英语翻译plc devicesection 1 background1.introductionA programmab

英语翻译
plc device
section 1 background
1.introduction
A programmable controller(pc) is basically a central unit(cpu) containing a program and connected to input and output(i/o) devices(i/o Devices).The program controls the PC so that when an input signal from an input device turns on,the appropriate response is made.The response normally involves turning on an output signal to sone sort of output device.The input device thar can produce a signal that can be input into the PC.The output devices could be solenoids,switches activating indicator lamps,relays turning on motors,or any other devices that can be activated by signals output output from the PC.
For example,a sentor detecting a product passing by turns on an input to the PC.The PC responds by turning on an output that activates a pusher that pushs the product onto another conveyor for further processing.Another sensor,positioned higher than the first,turns on a different input to indicate that the product is too tall.The PC responds by turning on another pusher pusher positioned before the pusher mentioned above to push the too-tall product into a rejectiong box.
Although this example involves only two inputs and two outputs,it is typical of the type of control operation that PCs can achieve.Actually even this example is much more complex than it may at first appear because of the timing that would be required,i.e,"How does the PC know when to activate each pusher?" Much more complicated operations,however,are also possible.The problem is how to get the desired control signals from avaiable inputs at appropriate times.
Desired control sequences are input to the PCs using a form of PC logic called ladder-diagram programming.
2.Relay circuits :the Roots of PC Logic
PCs historically originate in relay-based control systems.And although the integrated circuits and internal logic of the PC have taken the place of the discrete relays,timers,counters,and other such devices,actual PC operation proceeds as if those discrete devices were still in place.PC control,however,also provides computer capabilities and consistency to achieve a great deal more flexibility and reliability than is possible with relays.
The symbols and other control concepts used to describe PC operation also come from relaybased control and form the basis of the ladder-diagram programming method.Most of the terms used to describe these symbols and concepts,however,originated as computer terminology.
for example ,后面是sensor

plc设备
第1部分背景
1.introduction
一个可编程序控制器(个人计算机)基本上是包含节目的一套中央装置(cpu)和连接到输入和输出(输入/输出)设备(输出入装置).程序控制个人计算机,以便,当从输入装置的一个输入信号打开,适当的反应被做.反应通常介入打开输出信号到sone类输出设备.输入装置thar可能导致可以输入入PC.The输出设备可能是螺线管、开关激活显示器灯的,中转起动马达的,或者所有其他设备可以被从个人计算机输出的信号产品激活的信号.
例如,查出产品的sentor通过转动输入到PC.个人计算机通过打开激活那的推者在另一台传动机上的产品进一步处理的产品反应.另一个传感器,被安置高于第一,打开不同的输入表明产品是太高的.个人计算机通过打开在推者之前被安置的另一个推者推者反应以上提到推挤太高产品入箱子.
虽然这个例子只介入二输入和二产品,它是个人计算机可能达到的特点控制操作的种类.实际上甚而这个例子比它也许起初出现由于将需要,即, “的时间复杂怎么什么时候做个人计算机知道激活每个推者?” 更加复杂的操作,然而,也是可能的.问题是如何从输入得到期望控制信号在适当的时候.
使用个人计算机逻辑叫的梯子图编程的形式期望控制序列输入到个人计算机.
2.Relay电路：个人计算机逻辑根
个人计算机历史上发起于基于传递的控制系统.并且,虽然个人计算机的集成电路和内部逻辑代替分离中转,定时器、柜台和其他这样设备,实际个人计算机操作进行,好象那些分离设备到位.PC控制,然而,比对中转也提供计算机能力和一贯性非常达到更多灵活性和可靠性可能的.
被用于的标志和其他控制概念描述个人计算机操作也来自控制并且形成梯子图程序编制方法的依据.被用于的大多用语描述这些标志和概念,然而,发源当计算机术语.