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Application & OT Security · Intermediate

Remote Terminal Unit (RTU)

A field device that interfaces sensors and equipment at remote sites with a SCADA master, often over long-distance communications.

Definition

RTUs collect telemetry and execute control commands, frequently using protocols like DNP3, Modbus or IEC 60870-5-104. They are designed for harsh environments and low-bandwidth links.

Example

An RTU at an electrical substation reports breaker status to the SCADA master via DNP3.

Exam tip

RTUs are associated with SCADA; PLCs with local control (though roles overlap).

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