Remote Terminal Units (RTUs)

Remote Terminal Units (RTUs) are electronic devices used in [[industrial control systems (ICS)]] to connect various hardware in the field with the control system software in a central or master location. They are crucial components in [[Supervisory Control and Data Acquisition (SCADA)]] systems, playing a key role in monitoring and controlling equipment in remote or hard-to-reach areas.

RTUs collect data from sensors and other field instruments, and control physical equipment via output signals, such as opening or closing valves or breakers. They communicate with a central SCADA system or other control systems, transmitting collected data and receiving control commands.

RTUs are designed to operate reliably in harsh environmental conditions, such as extreme temperatures, humidity, or electromagnetic interference, common in remote industrial locations. They can perform some control functions autonomously, based on pre-programmed thresholds or conditions, even if communication with the central system is temporarily lost.

The process of how they work is as follows:

• RTUs are installed at remote sites where they interface with sensors and actuators.
• They continuously collect data from these field devices, such as temperature, pressure, flow rate, or equipment status.
• This data is then processed, stored, and sent over a communication network (like radio, satellite, or cellular networks) to a central SCADA system.
• The SCADA system uses this data for overall monitoring and control, and it can send commands back to the RTU to control field devices.

Remote Terminal Units (RTUs) are typically used for remote data acquisition and control in wide geographical areas, often where ruggedness and reliability over long distances and in challenging environments are required.

[[Programmable Logic Controllers (PLC)|Programmable Logic Controllers (PLCs)]], on the other hand, are more commonly used for real-time control in industrial environments like manufacturing plants, where complex logic control is needed.