RTU - Remote Terminal Units

What is RTU?
RTU — Remote Terminal Unit
RTU most commonly stands for Remote Terminal Unit, but is sometimes also used as an abbreviation for Remote Telemetry Unit or Remote Telecontrol Unit.
RTUs are devices that rely on microprocessors and communication interfaces to automatically monitor and control field devices and to function as gateway to the plant control or SCADA (supervisory control and data acquisition) systems.
- RTUs are commonly equipped with several communication ports and internal inputs and outputs to communicate with and monitor several devices at once.
- Depending on the project needs, some RTUs can be expanded with different circuit cards including communication interfaces, additional storage, backup power and additional I/Os.
- RTUs can often communicate with a range of devices in the facility, including meters, HMIs, IEDs, sensors and many others. They transfer the data they collect from these object to the servers the SCADA software operates on.
- RTUs use a range of standard communication protocols to control field devices, such as ModbusRTU, ModbusTCP, Profibus, DLMS, IEC 104, IEC 101, IEC 102, Procome, OPC or IEC 61850.
RTU vs PLC
RTU Advantages
- Ruggedness - RTUs are designed to resist extreme temperatures and electromagnetic charges.
- Internal I/Os - configurable and specifically designed for the industry.
- Easy programming — while PLCs often require programming know how in PLC software, RTUs can often be configured through a web interface or an included configuration software to set up communication channels.
- Back-up power — some RTU’s come with a backup battery and charging circuit.
PLC Advantages
- Cost - PLCs are often available at lower prices but many argue that in the long-term the superior ruggedness of the RTU makes it economically competitive or even superior.
- Proprietary RTUs — some RTUs might require specific programming languages or even PLC skills.

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Grid & Substation Automation
- RTU — Remote Terminal Unit
- SCADA — Supervisory Control and Data Acquisition
- IED — Intelligent Electronic Device
- SER — SEQUENCE OF EVENTS RECORDING
RTU most commonly stands for Remote Terminal Unit, but is sometimes also used as an abbreviation for Remote Telemetry Unit or Remote Telecontrol Unit.
RTUs are devices that rely on microprocessors and communication interfaces to automatically monitor and control field devices and establish a bridge to the plant control or SCADA (supervisory control and data acquisition) systems.
Supervisory control and data acquisition (SCADA) systems collect, monitor and process real-time data to:
- Automate and control industrial processes remotely or locally
- Provide a human-machine interface (HMI) to directly interact with devices such as relays, sensors, generators, pumps, valves and others
- Record events and automate reporting
An Intelligent Electronic Device (IED) is a term used in the electric power industry to describe microprocessor-based controllers of power system equipment, such as circuit breakers, transformers and capacitor banks.
Sequence of events recording (SER) is performed by microprocessor based systems, which monitor collected data inputs and record the time and sequences of the changes.
Sequence of events recorders rely on external time sources such as GPS or radio clocks to record the exact time of state of each change.
RTU & iGrid
iRTUs often play a central role in our solutions, which is why we have deployed more than 10,000 iRTUs in Asia and Europe alone.
Our iRTUs unite our unique configurable hardware features with state-of-the-art software functionalities and capabilities in one tiny device.

iRTU – With I/Os for Direct Data Acquisition

iGW‑S Substation Gateway
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