A remote terminal unit (RTU) is a microprocessor-based electronic device used in industrial control systems (ICS) to connect various hardware to distributed control systems (DCS) or supervisory control and data acquisition (SCADA). RTUs are also referred to as remote telemetry units or remote telecontrol units.
RTUs pass sensor data from input streams in control loops to an output stream to be forwarded on to centralized control in an ICS. RTUs automatically negotiate connections to either local or remote controls.
Found everywhere ICS are used, RTUs are part of the systems used in several processes, including:
- Petrochemical (oil) and refineries
- Nuclear power plants
- Quality control
- Chemical plants
- Sewage treatment plants
- Food processing
- Automobile manufacturing
- Pharmaceutical manufacturing
- Water treatment plants
RTUs monitor both analog and digital field data. An RTU gets the data from sensors monitoring target industrial process variables and then forwards that data onto centralized monitoring and control. The hardware of an RTU contains the setup software required to connect data output streams, communication protocols and built-in troubleshooting. The devices are often powered by AC mains with DC converters and sometimes battery backup.