RTU stands for Remote Terminal Unit, which is a microprocessor-based electronic device that interfaces objects in the physical world to a distributed control system or SCADA (supervisory control and data acquisition) system by transmitting telemetry data to a master system. An RTU monitors the field digital and analog parameters and transmits data to a SCADA Master Station. It runs setup software to connect data input streams to data output streams, define communication protocols, and troubleshoot installation problems in the field. An RTU may consist of one complex circuit card consisting of various sections needed to do a custom-fitted function, or may consist of many circuit cards including a CPU or processing with communications interface(s), and one or more of the following: (AI) analog input, (DI) digital (status) input, (DO/CO) digital (or control relay) output, or (AO) analog output card(s) .
RTUs are used in various industries, including petrochemical and refineries, nuclear power plants, agriculture, and more. They are also used in HVAC systems, specifically in roof top units (RTUs) that provide both heat and air conditioning for certain types of spaces. An RTU is a control device typically installed in a remote location as part of a large system. The main purpose of an RTU is to monitor and control field devices, such as valves, actuators, sensors, and more. RTUs are essential components of supervisory control and data acquisition (SCADA) systems, establishing interfaces between SCADA control and physical processes.
While RTUs and PLCs (programmable logic controllers) have similarities, there are several technical differences between them, and they have different applications for which one is better suited than the other.
