- PLC-dat - modbus-dat - RTU-dat
A Remote Terminal Unit (RTU) is a microprocessor-controlled 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, and by using messages from the master supervisory system to control connected objects.
Key functions and characteristics of an RTU include:
- Data Acquisition: Reading analog and digital inputs from sensors and field devices (e.g., temperature, pressure, flow, status of a switch).
- Control Output: Sending digital and analog output signals to control actuators (e.g., opening/closing a valve, starting/stopping a motor).
- Communication: Communicating with a central master station (often a SCADA master or a Distributed Control System - DCS) using various communication protocols (e.g., Modbus, DNP3, IEC 60870-5-101/104) over different media (radio, cellular, satellite, wired networks).
- Local Intelligence: Modern RTUs often have processing capabilities to perform local control logic, data logging, and alarming, even if communication with the master station is lost.
- Ruggedness: Designed to operate in harsh environmental conditions often found in industrial settings (e.g., wide temperature ranges, humidity, vibrations).
- Autonomy: Can operate autonomously for periods based on pre-programmed instructions.
Common Applications: RTUs are widely used in various industries for remote monitoring and control, such as:
- Oil and Gas: Monitoring pipelines, wellheads, and remote facilities.
- Water and Wastewater: Managing pumping stations, reservoirs, and treatment plants.
- Electric Utilities: Monitoring substations, reclosers, and distribution networks.
- Environmental Monitoring: Collecting data from remote sensor stations.
- Transportation: Monitoring traffic signals and railway systems.
In essence, an RTU acts as a bridge between the physical equipment in the field and the central supervisory control system.