Integration of PLC controlled air conditioning systems into PRTG

Originally published on January 30, 2023 by Michael Becker
Last updated on January 23, 2024 • 7 minute read

Air-conditioning systems in a data center are, among other factors, a guarantee of trouble-free operation of its servers, switches, storage systems and other hardware. Some manufacturers of air conditioning systems enable control of the devices via PLCs (Programmable Logic Controllers). In these cases, PLC technology is the key in the air-conditioning technology for energy-saving cooling. Intelligent control helps to reduce energy consumption and avoid unnecessary costs.

About PLCs

A Programmable Logic Controller or Programmable Controller is a device that is used to control or regulate a machine or facility and is programmed on a digital basis. In the simplest case, these devices have inputs, outputs, an operating system (firmware) and an interface that can be used to load the user program. The user program determines how the outputs are to be switched depending on the inputs.

PLC compatibility with networks

Some PLC manufacturers support a variety of industrial protocols, for example Modbus, OPC UA or SNMP, allowing them to be integrated into an existing network. This not only enables integrated management of air conditioning units to optimize system operation, but also integration with monitoring solutions. This is where Paessler PRTG comes into play. But what if PLCs send values as DINT (Double Integer) or UDINT (Unsigned Double Integer) data type?

Integration of PLCs into PRTG

This was exactly the challenge faced by a large German car manufacturer that wanted to integrate their PLCs of the air conditioning units into PRTG. However, the PLCs send data as integer values that represent bit fields.

Example:

Value 20.0 = Bit 1 (boolean) / (e.g. DINT 20.0 Operation)
Value 20.1 = Bit 2 (boolean) / (e.g. DINT 20.1 Malfunction)
Value 20.2 = Bit 3 (boolean) / (e.g. DINT 20.2 Pump)
Value 20.3 = Bit 4 (boolean) / (e.g. DINT 20.3 Compressor)

At first glance, this seemed impossible, but this was successfully resolved using lookups and the SNMP Custom Sensor. This is because Paessler PRTG can mask the values retrieved from an SNMP sensor bit by bit, which finally brought about the desired solution. Thus, all PLCs of the air conditioning units could be integrated into PRTG and monitored. In case of problems or malfunctions, responsible team members can now be informed using the numerous PRTG notification options. More information can be found in this KB article:

👉 Can I bit-wise mask values retrieved from an SNMP sensor?

Conclusion

Besides numerous native sensors that allow you to integrate almost all devices of your IT infrastructure into PRTG, our application also handles challenges that are not commonplace, as this example shows. Thanks to its flexibility, Paessler PRTG grows along with your challenges and enables comprehensive monitoring not only of
IT infrastructure, but also of OT infrastructure. In order to expand our application with new sensors and features, we work passionately on the development of our product. Take a look at our roadmap where we also collect feedback via surveys, which allows you to help us develop new features.