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Advantages of using Power over Ethernet (POE)

A recent project required the use of our GET-1008WM Wireless M-Bus dataloggers for multi-room, short term environmental monitoring. This involved deploying multiple GET-1008WM throughout the section of the building to be monitored. One of the issues with this deployment was the fact that the optimum locations for the dataloggers could not be predetermined as it depended on the location of the wireless sensors and the influence of the building fabric, location of equipment and other factors. Some of the issues encountered included:

  • The dataloggers were positioned in the corridors where there was very limited access to mains power.
  • It was important to minimise the disruption in the corridors by keeping the cabling to a minimum.
  • Each datalogger required a power connection and an Ethernet network connection.
  • The dataloggers required re-positioning during the setup phase to ensure all the Wireless M-Bus sensors could be read reliably.

This was a perfect use case for Power Over Ethernet (POE) to provide both power and communications to the dataloggers.

Interior of POE slave unit
Exterior view of POE slave unit








We used a central master datalogger panel which contained a datalogger, an Ethernet switch with POE connections and a POE splitter to power the datalogger. This panel had external RJ45 connectors which were wired up to the POE switch in the panel to allow connecting to the switch without the need to open the panel.

The slave dataloggers were housed in small enclosures along with a POE splitter. These enclosures also had an external RJ45 connector. This meant that each slave could be connected to the master panel with a single standard Ethernet cable of up to 100 meters in length. Once the optimum location for the slaves was determined, the Ethernet cables were made to length from a reel of Cat 5e cable which minimised the amount of cable deployed in the corridors.

Another advantage of only needing a single Cat 5e cable to connect the slaves is the fact that the cable was thin enough to fit under the doors in the corridors without causing any obstructions.

Connecting all the dataloggers together into their own private network, with a PC also connected, allowed continuous, automatic data collection of temperature and relative humidity from 70 wireless sensors.