The RTU is a microprocessor-based device that interfaces with a SCADA system by transmitting telemetry data to the master station and changing the state of connected switchgear based on control messages received from the master station or commands generated by the RTU itself. The RTU provides data to the master station and enables the master station to issue controls to the field equipment. Typical RTUs have physical hardware inputs to interface with field equipment and one or more communication ports .
Some common RTU software modules are:
- Central RTDB that interfaces with all other software modules.
- Physical I/O application:acquires data from the RTU hardware components that interface with physical I/O.
- Data collection application (DCA):acquires data from the devices with data communications capabilities via communication port(s). For example, IEDs.
- Data processing application (DPA):presents data to the master station or HMI.
- Some RTUs also have data translation applications (DTA) that manipulate data before they are presented to the master station or support stand-alone functionality at the RTU level.
Figure show a RTU &SCADA system data flow architecture.