机电工程英语省公共课一等奖全国赛课获奖课件.pptx

Lesson 13 Programmable Logic Controller可编程逻辑控制器可编程逻辑控制器Section I Words and PhrasesSection II Text and TranslationSection III Exercises and Answers词英汉练 End Next 答第1页Section I Words and Phrasesactuator 执行机构pneumatic nju(:)5mAtikadj.气动，气力n.气胎hydraulichai5drC:likadj.水力,水压，液压n.液压传动装置relay5ri:lein.电工继电器solenoid5sEulinCidn.电螺线管proprietary prE5praiEtEriadj.全部些人：属于一个全部些人或作为群体全部些人，或与之相关：camkAmn.凸轮automate 5C:tEmeitv.使自动化,自动操作initially I5nIFElIadv.最初,开头Topic Above Next End 第2页Section I Words and Phrasesladder 5lAdE(r)n.梯子，梯形inspire in5spaiEvt.作为原因或根源；引发；激励，勉励：激发行动，促动trace out描绘出apprehension 7Apri5henFEnn担心，忧虑circuit 5sE:kitn.电路load lEudn.负荷,重担,负载power supply电源module 5mCdju:ln.模数,模块,flexibility 7fleksE5bilitin.弹性,适应性,柔韧性Topic Above Next End 第3页Section II Text A programmable logic controller,PLC,or programmable contr-oller is a small computer used for automation of real-world processes,such as control of machinery on factory assembly lines.The PLC usua-lly uses a microprocessor.The program can often control complex seq-uencing and is often written by engineers.The program is stored in battery-backed memory1 and/or EEPROMs2.PLCs have the basic structure,shown in Figure 13-1.From the figure,the PLC has four main units:the Programme memory,the Data memory,the Output devices and the Input devices.The Programme memory is used for storing the instructions for the lo-gical control sequence.The status of switches,interlocks,past values of data and other working data is stored in the Data memory.Topic Above Next 汉 End 第4页Section II Text The main differences from other computers are the special input/output arrangements.These connect the PLC to sensors3 and actuators4.PLCs read limit switches,temperature indicators and the positions of complex positioning systems.Some even use machine visionOn the ac-tuator side,PLCs drive any kind of electric motor,pneumatic or hydra-ulic cylinders or diaphragms,magnetic relay-s or solenoids.The input/output arrangements may be built into a simple PLC,or the PLC may have external I/O modules attached to a proprietary computer network that plugs into the PLC.Topic Above Next 汉 End 第5页Section II Text PLCs were invented as less expensive replacements for older auto-mated systems that would use hundreds or thousands of relays and cam-timers.Often,a single PLC can be programmed to replace thousands of relays.Programmable controllers were initially adopted by the auto-motive manufacturing industry,where software revision replaced the rewiring of hard-wired control panels.The functionality of the PLC has evolved over the years to include typical relay control,sophisticated motion control,process control,Distributed Control Systems5 and complex networking.Topic Above Next 汉 End 第6页Section II Text The earliest PLCs expressed all decision making logic in simple ladder logic inspired from the electrical connection diagrams.The elect-ricians were quite able to trace out circuit problems with schematic dia-grams using ladder logic.This was chosen mainly to reduce the appreh-ension of the existing technicians.Today,the PLC has been proven very reliable,but the program-mable computer still has a ways to go.With the IEC 661131-3 standard,it is now possible to program these devices using structured programmi-ng languages,and logic elementary operations.A graphical programming notation called Sequential Function Charts7 is available on certain programmable controllers.Topic Above Next 汉 End 第7页Section II Text However,it should be noted that PLCs no longer have a very high cost(often thousands of dollars),typical of a generic solution.Modern PLCs with full capabilities are available for a few hundred USD8.There are other ways for automating machines,such as a custom micro-controller-based design,but there are differences among both:PLCs contain everything needed to handle high power loads right out of the box,while a microcontroller would need an electronics engineer to des-ign power supplies,power modules,etc.Also a microcontroller based design would not have the flexibility of in-field programmability of a PLC.That is why PLCs are used in production lines,for example.The-se typically are highly customized systems so the cost of a PLC is low compared to the cost of contacting a designer for a specific,one-timeTopic Above Next 汉 End 第8页Section II Text only design.On the other hand,in the case of mass-produced goods,customized control systems quickly pay for themsel-ves due to the lower cost of the components.Topic Above Next 汉 End 第9页Section II Translation 可编程逻辑控制器，PLC,或者称可编程控制器，它是一个小型计算机，用于自动化生产，比如控制工厂装配机械等。可编程控制器通常使用了微处理器进行控制。其程序可控制复杂加工工序，并由工程师编写。程序通常存放在随机存放器和（或）电可擦写可编程只读存放器中。PLC基本结构 如图13-所表示。从图中可见，PLC有四个主要部件：程序存放器，数据存放器，输出设备和输入设备。程序存放器用来存放逻辑控制序列指令。开关状态，联锁状态、数据初始值等其它工作数据存放在数据存放器中。Topic Above Next 英 End 第10页Section II Translation 与其它计算机比较，最大区分是PLC有专用输入输出装置。这些装置将PLC与传感器和执行机构相连接。PLC能读取限位开关、温 度指示器和复杂定位系统位置信息。有些甚至使用了机器视觉。执行机构方面，PLC能驱动任何一个电机、气压或液压装置、控光装置、电磁继电器或螺线管。输入输出装置可能是安装在PLC内部，或者经过外部I/O模块与专用计算机网络相连。Topic Above Next 英 End 第11页Section II Translation 用可编程控制器替换要使用成千上百个继电器和凸轮早期自动控制系统愈加实惠。经常是一台PLC能够经过编程来替换数千个继电器。可编程控制器已在自动化制造工业中使用，在那里经过对软件修改能够取代硬连线控制面板重新连线。可编程控制器经过多年发展，其功效包含经典继电器控制，复杂运动控制，过程控制，分布控制系统和复杂网络技术。Topic Above Next 英 End 第12页Section II Translation 最早PLC采取简单梯形图来描述其逻辑程序，梯形图源自于电气连线图。电气技师们使用逻辑图很轻易找出原理图中电路问题。这么大大降低了技术员忧虑。如今，PLC功效已经非常可靠，不过可编程计算机依然有其发展空间。依照国际电工委员会61131-3标准，现在PLC能够使用结构化编程语言和逻辑初等变换来进行编程。一些可编程控制器可使用一个图表式编程符号，这种符号称为次序功效图表。Topic Above Next 英 End 第13页Section II Translation 然而，值得注意是，PLC不再是非常昂贵产品（通常是数千美元），而成了一个普通产品。如今，功效完善PLC也只要数百美元。还有其它方法使机床自动化，比如传统基于微控制器设计，不过这二者之间有一些差异。PLC包含全部能直接操作大功率负载输出功效。而微控制器还需要专用电源和电源模块，等等。同时基于微控制器设计方式不具备PLC现场可编程柔韧性。那也正是PLC在生产线上利用原因之一。这是一些经典高度用户化系统，所以比起请一个设计人员作一个特殊一次性设计成本，一台PLC成本要低一些。Topic Above Next 英 End 第14页Section II Translation 然而，值得注意是，PLC不再是非常昂贵产品（通常要数千美元），而是一种普通产品。现在，功能完善PLC也只要数百美元。使机床实现自动化还有其它方法，比如传统基于微控制器设计，但是这两者之间有一些差别。PLC包含全部能直接操作大功率负载输出功能。而微控制器还需要专用电源和电源模块，等等。同时微控制器设计方式不具备PLC现场可编程灵活性。那也正是PLC在生产线上运用原因之一。采用PLC控制系统是一些典型高度用户化系统，所以比起一次请一个设计人员作一个专门设计成原来说，一台PLC成本要低一些。其次，在大批量生产中，用户化系统能很快收回成本，因为它构件成本低廉。Topic Above Next 英 End 第15页Section III ExercisesI.Fill in the blanks according to the words given in English The development of low cost (计算机)has brought the most recent resolution,the (可编程逻辑控制器).The advent of the PLCs began in the 1970s,and (梯形图)is the main (编程)method used for PLCs and has been developed to mimic (继电器)logic.The relays allow (电源)to be switched on and off without a mechanical switch.Topic Above 答Next End 第16页Section III ExercisesII.Place a“T”after the sentence which is true and an“F”after the sentence which is false1.The instructions for the logical control sequence are stored in the Data memory.()2.The I/O modules only can be built into PLCs.()3.Now,we can use structured programming languages,and logic elementary operations to program.()4.The simple ladder logic inspired from the electrical connection diagrams.()5.The programmability of a PLC is flexible.()Topic Above 答Next End 第17页Section III ExercisesIII.Translate the following paragraph into ChineseAn example of a relay in a simple control application is shown in the figure.In this system the first relay on the left is used as normally closed,and will allow current to flow until a voltage is applied to the input A.The second relay is normally open and will not allow current to flow until a voltage is applied to the input B.If current is flowing through the first two relays then current will flow through the coil in the third relay,and close the switch for output C.This circuit would normally be drawn in the ladder logic form.This can be read logically as C will be on if A is off and B is on.Topic Above 答Next End 第18页Section III ExercisesIV.Could you tell us the scanning process of PLCs?Topic Above 答Next End 第19页Figure Topic Above Return Next End 第20页Section III AnswersI.computer,Programmable Logic Controller,manufacturing,Ladder Logic,Programming,relays,power supplyII.1.F,2.F,3.T,4.T,5.TIII.如图所表示是一个使用继电器控制简单应用。在这个系统中，左端第一个继电器是常闭，直到一个电压信号提供给输入A点时才会断开。第二个断电器是常开，直到一个电压信号提供给输入B点时才会闭合。假如电流能够流经第一个和第二个继电器，那么电流也可流经第三个继电器线圈，并使输出点B点处开关闭合。这个电路通常可画成梯形图形式。假如A处于OFF 状态，同时B处于ON状态，那么C处于ON状态。Topic Above Next Return End 第21页Section III AnswersI.computer,Programmable Logic Controller,manufacturing,Ladder Logic,Programming,relays,power supplyII.1.F,2.F,3.T,4.T,5.TIII.如图所表示是一个使用继电器控制简单应用。在这个系统中，左端第一个继电器是常闭，直到一个电压信号提供给输入A点时才会断开。第二个断电器是常开，直到一个电压信号提供给输入B点时才会闭合。假如电流能够流经第一个和第二个继电器，那么电流也可流经第三个继电器线圈，并使输出点B点处开关闭合。这个电路通常可画成梯形图形式。假如A处于OFF 状态，同时B处于ON状态，那么C处于ON状态。Topic Above Next Return End 第22页Section III AnswersIV.Topic Above Next Return End 第23页Appendix1.battery-backed memory:随机存放器2.EEPROM：电可擦写可编程只读存放器3.sensor:传感器 4.actuator:执行器5.Distributive control system:分布式控制系6.IEC:国际电工委员会7.sequential function chart:次序功效图 8.USD：United States Dollar Topic Above Return End 第24页 Figure 13-1 Schematic of a PLCpowersupplycommu-nicationexpansionconnectionmemoryInput processing circuitoutput processing circuitcpupc for plc programmingplc controllerscrew terminals for input limesscrew terminals for output linesReturn Topic End 第25页