A Distributed Control System (DCS) is an automated control system that monitors and provides instructions to different parts of a machine. Commonly used in manufacturing equipment, a DCS utilizes input and output protocols to control distributed equipment. DCS systems are commonly used in process industries controlling breweries, refineries, chemical plants, paper mills, etc. The elements of a DCS may connect directly to physical equipment, such as controllers, historians and to Human Machine Interface (HMI) via SCADA.
The key advantage of DCSs is that they divide up the control tasks among multiple distributed systems; if any single part of the system should fail, the plant could keep operating. DCS systems also introduced the concept of data networking, thereby allowing hard wiring each control point, adding flexibility, and reducing the cost of making changes in the production process.
•Conventional DCS: a pure “process-only” control system. Typically purchased from one vendor and arranged into categories; small, medium and large.
•PLC-based DCS: a network of PLCs used to perform the task of conventional DCS and programmable functionality when required.
•Hybrid DCS: Performs both process and sequential control.
•Open DCS System: A Field-Bus control. Advantages include: low wiring costs, less failure, lower expansion costs and multi-vendor interoperability. DCS and PLCs can be more interconnected.