Unit-16-The-Application-of-PLC-机电专业英语-图文课件

1、Unit 16 The Application of PLCContentsNew Words & Expressions Text & TranslationComplex Sentence AnalysisKey to ExercisesNew Words & Expressions PLC (Programmable logic controllers) 可编程控制器SIMATIC (SIEMENS + Automatic) 西门子自动化系列产品品牌统称distinguish distigwi v. 区别, 识别chassis si n. 底盘, 底架sophisticated sfis

2、tikeitid adj. 复杂的, 精密的, 高度发展的pharmaceutical f:msju:tikl adj. 配药的;配药学的Ethernet i:net n.以太网commission kmin v. 交工试运转，委任, 委托, 将投入使用New Words & Expressions parameterization p,rmitraizein n. 参数化configuration knfigjurein n. 结构, 表面配置 transparency trnsprnsi n. 透明, 透明度mnemonic ni:mnik adj. 记忆的designation dezi

3、gnein n. 命名, 称号operand prnd n. 运算元, 操作数dispense dispens v. 分配, 分发simulate simjuleit v. 模仿, 模拟Text & TranslationProgrammable logic controllers（PLC） carry out a great many controlling functions for assembly line machines，mechanical tools，and other types of industrial equipment. 1An industrial control

4、system often includes a programmable logic controller for providing coordinated control of industrial control equipment，which includes various elements that are often either sensors for providing inputs to the PLC or relays for receiving outputs from the PLC，each under the control of an element cont

5、roller，and each connected to the PLC over a network via a network I/O device.Text & TranslationBased on the specific applications，PLCs fall into many catalogues. This chapter will introduce the SIMATIC S7 PLC and its applications.The S7 is the most powerful PLC in the SIMATIC controller family；the r

6、ange that enables successful automation solutions with totally integrated automation. The S7 is an automation platform for system solutions in the manufacturing and process industries，and is distinguished above all by its modularity and performance reserves.Text & TranslationThe S7 line comes in the

7、 S7200，S7300 and S7400 chassis styles. The higher the number，the more sophisticated and more expensive the system is. Within each chassis style，several CPUs are available，with varying speed，memory，and capabilities. Some systems provide redundant CPU operation for ultra high reliability control，as us

8、ed in the pharmaceutical manufacturing，for example.Each chassis consists of a power supply，and a backplane with slots for the addition of various option boards. Available options include serial and Ethernet communications，digital input and output cards，analog signal processing boards，counter cards，a

9、nd other specialized interface and function modules.Text & TranslationThe cards function with the software independently of which slot in the rack they are physically inserted into. Some slots require a specific type of card. This is not because of addressing，but is based on the bus and the power su

10、pply limitations of these slots.The S7 PLC is usually programmed with a very high level programming language environment called Step 7. Step 7 is used for programming，testing，and commissioning，and for automatic documentation of programs for S7 PLCs.Text & TranslationStep 7 incorporates the SIMATIC m

11、anager，the central tool for the software related handling of the project. 2This relates not only to a single CPU，but to the whole plantirrespective of how many controllers，drives and HMI devices. Using Step 7 also ensures that the data is kept consistent throughout the project. Step 7 incorporates b

12、oth the hardware configuration of the plant and the parameterization of the modules，so there are no more hardware settings to be made. Step 7 also includes the three basic languages：statement list (STL)，ladder diagram (LAD) and function block diagram (FBD). Step 7 also makes it possible to parameter

13、ize high speed data communications between networked CPUs.Text & TranslationStep 7 allows clearly structured programming，from simple AND/OR operations up to complex subroutine. A Step 7 program may，therefore，contain thousands of statements.To maintain maximum transparency，Step 7 offers a number of s

14、tructuring facilities：（1）Block technique. A linear operation sequence is divided into sections and packed into individual blocks.（2）Segments. Within blocks，fine structuring is possible by programming subtasks in individual segments.（3）Comments. Both a complete program as well as individual blocks or

15、 segments and individual statements can be directly provided with comments.Text & TranslationStep 7 programs can be represented in three different ways：（1）Statement list (STL). The program consists of a sequence of mnemonic codes of the commands executed one after another by the PLC.（2）Ladder diagra

16、m (LAD). Graphical representation of the automation task with symbols of the circuit diagram.（3）Function block diagram (FBD). Graphical representation of the automation task with symbols to DIN 40700/DIN 40719.Absolute or symbolic designations can be used for operands with all three methods of repre

17、sentation.Text & TranslationIn LAD and FBD complex functions and function block calls can be entered through function keys. They are displayed on the screen as graphical symbols.Generally speaking，PLCs like S7 will make use of 5 different blocks：（1）Organization blocks (OB). For managing the control

18、program.（2）Programming blocks (PB). Contain the control program structured according to functional or process oriented characteristics.（3）Sequence blocks (SB). For programming sequential controls.（4）Function blocks (FB). Contain frequently occurring and particularly complex program parts.（5）Data blo

19、cks (DB). For storing data required for processing the control program.Text & Translation3Some S7 PLCs have block types extended function blocks (FX)，and extended data blocks (DX)；these are not distinct block types，but rather are another set of available blocks due to the CPU having more memory and

20、addressing space.PLCs like S7 can be applied in many industrial processes. And here we will illustrate the application through an example.Suppose we are controlling lubricating oil being dispensed from a tank. This is possible by using two sensors. We put one near the bottom and one near the top, as

21、 shown in Fig.16.1.Text & TranslationFig. 16-1 Dispensing oil from a tankText & TranslationHere，we want the fill motor to pump lubricating oil into the tank until the high level sensor turns on. At that point we want to turn off the motor until the level falls below the low level sensor. Then we sho

22、uld turn on the fill motor and repeat the process.Here we have a need for 3 I/O：2 are inputs (the sensors) and 1 is an output (the fill motor). Both of our inputs will be NC (normally closed) fiber optic level sensors. When they are not immersed in liquid they will be ON. When they are immersed in l

23、iquid they will be OFF.Text & TranslationWe will give each input and output device an address. This lets the PLC know where they are physically connected. The addresses are shown in the Table.16.1. Text & TranslationTable 16-1I/O DisplayInput Address Output Address Internal Utility RelayLow 0000Moto

24、r 0500 1000High 0001 Text & TranslationFig.16.2 Ladder diagramText & TranslationFig.16.2 is what the ladder diagram will actually look like. Notice that we are using an internal utility relay in this example. You can use the contacts of these relays as many times as required. Here they are used twic

25、e to simulate a relay with 2 sets of contacts. Remember，these relays do not physically exist in the PLC but rather they are bits in a register that you can use to simulate a relay.Text & TranslationThe aim of using PLCs here is to replace real world relays. The internal utility relays make this acti

26、on possible. Its impossible to indicate how many internal relays are included with each brand of PLC. Some include 100s while others include 1 000s while still others include 10s of 1 000s! Typically，PLC size (not physical size but rather I/O size) is the deciding factor. If we are using a micro PLC

27、 with a few I/O we dont need many internal relays. If however，we are using a large PLC with 100s or 1 000s of I/O，well certainly need many more internal relays.If ever there is a question as to whether or not the manufacturer supplies enough internal relays，consult their specification sheets. In all

28、 but the largest of large applications，the supplied amount should be more than enough.Text & Translation可编程控制器在机器装配线、机械工具和其他工业设备中发挥了许多作用。一个工业控制系统经常使用可编程控制器，以实现工业设备的协同控制。这类工业设备通常有许多PLC可以处理的输入/输出部件，如提供输入信号的传感器和从PLC接收输出信号的继电器等，同时这些部件与PLC的网络控制系统相连。根据应用的需要，世界上有许多型号的PLC可供选择，这里我们介绍西门子S7PLC和它的应用。Text & Tran

29、slation在西门子SIMATIC PLC家族里（SIMATIC是西门子发明的一个对自己的自动化产品的一个称呼，是西门子和自动化的合成，即：SIements and autoMATIC）， S7系列是功能最强的，能为工业自动化领域提供成功的解决方案。S7系列PLC是一个工业制造和过程控制系统自动化平台，其卓越的性能体现在模块化和优良的存储空间。Text & TranslationS7系列包括S7-200、S7-300和S7-400，数字越大，其性能越成熟，同时价格越贵。每种S7PLC都提供几类CPU，其处理速度、存储空间和处理能力等能根据不同的应用对象而变化。有些甚至为高可靠性控制系统，例如

30、制药系统，提供了额外的功能。每种S7PLC底盘都包含电源和功能模块扩展底槽。可以选择的功能包括串口和网络通信、数字信号输入/输出卡、模拟信号处理板、记数卡和其他专用的接口功能模块。Text & Translation模块化功能是指槽架与软件模组分离，模块可以根据需要随时插入沟槽中。有些沟槽为某些类型的功能模块保留，这里不是强调它的这个功能，但在汽车和电源限制器里确实需要这个功能。S7PLC在编程时，使用了一种称为Step7的高级语言编程环境。Step7为S7PLC提供了编程、测试、调试和自动下载的功能。Text & TranslationStep7包含了SIMATIC管理器和编程有关的主工具条

31、。这不仅仅与单个的CPU有关，而且联系整个工厂，不管这个工厂有多少控制器、驱动器和集线器管理接口设备。它主要通过进程来确保数据的持续传输。Step7集成了硬件的外形结构和模块的参数，所以硬件参数无需设置。Step7也可以用三种基本语言编程：指令表（STL）、梯形图（LAD）和功能块（FBD），这样可以使处于同一网络中的CPU之间的数据高速传输变得可能。从简单的与/或到复杂的子程序，Step7允许清晰的结构化编程。所以，Step7程序包含了数千条指令。Text & Translation为保持最大限度的透明度，Step7提供了许多结构化的便利工具：（1）块技术。一个线性操作序列被分成几个部分，并

32、划分到各自的块中。（2）段。通过在各个段中编制功能子程序，使块合理组织变得可能。（3）注释。完整的程序、块、段甚至一条指令都可以用指令进行注释。Step7程序可以用三种不同的方式描述：（1）指令表（STL）。程序由一系列指令代码组成，PLC一条接着一条执行。（2）梯形图（LAD）。用电气控制回路中的符号来进行描述的图形。（3）功能块表（FBD）。用DIN 40700/DIN 40719规范中的符号来进行描述的图形。Text & Translation操作数可以用以上三种方式来进行完整或象征性地表达。在梯形图和功能块中，复杂的功能和功能块可以通过功能键实现。这些功能键在图形符号栏中显示。现成的块

33、有5种：（1）组织块（OB）。用于管理和控制程序。（2）编程块（PB）。包含控制程序，这些控制程序根据不同的功能或进程编制。（3）序列块（SB）。用于编程时的序列控制。（4）功能块（FB）。包括一些经常出现和比较复杂的功能程序。（5）数据块（DB）。存放程序运行时数据。Text & Translation一些S7PLC同时也有FX（扩展的功能块）和DX（扩展的数据块），这些并不是功能独特的块，而是当CPU有多余的存储和地址空间时，额外提供的功能块。在三种运行方式中，Step7各不相同：（1）基本操作（例如，链接、保存、装载和传送、记数、比较、算术运算、模块操作）。这些操作有可能在三种方式中都执

34、行。（2）辅助操作和复杂功能，（例如，替代指令、测试功能、字逻辑操作、加/减和跳转功能）。这些只能在STL中执行。Text & Translation（3）系统操作（直接进入操作系统）。只能在STL中执行。既然我们已经知道了PLC寄存器是如何工作的，下面我们将通过编程来加深理解程序的扫描工作。假想下面的应用：对油箱中的润滑油进行分配控制的操作。通过两个传感器可以实现这个过程，我们把一个传感器放在靠近底部的位置，把另一个放在靠近顶部的地方，如图16-1所示。Text & Translation图16-1油箱中配油Text & Translation我们想让供油马达把润滑油抽到油箱中，当油位上升碰

35、到高位传感器，使传感器工作，这时关闭马达，当油位下降碰到低位传感器，马达开始工作，重复上述过程。系统需要3个输入/输出口：两个输入（传感器）和一个输出（供油马达）。两个输入都是处于常开状态的光纤传感器，当油位没有碰到它们时，传感器内部的开关闭合，当传感器浸入油中时，开关断开。对每个输入/输出给出地址，让PLC知道硬件是怎么接的。地址分配如表16-1所示。Text & Translation表16-1 I/O显示输入 地址 输出 地址 内部用到的继电器 低 0000 马达 0500 1000高 0001 Text & Translation如图16-2所示为控制过程的梯形图。注意，图例使用的是P

36、LC内部可用的继电器。这些继电器的触点可以无限制地使用，这里我们使用了两个触点来模拟控制。这些继电器不是实际存在的，而是寄存器中虚拟继电器的为单元。Text & Translation图16-2梯形图Text & Translation必须记住，使用PLC的主要原因是用它来替代实际继电器。PLC内部虚拟继电器可以实现实际继电器的功能。想指出某种牌子的PLC内部有多少继电器可用是不可能的。一些包含100个，另一些包含1000个，甚至一些包含1000各种的10个。典型的，PLC的尺寸（不是物理尺寸而是I/O尺寸）才是起决定性的因素。如果我们正在应用I/O口较少的微型PLC时，我们不必使用很多内部继

37、电器。相反，如果应用I/O点数为100或1000的大型PLC时，当然得使用更多的内部继电器。如果想问制造商是否提供了足够的内部继电器，请参考他们的使用说明书。几乎所有的大型应用系统中，PLC提供的内部继电器比实际使用的要多。Complex Sentence Analysis1 An industrial control system often includes a programmable logic controller for providing coordinated control of industrial control equipment, which includes var

38、ious elements that are often either sensors for providing inputs to the PLC or relays for receiving outputs from the PLC, each under the control of an element controller, and each connected to the PLC over a network via a network I/O device. 一个工业控制系统经常使用可编程控制器，以实现工业设备的协同控制。这类工业设备通常有许多PLC可以处理的输入/输出部件

39、，如提供输入信号的传感器和从PLC接收输出信号的继电器等，同时这些部件与PLC的网络控制系统相连。 which includes various elements：是非限定性定语从句，其先行词是industrial control equipment that are often either sensors for providing inputs to the PLC or relays for receiving outputs from the PLC 是that引导的定语从句，修饰先行词elements，句中eitheror是“或者或者”的意思Complex Sentence Ana

40、lysis2 This relates not only to a single CPU, but to the whole plant irrespective of how many controllers, drives and HMI devices. 这不仅仅与单个的CPU有关，而且联系整个工厂，不管这个工厂有多少控制器、驱动器和集线器管理接口设备。 relate to：与相关，有联系 irrespective of：不顾的，不考虑的，无论Complex Sentence Analysis3 Some S7 PLCs also have block types FX (Extended Fun