SCADA (supervisory control and data acquisition) is a computerized system that gathers data from remote or distributed equipment and lets operators monitor and control it. It is common in utilities, pipelines, and plants spread over large areas.
A SCADA system typically includes field devices (PLCs and remote terminal units, RTUs) that read sensors and drive actuators, a communication network, a central master or server, and human-machine interface (HMI) screens for operators. Data is often stored in a historian for trending and reporting.
SCADA is supervisory. The fast, closed-loop control usually runs in the PLCs or RTUs. SCADA collects data, raises alarms, and sends setpoints or commands. NIST notes SCADA was designed to cope with long distances and imperfect links such as phone lines, radio, and satellite.
The term is often confused with DCS (distributed control system). A DCS is typically used for continuous process control within one plant, with tightly integrated controllers. SCADA is usually used across wide areas. The line has blurred as products converge. SCADA networks are a known target for cyberattacks and are covered by NIST's OT security guidance.
Questions about SCADA
What is the difference between SCADA and a DCS?
SCADA is usually used across wide areas, such as utilities and pipelines. A DCS is typically used for continuous process control within one plant, with tightly integrated controllers. The line has blurred as products converge.
Is SCADA the same as an HMI?
No. HMI screens are the part operators look at. A SCADA system also typically includes field devices such as PLCs and remote terminal units, a communication network and a central master or server.
Related terms
PLC (programmable logic controller)
A PLC (programmable logic controller) is a ruggedized industrial computer that reads inputs from sensors, runs a user program, and drives outputs such as motors and valves in real time.
DCS (distributed control system)
A DCS (distributed control system) is a plant control system in which control functions are spread across many autonomous controllers near the equipment, linked by a network to central operator stations.
Process historian
A process historian is a time-series database that collects, compresses and stores data from plant control systems, such as sensor readings, setpoints and alarms, so it can be trended, analyzed and retrieved later.
OT cybersecurity
OT cybersecurity is the protection of operational technology, the control systems and networks that run physical processes, against cyber threats, with safety, availability and reliable operation as the first priorities.
ISA-95
ISA-95 is an international standard series, also published as IEC 62264, for integrating enterprise business systems with manufacturing control systems.