Power Over Ethernet with Andover Continuum Controllers

Issue

While Continuum controllers and SmartStruxure controllers do not utilize Power over Ethernet (POE), can plugging in a Continuum or SmartStruxure controller into a POE switch damage either the POE port or the controller?

Product Line

Andover Continuum, SmartStruxure Solution

Environment

  • PoE
  • Ethernet

Cause

Controllers must be installed on a subnet served by a POE switch.

Resolution

  • According to the IEEE standard, a POE switch shall determine if the connected device is POE capable before turning on the power.
  • The detection if a connected unit is POE capable is done by measuring the resistance between the pair #2 - #3 and pairs #1 - #4.
  • On a POE capable unit the resistance is 25kohm, with some tolerance. If it is lower or higher it is not considered to be POE capable.
  • As there are no Continuum or SmartStruxure ethernet controllers that apply a 25K ohm load, a properly functioning switch port will not enable PoE power and the device will not be damaged.

Information on the PoE standard can be found in the following document.

The Fundamentals of Power Over Ethernet (PoE)