What's PLC?

A Programmable Logic Controller or PLC. It's simply special computer. That's program  control some process industry,  likes steel plant, automobile, and  power plant etcetera. It is a device, that a user can program to perform, a series or sequence of events. These events, are triggered by inputs received, at the programmable logic controller, through delayed actions, such as time delays. every PLC most three parts, input, CPU and output.

 Suppose we have push button, and conveyor belt, when push button press, then conveyor belt run. First a programmer, load a program on CPU, then when come some  input signal, then CPU  process  the signal, and through output, then run conveyor belt. Now explain,  when press the push button, PLC input electrical row signal, but CPU not process electrical raw  signal, so input module convert, electrical raw  signal to process data. This process data, CPU process and through output module. whatever the output module , convert process data  to electrical raw  signal. Then conveyor belt run.  Thanks for watching.