A collection of processing elements, which are inter connected both logically and physically with decentralized system, wide control of resources for co-operative execution of application programs.
A DCS consists of a number of microprocessor – based modules that work together to control and monitor a plant’s operations. The modules are distributed graphically.
Distributed processing is useful in process control for the following reasons:
- DCS gives increased performance through resource sharing.
- Increased reliability.
- Modularity and expandability.
- Reduced cabling cost (i.e., field wiring and installation)
- It also reduces risk by distributing the control function throughout a number of small modules rather than concentrating it in one large module.
Disadvantages of Distributed control system:
Increased software development cost, more complex failure diagnosis and dependence on communication technology. These have been over come to a great extent by the development of high – level languages and structured – programming concept, communication technology (e.g. fiber optics) and fault – diagnosis methods.