling all the alarm limits –typically for a SCADA system –was also driving the network to it’s limits.Finally the contract with Orsi was cancelled and an upgrade of the D/3 system was the only possible solution. It was finally carried out in march 2003.In any case it should be mentioned that the Cube approach had the advantage of a homogeneous configuration environment (for the Cube front end controllers) –compared with heterogeneous environments for ‘pure’ SCADA systems.SCADA (PVSS-II)The H1 experiment at the HERA accelerator decided to use PVSS-II for an upgrade of their slow control systems[3].The existing systems were developed by several members of the H1 collaboration and were difficult to maintain. The decision to use PVSS as a WordStrment was driven by the results of an extensive survey carried out at CERN by the Joint Controls Project [4]. PVSS is a ‘pure’ Supervisory And Data Acquisition System (SCADA). It provides a set of drivers for several field buses and generic socket libraries to implement communication over TCP/IP. The core element is the so called event manager. It collects the data (mostly by polling) from the I/O devices and provides an event service to the attached management services like: control manager, database manager, user interface, API manager and the built in HTTP server. The PVSS scripting library allows to implement complex sequences as well as complex graphics.Compared with other SCADA systems PVSS comes with one basic feature: it provides a true object oriented API to the device’s data.One major disadvantage of SCADA systems is the fact that two databases, the one for the PLC and the one for the SCADA system must be maintained. Integrated environments try to overcome this restriction.EPICSEPICS has emerged at DESY from a problem solver to a fully integrated control system. Starting from the data collector and number cruncher for the cryogenic control system, EPICS made it’s way to become the core application for the DESY utility group. In addition it is used wherever data is available through VME boards or by means of Industry Pack (IP) modules. For those cryogenic systems which are not controlled by the D/3 system EPICS is used with it’s complete functionality. In total about 50 Input Output Controller (IOC) are operational processing about 25 thousand records.1 EPICS as a SCADA SystemThe utility group ( water, electrical power, compressed air, heating and air conditioning) is using a variety of PLC’s spread out over the whole DESY site. EPICS is used to collect the data from these PLC’s over Profibus (FMS and DP) and over Ethernet (Siemens H1 and TCP). The IOC’s provide the interfaces to the buses and collect the data. The built in alarm checking of the EPICS records is used to store and forward alarm states to the alarm handler (alh) of the EPICS toolkit. In addition tools like the channel archiver and the graphic display (dm2k) are used. The default name resolution (by UDP broadcast) and the directory server (name server) are used to connectclient and server applications over TCP. All of these are basically SCADA functions.The textual representation of all configuration files ( for the IOC, the graphic tool, the alarm handler and the archiver) provides a flexible configuration scheme. At DESY the utility group has developed a set of tools to create IOC databases and alarm configuration files from Oracle. Thisway the controls group provides the service to maintain the EPICS tools and the IOC’s while the users can concentrate on the equipment being controlled.2 EPICS as a DCS SystemBesides the basic components of a SCADA system EPICS also provides a full flavoured Input Output Controller (IOC).The IOC provides all of the function a DCS system requires, such as: a standard set of properties implemented in each record, built in alarm checking processed during the execution of each record; control records like PID etc.;configuration tools for the processing engine. The flexible naming scheme and the default display and alarm properties for each record ease the connection between the operator tools and the IOC’s. The flexible data acquisition supports the poll mode as well as the publish subscribe mode. The latter reduces the traffic drastically.PLC’sPLC’s provide nowadays the same rich functionality as it was known from stand alone control systems in the past.Besides the basic features like the periodic execution of a defined set of functions they also allow extensive communication over Ethernet including embedded http servers and different sets of communication programs.Besides the communication processors, display processors can be linked to PLC’s to provide local displays which can be comprised as touch panels for operator intervention and value settings.These kind of PLC’s are att ractive for turn key systems which are commissioned at the vendors site and later integrated into the customers control system.Intelligent I/ONew developments in I/O devices allow to ‘cluster’ I/O in even smaller groups and connect theses clustered I/O channels directly to the control system. PLC’s are not any more necessary for distributed I/O. Simple communication processors for any kind of field buses or for Ethernet allow an easy integration into the existing controls infrastructure.Little local engines can run IEC 61131 programs. Thedifferences between PLC’s and intelligent I/O subsystems fade away.FUNCTIONALITYThe ever lasting question why control systems for accelerators and other highly specialized equipment are often home grown or at least developed in a collaboration but only in rare cases commercial shall not be answered here. We try to summarize here basic functionalities of different controls approaches.Front-end ControllerOne of the core elements of a control system is the front-end controller. PLC’s can be used to implement most of the functions to control the equipment. The disadvantage is the complicated access to the controls properties. For instance all of the properties of a control loop like the P, I and D parameter, but also the alarm limits and other additional properties must be addressed individually in order to identify them in the communication protocol and last not least in the display-, alarm- and archive programs. In addition any kind of modifications of these embedded properties is difficult to track because two or more systems are involved. This might be one strong argument why control loops are mainly implemented on the IOC level rather than PLC’s.1 I/O and Control LoopsComplex control algorithms and control loops are the domain of DCS alike control systems. The support for sets of predefined display and controls properties is essential. If not already available (like in DCS systems) such sets of generic properties are typically specified throughout a complete control system (see namespaces).2 Sequence/ State programsSequence programs can run on any processor in a control system. The runtime environment depends on the relevance of the code for the control system. Programs fulfilling watchdog functions have to run on the front-end processor directly. Sequence programs for complicated startup and shutdown procedures could be run on a workstation as well.The basic functionality of a state machine can be even implemented in IEC 61131. Code generators can produce ‘C’ code which can be compiled for the runtime environment.3 Supported HardwareThe support for field buses and Ethernet based I/O is a basic functionality for SCADA type systems it is commercially available from any SCADA system on the market. The integration of specific hardware with specific drivers and data conversion is the hard part in a commercial environment. Open API’s or scripting support sometimes help to integrate custom hardware. If these tools are not provided for the control system it is difficult –if not impossible - to integrate custom hardware.New industrial standards like OPC allow the communication with OPC aware devices and the communication between control systems. One boundary condition for this kind of functionality is the underlying operating system. In the case of OPC it is bound to DCOM which is a Microsoft standard. UNIX based control systems have a hard time to get connected. Only control systems supporting multiple platforms can play a major role in a heterogeneous environments.As a result the limited support for custom- or specialized hardware may give reason for the development of a new control system.Display and OperationBesides the front-end system the operator interfaces play a major role for the acceptance of a control system. SCADA tools come with a homogeneous look and feel throughout their set of tools. Toolkits implemented in a collaboration might vary because the individual tools were developed by different teams.1 GraphicSynoptic displays are the advertising sign for any control system. Commercial synoptic displays come with a rich functionality and lots of special features. Starting to make use of all these features one will find out that all individualproperties of the graphic objects must be specified individually. Since SCADA systems must be generic they cannot foresee that an input channel does not only consist ofa value but also consists of properties like display ranges andalarm values. Defining all of these properties again and again can be a pretty boring job. Some systems allow to generate prototypes of graphic objects. These prototype or template graphics are complex and need a specialist to generate them.DCS or custom synoptic display programs can make use of the common set of properties each I/O point provides. This predefined naming scheme will fill in all standard property values and thus only require to enter the record – or device name into the configuration tool. A clear advantage for control systems with a notion of I/O objects rather than I/O points.2 AlarmingAlarms are good candidates to distinguish between different control system architectures. Those systems which have I/O object implemented also provide alarm checking on the front-end computer. Those systems which only know about I/O points have to add alarm checking into the I/O processing. While the I/O object approach allows to implement alarm checking in the native programming language of the front-end system, I/O point oriented systems typically have to implement this functionality in their nativescripting language. This is typically less efficient and error prone because all properties must be individually configured.This leads to a flood of properties. Not only the error states for each I/O point wind up to be individual I/O points but also the alarm limits and the alarm severity of each limit must be defined as I/O points if it is desired to be able to change their values during runtime.Besides this impact on the configuration side the processing and forwarding of alarms makes the difference between SCADA and DCS systems. Since SCADA systems inherently do not ‘know’ about alarms, each alarm state must be polled either directly from the client application or in advanced cases from an event manager which will forward alarm states to the clients. In any case a lot of overhead for ‘just’ checking alarm limits. DCS system again have the advantage that clients can either register themselves for alarm states und thus get the information forwarded or are configured to send alarmchanges to certain destinations spread around the control system. The latter case is only possible for systems which in total are configured with all the nodes taking part in the controls network.3 Trending and ArchivingTrending has become an important business in control systems architectures. Trends are necessary to trace error conditions or for post mortem and performance analysis of the controlled plant. Besides some custom implementations which are capable to store the data of complete control objects, most of the trending tools archive scalar data.Additional features like conditional trending or correlation plots make up the difference between individual implementations.4 Programming InterfacesWith respect to open programming interfaces PLC’s and DCS systems have a common strategy. They are running reliably because there’s no way to integrate custom code which could interfere with the internal processing. As a consequence the customer has to order ‘specials’ - which are extremely expensive – or forget about it and use the system as a black box.Since SCADA systems by definition must be able to communicate with a variety of I/O subsystems they already have some built in API’s which allow to integrate custom functionality.Specially collaborative systems need a certain openness to fulfill all the requirements from various development groups.Programming interfaces on all levels like font-end I/O, front-end processing, networking etc. are mandatory. A clear advantage for this type of system.5 RedundancyIf redundancy means the seamless switch which takes over all the states and all the values of the I/O and all states of all programs currently running, it is a domain of only a few DCS systems. Custom or CCS implementation do not provide this kind of functionality. Maybe because of the immense effort and the fact that it is only required in rare cases.Besides processor redundancy, redundant networks or I/O subsystems are available for certain commercial DCS systems. Again – a domain which is not covered by SCADA or CCS implementations.Advanced safety requirements may be covered byredundant PLC subsystems. These are for instance installed in (nuclear) power plants. Requirements for Personal Protection Systems (PPS) can sometimes only be fulfilled by redundant PLC’s. In process controls redundant PLC’s are only used in rare cases.6 NamespaceThe flat namespace of SCADA systems has already been described in the alarm section. Some SCADA systems (like PVSS-II) provide the notion of control objects or structured data which is a rare case. In all other cases so called field objects must be specified. These are objects which consist ofa list of properties (implemented as I/O points) and a set ofmethods ( implemented asmacros or function calls). One of these approaches is the UniNified Industrial COntrol System (UNICOS) at CERN [5].DCS systems and most of the custom/ collaborative systems are record –or device oriented. The difference being that typically one record is connected to a single I/O point and provides this way all sub features of a record implementation like individual engineering units, display- and alarm limits. The device oriented approach allows to connect several I/O points. The major difference being the fact that an object oriented device implementation provides methods and states for a device while (EPICS) records only serve a certain set of built in functions.Naming hierarchies are not specific to a type of implementation. They are available for some systems of any kind. For sure hierarchical naming schemes are desirable.IMPLEMENTATION STRATEGIESAfter having shown all the possible controls approaches it is time to have a look at the implementation of control systems.Starting from the I/O level one has to decide whether commercial solution are required, feasible or wanted.Special I/O does not always require custom solution for the font-end controller. Signals can be converted into standard signals but this does not apply for all kinds of signals.Resolution, repetition rates and signal levels might require custom developments which must be integrated into the overall control architecture. Even if the signals can not beconnected to standard I/O interfaces it might be possible to develop I/O controllers which implement a field bus interface which allow the integration with commercial control systems. Once this level of integration is not possible custom front-end controllers like VME crates come into play.Besides the decision whether special I/O requires dedicated custom solutions one has to decide who will do which part of the work? Does for instance the necessity of VME crates prohibit the delivery of a ‘turn key’ system built by industry?Or does a PLC based front-end system require a commercial SCADA system for high level controls?Turn Key SystemsIt is a clear trend in industry to deliver turn key systems. It allows a modular design of the whole system. Individual components can be subcontracted to several companies and tested locally. Once delivered to the construction site the primary acceptance tests have already been passed and the second phase, to integrate the subsystem into the global control system begins.While the detailed specification of control loops etc. is now part of the subsystems contract, the customer has to specify clearly how much information of the subsystem must be made available, what the data structures will look like and which connection (field bus/ Ethernet) will be used.Most turn key systems are delivered with PLC’s. The construction of the Swiss Light Source (SLS) has shown that also a VME based I/O system running a CCS – in this case EPICS – can be successfully commissioned [6].PLC Based SystemsPLC based systems are a consequence of the turn key ansatz. The next obvious approach might be to look besides commercial PLC’s also for commercial SCADA systems.The advantage is clearly the same like for the PLC: stable software, no programming – only configuration, support and good documentation. At DESY we have successfully established a relation between the controls group which provides a CCS service based on EPICS and the utility group which uses the EPICS configuration tools to set up their control environment. The big advantage though beingthat the EPICS code can be adjusted to the special requirements from both sides.Industrial SolutionsThe difference between CCS solutions and commercial solutions is fading away as soon as industry starts to deliver and support collaborative control systems. At KEK a company was contracted to supply programmers for the KEK-B upgrade. These programmers were trained in writing drivers and application code for EPICS. As a result the KEK-B control system is a mixture of software developed partly by industry and partly in house. This is another example for an industrial involvement for a CCS implementation.COSTThe question: “Was is the total cost of ownership (TCO) ofa PC?” has kept people busy since PC’s exist. The answersvary to all extremes. The question what is the TCO of a control system might give similar results.If you go commercial you have to pay for the initial licenses the implementation which is typically carried out by the supplier or by a subcontractor, and you pay for the on going software support which might or might not include the update license fee.If you go for a collaborative approach, you might contract a company or implement everything on your own. A question of ‘time and money’ as industry says. You will have more freedom and flexibility for your implementations but also a steeper learning curve. You can rely on the collaboration to provide new features and versions or you can contribute yourself. A major difference calculating the long term costs for a control system.At DESY one can roughly estimate that the (controls application)-support for a commercial approach – here D/3 - and the -support for a collaborative approach – here EPICS - is nearly the same. The software support and upgrade license fee is equivalent to one and a half FTE’s – which is about the manpower necessary to support new hardware and to upgrade EPICS.CONCLUSIONSDepending on the size and the requirements for a controls project the combination of commercial solutions and solutions based on a collaborative approach is possible in any rate between 0 and 100 percent. This applies for all levels from implementation to long term support. Special requirements on safety issues or a lack of manpower might turn the scale commercial. The necessity to interface special hardware, special timing requirements, the ‘having the code in my hands’ argument or the initial costs for commercial solutions will turn the scale collaborative. As long as collaborative approaches like EPICS stay up to date and run as stable and robust as commercial solutions, both will keep their position in the controls world in a complementary symbiosis.外文资料翻译外文翻译译文工业控制系统和协同控制系统现今的控制系统被广泛运用于许多领域.从纯真的工业控制系统到协同控制系统（CCS），控制系统不竭变动，不竭升级，现在则趋向于家庭控制系统，而它则是这两者的变种.被应用的控制系统的种类取决于技术要求.而且，实践标明，经济和社会因素也对此很重要.任何决建都有它的优缺点.工业控制要求可靠性，完整的文献记载和技术支持.经济因素使决定趋向于协同工具.能够亲自接触源码并可以更快速地解决问题是家庭控制系统的要求.多年的把持经验标明哪个解决方法是最主要的不重要，重要的是哪个可行.由于异类系统的存在，针对分歧协议的支持也是至关重要的.本文介绍工业控制系统，PlC controlled turn key系统，和CCS 工具，以及它们之间的把持.引言：80年代早期，随着为HERA(Hadron-Elektron-Ring-Anlage)加速器装置高温控制系统，德国电子同步加速器研究所普遍开始研究过程控制.这项新技术是必需的，因为可是现有的硬件没有能力来处置标准过程控制信号，如4至20毫安的电流输入和输出信号.而且软件无法在秒的稳定重复率下运行PID控制回路.另外，在实现对复杂的高温冷藏系统的开闭过程中，频率项目显得尤为重要.有需要增加接口解决总线问题并增加运算能力，以便于高温控制.因为已装置的D / 3系统[1] 只提供了与多总线板串行连接，以实现DMA与VME的连接并用其模拟多总线板的功能.温度转换器的计算功能来自一个摩托罗拉MVME 167 CPU和总线适配器，以及一个MVME 162 CPU.其把持系统是VxWorks，而应用法式是EPICS.由于对它的应用相当胜利，其还被运用于正在寻找一个通用的解决方案以监督他们的分布式PLC的公共事业管理.德国电子同步加速器研究所对过程管理系统的筛选集散控制系统（D/ 3）：市场调查标明：来自GSE的D / 3系统被HERA高温冷藏工厂选中.因为集散控制系统（D/ 3）的特性，所以这决定很不错.在展示端和I / O端扩展此系统的可能将有助于解决日益增加的HERA试验控制的要求.制约系统的年夜小的因素不是I / O的总数，通信网络的疏通与否.而通信网络的疏通与否取决于不存档的数据总量，不取决于报警系统中配置的数据.拥有DCS特点（Cube）的SCADA系统：相对Y2K问题促使我们寻找一个升级版或者取代版来取代现有的系统而言，以上提到的D / 3系统有一些硬编码的限制.由于急需给Orsi公司提供他们的产物，Cube开始起作用了[2].该项目包括装置功能的完全更换.这包括D / 3，以及德国电子同步加速器研究所的集成总线SEDAC和VME的温度转换器.该项目很有前景.可是因为HERA试验原按时间是有限制的，所以技术问题和组织问题也迫使计划提前.在供应商网站上的最后验收测试又呈现了戏剧性的性能问题.有两个因素引起了这些问题.第一个跟低估在1赫兹运行的6级温度转换器的CPU负荷有关.第二个由现有D / 3系统复杂的功能造成的额外负荷引起的.每个数字和模拟输入和输出通道在D / 3系统里的自身报警限值也被低估了.所有的附加功能都必需添加进去.最后，所有网络负载的报警限值，尤其是SCADA系统，也促使网络生成了限制.最后，与Orsi公司的合同被取消了.升级的D / 3系统是唯一可能的解决法子.在2003年3月，此系统最后被付诸实践.现在，相比“纯洁”SCADA系统的异质环境，Cube有同质配置环境的优势.SCADA（PVSS -Ⅱ）：在HERA加速器上的H1实验中，实验人员为升级他们的低速控制系统，决定使用PVSS -Ⅱ.现有的系统是由H1合作组的几名成员开发的，而现在却难以维持了.在CERN由联合控制项目[4]进行的广泛调查促使他们做出使用PVSS作为取代品的决定.PVSS是一个“纯洁”的监控和数据收集系统（SCADA系统）.其核心元素叫做事件管理器.它收集的数据主要是由I/ O设备提供.它还提供附加的管理服务，如：控制经理，数据库管理，用户界面，API经理以及在建的HTTP服务器.该PVSS脚本库允许执行复杂的序列以及复杂的图形.相比其他SCADA系统PVSS带有一个基本特点：它提供了API给设备的数据.SCADA系统的一个主要缺点是其中的两个数据库，一个为PLC’s服务，另一个为SCADA系统服务，这两个数据库必需维持.集成环境将努力克服这个限制.EPICS：在德国电子同步加速器研究所，EPICS从问题解决系统演化成了全集成控制系统.从成为高温控制系统的数据收集器和数量控制器，EPICS成了德国电子同步加速器研究所公用事业集团使用的核心系统.另外，通过 Industry Pack（IP）模块的手段，它还能运用于通过VME板卡的任何数据.EPICS通过其完整的功能，运用于没有由D / 3系统控制的高温冷藏系统.所有年夜约50个输入输出控制器运作年夜约25000业务处置记录.作为一个SCADA系统的EPICS：该公共事业组（水，电，压缩空气，加热和调温）使用各种散布在整个德国电子同步加速器研究所网站上的PLC.IOC向客户提供接口并收集数据.另外，如通道归档和图形显示（dm2k）会被使用.默认名决议和目录服务器（域名服务器）用于连接在TCP客户端和服务器应用法式.所有这些都是基本的SCADA功能.所有的配置文件（图形工具，报警处置法式和归档）提供了一种灵活的配置方案.德国电子同步加速器研究所公用事业集团已制定了一套工具来创立IOC数据库和配置文件.这样，控制组提供的服务坚持EPICS工具，而用户可以精力集中在被控制的设备上了.作为一个DCS系统的EPICS：作为SCADA系统的基本组成部份，EPICS还提供完整的输入输出控制器（IOC）.IOC提供所有功能DCS系统要求，如：实施每个记录的标准的属性；执行每个记录时的报警检查过程；控制记录，如PID.灵活的命名方案，默认的显示和每个记录的报警属性缓和了运作工具和IOC之间的连接.灵活的数据收集模式，支持调查模式以及发布定阅模式.。

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一、PLC概述可编程控制器是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。

以执行逻辑判断、计时、计数等顺序控制功能。

提出PLC概念的是美国通用汽车公司。

PLC 的基本设计思想是把计算机功能完善、灵活、通用等优点和继电器控制系统的简单易懂、操作方便、价格便宜等优点结合起来，控制器的硬件是标准的、通用的。

根据实际应用对象，将控制内容编成软件写入控制器的用户程序存储器内,使控制器和被控对象连接方便。

70年代中期以后，PLC已广泛地使用微处理器作为中央处理器，输入输出模块和外围电路也都采用了中、大规模甚至超大规模的集成电路，这时的PLC已不再是仅有逻辑(Logic)判断功能，还同时具有数据处理、PID调节和数据通信功能。

国际电工委员会(IEC)颁布的可编程控制器标准草案中对可编程控制器作了如下的定义：可编程控制器是一种数字运算操作的电子系统，专为在工业环境下应用而设计。

它采用了可编程序的存储器，用来在其内部存储执行逻辑运算，顺序控制、定时、计数和算术运算等操作的指令，并通过数字式和模拟式的输入和输出，控制各种类型的机械或生产过程。

可编程控制器及其有关外围设备，易于与工业控制系统联成一个整体，易于扩充其功能的设计。

可编程控制器对用户来说，是一种无触点设备，改变程序即可改变生产工艺。

目前，可编程控制器已成为工厂自动化的强有力工具，得到了广泛的普及推广应用。

可编程控制器是面向用户的专用工业控制计算机，具有许多明显的特点。

①可靠性高，抗干扰能力强；②编程直观、简单；③适应性好；④功能完善，接口功能强二、PLC的历史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。

初期可编程控制器只是用一种类似于语言的软件逻辑于代替继电器硬件逻辑，并且使开发时间由6个月缩短到6天。

虽然计算机控制技术已经产生，但是PLC控制因为它的高性能、成本低、并且对恶劣的环境有很强的适应能力而在工业控制的广泛应用中保持优势。

而且，尽管硬件的价格在逐渐下跌，据估计，根据Frost和Sullivan对PLC市场的调查研究表明，每年销售硬件的价格要比销售PLC的价格（一千五百万）至少多出八十亿美元。

PLC的创造者Richard E. Morley十分肯定的认为目前PLC市场是一个价值五十亿的工业虽然PLC广泛应用于工业控制中，PLC控制系统的程序依然和语法有关。

和软件过程一样，PLC的软件设计也以同样的方式会遇到软件错误或危机。

Morley在演讲中着重强调了这个方面。

如果房子建造的像软件过程一样，那么仅仅一只啄木鸟就可以摧毁文明。

特别的，PLC程序要解决的实际问题是消除软件错误和减少老式梯形逻辑语言的花费。

尽管PLC的硬件成本在继续下降，但是在工业控制上减少梯形逻辑的扫描时间仍然是一个问题，以至于可以用到低耗时的PLC。

一般来说，和其他领域相比生产PLC的周期要短很多。

例如，在实践中，VISI设计是一种有效的计算机辅助设计。

PLC不需要使用目前的以软件设计为基础软件工程方法论，因为PLC程序要求对软件和硬件搜都要考虑到。

因此，软件设计越来越成为花费动力。

在许多的工业设计工程中，多数人力分配给了控制系统设计和安装，并且他们被要求对PLC进行程序测试和错误排除。

再者，PLC控制系统不适合设计对适应性和重构有越来越多要求的生产系统。

一个更深入的问题是在大规模的工程中软件越来越复杂，促使要有一个系统化的设计方法论。

主题的客观性是为PLC自动控制系统建立一个系统化的软件设计方法论。

这个设计方法论包括以状态转换模型为基础的精确的描述，这个转台转换模型是自动控制系统的抽象系统。

方法论还包括一个逐步的设计过程，并且要设置一个设计规则，这样才能为一个成功的设计提供导向和方法。

这项研究的真正目的是找到一个减少控制软件发展过程的不稳定性的方法，也就是说，减少程序和调试时间以及他们的变化，以增强自动控制系统的适应性，并且通过调整软件使得软件可以再度使用。

这样的目的是为了克服目前程序策略的不足之处，而目前的程序策略是以个人软件开发者的经验为基础的。

三、现今的PLC从结构上分，PLC分为固定式和模块式两种。

固定式PLC包括CPU板、I/O 板、显示面板、内存块、电源等，这些元素组合成一个不可拆卸的整体。

模块式PLC包括CPU模块、I/O模块、内存、电源模块、底板或机架，这些模块可以按照一定规则组合配置。

在使用者看来，不必要详细分析CPU的内部电路，但对各部分的工作机制还是应有足够的理解。

CPU的控制器控制CPU工作，由它读取指令、解释指令及执行指令。

但工作节奏由震荡信号控制。

运算器用于进行数字或逻辑运算，在控制器指挥下工作。

寄存器参与运算，并存储运算的中间结果，它也是在控制器指挥下工作。

CPU速度和内存容量是PLC的重要参数，它们决定着PLC的工作速度，IO数量及软件容量等，因此限制着控制规模。

中央处理器(CPU)是PLC控制器的大脑。

通常CPU本身就是一个微控制器。

起先是8位微控制器例如8051,现在发展为16位和32位微控制器。

你会发现大部分由日本制造商制造的PLC中是日立和Fujicu的微控制器,西门子的微控制器多应用在欧洲的PLC中,摩托罗拉生产的微控制器则独占美国市场。

CPU同样关注通信, PLC控制器,操作程序的执行,监督记忆设置的输入和输出等部分的关联性。

PLC使用系统存储器（现在大部分采用闪存技术了）用于过程控制系统。

除了这个操作系统之外，它还包括一个由梯形图翻译成而进制形式的用户程序。

快擦型存储器（FLASH memory）的内容只有在改变用户程序的时候可以被改变。

PLC控制器比快擦型存储器使用得更早，EPROM存储器比快擦型存储器也更早，快擦型存储器必须用紫外线（UV，Ultra-Violet Ray）灯擦除，并在编程器上进行编程。

由于快擦型存储器技术的应用，使得这个过程大大缩短了。

在应用程序开发中，通过一个串行电缆可以对程序存储器进行重新编程。

用户存储器被分成具有特殊功能的块。

一部分存储器用来存储输入和输出状态。

一个输入的实际状态存储状态存储在专用存储器位上，为“1”或者“0”。

每一个输入和输出在存储器中都有一个相应的位。

另外一部分存储器用来存储用户程序中的变量的内容。

例如，定时器值，或者记数器值存放在存储器的这个部分。

PLC控制器可以通过计算机（通常方式）重新编程，但是也可以通过人工编程器9控制台）编程。

实际上，这意味着，如果你有编程所需要的软件，早期PLC控制器可以通过计算机进行编程。

今天的传输计算机是工厂自己对PLC控制器进行重新编程的理想设备。

这对于工业企业来说是非常重要的。

一旦系统修改结束，将正确的程序重新读入PLC控制器也是非常重要的。

定期检查PLC中的程序是否改变是非常好的事情。

这有助于避免车间发生危险情况（一些汽车制造商已经建立了通信网络，可以定期检查PLC中的程序，以保证运行的程序都是正确的）。

几乎所有用于为PLC控制器编程的程序都拥有各种不同的选项，例如系统输入/输出（I/O线）的强制开关，程序实时跟踪以及图表验证。

图表验证对于理解、定义失败和故障非常必要。

程序员可以添加标记，书日和输出设备名称，以及对于查找错误或者对于系统维护很有用的注释。

添加注释和标记可以使技术人员（不仅仅是开发人员）很快理解梯形图。

注释和标记甚至还可以准确地引用零件号，如果需要更换零件的话。

这将加快由于损坏零件而引起的任何问题的修理速度。

响应的旧方法是这样的，开发系统的人必须保护这个程序，他旁边再没有人知道系统是怎样完成的。

正确的、备有证明文件的梯形图使任何技术人员都能彻底理解系统的功能。

电源是为中央处理单元提供电源的。

大部分PLC控制器的工作电压为24VDC或者220VAC。

在有些PLC控制器上，你可以看见作为独立模块的电源。

用户必须确定从I/O模块取出多大电流来保证电源提供适当的电流。

不同的模块使用不同的电流量。

该电源一般不用于启动外部输入或输出。

用户必须提供独立的电源来启动PLC 控制器的输入和输出，因为这样可以保证PLC控制器的所谓“纯电源”。

使用纯电源意味着工业环境中的电源不会严重影响它。

有些较小的PLC控制器从与PLC控制器集成在一起的小电源为它们的输入提供电压源。

四、PLC的设计标准一个系统化的设计PLC程序的方法可以克服传统程序生产控制系统的缺点，并且在一些工业应用总有很大的不同。

自动控制系统是状态模型用公式语言或等价的语言描述的。

公式描述对被控制的系统的行为提供一个精确的描述。

可以通过分析估计看状态模型是否达到想要的目标。

第二，为状态模型的描述提供结构描述，这个结构描述可以说明逻辑要求和如细节安全规则的限制。

第三，好的控制系统设计是对自动控制代码生成有益的——一种能够产生可执行的控制软件的能力，不同的逻辑控制器可以减少程序扫描时间和执行那个时间。

特别的，这个主题与随后的部分的是有关的。

在现代制造业中，系统是用过程和结果的革新来描述的，并且因此不得不改变系统性能以快速做出反应。

因此，一个大的挑战是提供技术以限制自动控制系统对变化需要和新机会的反应，所以，设计和操作知识可以实时的被再次利用，在工业实践中提供了一个重要的竞争面。

研究表明，在自动化系统中，程序实现的方法已经与计算机资源应用的急速增长不能匹配。

例如，可编程逻辑控制器（ＰＬＣ）程序仍然依靠一种方便的有逻辑梯形图的程序实现模式。

结果，程序上的延迟和资源成了生产工业过程的主要绊脚石。

在可编程逻辑控制器程序设计过程中，测试和调试可能会占用超过百分之五十的人力。

在发展和传播“ＳＴＡＴＥ－ＯＦ－ＴＨＥ－ＡＲＴ”已经形成标准[IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999]，但是，基本上这些标准都不能参与有效的程序和系统设计方面知识的革新。

系统的方法通过使用原有的软件模块，有助于增加设计自动化的水平，同时也将提供一种可管理的大规模系统设计的方法。

同样的，它也将改善软件的质量的可靠性，以及关系到系统的较高安全标准，尤其是这些对环境有危害影响的，比如：机场控制、公共铁路运输。

软件工业被认为是系统性能的破坏者和系统复杂性的产生者。

逐渐下降的硬件价格，破坏了对通过优化程序获得的软件性能的需要。

其结果是，一方面造成了大量而低效率的程序代码，另一方面并没有获得高的硬件性能。

其次，软件变得难以掌握其程度的复杂；在现代自动化系统中，软件设计和保持系统本质几乎变得不可能。

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