Distributed Control Systems are extension of traditional controllers. The major concept of distributed control systems application is derived from the idea of decentralizing the control unit and establishing a common network between the operator, engineering stations.
DCS tends to be used on large continuous process plants where high reliability and security is important, and the control room is not geographically remote. DCSs are connected to sensors and actuators and use set point control to control the flow of material through the plant. Although 4—20 mA has been the main field signalling standard, modern DCS systems can also support field bus digital protocols, such as Foundation Fieldbus, profibus, HART, Modbus, PC Link, etc., and other digital communication protocols such as modbus.