【机械类文献翻译】PLC概述
PLC技术简介与应用论文文献综述(1)
PLC技术简介与应用论文文献综述(1)PLC技术简介与应用论文文献综述PLC技术是一种基于数字化电气成本制造技术，它主要是以嵌入式式继电器为控制核心，利用可编程的编程语言编制应用程序来实现自动化工控系统。
随着科技的不断发展，PLC技术已经得到了广泛的应用，被广泛应用于工业自动化、机械制造、信息管理、办公自动化等领域。
本文将从简介PLC技术的基本概念、工作原理和特点等方面，对PLC技术的应用进行阐述，以期展现出PLC技术在现代化生产工业制造中的广泛应用和重要作用。
一、PLC技术的基本概念PLC技术是可编程逻辑控制器的简称，也叫做可编程控制器。
它是一款能够根据特定的逻辑运算程序来控制自动化设备的电气控制设备。
在PLC技术出现之前，工业自动化普遍采用的是传统的电子管、继电器等硬件式控制设备，这些硬件设备控制精度不高、运行速度慢、体积大、功耗太高等缺点阻碍了生产工业的进一步现代化。
PLC技术从20世纪60年代初开始出现并逐渐普及，其采用数字化技术来控制设备，利用存储器等硬件组件来自动故障检测和纠正，具有控制精度高、运行速度快、可靠性强等优点。
PLC技术的应用范围涵盖了所有需要控制和监控的生产工业，特别是机械制造、食品加工、石化、水处理、电力、电通讯以及交通等领域。
二、PLC技术的工作原理PLC技术采用数字化技术来进行控制，主要分为四个步骤：输入、处理、输出和存储。
具体来说，PLC技术的工作原理可以总结为以下五点：1.输入信号：PLC根据外部输入的信号来判断生产工艺的状态，输入信号包括开关、按钮、传感器等。
2.处理：PLC芯片将输入信号通过逻辑运算后进行处理，处理后的信号被送到输出端进行控制。
3.输出：处理好的信号经过硬件组件的调整，最终输出指令给设备进行对应的行动。
4.存储：PLC芯片和存储器的应用，保证了输入信号的稳定性、可重复性和可编程性。
5.编程：PLC技术的特别之处在于其采用可编程的编程语言，程序员可以通过编程语言编制应用程序来实现自动化工控系统。
PLC概述和主要特点
PLC发展概述可编程控制器(Programmable Logical Controller)简称PLC，是一种以微处理器为基础，综合了现代计算机技术、自动控制技术和通信技术发展起来的一种通用的工业自动控制装置。
它是从早期的继电器逻辑控制系统发展而来的，从最初的逻辑控制、顺序控制，发展为具有逻辑判断、定时、计数、记忆和算术运算、数据处理、联网通信及PID回路调节等功能的现代PLC。
它具有可靠性高、模块化组合灵活、功能强、编程方便、适应工业环境、安装维护简单以及运行速度快等特点。
由于它具有体积小、功能强、程序设计简单、维护方便等优点，特别是它适应恶劣工业环境的能力和它的高可靠性，使它的应用越来越广泛，已经被称为现代工业的三大支柱(即PLC、机器人和CAD／CAM)之一。
PLC是基于计算机技术和自动控制理论发展而来的，它既不同于普通的计算机，又不同于一般的计算机控制系统，作为一种特殊形式的计算机控制装置，它在系统结构，硬件组成，软件结构以及多通道用户界面等许多方面都有其特殊性。
从原理上说，可编程控制器和计算机是一致的，为了和工业控制相适应，PLC采用扫描原理来工作。
之所以采用这样的工作方式，是因为PLC是由继电器控制发展而来的，而CPU 扫描用户程序的时间远远短于继电器的动作时间，只要采用循环扫描的方法就可以解决其中的矛盾。
循环扫描的工作方式是PLC区别于普通的计算机控制系统的一个重要方面。
虽然各种PLC的组成各不相同，但是在结构上是基本相同的，一般由CPU、存储器、输入输出设备(I/O)和其他可选部件组成。
其他的可选部件包括编程器、外存储器、模拟I/O盘、通信接口、扩展接口等。
CPU是PLC的核心，它用于输入各种指令，完成预定的任务起到了大脑的作用；存储器包括随机存储器RAM和只读存储器ROM，通常将程序以及所有的指定参数同化在ROM中，RAM则为程序运行提供了存储实时数据与计算中间变量的空间；输入输出系统(I/O)使过程状态和参数输入到PLC的通道以及实时控制信号输出的通道，这些通道可以有模拟量输入、模拟量输出、开关量输入、脉冲量输入等，使PLC的应用十分广泛。
PLC外文翻译--PLC和电气工程技术概述
附录1：外文资料翻译A1.1：PLC和电气工程技术概述（译文）可编程逻辑控制器（PLC）或可编程控制器是一种数字化的计算机，应用于机电自动化过程的控制，如工厂流水线机械，游戏机，或照明装置。
可编程控制器可用于许多工业和机器。
不同于通用计算机，可编程控制器是专为多输入多输出控制要求而设计的装置，PLC能适应更大的工作温度范围，更高的抗电气噪音干扰能力，以及更好的抗震抗冲击能力。
控制机器操作的程序通常存储于备用电池或非挥发性内存中。
PLC是一个实时系统实例，因为，其输出结果必须在输入条件下满足响应时间范围才能产生。
否则将会导致误操作。
plc与其他控制系统的比较。
PLC 广泛的适用于自动化类任务处理。
在工业生产过程中，自动化系统的开发和维护成本占系统总成本较大比例，并且在使用寿命期内系统的变化是可预期的。
Plc包含的输入输出设备和工业试验装置和控制元件相兼容，小型电气设计中的需求和设计问题集中在如何表达所需的操作程序。
PLC 应用是典型的高度定制系统，因此一个成套的PLC价格相较一个具体定制的控制器设计要低。
另一方面，就大批量生产商品而言，用户定制控制系统更经济，这归因于该控制系统部件的成本更低，它是替代“泛型”解决方案的更好选择，并且一次性成本可以覆盖成千上万台器件。
对于大批量的或非常简单的自动化任务，可以使用不同的技术。
例如，一个用户洗碗机可以由一个量产成本只有几美元的机电凸轮计时器控制基于微控制器的设计适用于数百或数千个器件的生产，由此可令开发成本（电源设计，输入/输出硬件和必要的测试和认证）消化在更多的销售量中，并且终端用户无需改变其控制结构。
汽车自动化应用就是例证；每年产出数以百万计的元件，且很少终端用户会修改这些控制器的程序。
但是，一些特殊的汽车，例如运输车使用PLC代替定制型控制器更经济，因为其容量小并且开发成本会不经济。
应用在一些非常复杂的过程控制，例如化学工业时，可能需要使用较高等的算法和执行能力，甚至超过了高性能PLC的性能所及，高速和高精度控制可能同样需要用户定制的解决方案；例如航天器飞行控制器。
PLC外文文献翻译
外文翻译题目Programmable Logic Controller目录Programmable Logic Controller (PLC) (1)1. About Programmable Logic Controller (PLC) (1)2. INTRODUCTION (2)3. OPERATION SEQUENCE (4)3 .1 The Input and Output Scans (5)3.2 The Logic Scan (5)4 PLC STATUS (6)5. MEMORY TYPES (7)6. SOFTWARE BASED PLCS (8)7. SUMMARY (8)8. PRACTICE PROBLEMS (8)9. PRACTICE PROBLEM SOLUTIONS (9)中文翻译 (11)1. PLC介绍 (11)2．指令 (12)3．运行顺序 (13)3.1 输入输出扫描 (14)3．2 逻辑扫描 (14)4．PLC状态显示 (15)5．存储器类型 (16)6．基于软件的PLC系统 (16)7．概要 (17)8．实际问题 (17)9．实际问题解答 (17)Programmable Logic Controller (PLC)1. About Programmable Logic Controller (PLC)PLC (programmable logic controllers) is the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options.Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels. Number of points is the sum of the inputs and the outputs. PLC may be specified by any possible combination of these values. Expandable units may be stacked or linked together to increase total control capacity. Maximum number of channels refers to the maximum total number of input and output channels in an expanded system. PLC system specifications to consider include scan time, number of instructions, data memory, and program memory. Scan time is the time required by the PLC to check the states of its inputs and outputs. Instructions are standard operations (such as math functions) available to PLC software. Data memory is the capacity for data storage. Program memory is the capacity for control software.Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs. Outputs for PLC include DC, AC, relay, analog, frequency or pulse, transistor and triac. Programming options for PLC include front panel, hand held and computer.Programmable logic controllers use a variety of software programming languages for control. These include IEC 61131-3, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD),structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic. The IEC 61131-3 programming environment provides support for five languages specified by the global standard: Sequential Function Chart, Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multi-vendor compatibility and multi-language programming. SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallelsequences. FBD uses a broad function library to build complex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable communication and interface functions. LD is a graphic language for discrete control and interlocking logic. It is completely compatible with FBD for discrete function control. ST is a text language used for complex mathematical procedures and calculations less well suited to graphical languages. IL is a low-level language similar to assembly code. It is used in relatively simple logic instructions. Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLC). Ladder logic programming is a graphical representation of the program designed to look like relay logic. Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries. C is a high level programming language suited to handle the most complex computation, sequential, and data logging tasks. It is typically developed and debugged on a PC. BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions. Programmable logic controllers can also be specified with a number of computer interface options, network specifications and features. PLC power options, mounting options and environmental operating conditions are all also important to consider.2. INTRODUCTIONFor simple programming the relay model of the PLC is sufficient. As more complex functions are used the more complex V onNeuman model of the PLC must be used. A V onNeuman computer processes one instruction at a time. Most computers operate this way, although they appear to be doing many things at once. Consider the computer components shown in Figure 1.Figure 1 Simplified Personal Computer ArchitectureInput is obtained from the keyboard and mouse, output is sent to the screen, and the disk and memory are used for both input and output for storage. (Note: the directions of these arrows are very important to engineers, always pay attention to indicate where information is flowing.) This figure can be redrawn as in Figure 2 to clarify the role of inputs and outputs.Figure 2 An Input-Output Oriented ArchitectureIn this figure the data enters the left side through the inputs. (Note: most engineering diagrams have inputs on the left and outputs on the right.) It travels through buffering circuits before it enters the CPU. The CPU outputs data through other circuits. Memory and disks are used for storage of data that is not destined for output. If we look at a personal computer as a controller, it is controlling the user by outputting stimuli on the screen, and inputting responses from the mouse and the keyboard.A PLC is also a computer controlling a process. When fully integrated into an application the analogies become;Inputs - the keyboard is analogous to a proximity switchInput -circuits - the serial input chip is like a 24Vdc input cardComputer - the 686 CPU is like a PLC CPU unitOutput - circuits - a graphics card is like a triac output cardOutputs - a monitor is like a lightStorage - memory in PLC is similar to memories in personal computersIt is also possible to implement a PLC using a normal Personal Computer, although this is not advisable. In the case of a PLC the inputs and outputs are designed to be more reliable and rugged for harsh production environments.3. OPERATION SEQUENCEAll PLCs have four basic stages of operations that are repeated many times per second. Initia lly when turned on the first time it will check it’s own hardware and software for faults. If there are no problems it will copy all the input and copy their values into memory, this is called the input scan. Using only the memory copy of the inputs the ladder logic program will be solved once, this is called the logic scan. While solving the ladder logic the output values are only changed in temporary memory. When the ladder scan is done the outputs will be updated using the temporary values in memory, this is called the output scan. The PLC now restarts the process by starting a self check for faults. This process typically repeats 10 to 100 times per second as is shown in Figure 3.Figure 3 PLC Scan CycleSELF TEST - Checks to see if all cards error free, reset watch-dog timer, etc. (A watchdog timer will cause an error, and shut down the PLC if not reset within a short period of time - this would indicate that the ladder logic is not being scanned normally).INPUT SCAN-Reads input values from the chips in the input cards, and copies their values to memory. This makes the PLC operation faster, and avoids cases where an input changes from the start to the end of the program (e.g., an emergency stop). There are special PLC functions that read the inputs directly, and avoid the input tables.LOGIC SOLVE/SCAN-Based on the input table in memory, the program is executed 1 step at a time, and outputs are updated. This is the focus of the later sections.OUTPUT SCAN-The output table is copied from memory to the output chips. These chips then drive the output devices.The input and output scans often confuse the beginner, but they are important. The input scan takes a snapshot of the inputs, and solves the logic. This preventspotential problems that might occur if an input that is used in multiple places in the ladder logic program changed while half ways through a ladder scan. Thus changing the behaviors of half of the ladder logic program. This problem could have severe effects on complex programs that are developed later in the book. One side effect of the input scan is that if a change in input is too short in duration, it might fall between input scans and be missed.When the PLC is initially turned on the normal outputs will be turned off. This does not affect the values of the inputs.3 .1 The Input and Output ScansWhen the inputs to the PLC are scanned the physical input values are copied into memory. When the outputs to a PLC are scanned they are copied from memory to the physical outputs. When the ladder logic is scanned it uses the values in memory, not the actual input or output values. The primary reason for doing this is so that if a program uses an input value in multiple places, a change in the input value will not invalidate the logic. Also, if output bits were changed as each bit was changed, instead of all at once at the end of the scan the PLC would operate much slower.3.2 The Logic ScanLadder logic programs are modelled after relay logic. In relay logic each element in the ladder will switch as quickly as possible. But in a program elements can only be examines one at a time in a fixed sequence. Consider the ladder logic in Figure 4, the ladder logic will be interpreted left-to-right, top-to-bottom. In the figure the ladder logic scan begins at the top rung. At the end of the rung it interprets the top output first, then the output branched below it. On the second rung it solves branches, before moving along the ladder logic rung.Figure 4 Ladder Logic Execution SequenceThe logic scan sequence become important when solving ladder logic programs which use outputs as inputs. It also becomes important when considering output usage. Consider Figure 5, the first line of ladder logic will examine input A and set output X to have the same value. The second line will examine input B and set the output X to have the opposite value. So the value of X was only equal to A until the second line of ladder logic was scanned. Recall that during the logic scan the outputs are only changed in memory, the actual outputs are only updated when the ladder logic scan is complete. Therefore the output scan would update the real outputs based upon the second line of ladder logic, and the first line of ladder logic would be ineffective.Figure 5 A Duplicated Output Error4 PLC STATUSThe lack of keyboard and other input-output devices is very noticeable on a PLC. On the front of the PLC there are normally limited status lights. Common lights indicate:Power on - this will be on whenever the PLC has power.Program running - this will often indicate if a program is running, or if no program is running.Fault - this will indicate when the PLC has experienced a major hardware or software problem.These lights are normally used for debugging. Limited buttons will also be provided for PLC hardware. The most common will be a run/program switch that will be switched to program when maintenance is being conducted, and back to run when in production. This switch normally requires a key to keep unauthorized personnel from altering the PLC program or stopping execution. A PLC will almost never havean on-off switch or reset button on the front. This needs to be designed into the remainder of the system.The status of the PLC can be detected by ladder logic also. It is common for programs to check to see if they are being executed for the first time, as shown in Figure 6. The ’first scan’ input will be true on the very first time the ladder logic is scanned, but false on every other scan. In this case the address for ’first scan’ in a PLC-5 is ’S2:1/14’. With the logic in the example the first scan will seal on ’light’, until ’clear’ is turned on. So the light will turn on after the PLC has been turned on, but it will turn off and stay off after ’clear’ is turned on. The ’first scan’ bit is also referred to at the ’first pass’ bit.Figure 6 An program that checks for the first scan of the PLC5. MEMORY TYPESThere are a few basic types of computer memory that are in use today.RAM (Random Access Memory) - this memory is fast, but it will lose its contents when power is lost, this is known as volatile memory. Every PLC uses this memory for the central CPU when running the PLC.ROM (Read Only Memory) - this memory is permanent and cannot be erased. It is often used for storing the operating system for the PLC.EPROM (Erasable Programmable Read Only Memory) - this is memory that can be programmed to behave like ROM, but it can be erased with ultraviolet light and reprogrammed.EEPROM (Electronically Erasable Programmable Read Only Memory) –This memory can store programs like ROM. It can be programmed and erased using a voltage, so it is becoming more popular than EPROMs.All PLCs use RAM for the CPU and ROM to store the basic operating system for the PLC. When the power is on the contents of the RAM will be kept, but the issue is what happens when power to the memory is lost. Originally PLC vendors usedRAM with a battery so that the memory contents would not be lost if the power was lost. This method is still in use, but is losing favor. EPROMs have also been a popular choice for programming PLCs. The EPROM is programmed out of the PLC, and then placed in the PLC. When the PLC is turned on the ladder logic program on the EPROM is loaded into the PLC and run. This method can be very reliable, but the erasing and programming technique can be time consuming. EEPROM memories are a permanent part of the PLC, and programs can be stored in them like EPROM. Memory costs continue to drop, and newer types (such as flash memory) are becoming available, and these changes will continue to impact PLCs.6. SOFTW ARE BASED PLCSThe dropping cost of personal computers is increasing their use in control, including the replacement of PLCs. Software is installed that allows the personal computer to solve ladder logic, read inputs from sensors and update outputs to actuators. These are important to mention here because they don’t obey the previous timing model. For example, if the computer is running a game it may slow or halt the computer. This issue and others are currently being investigated and good solutions should be expected soon.7. SUMMARY• A PLC and computer are similar with inputs, outputs, memory, etc.• The PLC continuously goes through a cycle including a sanity check, input scan, logic scan, and output scan.• While the logic is being scanned, changes in the inputs are not detected, and the outputs are not updated.• PLCs use RAM, and sometime EPROMs are used for permanent programs.8. PRACTICE PROBLEMS1. Does a PLC normally contain RAM, ROM, EPROM and/or batteries?2. What are the indicator lights on a PLC used for?3. A PLC can only go through the ladder logic a few times per second. Why?4. What will happen if the scan time for a PLC is greater than the time for an input pulse? Why?5. What is the difference between a PLC and a desktop computer?6. Why do PLCs do a self check every scan?7. Will the test time for a PLC be long compared to the time required for a simple program?8. What is wrong with the following ladder logic? What will happen if it is used?9. What is the address for a memory location that indicates when a PLC has just been turned on?9. PRACTICE PROBLEM SOLUTIONS1. Every PLC contains RAM and ROM, but they may also contain EPROM or batteries.2. Diagnostic and maintenance3. Even if the program was empty the PLC would still need to scan inputs and outputs, and do a self check.4. The pulse may be missed if it occurs between the input scans5. Some key differences include inputs, outputs, and uses. A PLC has been designed for the factory floor, so it does not have inputs such as keyboards and mice (although some newer types can). They also do not have outputs such as a screen or sound. Instead they have inputs and outputs for voltages and current. The PLC runs user designed programs for specialized tasks, whereas on a personal computer it is uncommon for a user to program their system.6. This helps detect faulty hardware or software. If an error were to occur, and the PLC continued operating, the controller might behave in an unpredictable way and become dangerous to people and equipment. The self check helps detect these types of faults, and shut the system down safely.7. Yes, the self check is equivalent to about 1ms in many PLCs, but a singleprogram instruction is about 1 micro second.8. The normal output Y is repeated twice. In this example the value of Y would always match B, and the earlier rung with A would have no effect on Y.9. S2:1/14 for micro logy, S2:1/15 for PLC-5.中文翻译1. PLC介绍PLCS（可编程逻辑控制器）是用于各种自动控制系统和过程的可控网络集线器。
【机械类文献翻译】PLC控制下的电梯系统
机械专业中英文文献翻译Elevator System Based on PLCComposed by the order of relay control system is a realization of the first elevator control method. However, to enter the nineties, with the development of science and technology and the widespread application of computer technology, the safety of elevators, reliability of the increasingly high demand on the relay control weaknesses are becoming evident.Elevator control system relays the failure rate high, greatly reduces the reliability and safety of elevators, and escalators stopped often to take with the staff about the inconvenience and fear. And the event rather than taking the lift or squat at the end of the lift will not only cause damage to mechanical components, but also personal accident may occur.Programmable Logic Controller (PLC) is the first order logic control in accordance with the needs of developed specifically for industrial environment applications to operate the electronic digital computing device. Given its advantages, at present, the relay control the lift has been gradually replaced by PLC control. At the same time, AC variable frequency motor speed control technology, the way the lift drag speed has been a gradual transition from DC to AC frequency converter. Thus, PLC control technology increases VVVF Elevator modern technology has become a hot industry.1. PLC elevator control advantages(1) used in elevator control PLC, with software for automatic control of liftoperation, reliability greatly increased.(2) layer was removed and a majority of the relay, the control system structure issimple, to simplify the external circuit.(3) PLC can be a variety of complex control system, easy to add or changecontrol functions.(4) PLC can be automated fault detection and alarm display to improve theoperation of security and ease of maintenance.(5) for the group control the allocation and management, and improve theefficiency of elevator operation.(6) do not need to change the control scheme changes when the hardware connection.2. VVVF elevator control characteristicsWith the power electronics, microelectronics and computer technology to control the rapid development of technology, communication technology VVVF also a very rapid rate. AC variable frequency motor speed control technology is the power to improve the process in order to improve product quality and improving the environment and promoting technological progress as a primary means. Frequency of its excellent performance and the speed brake from a smooth performance, high efficiency, high power factor and power-saving effect of a broad scope of application and many other advantages of being at home and abroad recognized as the most promising approach speedExchange characteristics of VVVF Elevator(1)low energy consumption(2) low load circuit, the required emergency power supply device of smallIn the acceleration stage, the required start-up current of less than 2.5 times the rated current. Peak starting current and time is short. Since the starting current is drastically reduced, so power consumption and power supply cable diameter can be reduced a lot. Required for emergency power supply devices are also relatively small size.(3) high reliability and long service life.(4) good comfortElevator operation is best to follow the speed curve of a given operation. Their characteristics can be adapted to human feelings, and to ensure that noise operation, smooth brakePing layer and high precision(5) Stable noise-free(6) In the car, the engine room and adjacent areas to ensure that noise. Because their systems use a high clock frequency. Always produce a true sine wave power supply current yet. Motor torque ripple does not appear. Therefore, to eliminate vibration and noise.3. Elevator control technologyThe so-called elevator control technology refers to the elevator drive system and electrical control system of automatic control. 70 as the 20th century in China's elevator was marked by the exchange of two-speed elevator. Its speed is used to change the elevator traction motor of the very few, two or multi-level approach to the number of windings, very few of them as high-speed winding of the winding, a very few number of windings as the low-speed winding. Windings for high-speedelevator-speed start-up and running, low-speed windings for braking and the maintenance of elevators.The early 80s, VVVF inverter controlled variable lift system available. It uses AC motor drives, are able to reach the level of DC motor, control the speed of the current has reached 6 m / sec. Its small size, light weight, high efficiency, energy saving, including the past almost all the advantages of the lift. Is the latest elevator drive system.Operation in vertical lift, there is also the starting point of the terminus station. For more than three-story elevator buildings, the starting point of the terminal stations and stops between the had not, the starting point for these stations at the first floor of the terminal located at the highest floor. Starting point in the first floor of the station known as base stations, known as the starting point at both ends of the terminal stations and stations at both ends of intermediate stops between stations.Outside the station has a call box, box set are used by staff for elevator call button or touch the call button, the general ends of the lift stations in the call box on the Settings button or touch of a button. Middle layer of the station set up the call box button or touch button 2. No drivers for the control of elevators, at various stations are set up calls me on a button or touch button. Elevator car and the internal settings (except for debris elevator) to manipulate me. Control box switch on the handle or set up stations and the corresponding layer of buttons or touch-button control box on the touch-control button or command button or touch the city button. Outside the command button or touch-button issue as the signal outside the command signal, within the command button or touch-button issue within the signal as a command signal. 80 In the mid-20th century, the touch button has been replaced by micro-button.As the elevator call box outside the base station, in addition to set up a call button or touch button, but also set a key switch in order to work the elevator clearance. Drivers or management staff to open the elevator to the base station can wriggle through a dedicated key to the key switch. Close the elevator in place to automatically cut off the elevator control power supply or power supply.4. PLC Control Elevator DesignWith the continuous development of urban construction, the increasing high-rise buildings, elevators and life in the national economy has a broad application. Elevator high-rise buildings as a means of transport in the vertical run of daily life has beeninextricably linked with people. In fact the lift is based on external call control signals, as well as the laws of their own, such as running, and the call is random, the lift is actually a man-machine interactive control system, simple to use control or logic control order can not meet the control requirements, and therefore , elevator control system uses a random control logic. Elevator control is currently generally used in two ways, first, the use of computer as a signal control unit, the completion of the lift signal acquisition, operation and function of the set, to achieve the lift and set the automatic scheduling function to run the election, drag the control from inverter to complete; the second control mode with programmable logic controller (PLC) to replace the computer control signal sets the election. From the control and performance, these two types of methods and there is no significant difference. Most of the domestic manufacturers to choose the second approach, because the smaller scale of production, their design and manufacture of high cost of computer control devices; and PLC high reliability, convenient and flexible program design, anti-interference ability, stable and reliable operation of the characteristics of Therefore, the elevator control system is now widely used to realize programmable controller.5. Elevator control system characteristicsOperation of the lift curve is above the start to run comfort indicators lift the key features, and comfort are directly related with the acceleration, according to control theory, for a certain amount of change according to the law must be directly controlled, for elevator control system, according to the ideal acceleration curve acceleration feedback to be used, in accordance with the motor torque equation: M-MZ = ΔM = J (dn / dt), can be seen reflected in the rate of change of acceleration of the system of dynamic torque changes on the control system to control the acceleration of the dynamic torque ΔM = M-MZ. Therefore, during this time to control the use of the principle of acceleration, when the start rate of increase in steady-state value above 90%, the acceleration control system by the switch to speed control, as in paragraph steady speed, speed control for the constant fluctuations in the smaller, little change in acceleration, speed and the use of closed-loop control can maintain a steady-state speed accuracy and precision for the braking section to create the conditions ping layer. Is rising at a rate in the system, and although the above-speed PI regulator used to control, but two of the PI parameters are different in order to improve the system dynamic response indicators. The brake in the system,that is, to reduce the speed of control necessary to ensure the comfort, but also strictly in accordance with the operation of the lift of the relationship between speed and distance control to ensure the accuracy of flat layers. To the speed in the system before 120r/min, in order to take into account both be taken to control the acceleration of time-based and at the same time in each braking distance based on actual speed and speed deviations from the theory to fix the acceleration curve of a given method. For example, from a flat layer at the distance L, the speed should be reduced to Vm / s, while the actual high speed V'm / s, is illustrated by the increase in the braking torque is not enough here, therefore to calculate value determined by the speed-ag after it combined with a negative deviation of ε, even here the value given by the speed of amended - (ag + ε) so that a given rate of deceleration and the actual increase of negative bias, which increases braking torque big, so fast down to the standard value, when the motor speed 120r/min down after the car at this time only a dozen or so cm layer anomaly, low speed lift, in order to prevent yet floor parking area on the phenomenon in order to enable faster access to the lift to floor area ratio adjustment used in this paragraph and the use of optimal control of time in order to ensure accurate and timely access to elevator floor area, in order to achieve accurate and reliable level layer.PLC控制下的电梯系统由继电器组成的顺序控制系统是最早的一种实现电梯控制的方法。
PLC文献及翻译
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。
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。
PLC概述
PLC概述
PLC概述名称|定义|起源|品牌|结构|应用领域1.PLC的名称英文全称programmblelogiccontroller中文全称
可编程序逻辑控制器2.PLC的定义一种电子装置。
主要用于工业环境。
可以执行逻辑运算、顺序控制、定时、计数、算术运算等指令。
可以控制各种机械设备。
3.PLC的起源1968年美国通用汽车公司（GM）提出设计PLC的构想。
1969年美国数字设备公司（D EC）研制出了第一台PLC。
4.PLC的主流品牌德国---西门子日本---欧姆龙、三菱美国---A-B中国---汇川5.PLC
的结构CPU模块Ｉ／Ｏ模块编程设备电源模块6.PLC的应用领域开关量控制运动控制过程控制数据处理联网通讯。
PLC概述
PLC概述可编程控制器是以中央处理器（CPU）为基础，融合高集成控制电路构成的一种具有数学运算能力的工业控制装置。
因为它是由CPU 组成的，所以又被称为PC（Programmable Controller）机，其在20世纪60年代早期主要应用于继电器的逻辑控制中，所以简称为PLC （Programmable Logic Controller）。
由于PLC 编程灵活、运算能力强、功能齐全、结构紧凑、重量轻、功耗低、可靠性强，因而它在各种机械设备和生产过程的控制系统中得到广泛的应用，成为工业控制中的主要装置之一。
1.1 PLC的定义PLC 是指以计算机技术为基础的新型工业控制装置。
在1987 年国际电工委员会（International Electrical Committee）颁布的PLC 标准草案中对PLC 做了如下定义：PLC 英文全称Programmable Logic Controller，中文全称为可编程逻辑控制器，是一种专门为在工业环境下应用而设计的数字运算的电子系统。
它采用一类可编程的存储器，在其内部存储程序，执行逻辑运算、顺序控制、定时、计数与算术操作等面向用户的指令；并通过数字式或模拟式的输入/输出（I/O）控制各种类型的机械生产过程。
PLC也是一种可编程逻辑电路，使用和硬件结合很紧密的编程语言，在半导体领域有很重要的应用。
PLC及其有关的外围设备都应该按照易于与工业控制系统形成一个整体、易于扩展其功能这样的原则来设计。
1.2 PLC的特点1．可靠性高所有的I/O接口电路均采用光电隔离，使工业现场的外围电路与PLC内部电路之间电气隔离。
① 各输入端均采用RC滤波器，其滤波时间常数一般为10～20ms。
② 各模块均采用屏蔽措施，以防止辐射干扰。
③ 采用性能优良的开关电源。
④ 对采用的器件进行严格的筛选。
⑤ 良好的自诊断功能，一旦电源或其他软、硬件发生异常情况，CPU 立即采用有效措施，以防止故障扩大。
PLC技术简介与应用论文文献综述-V1
PLC技术简介与应用论文文献综述-V1
PLC技术简介与应用论文文献综述
1. PLC技术简介：
PLC，即可编程逻辑控制器，是一种专门用于控制工业自动化生产过程
的控制设备。
PLC的工作原理是通过在控制器内部设置一些逻辑控制程序，并将输入设备与输出设备利用PLC的输入输出模块连接起来，从
而实现自动化生产的控制。
PLC系统具有灵活性、可靠性高、易于维护等优点，因此广泛应用于各个领域，如自动化生产线、工业机械设备等。
2. PLC技术应用：
PLC技术已在自动化生产领域得到了广泛应用，下面以一些研究者的论文为例，阐述PLC技术的应用。
（1）在汽车生产制造方面，PLC技术已广泛应用。
王宗良（2019）在
其论文中指出，通过对汽车生产线上关键环节的PLC控制，可以实现
对生产过程的全面监控与把控，提升汽车制造的生产效率。
（2）在机械设备生产方面，PLC技术也发挥了重要作用。
李德洲（2020）在其论文中研究了PLC控制器在数控车床上的应用，实现了
机械设备的高精度加工，提高了生产效率。
（3）在物流行业方面，PLC技术也被广泛应用。
李华（2018）在其论
文中介绍了PLC技术在物流自动化中的应用，通过对物流管理的PLC
控制，实现了物流的自动化管理，减少了人力成本，提高了货运效率。
综上所述，PLC技术的应用范围非常广泛，已成为自动化生产领域的重要技术手段。
第一章PLC概述
第一章PLC概述PLC（可编程逻辑控制器）是一种专用的电子设备，用于实现自动化控制系统中的逻辑运算、定时任务、计数和数据处理等功能。
它由中央处理单元（CPU）、输入输出（I/O）模块、存储器和通讯接口等部分组成，广泛应用于工业自动化领域。
PLC的发展可以追溯到20世纪60年代，最初是应用于实现自动化生产线上的控制任务。
与传统的继电器控制相比，PLC不仅能够实现更为复杂的控制逻辑，而且还具有编程灵活、可重复使用和易于维护等优点。
随着技术的不断进步，PLC在规模化、网络化和多功能化方面得到了进一步发展。
PLC的工作原理主要基于两个重要概念：输入和输出。
输入是指PLC从外部设备（如传感器、按钮等）接收的信号，输出则是PLC通过输出模块向外部设备（如电机、阀门等）发送的控制信号。
PLC通过其内部的逻辑和控制算法，根据输入信号的状态变化生成相应的输出信号，从而实现对外部设备的控制。
PLC的编程一般采用类似于传统绘图的梯形图（或称为梯级图）方式，以便于工程师理解和编写。
梯形图是由一系列水平线和垂直线组成的，水平线上的每个元件表示一个逻辑功能，垂直线上表示不同的运算周期。
通过使用梯形图，工程师可以直观地表示出控制逻辑和时间顺序，从而更好地理解和调试程序。
PLC具有很多应用领域，包括制造业、交通运输、冶金、电力、石化等。
在制造业中，PLC被广泛用于控制生产线、机械设备和自动化工艺。
它可以实现自动化生产，提高生产效率和产品质量，并减少人工操作的错误和劳动强度。
在交通运输中，PLC被用于控制信号灯、电梯、自动扶梯等设备，提高交通安全和效率。
在电力系统中，PLC用于监测和控制变电站、发电厂和输电线路等设备，保证电力系统的安全稳定运行。
随着信息技术的快速发展，PLC也面临着新的挑战和机遇。
现代的PLC不仅具备高性能的硬件，还具备数据采集、处理和通讯功能，能够与上位机、SCADA系统和云平台等进行数据交互和远程监控。
这使得PLC在实现工业物联网和智能制造方面具有广阔的应用前景。
第一章 PLC的概述
第一章 PLC的概述1.11969 年，美国数字设备公司研制出了第一台可编程控制器 PDP—14 ，在美国通用汽车公司的生产线上试用成功，首次采用程序化的手段应用于电气控制，这是第一代可编程序控制器，称Programmable，是世界上公认的第一台PLC。
PLC主要结构与其组成：1. CPU——是PLC的核心部分。
与通用微机CPU一样，CPU在PC系统中的作用类似于人体的神经中枢。
2. 存储器3. I/O（输入/输出部件）（I/O模块：接口电路、I/O映像存储器）4. 编程器等外部设备5. 电源：内部——开关稳压电源，供内部电路使用；大多数机型还可以向外提供DC24V 稳压电源，为现场的开关信号、外部传感器供电。
PLC的结构组成与特点： CPU——是PLC 的核心部分。
与通用微机CPU一样，CPU在PC系统中的作用类似于人体的神经中枢。
2. 存储器3. I/O（输入/输出部件）（I/O模块：接口电路、I/O映像存储器）4. 编程器等外部设备5. 电源：内部——开关稳压电源，供内部电路使用；大多数机型还可以向外提供DC24V 稳压电源，为现场的开关信号、外部传感器供电。
主要功能1.2可编程控制器未来发展前景PLC的应用领域仍在扩展，在日本，PLC的应用范围已从传统的产业设备和机械的自动控制，扩展到以下应用领域：中小型过程控制系统、远程维护服务系统、节能监视控制系统，以及与生活关联的机器、与环境关联的机器，而且均有急速的上升趋势。
值得注意的是，随着PLC、DCS相互渗透，二者的界线日趋模糊的时候，PLC从传统的应用于离散的制造业向应用到连续的流程工业扩展1.7 可编程控制器使用中应注意的问题2.5元器件的选择参考文献。
【机械专业文献翻译】可编程控制器
机械专业中英文文献翻译毕业设计中英文翻译院系专业班级姓名学号指导教师20**年 4 月Programmable Logic Controllers (PLC)1、MotivationProgrammable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating [Moody and Morley, 1999, p. 110]:`If houses were built like software projects, a single woodpecker could destroy civilization.”Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.In general, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC basedsoftware design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than SO0/a of the manpower allocated for the control system design and installation is scheduled for testing and debugging PLC programs [Rockwell, 1999].In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigurability of manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects.PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options.Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels. Number of points is the sum of the inputs and the outputs. PLCs may be specified by any possible combination of these values. Expandable units may be stacked or linked together to increase total control capacity. Maximum number of channels refers to the maximum total number of input and output channels in an expanded system. PLC system specifications to consider include scan time, number of instructions, data memory, and program memory. Scan time is the time required by the PLC to check the states of its inputs and outputs. Instructions are standard operations (such as math functions) available to PLC software. Data memory is the capacity for data storage. Program memory is the capacity for control software.Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs. Outputs for PLCs include DC, AC, relay, analog, frequency or pulse, transistor, and triac. Programming options for PLCs include front panel, hand held, and computer.Programmable logic controllers use a variety of software programming languages for control. These include IEC 61131-3, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD), structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic. The IEC 61131-3 programming environment provides support for five languages specified by the global standard: Sequential Function Chart,Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multi-vendor compatibility and multi-language programming. SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallel sequences. FBD uses a broad function library to build complex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable communication and interface functions. LD is a graphic language for discrete control and interlocking logic. It is completely compatible with FBD for discrete function control. ST is a text language used for complex mathematical procedures and calculations less well suited to graphical languages. IL is a low-level language similar to assembly code. It is used in relatively simple logic instructions. Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLCs). Ladder logic programming is a graphical representation of the program designed to look like relay logic. Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries. C is a high level programming language suited to handle the most complex computation, sequential, and data logging tasks. It is typically developed and debugged on a PC. BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions.Programmable logic controllers can also be specified with a number of computer interface options, network specifications and features. PLC power options, mounting options and environmental operating conditions are all also important to consider.2、ResumeA PLC (programmable Logic Controller) is a device that was invented to replace the necessary sequential relay circuits for control.The PLC works by looking at its input and depending upon their state, turning on/off its outputs. The user enters a program, usually via software or programmer, which gives the desired results.PLC is used in many "real world" applications. If there is industry present, chance are good that there is a PLC present. If you are involved in machining, packing, material handling, automated assembly or countless other industries, you are probably already using them. If you are not, you are wasting money and time. Almost any application that needs some type of electrical control has a need for a PLC.For example, let's assume that when a switch turns on we want to turn a solenoid on for 5second and then turn it off regardless of how long the switch is on for. We can do this with a simple external timer. But what if the process included 10 switches and solenoids? We should need 10 external times. What if the process also needed to count how many times the switch individually turned on? We need a lot of external counters.As you can see the bigger the process the more of a need we have for a PLC. We can simply program the PLC to count its input and turn the solenoids on for the specified time.We will take a look at what is considered to be the "top 20" PLC instructions. It can be safely estimated that with a firm understanding of these instructions one can solve more than 80% of the applications in existence.Of course we will learn more than just these instruction to help you solve almost ALL potential PLC applications.The PLC mainly consists of a CPU, memory areas, and appropriate circuits to receive input/output data. We can actually consider the PLC to be a box full of hundreds or thousands of separate relay, counters, times and data storage locations,Do these counters,timers, etc. really exist? No,they don't "physically" exist but rather they simulated and be considered software counters, timers, etc. . These internal relays are simulated through bit locations in registers.What does each part do? Let me tell you.Input RelaysThese are connected to the outside world.They physically exsit and receive signals from switches,sensors,ect..Typically they are not relays but rather they are transistors.Internal Utility RelaysThese do not receive signals from the outside world nor do they physically exist.they are simulated relays and are what enables a PLC to eliminate external relays.There are also some special relays that are dedicated to performing only one task.Some are always on while some are always off.Some are on only once during power-on and are typically used for initializing data that was stored.CountersThese again do not physically exist. They are simulated counters and they can be programmed to count pulses.Typically these counters can count up,down or both up anddown.Since they are simulated,they are limited in their counting speed.Some manufacturers also include high-speed counters that are hardware based.We think of these as physically existing.Most times these counters can count up,down or up and down.TimersThese also do not physically exist.They come in many varieties and increments.The most common type is an on-delay type.Others include off-delays and both retentive and non-retentive types.Increments vary from 1ms through 1s.Output RelaysThere are connected to the outside world.They physically exist and send on/off signals to solenoids,lights,etc..They can be transistors,relays,or triacs depending upon the model chosen Data StorageTypically there are registers assigned to simply store data.They are usually used as temporary storage for math or data manipulation.They can also typically be used to store data when power is removed form the PLC.Upon power-up they will still have the same contents as before power was moved.Very convenient and necessary!A PLC works by continually scanning a program.We can think of this scan cycle as consisting of 3 important steps.There are typically more than 3 but we can focus on the important parts and not worry about the others,Typically the others are checking the system and updating the current internal counter and timer values,Step 1 is to check input status,First the PLC takes a look at each input to determine if it is on off.In other words,is the sensor connected to the first input on?How about the third...It records this data into its memory to be used during the next step.Step 2 is to execute program.Next the PLC executes your program one instruction at a time.Maybe your program said that if the first input was on then it should turn on the first output.Since it already knows which inputs are on/off from the previous step,it will be able to decide whether the first output should be turned on based on the state of the first input.It will store the execution results for use later during the next step.Step 3 is to update output status.Finally the PLC updates the status the outputs.It updates the outputs based on which inputs were on during the first step and the results executing your program during the second step.Based on the example in step 2 it would now turn on the firstoutput because the first input was on and your program said to turn on the first output when this condition is true.After the third step the PLC goes back to step one repeats the steps continuously.One scan time is defined as the time it takes to execute the 3 steps continuously.One scan time is defined as the time it takes to execute the 3 steps listed above.Thus a practical system is controlled to perform specified operations as desired.3、PLC StatusThe lack of keyboard, and other input-output devices is very noticeable on a PLC. On the front of the PLC there are normally limited status lights. Common lights indicate;power on - this will be on whenever the PLC has powerprogram running - this will often indicate if a program is running, or if no program is runningfault - this will indicate when the PLC has experienced a major hardware or software problemThese lights are normally used for debugging. Limited buttons will also be provided for PLC hardware. The most common will be a run/program switch that will be switched to program when maintenance is being conducted, and back to run when in production. This switch normally requires a key to keep unauthorized personnel from altering the PLC program or stopping execution. A PLC will almost never have an on-off switch or reset button on the front. This needs to be designed into the remainder of the system.The status of the PLC can be detected by ladder logic also. It is common for programs to check to see if they are being executed for the first time, as shown in Figure 1. The ’first scan’ input will be true on the very first time the ladder logic is scanned, but false on every other scan. In this case the address for ’first scan’ in a PLC-5 is ’S2:1/14’. With the logic in the example the first scan will seal on ’light’, until ’clear’ is turned on. So the light will turn on after the PLC has been turned on, but it will turn off and stay off after ’clear’ is turned on. The ’first scan’ bit is also referred to at the ’first pass’ bit.Figure 1 An program that checks for the first scan of the PLC4、Memory TypesThere are a few basic types of computer memory that are in use today.RAM (Random Access Memory) - this memory is fast, but it will lose its contents when power is lost, this is known as volatile memory. Every PLC uses this memory for the central CPU when running the PLC.ROM (Read Only Memory) - this memory is permanent and cannot be erased. It is often used for storing the operating system for the PLC.EPROM (Erasable Programmable Read Only Memory) - this is memory that can be programmed to behave like ROM, but it can be erased with ultraviolet light and reprogrammed.EEPROM (Electronically Erasable Programmable Read Only Memory) – This memory can store programs like ROM. It can be programmed and erased using a voltage, so it is becoming more popular than EPROMs.All PLCs use RAM for the CPU and ROM to store the basic operating system for the PLC. When the power is on the contents of the RAM will be kept, but the issue is what happens when power to the memory is lost. Originally PLC vendors used RAM with a battery so that the memory contents would not be lost if the power was lost. This method is still in use, but is losing favor. EPROMs have also been a popular choice for programming PLCs. The EPROM is programmed out of the PLC, and then placed in the PLC. When the PLC is turned on the ladder logic program on the EPROM is loaded into the PLC and run. This method can be very reliable, but the erasing and programming technique can be time consuming. EEPROM memories are a permanent part of the PLC, and programs can be stored in them like EPROM. Memory costs continue to drop, and newer types (such as flash memory) are becoming available, and these changes will continue to impact PLCs.5、Objective and Significance of the ThesisThe objective of this thesis is to develop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discrete event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in managing the control software development process, that is, reducing programming and debugging time and their variation, increasing flexibility of theautomation systems, and enabling software reusability through modularity. The goal is to overcome shortcomings of current programming strategies that are based on the experience of the individual software developer.A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired goals. Secondly, a state machine description provides a structured representation to convey the logical requirements and constraints such as detailed safety rules. Thirdly, well-defined control systems design outcomes are conducive to automatic code generation- An ability to produce control software executable on commercial distinct logic controllers can reduce programming lead-time and labor cost. In particular, the thesis is relevant with respect to the following aspect Customer-Driven ManufacturingIn modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements.A major challenge is therefore to provide enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industrial practice.Higher Degree of Design Automation and Software QualityStudies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60848, 1999; IEC-61131-3, 1993; IEC 61499, 1998; ISO 15745-1, 1999] have been formed to fix and disseminate state-of-the-art design methods, but they normally cannot participate in advancingthe knowledge of efficient program and system design.A systematic approach will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.System ComplexityThe software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes nearly impossible. Particularly, PLC programs have evolved from a couple lines of code 25 years ago to thousands of lines of code with a similar number of 1/O points. Increased safety, for instance new policies on fire protection, and the flexibility of modern automation systems add complexity to the program design process. Consequently, the life-cycle cost of software is a permanently growing fraction of the total cost. 80-90% of these costs are going into software maintenance, debugging, adaptation and expansion to meet changing needs [Simmons et al., 1998].Design Theory DevelopmentToday, the primary focus of most design research is based on mechanical or electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design. A system design theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Furthermore, building a bridge between design theory and the latest epistemological outcomes of formal representations in computer sciences and operations research, such as discrete event system modeling, can advance future development in engineering design.Application in Logical Hardware DesignFrom a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely complex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is tested through simulation. In general, a complete verification is impossible. Hence, a systematic approach as exemplified for the PLC program design may impact the logical hardware design.可编程控制器1、前言可编程序的逻辑控制器（PLC），是由Richard E.Morley 于1968年发明的，如今已经被广泛的应用于生产、运输、化学等工业中。
plc简介带引用
plc简介带引用
可编程逻辑控制器（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 采用一种可编程的存储器，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，通过数字式或模拟式的输入输出来控制各种类型的机械设备或生产过程。
PLC 具有可靠性高、抗干扰能力强、编程简单、使用方便等优点，已经成为现代工业控制的重要组成部分。
美国通用汽车公司在 1968 年提出了取代继电器控制装置的要求，第二年，美国数字设备公司研制出了第一代可编程控制器，满足了通用汽车公司的要求。
随着计算机技术的发展，PLC 的功能也不断得到扩展和完善。
在现代工业中，PLC 广泛应用于各种控制系统，如自动化生产线、机械加工设备、食品加工设备、印刷设备、电梯控制等。
PLC 的应用不仅提高了生产效率和产品质量，而且降低了生产成本和劳动强度。
总的来说，PLC 是一种非常重要的工业控制设备，它的出现和发展为工业自动化的发展做出了重要贡献。
随着科技的不断进步，PLC 的应用前景将会更加广阔。
PLC概述
第四章 PLC概述
四、可编程控制器的应用
应用形式： 应用形式： 1、开关逻辑控制 3、顺序（步进）控制 顺序（步进） 5、计数控制 7、数据处理 2、模拟量控制 4、定时控制 6、闭环过程控制 8、通信和联网
第四章 PLC概述
可编程控制器的应用领域
第四章 PLC概述
可编程控制器的应用领域
第四章 PLC概述
第四章 PLC概述
五、可编程控制器的发展趋势
向小型化和大型化两个方向发展
小型PLC由整体结构向小型模块化结构发展 小型 PLC由整体结构向小型模块化结构发展 ， 使配置 PLC 由整体结构向小型模块化结构发展， 更加灵活，为了市场需要已开发了各种简易、经济的 更加灵活，为了市场需要已开发了各种简易、 超小型微型PLC 最小配置的I/O点数为8 16点 PLC， I/O点数为 超小型微型 PLC， 最小配置的 I/O 点数为 8 ～ 16 点 ， 以 适应单机及小型自动控制的需要。 适应单机及小型自动控制的需要。 大型化是指大中型PLC 向大容量、 大型化是指大中型PLC 向大容量、智能化和网络化发 使之能与计算机组成集成控制系统，对大规模、 展，使之能与计算机组成集成控制系统，对大规模、 复杂系统进行综合性的自动控制。现已有I/O I/O点数达 复杂系统进行综合性的自动控制 。 现已有 I/O 点数达 14336点的超大型PLC，其使用32位微处理器， 点的超大型PLC 32位微处理器 14336 点的超大型 PLC， 其使用 32 位微处理器 ， 多 CPU 并行工作和大容量存储器，功能强。 并行工作和大容量存储器，功能强。
第四章 PLC概述
五、可编程控制器的发展趋势
大力开发智能模块， 大力开发智能模块，加强联网与通信能力
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ONE、PLC overviewProgrammable controller is the first in the late1960s 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 anon-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 in1968,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 withsoft-wired logic or so-called relay ladder logic(RLL),a programming language visually resembling the hardwired logic,and reduced thereby the configuration time from6months down to6days[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 to15million PLCs per year with the hardware value of more than8billion 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 a5-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 becausePLC-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 toachieve 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 were8-bit microcontrollers such as8051,and now these are16-and32-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 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 aninput 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 ments 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 at24VDC or220VAC.On some PLC controllers you’ll find electrical supply as a separate module.Those are usually bigger PLC controllers,while small and medium series already contain the supply er 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 in real-time,therefore,giving a significant competitive edge in industrial practice.Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources.For instance,the programming of 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 over50%of the manpower allocated for the PLC program design.Standards[IEC60848,1999; IEC-61131-3,1993;IEC61499,1998;ISO15745-1,1999]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 resultis that massive and less efficient software code on one hand outpaces thegains 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 code25years ago to thousands of lines of code with a similar number of1/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 of3years[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.Five、AK1703ACPFollowing the principle of our product development,AK1703ACP 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.AK1703ACP is thus perfectly suitable for automation with integrated telecontrol technology as:•Telecontrol substation or central device•Automation unit with autonomous functional groups•Data node,station control device,front-end or gateway•With local or remote peripherals•For rear panel installation or19inch 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-TM1703The Base Unit AK1703ACP with Peripheral Elements has one basic system element CP-2010/CPC25(Master control element)andCP-2012/PCCE25(Processing and communication element),one bus line with max.16peripheral elements can be connected.CP-2010/CPC25Features 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 of10msSynchronization 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 Ax1703peripheral busFunctions for Automatoin:•Open-/closed-loop control function for the execution of freely definable user programs which are created with CAEX plus according to IEC61131-3,ing function diagram technology512KB for user programApprox50.000variables and signals,2.000of them retainedCycle of10ms 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 Ax1703peripheral busSIX、SIEMENS PLCSIMATIC S7-300series 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 of60℃;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 S7-300type PLC's a very unique feature,which allows S7-300-PLC can deal openly with any other communications equipment,communications controller,or PLC S7-300type can be defined by the user's own Communications protocol(of the agreement ASCII),the baud rate to1.5Mbit/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 topPC-connected,and so can be ers can program to develop communication protocols,the exchange of data(for example:ASCII character code),RS232interfaces 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-Chineseinterface,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 WINDOWS98or WINDOWS NT4.0operating system,running on a PC object-oriented class32-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 MAP2.1standard.Yet2.1-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.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。