Supervisory control and data acquisition – SCADA refers to ICS (industrial control systems) used to control infrastructure processes (water treatment, wastewater treatment, gas pipelines, wind farms, etc), facility-based processes (airports, space stations, ships, etc,) or industrial processes (production, manufacturing, refining, power generation, etc).
The following subsystems are usually present in SCADA systems:
• The apparatus used by a human operator; all the processed data are presented to the operator
• A supervisory system that gathers all the required data about the process
• Remote Terminal Units (RTUs) connected to the sensors of the process, which helps to convert the sensor signals to the digital data and send the data to supervisory stream.
• Programmable Logic Controller (PLCs) used as field devices
• Communication infrastructure connects the Remote Terminal Units to supervisory system.
Generally, a SCADA system does not control the processes in real time – it usually refers to the system that coordinates the processes in real time.