Albert O'Grady
Analog Devices

A programmable-logic controller (PLC) is a compact computerbased electronic system that uses digital or analog input/output modules to control machines, processes, and other control modules. A PLC is able to receive (input) and transmit (output) various types of electrical and electronic signals and use them to control and monitor practically any kind of mechanical and/ or electrical system. PLCs are classified by the number of I/O functions provided. For example, a nano PLC incorporates fewer than 32 I/Os, a micro PLC has between 32 and 128 I/Os, a small PLC has between 128 and 256 I/Os, and so on. Read on to learn more about PLCs.