Glossary · Electrical engineering and control panels
Remote terminal unit (RTU)
Also known as: RTU, Remote telemetry unit, Telecontrol station
German: RTU (Remote Terminal Unit)
In SCADA and telecontrol systems, a remote terminal unit (RTU) is a microprocessor-based field device at a remote site that acquires signals, executes local logic and communicates with a central SCADA system over telemetry links using protocols such as IEC 60870-5-101/104 or DNP3.
- Control panels
- OT security
In one sentence
An RTU is a field device at a remote site that acquires signals and communicates with a central SCADA system via telecontrol protocols.
Example
Each pumping station of the water network has an RTU that reports levels and pump states to the control center every minute and on change.
How it applies
- Engineering: RTUs are designed for remote, often harsh sites: wide temperature ranges, low power, communication over radio, cellular or leased lines, time-stamped events and local buffering during link outages (Store-and-forward). Telecontrol protocols such as IEC 60870-5 and DNP3 (IEEE 1815) are typical.
- Security: RTUs connect to wide-area networks, which makes secure communication and access control important; apply IEC 62443 principles and protocol security extensions where available.
- Documentation: Document point lists (signal addresses and meanings), communication settings, time synchronization and failure behavior. The SCADA and RTU point lists must match exactly.
RTU vs. PLC
A PLC focuses on fast local control; an RTU focuses on telemetry, time-stamping and remote communication. Modern devices often combine both roles, so document which functions a device actually performs.