Programmable Logic Controllers
The modern solution for the problem of how to provide discrete-state control is to use a computer-based device called a programmable controller (PC) or programmable logic controller (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, that gives the desired results. Continue Reading