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Remote Terminal Unit

Also known as:RTU

Remote Terminal Unit: Field device that captures measurements from a remote site and executes control commands from the control centre. The RTU links the physical plant to the SCADASCADAControl system for monitoring and operating geographically distributed industrial processes. system.

How it works and where it fits

RTUs sit in substations, pumping stations, gas pressure regulating facilities, or unstaffed remote sites. They digitise analogue measurements, capture binary states such as breaker positions, and map incoming control commands onto outputs. They connect over telecontrol protocols, often DNP3 or IEC 60870-5-104, sometimes still via serial links and cellular. Their configuration typically records which peer counts as the control centre and which data points are writable.

Practical security relevance

What matters for security is how that assignment is enforced. A plain address list without cryptographic verification can be bypassed by any system on the same network that sends the right packets — the authorization then exists only on paper. Where devices support it, secure authentication belongs enabled; strict zone separation, protocol filtering at the boundary, and monitoring of write commands secure the site further.

  • SCADASCADAControl system for monitoring and operating geographically distributed industrial processes.: Control system for monitoring and operating geographically distributed industrial processes.
  • Operational TechnologyOperational TechnologyHardware and software used to monitor or control physical equipment, machinery, and industrial processes.: Hardware and software used to monitor or control physical equipment, machinery, and industrial processes.
  • Programmable Logic ControllerProgrammable Logic ControllerIndustrial computer that cyclically reads sensor values and derives actuator commands for a process.: Industrial computer that cyclically reads sensor values and derives actuator commands for a process.
  • Operational Technology SecurityOperational Technology SecurityProtects industrial control, production, and process control systems.: Protects industrial control, production, and process control systems.

Related terms