机电工程专业英语 朱晓玲 Lesson 13新.ppt

Lesson 13 Programmable Logic Controller可编程逻辑控制器 Section I Words and Phrases Section II Text and Translation Section III Exercises and Answers Section I Words and Phrases actuator 执行机构 pneumatic ［nju(:)5mAtik］adj.气动的，气力的　n.气胎 hydraulic［hai5drC:lik］adj. 水力的, 水压的，液压的　　n.液压传动装置 relay［5ri:lei］n. [电工]继电器 solenoid［5sEulinCid］n. [电]螺线管 proprietary ［prE5praiEtEri］adj. 所有人的：属于一个所有人或作为群体的所有人的，或与之有关的： cam［kAm］n.凸轮 automate [5C:tEmeit]v.使自动化, 自动操作 initially [I5nIFElI]adv.最初, 开头 Section I Words and Phrases ladder [5lAdE(r)]n.梯子，梯形 inspire [in5spaiE]vt. 作为…原因或根源；引起；激励，鼓励：激发行动，促动 trace out描绘出 apprehension [7Apri5henFEn]n. 担心，忧虑 circuit [5sE:kit]n.电路 load [lEud]n.负荷, 重担,负载 power supply电源 module [5mCdju:l]n.模数, 模块, flexibility [7fleksE5biliti]n.弹性, 适应性,柔韧性 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. 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 vision.On the ac-tuator side, PLCs drive any kind of electric motor, pneumatic or hydra-ulic cylinders or d