RTU stands for Remote Terminal Unit. An RTU is an electronic device that is controlled by a microprocessor. This device interfaces objects in physical world  to a Distributed Control System (DCS) or Supervisory Control and Data Acquisition (SCADA) system by transmitting telemetry data to the system. Telemetry data in the sense means the measurements or other data that are collected at remote or inaccessible points and transmitted to receiving equipment for monitoring. An RTU is a device installed at a remote location to collect datas, codes the datas into a format that is transmittable and transmits the data back to a central station, or master.

It is typically utilized in an industrial environment and serves a similar purpose to programmable logic circuits (PLCs) but to a higher degree i.e ( RTUs are often considered for gathering telemetry data over large geographical areas, because they use wireless communication whereas PLC’s are commonly implemented in situations where local control is needed).  An RTU is considered a self-contained computer as it has all the basic parts that, together, define a computer: a processor, memory and storage.