A distributed control system (DCS) distributes control elements throughout a plant or process as opposed to using a single centralized controller. A DCS uses custom processors as controllers and proprietary and standard communication protocols to connect components. DCS systems are commonly used in industries like oil refineries, power plants, manufacturing facilities, and more.

1. 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. A DCS typically uses custom designed
processors as controllers and uses both proprietary interconnections and standard
communications protocol for communication.
Block Diagram of DCS Industries where a DCS might be used
include:
• Petrochemical (oil) and refineries
• Boiler controls and power plant
• Nuclear power plants
• Metallurgical process plants
• Pharmaceutical manufacturing
• Water management systems
• Sugar refining plants
Communication Protocols Used
IEC101 / 104 - IEC 101 / 104 is one of the IEC 60870 set of standards which define systems used for
telecontrol (supervisory control and data acquisition - SCADA) in electrical engineering and power
system automation applications.
OPC - OPC is a widely accepted industrial communication standard Client / Server technology that
enables the exchange of data between multi-vendor devices and control applications without any
proprietary restrictions.
Modbus - Modbus protocol supports serial communication among many (approximately 247)
devices connected to the same network, for example a system that measures temperature and
humidity and communicates the results to a computer. Modbus is often used to connect a
supervisory computer with a remote terminal unit (RTU) in supervisory control and data acquisition
(SCADA) systems.