Programmable Logic Controller

Programmable Logic Controller (PLC) is an industrially hardened computer-based unit that performs discrete or continuous control functions in a variety of processing plant and factory environments. It was originally intended as a relay replacement equipment for the automotive industry. As opposed to DCS, they can be sold as stand-alone equipment (instead of an integrated system as DCS).

Definitions

According to the CyBOK (version 1),

Programmable Logic Controller (PLC). An industrially hardened computer-based unit that performs discrete or continuous control functions in a variety of processing plant and factory environments. It was originally intended as a relay replacement equipment for the automotive industry. As opposed to DCS, they can be sold as stand-alone equipment (instead of an integrated system as DCS).