A distributed control system (DCS) is a control system for a process or plant, wherein control elements are distributed throughout the system. This is in contrast to non-distributed systems, which use a single controller at a central location. In a DCS, a hierarchy of controllers is connected by communications networks for command and monitoring. Example scenarios where a DCS might be used include: • Chemical plants • Petrochemical (oil) and refineries • Pulp and Paper Mills • Boiler controls and power plant systems • Nuclear power plants • Environmental control systems • Water management systems • Metallurgical process plants • Pharmaceutical manufacturing • Sugar refining plants • Dry cargo and bulk oil carrier ships • Formation control of multi-agent systems A DCS typically uses custom designed processors as controllers and uses both proprietary interconnections and standard communications protocol for communication. Input and output modules form component parts of the DCS. The processor receives information from input modules and sends information to output modules. The input modules receive information from input instruments in the process (or field) and the output modules transmit instructions to the output instruments in the field. The inputs and outputs can be either analog signal which are continuously changing or discrete signals which are 2 state either on or off . Computer buses or electrical buses connect the processor and modules through multiplexer or demultiplexers. Buses also connect the distributed controllers with the central controller and finally to the Human-machine interface (HMI) or control consoles. See Process automation systems. Journal of Electrical Engineering and Electronic Technology is a peer-reviewed scholarly journal in the field of electrical engineering and electronics that aims to publish the most complete and reliable source of information on the discoveries and current developments in the mode of research articles, review articles, case reports, short communications, etc. in all areas of electrical engineering and electronics and making them accessible online freely without any restrictions or any other subscriptions to researchers worldwide.