SCADA

Supervisory control and data acquisition (SCADA) is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and actuators, which are monitored and controlled from programmable logic controllers, or a distributed control system (DCS), which interfaces with process plant or machinery. The operator interfaces, which enable monitoring and the issuing of process commands, such as controller setpoint changes, are handled through the SCADA computer system. The subordinated operations, e.g. the real-time control logic or controller calculations, are performed by networked modules connected to the field sensors and actuators. The SCADA concept was developed to be a universal means of remote access to a variety of local control modules, which could be from different manufacturers and allow access through standard automation protocols. In practice, large SCADA systems have grown to become similar to DCSs in function, while using multiple means of interfacing with the plant. They can control large-scale processes spanning multiple sites, and work over large distances. It is one of the most commonly used types of industrial control systems.