可編程控制器的外文翻譯及原文

1、<p>　　Programmable logic controller</p><p>　　Cynthia Cooper</p><p>　　From Wikipedia, the free encyclopedia</p><p>　　A programmable logic controller or simply programmable contr

2、oller is a digital computer used for automation of industrial processes, such as control of machinery on factory assembly lines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrang

3、ements, 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

4、</p><p><b>　　Features</b></p><p>　　Control panel with PLC (grey elements in the center). The unit consists of separate elements, from left to right; power supply, controller, relay u

5、nits for input and output.</p><p>　　The main difference from other computers is that PLCs are armored for severe condition (dust, moisture, heat, cold, etc) and have the facility for extensive input/output (

6、I/O) arrangements. These connect the PLC to sensors and actuators. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. Some even use ma

7、chine vision. On the actuator side, PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic </p><p>　　PLCs were invented as replacements for automated systems that would use hundreds or thou

8、sands of relays, cam timers, and drum sequencers. Often, a single PLC can be programmed to replace thousands of relays. Programmable controllers were initially adopted by the automotive manufacturing industry, where soft

9、ware revision replaced the re-wiring of hard-wired control panels when production models changed.</p><p>　　Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared

10、similar to electrical schematic diagrams. The electricians were quite able to trace out circuit problems with schematic diagrams using ladder logic. This program notation was chosen to reduce training demands for the exi

11、sting technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.</p><p>　　The functionality of the PLC has evolved over the years to include sequential re

12、lay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to de

13、sktop computers. PLC-like programming combined with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain applications.</p><p>　　Under the IEC 61131-3 standard, PLCs c

14、an be programmed using standards-based programming languages. A graphical programming notation called Sequential Function Charts is available on certain programmable controllers.</p><p>　　PLC compared with o

15、ther control systems</p><p>　　PLCs are well-adapted to a range of automation tasks. These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation syste

16、m is high relative to the total cost of the automation.PLCs contain input and output devices compatible with industrial pilot devices and controls.PLC applications are typically highly customized systems so the cost of a

17、 packaged PLC is low compared to the cost of a specific custom-built controller design. On the other ha</p><p>　　For high volume or very simple fixed automation tasks, different techniques are used. For exam

18、ple, a consumer dishwasher would be controlled by an electromechanical cam timer costing only a few dollars in production quantities.</p><p>　　A microcontroller-based design would be appropriate where hundre

19、ds or thousands of units will be produced and so the development cost (design of power supplies and input/output hardware) can be spread over many sales, and where the end-user would not need to alter the control. Automo

20、tive applications are an example; millions of units are built each year, and very few end-users alter the programming of these controllers. However, some specialty vehicles such as transit busses economically use PLC<

21、/p><p>　　Very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed or precision controls ma

22、y also require customized solutions; for example, aircraft flight controls.</p><p>　　PLCs may include logic for single-variable feedback analog control loop, a "proportional, integral, derivative"

23、or "PID controller." A PID loop could be used to control the temperature of a manufacturing process, for example. Historically PLCs were usually configured with only a few analog control loops; where processes

24、required hundreds or thousands of loops, a distributed control system (DCS) would instead be used. However, as PLCs have become more powerful, the boundary between DCS and PLC ap</p><p>　　Digital and analog

25、signals</p><p>　　Digital or discrete signals behave as binary switches, yielding simply an On or Off signal (1 or 0, True or False, respectively). Push buttons, limit switches, and photoelectric sensors are

26、examples of devices providing a discrete signal. Discrete signals are sent using either voltage or current, where a specific range is designated as On and another as Off. For example, a PLC might use 24 V DC I/O, with va

27、lues above 22 V DC representing On, values below 2VDC representing Off, and intermediate v</p><p>　　Analog signals are like volume controls, with a range of values between zero and full-scale. These are typi

28、cally interpreted as integer values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of bits available to store the data. As PLCs typically use 16-bit signed binary processors,

29、the integer values are limited between -32,768 and +32,767. Pressure, temperature, flow, and weight are often represented by analog signals. Analog signals can use voltage o</p><p><b>　　Example</b&g

30、t;</p><p>　　As an example, say a facility needs to store water in a tank. The water is drawn from the tank by another system, as needed, and our example system must manage the water level in the tank.</p&

31、gt;<p>　　Using only digital signals, the PLC has two digital inputs from float switches (tank empty and tank full). The PLC uses a digital output to open and close the inlet valve into the tank.</p><p&g

32、t;　　When the water level drops enough so that the tank empty float switch is off (down), the PLC will open the valve to let more water in. Once the water level raises enough so that the tank full switch is on (up), the P

33、LC will shut the inlet to stop the water from overflowing.</p><p>　　An analog system might use a water pressure sensor or a load cell, and an adjustable (throttling)dripping out of the tank, the valve adjust

34、s to slowly drip water back into the tank.</p><p>　　In this system, to avoid 'flutter' adjustments that can wear out the valve, many PLCs incorporate "hysteresis" which essentially creates

35、a "deadband" of activity. A technician adjusts this deadband so the valve moves only for a significant change in rate. This will in turn minimize the motion of the valve, and reduce its wear.</p><p&g

36、t;　　A real system might combine both approaches, using float switches and simple valves to prevent spills, and a rate sensor and rate valve to optimize refill rates and prevent water hammer. Backup and maintenance method

37、s can make a real system very complicated.</p><p>　　System scale</p><p>　　A small PLC will have a fixed number of connections built in for inputs and outputs. Typically, expansions are available

38、 if the base model does not have enough I/O.</p><p>　　PLCs used in larger I/O systems may have peer-to-peer (P2P) communication between processors. This allows separate parts of a complex process to have ind

39、ividual control while allowing the subsystems to co-ordinate over the communication link. These communication links are also often used for HMI (Human-Machine Interface) devices such as keypads or PC-type workstations. S

40、ome of today's PLCs can communicate over a wide range of media including RS-485, Coaxial, and even Ethernet for I/O control at </p><p>　　Programming</p><p>　　Early PLCs, up to the mid-1980s,

41、 were programmed using proprietary programming panels or special-purpose programming terminals. they were designed to replace relay logic systems. These PLCs were programmed in "ladder logic", which strongly re

42、sembles a schematic diagram of relay logic. Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a Very High

43、Level Programming Language designed to</p><p>　　Recently, the International standard IEC 61131-3 has become popular. IEC 61131-3 currently defines five programming languages for programmable control systems:

44、 FBD (Function block diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming language), IL (Instruction list, similar to assembly language) and SFC (Sequential function chart). These techniq

45、ues emphasize logical organization of operations.</p><p>　　While the fundamental concepts of PLC programming are common to all manufacturers, differences in I/O addressing, memory organization and instructio

46、n sets mean that PLC programs are never perfectly interchangeable between different makers. Even within the same product line of a single manufacturer, different models may not be directly compatible.</p><p>

47、;　　User interface</p><p>　　PLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday control. A Human-Machine Interface (HMI) is employed for this purpose. HMI's

48、 are also referred to as MMI's (Man Machine Interface) and GUI (Graphical User Interface).</p><p>　　A simple system may use buttons and lights to interact with the user. Text displays are available as we

49、ll as graphical touch screens. Most modern PLCs can communicate over a network to some other system, such as a computer running a SCADA (Supervisory Control And Data Acquisition) system or web browser.</p><p&g

50、t;　　Communications</p><p>　　PLCs usually have built in communications ports usually 9-Pin RS232, and optionally for RS485 and Ethernet. Modbus or DF1 is usually included as one of the communications protocol

51、s. Others' options include various fieldbuses such as DeviceNet or Profibus. </p><p><b>　　History</b></p><p>　　The PLC was invented in response to the needs of the American autom

52、otive industry. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using relays, timers and dedicated closed-loop controllers. The process for updating such fac

53、ilities for the yearly model change-over was very time consuming and expensive, as the relay systems needed to be rewired by skilled electricians. In 1968 GM Hydramatic (the automatic transmission division of Gene</p&

54、gt;<p>　　The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result. Bedford Associa

55、tes started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley

56、, who is considered to be the "father" of the PLC. The Modicon brand was sold in</p><p>　　The automotive industry is still one of the largest users of PLCs, and Modicon still numbers some of its co

57、ntroller models. PLCs are used in many different industries and machines such as packaging and semiconductor machines. Well known PLC brands are Toshiba, Siemens, Allen-Bradley, ABB, Mitsubishi, Omron, and General Electr

58、ic.</p><p><b>　　可編程邏輯控制器</b></p><p><b>　　辛西婭.庫珀</b></p><p><b>　　維基自由百科全書</b></p><p>　　可編程邏輯控制器或者簡易可編程控制器是一種數(shù)字化的計算機，它應用于工業(yè)自動化的生產(chǎn)過程中，比

59、如工廠裝配生產(chǎn)線中機械的控制。不同于普通用途的計算機，可編程邏輯控制器是專為安排多輸入和多輸出而設計的，它拓展了工作溫度范圍，可抑制電氣噪聲，抗振動和干擾。Programs to control machine operation are typically stored in battery-backed or non-volatile memory.程序控制機器操作指令通常存儲在備用電池或非易失性存儲器中。A PLC is an e

60、xample of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will resulPLC要求實時系統(tǒng)的輸出結果在一個時間范圍內(nèi)必須對輸入條件做出響應，否則會導致意想不到的結果。</p>

61、<p><b>　　特征</b></p><p>　　PLC的 Control panel with PLC (grey elements in the center).控制面板（灰色元素的中心），它的每個The unit consists of separate elements, from left to right; power supply , controller,

62、relay units for in- and output單位都是由單獨的元素組成的，由左向右分別是：電源供應器，控制器，繼電器單元的輸入輸出。</p><p>　　PLC和其他計算機的The main difference from other computers is that PLCs are armored for severe condition (dust, moisture, heat, cold

63、, etc) and have the facility for extensive input/output (I/O) arrangements.主要區(qū)別是它適用于各種惡劣環(huán)境條件下（如灰塵，潮濕，高溫，低溫等），并配備了適合于各種輸入/輸出端口的設備。 These connect the PLC to sensors and actuators .這些設備將PLC連接到相應的傳感器和信號發(fā)生器上。PLCs read limit s

64、witches , analog process variables (such as temperature and pressure), and the positions of complex positioning sPLC可以定義各種開關量，模擬量（如溫度和壓力等）用來配置各種復雜系統(tǒng)的各種變量，一些</p><p>　　PLC的出現(xiàn)改變了過去使用成百上千的繼電器，凸輪定時器，鼓音序器來構建一個自動化系

65、統(tǒng)的時代。Often, a single PLC can be programmed to replace thousands of relays .通常，一個簡單可編程控制器通過編程，以取代成千上萬的繼電器。 Programmable controllers were initially adopted by the automotive manufacturing industry, where software revision

66、replaced the re-wiring of hard-wired control panels when production models changed.可編程控制器最初應用于汽車制造業(yè)中，軟件修改取代了硬連線控制面板的重新布線，這標志著生產(chǎn)模式發(fā)生了徹底的改變。</p><p>　　許多早期的PLC設計表明，在簡單的梯形邏輯的決策中，已經(jīng)出現(xiàn)了類似梯形圖的電氣原理圖。The electricians

67、 were quite able to trace out circuit problems with schematic diagrams using ladder logic.電工們通過使用梯形邏輯能夠很方便的查找出電路示意圖的問題。This program notation was chosen to reduce training demands for the existing technicians.這項計劃符號的選擇使用可

68、以降低培訓其現(xiàn)有的技術人員的要求。而Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.其他早期的PLC則使用一種基于堆棧的邏輯解決方法——指令表編程的方式。 </p><p>　　PLC的功能經(jīng)過多年的發(fā)展，已經(jīng)包括順序控制，運動控制，過程控制，分布式控制系統(tǒng)和網(wǎng)絡控制

69、系統(tǒng)等多個方面。一些現(xiàn)代的PLC的The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers .數(shù)據(jù)處理，儲存，整理能力和通信能力，已大約相當于臺式電腦了。PLC-like programming combi

70、ned with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain application可編程控制器的編程結合遠程I/O硬件，允許通用臺式電腦進行一些PLC方面的特定應用。</p><p>　　根據(jù)國際電工委員會61131-3標準，PLC的編程可以使用基于標準的編程語言。所謂

71、順序功能圖的圖形符號編程適用于某些特定的可編程控制器。</p><p>　　可編程控制器與其他控制系統(tǒng)</p><p>　　PLC可以很好的適應各種自動化任務。這些都是典型的工業(yè)機械生產(chǎn)，在這些部門自動控制系統(tǒng)的高額費用是與其昂貴的的制造維護費用分不開的。PLC能控制輸入輸出設備并兼容工業(yè)試驗裝置和控制。通常PLC應用于高度定制的系統(tǒng),以便使組裝PLC的成本低于設計控制器的成本。另外，在大

72、規(guī)模生產(chǎn)產(chǎn)品方面，自定義的控制系統(tǒng)是經(jīng)濟的，由于他的組成部分成本較低。這是代替通用解決方案的最佳選擇。</p><p>　　為大批量或者簡單的固定自動化任務，不同的技術被采用。例如：消費者洗碗機被成本只有幾美元的機電凸輪計時器控制。</p><p>　　微處理器的設計要考慮成百上千的組成單元，以便開發(fā)成本（電源供應器和輸入輸出硬件的設計）能遍布到很多銷售領域，并且最終用戶不需要改變控制。汽

73、車應用是一個例子，每年有數(shù)以百萬輛汽車被制造，只有極少數(shù)最終用戶改變控制程序。然而，一些特殊車輛，如使用PLC系統(tǒng)代替定制設計控制的過境巴士因為使用量少所以開發(fā)費用不夠經(jīng)濟。</p><p>　　復雜的過程控制，如用于化學工業(yè)的過程控制要求的算法和性能甚至超過了高性能的PLC控制。高速度和精度的控制也可能需要量身定制的解決方案，如飛機的飛行控制。</p><p>　　PLC系統(tǒng)包括邏輯單變

74、量反饋模擬控制回路，一個“比例、積分、導數(shù)”或“控制器”。PID回路可用于控制制造過程的溫度，例如歷史上的PLC通常只用于少數(shù)模擬控制回路這個過程需要成百上千的循環(huán)、分布式控制系統(tǒng)（DCS）將代替使用。然而，由于PLC的功能越來越強大，DCS與PLC的界定越發(fā)的不明確。</p><p><b>　　數(shù)字和模擬信號</b></p><p>　　數(shù)字或離散信號表現(xiàn)為二進制

75、開關信號，收益率只是一個閉合或關斷信號。按鈕、限位開關、光電傳感器能提供了一個離散信號。離散信號以電壓或電流的形式傳送，它在一個特定的范圍內(nèi)被設置成開和關。例如：PLC必須使用24伏直流電壓的I/O口，高于22伏直流電壓代表開，低于2伏直流電壓代表關，中間值不確定。最初，PLC只有離散的I/O接口。</p><p>　　模擬信號和音量控制一樣，在零和滿量程之間有一系列的值。這些常常被定義為PLC中的整數(shù)，它的范圍

76、取決于設備中可用來存儲比特數(shù)據(jù)的存儲單元的數(shù)量。由于PLC通常使用16位有符號二進制處理器，整數(shù)值被限定在-32768—+32767之間。壓力、溫度、流量、重量往往代表的模擬信號。模擬型號可以使用與原信號成正比的電壓或電流信號。例如：一個4-20mA的電流信號或者0-10V的電壓信號將被轉化成一個0-32767之間的整型值。</p><p><b>　　事例</b></p>&

77、lt;p>　　水箱可以作為一個例子。一個設備用于向水箱中注水，另一個設備用于從水箱中取水，根據(jù)需要，我們必須建立一個系統(tǒng)去控制水箱的水位。</p><p>　　若只用數(shù)字信號，PLC有兩個數(shù)字輸入開關量（水箱空和水箱滿）。PLC有一個數(shù)字輸出量去控制水箱閥門的開關。</p><p>　　當水位下降使得水箱空箱開關關閉時，PLC將會打開閥門使更多的水進入。一旦水位升高到一定高度使得滿箱

78、開關閉合，PLC將會臨時關閉進水閥門防止水的溢出。</p><p>　　一個模擬系統(tǒng)可能會使用水位的壓力傳感器、可調(diào)（節(jié)流）出水閥和調(diào)節(jié)閥來逐漸提高水箱水位。</p><p>　　在這一系統(tǒng)中，為了避免損壞閥的擾動調(diào)節(jié)器，很多的PLC加入“滯后”環(huán)節(jié)，基本上實現(xiàn)了“死區(qū)”的活動。 A technician adjusts this deadband so the valve moves o

79、nly for a significant change in rate.技術員通過調(diào)整死區(qū)，使閥只在有一個顯著變化率的時刻動作。This will in turn minimize the motion of the valve, and reduce its wear.這將依次把閥門的動作減到最少，從而減少其磨損。</p><p>　　一個真正的系統(tǒng)可能把這兩種做法結合起來，使用浮動開關和簡單閥門來防止泄漏，

80、使用速率傳感器和速度閥來優(yōu)化水位上升速率并防止水錐的發(fā)生。考慮到Backup and maintenance methods can make a real system very complicated.支持性的維護方法，一個實際的系統(tǒng)將會非常復雜。</p><p><b>　　系統(tǒng)規(guī)模</b></p><p>　　A small PLC will have a f

81、ixed number of connections built in for inputs and outputs.一個小型PLC將有固定數(shù)量的I/O接口。Typically, expansions are available if the base model does not have enough I/O.通常情況下，如果相應的模型并沒有足夠的I/O接口，則需要擴展I/O口。</p><p>　　在較大的

82、I/O系統(tǒng)中，PLC可能使用點對點（P2P）的處理器通信。This allows separate parts of a complex process to have individual control while allowing the subsystems to co-ordinate over the communication link.這使得一個復雜過程的單獨部分有各自的控制，同時又允許各子系統(tǒng)同級之間進行通信聯(lián)系。Th

83、ese communication links are also often used for HMI (Human-Machine Interface) devices such as keypads or PC -type workstations.這些通訊聯(lián)系常常被用于HMI（人機界面）設備，如鍵盤或PC型工作站。當今Some of today's PLCs can communicate over a wide rang

84、e of media including RS-485, Coaxial, and even Ethernet for </p><p><b>　　編程</b></p><p>　　早期的PLC（直至20世紀80年代中期）使用專有的編程渠道或特殊用途的編程終端進行編程。它們是用來取代繼電器邏輯系統(tǒng)的。These PLCs were programmed in &qu

85、ot; ladder logic ", which strongly resembles a schematic diagram of relay logic.這些PLC用梯形圖編程，其非常類似于繼電器邏輯示意圖。Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming langua

86、ges such as BASIC and C. Another method is State Logic , a Very High Level Programming Language designed to program PLCs based on State Transition Diagrams .現(xiàn)代的PLC可以以各種方式編程，從梯形圖到更傳統(tǒng)的編程語言，如BASIC和C，另</p><p>　　

87、Recently, the International standard IEC 61131-3 has become popular.最近，國際標準IEC61131-3已經(jīng)流行。IEC 61131-3 currently defines five programming languages for programmable control systems: FBD ( Function block diagram ), LD ( La

88、dder diagram ), ST ( Structured text , similar to the Pascal programming language ), IL ( Instruction list , similar to assembly language ) and SFC ( Sequential function chart ).目前的IEC61131-3為可編程控制系統(tǒng)定義了5編程語言：FBD（功能框圖），LD

89、（梯形圖），ST（結構化文本），IL（指示表）和SFC（順序功能圖）。These techniques emphasiz</p><p>　　While the fundamental concepts of PLC programming are common to all manufacturers, differences in I/O addressing, memory organization and

90、 instruction sets mean that PLC programs are never perfectly interchangeable between different makers.所有制造商PLC編程的基本概念是共同的，分歧在于I/O的選擇，存儲組織的安排和指令集，所以不同生產(chǎn)商之間的PLC程序從來都不可以完全的互換。Even within the same product line of a single ma

91、nufacturer, different models may not be directly compatible.即使是同一制造商同一產(chǎn)品線，不同的模式也可能無法兼容。</p><p><b>　　用戶界面</b></p><p>　　PLC為了配置，報警或日常控制的目的可能需要人機互動交流。HMI（人機界面）因此而產(chǎn)生。人機界面包括MMI（人機接口）和GUI（

92、圖形用戶界面）。</p><p>　　A simple system may use buttons and lights to interact with the user.一個簡單的系統(tǒng)可以使用按鈕和燈來與用戶互動。Text displays are available as well as graphical touch screens.文字顯示以及圖形化的觸摸屏也可能用到。Most modern PLCs

93、 can communicate over a network to some other system, such as a computer running a SCADA (Supervisory Control And Data Acquisition) system or web browser.最現(xiàn)代的PLC可以通過網(wǎng)絡連接到其他的系統(tǒng)，如運行SCADA（監(jiān)控和數(shù)據(jù)采集系統(tǒng)）的計算機系統(tǒng)或網(wǎng)絡瀏覽器。</p>

94、<p><b>　　通信</b></p><p>　　PLC的內(nèi)置通信端口通常使用9針的RS232串口 ，并選擇性使用RS485的和以太網(wǎng)。Modbus協(xié)議或DF1是常用的一種通信協(xié)議。Others' options include various fieldbuses such as DeviceNet or Profibus .其他通信協(xié)議包括各種現(xiàn)場總線，如Devic

95、eNet現(xiàn)場總線或Profibus現(xiàn)場總線等。</p><p><b>　　歷史</b></p><p>　　PLC是應The PLC was invented in response to the needs of the American automotive industry.PLCPLCPLCPLCPLC是應美國汽車業(yè)發(fā)展的需要而產(chǎn)生的。在Before the

96、 PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using relays, timers and dedicated closed-loop controllers.PLC產(chǎn)生之前，汽車使用繼電器進行順序控制和安全聯(lián)鎖邏輯，制造定時器和專用閉環(huán)控制器。每年模型轉換是非常耗時和昂貴的Th

97、e process for updating such facilities for the yearly model change-over was very time consuming and expensive, as the relay systems needed to be rewir</p><p>　　中標投標書來自貝德福德，馬薩諸塞州的貝德福德聯(lián)營公司。The winning proposal

98、 came from Bedford Associates of Bedford, Massachusetts .The first PLC, designated the 084 because it was Bedford Associates' eighty-fourth project, was the result.第一個PLC，被命名為084 ，因為它是貝德福德的第八十四個項目的結果。Bedford Associat

99、es started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller.貝德福德聯(lián)營協(xié)會創(chuàng)建了一個新的公司，它致力于開發(fā)，制造，銷售和服務這一新產(chǎn)品：莫迪康，它代表模塊化數(shù)字控制器。One of