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What is PoM or Power over Modbus?

  
Sentera products share information via Modbus communication. Modbus is a serial communication protocol that uses RS485 technology.
  
Based on that technology, Sentera developed the concept Power over Modbus or PoM to interconnect Sentera products. The PoM concept means that Modbus data communication and 24 Volt supply voltage are distributed via one single UTP cable (Unshielded Twisted Pair cable). 
  
The PoM concept reduces the risk of data losses due to disturbances. When Sentera products are interconnected via PoM technology, the combined branch lenghts become less critical compared to a standard Modbus network. More and longer branches can be added to the network before disturbances and data losses will occur.   
  
The PoM concept makes wiring easier and more efficient. The PoM concept makes it possible to connect different HVAC sensors, potentiometers and other Sentera devices via one cable. Sentera -M series HVAC sensors feature an RJ45 socket. These sensors can be connected via one simple RJ45 connector! It reduces the risk of wiring errors. Sentera 24 VDC power supplies are also available with RJ45 connectors. To simplify wiring, we also offer RJ45 splitters and distribution boxes. 
  
 Sentera PoM cable with RJ45 connector
  
Modbus communication offers the advantage of higher cable lengths compared to analogue signals. The PoM concept makes even longer cable lengths possible.
When a fan is controlled via an analogue signal, you know what the requested fan speed is. When using the PoM concept, extra information from the connected devices is available. Actual motor speed, motor status, motor temperature and much more information can be monitored and logged.     
  
Crimping an RJ45 connector is more efficient then classic wiring. This movie shows how easy it is to crimp an RJ45 connector:
   
video
 
  
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