The RTU is the device that makes remote monitoring possible. Where a PLC lives on a machine or skid, an RTU is purpose-built for the far edge of the network - a wellhead in the Permian, a pipeline valve station, a remote tank - where power is scarce, temperatures are extreme, and communications are intermittent. This guide explains what an RTU is, how it works, and why it is central to oil and gas telemetry.
An RTU (Remote Terminal Unit) in plain English: A Remote Terminal Unit is a field device that collects data from sensors at a remote site and transmits it back to a central SCADA system, often over cellular, radio, or satellite. RTUs are built for low power, harsh environments, and unreliable communications.
Oil and gas operations are spread across enormous distances - hundreds of wells, gathering lines, and remote facilities, often with no mains power and no reliable network. An RTU is engineered for exactly that: it draws little power (frequently solar with a battery), tolerates temperature extremes, and, crucially, buffers data when the communications link drops so nothing is lost. When the link returns, it forwards what it stored - a behavior called store-and-forward.
This is the key difference from a general-purpose controller: an RTU assumes the network is unreliable and is designed around that assumption.
An RTU reads local instruments - pressure and temperature transmitters, level sensors, flow meters, tank gauges - through analog and digital inputs. It timestamps the readings, applies any local logic or reporting rules, and communicates them upstream to SCADA. Many RTUs report by exception, sending data only when a value changes beyond a threshold, which conserves bandwidth and battery on cellular and satellite links.
RTUs commonly speak DNP3, a protocol designed for telemetry over marginal links with strong timestamping and reporting features, as well as Modbus. A SCADA platform polls or subscribes to the RTU over one of these protocols. Merobix supports DNP3, Modbus, and IEC 60870-5-104 among its drivers, so it can read the same RTUs a legacy telemetry system does.
The practical distinction: a PLC is optimized for fast, deterministic local control of a machine or process, usually with reliable power and network. An RTU is optimized for remote data acquisition over unreliable comms with minimal power. Modern devices blur the line - many RTUs now run control logic, and many PLCs support telemetry - but if your challenge is a marginal cellular link at a lonely wellsite, you want the RTU's store-and-forward and low-power design.
An RTU (Remote Terminal Unit) is the field device that collects sensor data at a remote site and sends it to the central SCADA system, typically over cellular, radio, or satellite. It is the data-acquisition endpoint of a telemetry network.
An RTU is built for remote sites - low power, harsh conditions, and unreliable comms with store-and-forward buffering. A PLC is built for fast, deterministic local control, usually with reliable power and network. Modern devices overlap, but the design emphasis differs.
DNP3 is the classic telemetry protocol for RTUs (strong timestamping, report-by-exception, store-and-forward). Modbus and IEC 60870-5-104 are also common. A SCADA platform must speak the RTU's protocol to read its data.
Yes. A cloud-native SCADA that supports DNP3, Modbus, and IEC 60870-5-104 - such as Merobix - can poll your existing RTUs and flow computers in parallel with, or in place of, a legacy telemetry host, with no field rewiring.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
Merobix polls DNP3, Modbus, and IEC 60870 RTUs over cellular - web-native monitoring for remote wells and pipeline sites.