PLCs
PLCs provide boolean logic operations, timers, and (in some models) continuous control. The proportional, integral, and/or differential gains of the PLC continuous control feature may be tuned to provide the desired tolerance as well as the rate of self-correction during process upsets. DCSs are used extensively in process-based industries. PLCs are computer-based solid-state devices that control industrial equipment and processes. While PLCs can control system components used throughout SCADA and DCS systems, they are often the primary components in smaller control system configurations. They are used to provide regulatory control of discrete processes such as automobile assembly lines and power plant soot blower controls and are used extensively in almost all industrial processes.
Read more about this topic: Industrial Control System