Hi,
I have RB450Gx4 what is powered by 24V DC adapter, and try to attach hAP AC lite over PoE but it didn’t work. Then I measured the voltage on RB450Gx4 PoE out (Eth5) with a multimeter and only 9V. Why? What could be the problem? (rOS v7.11)
FYI: I measured 24V on hAP AC lite PoE out interface when I powered in a 24V DC adapter.
Regards
MT devices typically don’t do voltage conversions for PoE. If you measured much lower PoE out voltage than supply voltage (0.1V is acceptable, 15V is not), then there’s a hardware damage in your device.
I tested my hAP AC lite PoE out voltage again, and I measured same 9,6V when the port PoE settings is off or auto on (not attached PoE device) or the device is shutdowned. When I set this port forced on, then measured 24V.
So I’m thinking it possible it’s just a bug in rOS 7.11 or a bug in RB450Gx4 firmware.
Both mentioned devices have passive poe-out ports: they perform resistance check and if it’s in specific range, the port is turned on (https://help.mikrotik.com/docs/display/ROS/PoE-Out#PoEOut-MikroTiksupportedPoE-Outstandards) The voltage you measure is “detection” voltage in order for the PSE to measure resistance, this is done on any PSE.
To add to Reinis post - it means the port is not yet on. It will be turned on, when a device is connected.
Thanks, but the port won’t turn it on if I connect a device (hAP AC lite) to it, no matter how it’s configured in the rOS 7.11 (auto on or forced on). I tried it more PSU like 24V 0,8A, 24V 1,5A, 12V 1,5A.
Any other ideas?
If setting poe-out=forced-on on PSE (RB450Gx4) does not turn voltage on B pairs above detection voltage (9V), then most likely something has burnt/degraded.
Note: forced-on mode should always enable voltage on port, no matter what is at the other end, ofc, not if port is shorted.
Then it seems to be really harver problem.