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What Is a Remote Terminal Unit? The Meaning of RTU

In this article, you will learn the meaning of RTU and how remote monitoring can be used to protect your network.

In Telecom and IT industries, a Remote Telemetry Unit or Remote Terminal Unit (RTU) is a microprocessor-based remote device that monitors and reports events occurring at a remote location.

Remote location, meaning somewhere away from you or your central office. You might have multiple towers spread around the area you cover, not just at your office. To monitor one of the towers, you would have to be able to access your RTU "remotely."

Telemetry, meaning the collection and processing of data, to ultimately transmit data from a remote source to you.

This allows you, the network operator or telemetry technician, to manage the network more effectively, keeping service flowing to your customers and protecting your revenue stream.

Different from PLCs that require the knowledge of ladder logic, RTUs can be programmed through a simple web browser interface.

Some RTUs are also capable of remote controlling system devices using control relay contacts or protocol-based commands. Without this ability, an RTU only collects data and reports remote events to you. While this is valuable, you still must physically travel to the monitored location if a change must be made.

An RTU that includes remote control capability reduces costly truck rolls to a simple mouse click. Some are even capable of a fully automated response.

RTUs are important components of SCADA systems. Supervisory Control and Data Acquisition (SCADA) systems are used to monitor and control equipment and processes from remote sources. The SCADA architecture begins with RTUs since these devices are responsible for collecting information and sending it to you or your master station.

An RTU will have multiple inputs and outputs. Inputs may monitor the power supply of the RTU itself or maybe even vital signs in certain health systems. An output may be a control relay to start a generator.

When looking for an RTU, ensure your vendor can give you exactly what you need. If you need wireless remote telemetry for long-range communication, your vendor should have no problem finding a solution for you. At DPS, we build customized, cost-effective telemetry systems to meet your needs.

How RTUs Gather Information

RTU units collect information from their local environments in several ways.

First, the gear that forms the backbone of your network will generally report problems as they occur. These reports take the form of discrete contact closure alarms or detailed protocol messages.

Second, your RTU may have onboard and external sensors that measure levels like temperature and humidity. Also, important technical values like battery and tank levels and power voltages may be monitored.

Once your RTU has collected important information, it needs a way to tell you about it. First, you have to choose one or more communication channels for the transmission of data. In many cases, you'll simply use LAN/Ethernet. For more remote sites (or those with legacy tech), you might use another method like a dial-up modem, wireless GSM/CDMA, or dedicated RS232/RS485 serial.

What is an RTU
Monitor mission-critical network gear and environmental conditions with an RTU.
Once the channel is set, your RTU will use a protocol to send status information. One of the most common is SNMP ("Simple Network Management Protocol")

This is common on RTUs designed for either Telecom or IT environments. Directly monitored RTUs can use an onboard web interface that you can access from any web browser on the network. SCADA RTUs will tend to use DNP3 or Modbus to communicate.

Many older RTUs use protocols specific to the vendor that are only compatible with master stations from that same vendor. Another option would be a master station that supports multiple protocols like T/Mon.

With data logged from your RTU and sent as discussed above, how will you receive information so you can take action? In larger RTU deployments, you might have dozens or hundreds of units in the field. After ten or more units, we highly recommend investing in a master station. In its simplest form, a master station collects data from all RTUs and displays them to you in a single interface.

If you have just a few RTUs, you can monitor each unit using its web interface that displays events the RTU collected. More advanced RTUs and master stations can also send you a text message or phone calls to alert you to serious problems.

DPS Telecom even has a few clients who run sandwich shops (monitor temperature of deli meats), car washes (detect gear status and times when pipes might freeze and burst), and pig farms (pigs are very sensitive to changing temperatures and humidity).

In summation, an RTU is a device that provides supervisory control and data acquisition over remote sites. They're used in all sorts of businesses, from telecom to utilities to public safety and more.

No matter the industry, RTUs are adaptable and efficient automation devices; reducing manual and repetitive labor key to mission-critical operations.

Related Topics:

RTUs: the building blocks of monitoring | Remote Telemetry Units FAQ

View Our Complete List of RTUs