PLC（即可编程逻辑控制器）是机械控制中为替代必要的继电器时序电路而发明的一种设备。PLC工作时通过查询输入端并根据其状态打开或关闭输出。用户通常用软件或编程器输入程序，从而获得期望的结果。
很多实际应用都采用PLC。工业生产中应用PLC的可能性很高。如果你在进行机械制造、产品包装、材料处理、自动化装配及无数其他工业生产，你可能已经用到了PLC。如果没有用到，那就是在浪费金钱和时间。几乎所有需要电气控制的地方都需要PLC。
A PLC (i.e. Programmable Logic Controller) is a device that was invented to replace the necessary sequential relay circuits for machine control The PLC works by looking at its inputs and depending upon their state, turning on/off its outputs. The user enters a program, usually via software or programmer, that gives the desired results.
PLCs are used in many “real world” applications. If there is industry present , chances are
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