POE voltage rise time

[cwachs]

This may simply be a limitation of the Netonix product line but I thought I'd ask. We have a radio vendor whose radios prefer 802.3af, 802.3at, 802.3at+, or 802.3bt PoE but will work with passive injectors as well. However, we found they would not always power up when plugged into our Netonix switches. We would end up having to cycle the port a number of time and eventually, the radio would fire up - usually.

In discussion with the vendor and testing with Netonix switches on their bench, they found the voltage rise time in the Netonix was out of the IEEE 802.3 Section Two spec for voltage rise time and as a result, a transistor in the Ethernet chip would go into oscillation and prevent the radio from powering up.

A solution we have found is to put a passive to active Ethernet midspan adapter in line between the Netonix and the radio.

I don't think Netonix claims to follow the 802.3 specification for POE - at least as rise time is concerned. However, is this something that could be addressed in firmware or is it tied to the hardware?

[Dave]

Netonix are passive POE only...we do not meet the POE identification phase, which is probably what he means by rise time, and nothing we can do about it. Sounds more like a possible design issue with the radio in question, as this is the first I have ever heard of this. But to be fair, I am sure when they designed the product they didn't think it would be used with a passive POE switch...

So sorry, nothing we can do about this in software.