Both DCS and SCADA are monitoring and control systems used in industrial applications. The systems monitor equipment and processes to ensure all processes and equipment are performing within the required tolerances and specifications.
Supervisory Control and Data Acquisition (SCADA) collects data from various sensors and monitoring equipment throughout a factory or industrial complex and sends it to a central computer for processing. In a Distributed Control System (DCS), the controller elements are not centralized, but distributed throughout the factory or industrial complex.
A DCS is more reliable than a SCADA system. Since DCS controllers are distributed, a single industrial accident will not bring down the system. On the other hand, a single incident can cripple a SCADA-based system.
With one computer as a central controller, a SCADA system is less costly and is therefore applicable for small-scale industrial systems. DCS is a better solution for larger, more complex and geographically dispersed systems where multiple, distributed controllers are essential.