PLC - Programmable Logic Controller

 

A Programmable Logic Controller (PLC) is used for automation of electromechanical processes. A PLC is a real-time system that controls outputs depending on the input conditions. They often must withstand harsh environments on the factory floor.

A small PLC will have a fixed number of connections built in for inputs and outputs. Typically, expansions are available if the base model does not have enough I/O.

Modular PLCs, allows the processor and the selection of I/O and communication modules to be customised for the particular application. This system may or may not require a chassis (also called a rack), into which these module are placed.  Several racks can be administered by a single processor, and may have thousands of inputs and outputs. Different types of networks can be implemented so that racks or I/O modules can be distributed away from the processor, reducing the wiring costs for large plants.