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SPOM
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RTFC11: how to power with PoE 802.11at/af?

Mon Jan 20, 2025 5:16 am

I can get it working with 24v PoE, but thats a big hassle as its a separate injector (so no control over power to reset, additional plug needed, etc) when I'd prefer to use the listed supported standard. I've tried powering from a Cisco switch, using multiple brands of PoE Injectors (to see if it was the switch) and nothing at 48v ever powers them on. Any suggestions on getting this to work?
 
jaclaz
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Re: RTFC11: how to power with PoE 802.11at/af?

Mon Jan 20, 2025 12:23 pm

You mean the RBTFC11:
https://mikrotik.com/product/RBFTC11
?

By default it comes with an injector that is this one:
https://mikrotik.com/product/RBGPOE

That definitely uses mode B (4,5+/7,8-).

In theory a 802.3af/at compliant PD should accept both Mode A and mode B (it is the PSE that decides on which pins to apply power).

Your Cisco most probably uses mode A (1,2+/3,6-).

It is possible that either the thingy is not fully 802.3af/at compatible or that (for whatever reasons) it is defective and only powers from mode B.

You can try extracting the 48V from the Cisco and inject the voltage back in the RBGPOE connected to the RBFTC11, with something like this:
https://www.wirmax.net/en/alimentazione ... itter.html
 
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mkx
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Re: RTFC11: how to power with PoE 802.11at/af?

Mon Jan 20, 2025 6:14 pm

In theory a 802.3af/at compliant PD should accept both Mode A and mode B (it is the PSE that decides on which pins to apply power).

Your Cisco most probably uses mode A (1,2+/3,6-).

It is possible that either the thingy is not fully 802.3af/at compatible or that (for whatever reasons) it is defective and only powers from mode B.

Yup. Product page says
Unit has 12-57V PoE with 802.3af/at support (with unshielded cross cable)
(emphasis is mine)
 
jaclaz
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Re: RTFC11: how to power with PoE 802.11at/af?

Mon Jan 20, 2025 7:00 pm

Yup. Product page says
Unit has 12-57V PoE with 802.3af/at support (with unshielded cross cable)
(emphasis is mine)
In addition to emphasis, can you also translate from Mikrotikish?

What (the heck) is a cross cable?

Does it mean crossover ?
But in crossover cables the 4,5,7,8 used for PoE remain straight and it shouldn't apply anyway to data because of auto mdi/x (of a 10/100/1000 port).

A previous thread (where no actual detail/useful answer is provided):
viewtopic.php?t=194596
 
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mkx
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Re: RTFC11: how to power with PoE 802.11at/af?

Tue Jan 21, 2025 9:14 am

Yup. Product page says



(emphasis is mine)
In addition to emphasis, can you also translate from Mikrotikish?

What (the heck) is a cross cable?
I've no idea ... perhaps @OP should ask MT support directly (and post their answer here, it should be interesting).
 
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Re: RTFC11: how to power with PoE 802.11at/af?

Mon Jan 27, 2025 10:23 am

Only to keep things as together as possible:
viewtopic.php?t=194596

It seems like "cross" translated from Mikrotikish means crossover (maybe).
 
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Re: RTFC11: how to power with PoE 802.11at/af?

Mon Jan 27, 2025 5:01 pm

Mikrotik Support asked what kind of Injector I was using and followed up with "Try with a crossover cable" ("crossover" was the term they used, not "cross" so I think that points to that meaning, unless Support is just as confused as we are about the terminology in place). I'm not able to do that for a few weeks, but will report back all my info once I do. But clearly we don't have full standard 802.3 aft/at support, and is a subset of that somehow (and not really documented).