Programmable logic controllers

Control engineering has evolved over time. In the last human were the primary method of controlling a system. More recently, electricity has been used for the control and power was initially based on relays. These relays are able to be switched and outdoors without a mechanical switch. It is common to use the relay to make simple logical control decisions. The development of low-cost computer has made the most recent revolution, the programmable logic controller (PLC). The advent of the PLC began in the 1970s and became the most common choice for manufacturing controls.