What is an RTU?

Have you ever wondered how much the electricity you use costs? Sure we try to conserve energy, turn off lights, and make sure our remote sites aren’t running when idle, but the actual economics behind our energy use is oft-forgotten.

Though the world is still heavily reliant on energy derived from fossil fuels, recent trends in renewable energy have made the traditionally cost-prohibitive energy sources much more accessible.

Before diving into a cost breakdown for renewable energy, let’s first talk about how organizations can begin to calculate and monitor their energy costs.


What is an RTU?

RTU stands for Remote Terminal (or Telemetry) Unit and refers to an electronic control unit that connects to various systems for the purpose of remote monitoring and management (RMM). An RTU can be automated to take different types of input from those systems and translate that data into something readable in a centralized database.  

It is also possible to update and maintain an RTU’s programming remotely. When talking about RTUs it’s important to understand their counterpoint and rival, PLCs. 

What is a PLC

A data collection unit that is often used in tandem with or as an alternative to RTUs is the PLC. PLC stands for Programmable Line Controller, and it is used mostly for automating production lines in factories and other physical systems that require precise, repetitive execution with the added benefit of built-in fail-safes and redundancy. 


Like an RTU, a PLC is used as an interface for controlling basic processes in systems of electronics. It has the capacity to be programmed with the same kind of communication and information processing instructions. When it comes to connecting and automating systems, PLCs operate on much the same terms as RCUs.  

However, unlike an RTU the PLC is not remotely accessible, except when adding extra functionality or linking to an RTU. Moreover, RTUs often come with accessible presets and dashboards while setting up a PLC requires knowledge of a specific programming language. 

In summary, a PLC will fit your needs if you’re looking to automate physical tasks in one facility and need a high level of customizability. If you want remote visibility and access to multiple sites, an RTU is the best choice. You can also combine both units within a network system to achieve both remote visibility and detailed control. 

How do RTUs work?

A site or resource in need of monitoring often uses multiple RTUs modules to remotely collect data from its assets. An RTU takes input from several sources based on the types of connections installed in the unit and the number of extension modules. It then transmits the data wirelessly to a server. So, what exactly is inside each RTU? 

Parts of an RTU

These components exist in some form in all RTUs, and the design for and modules included are based on standards established and maintained by the International Electrotechnical Commission, the American National Standards Institute, and the Institute of Electrical and Electronics Engineers.


The active functionality and capabilities of an RTU come from a built-in computer processing unit. This part controls the memory and all the connections to inputs and outputs. It is also the part that uses ethernet to interact with other systems. An RTU can have a backup CPU for additional redundancy. 

Memory Storage

Connected to the CPU, an SD Card or other storage device temporarily retains collected data as well as holding local data and instructions.

Power Supply

Once introduced to a system, RTUs can connect to the site or facility power supply, but in case of failure or inconsistent availability, the unit has its own source of power. An RTU can come equipped with a solar panel for extra resilience in remote sites.


The data collection in an RTU can occur through either Analog or Digital receivers.

Analog data collection tracks several types of electrical signals like mA or V across an available range of magnitudes to produce different internally proportional measurements. These signals can be further specified based on each piece of equipment in the connection.

Digital data collection only looks for on/off signals, 0 or 1, the presence or absence of a signal that indicates a flipped circuit, triggered alarm, or another binary signal.


RTUs can transmit the data they collect to either Analog or Digital receivers via antennae 

Analog transmissions take the variable analog inputs and produce complex data like visual graphing elements or charts 

Similar to Status inputs, the Digital output system is used to send binary signals that can flip switches and turn equipment on or off 

Communication Interface

The RTU interfaces with other equipment and servers using standardized definitions for electrical signals and their configuration such as RS485. This interface is based on a broadly shared protocol like Modbus so that it can process inputs collected from various extension units. The RTU then transmits this RS485 data to the server via a cellular modem aided by an external antenna.

So now that we know how they work, what exactly can you do with an RTU? 

What are some use cases for RTUs?

Due to the versatility of the array of inputs and outputs possible for an RTU they can be included in almost any energy or data-based system. A few examples include: 

  • Improved energy efficiency, reduced operational costs, and diminished environmental impact of data centers and telecom sites 
  • Enhanced monitoring and efficiency for smart systems like cities, factories, grids, homes, and traffic  
  • Boosted connectivity and data collection for agricultural or industrial sensors and equipment 

Plugging in to your energy performance with Galooli

All those cases exemplify the utility and versatility of RTU, but where can you find the unit that’s right for you? Galooli is here to help 

In the world of RTUs, Galooli offers one of the top solutions. The Elara is an agnostic RTU that comes with Galooli’s Live service as well as fully supported system integration, detailed analytics, asset management, and more. 

Whether it’s tracking batteries and overall site performance, improving energy efficiency in equipment and data centers, or pushing the boundaries of sustainability, Galooli’s Elara does it all. 

Contact us to learn more about what Galooli can do to boost your sites today. 

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