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Nukleari
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hEX PoE (RB960PGS)

Fri Apr 19, 2024 6:16 pm

I'm looking for a small poe powered poe switch, that I'm planning to power with my RB5009UPr+S+IN.
I never used a device with passive poe before I only used 802.3af devices and I have a few questions about it.
Would my RB5009 be able to power the hEX PoE via poe?
Would I need to switch the port to poe forced on or would auto on also work with it? (assuming I can power it with the RB5009 )
When powered with this my RB5009 (using its included 48v adapter) would the ports on the hEX PoE be standard 802.3af? (also assuming I can power it with the RB5009 )
 
gigabyte091
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Re: hEX PoE (RB960PGS)

Sat Apr 20, 2024 6:44 am

PoE in on hEX PoE is passive so while it's possible to power it by RB5009 which is active PoE you will most likely need to force PoE on on the desired port on the RB5009.

Reason is that active PoE uses negotiation with client that requests PoE to be turned on. And passive PoE just sends and receives power.

But be careful and remember that you forced PoE on... Some devices might not like 48-52V on their port. (Talking about the future and if you ever want to plug something else instead of the hEX PoE)

If you power hEX PoE with separate power adaptor then you will have active PoE on it, as stated on product page.
 
jaclaz
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Re: hEX PoE (RB960PGS)

Sat Apr 20, 2024 2:00 pm

It is a complication, but you could use a PoE splitter and converter with input 802.3at compatible and output 48V passive, and power the hex with the jack.

The common issue (it depends on the other devices) is that the PoE output of the RB5009 is limited to:
Max out per port output (input 30-57 V) 440 mA
and then the hex Poe output is as well limited:
Max out per port output (input 30-57 V) 450 mA

So, you have out of the RB5009 some 48Vx0.44A=21 W, of these the Hex Poe will use some 6W (or so) and you remain with max 15W (very likely less due to losses on the cables) total available for the further device(s).

If possible, using external PoE injectors and splitters allows for much more flexibility and power deliverable to different devices.
 
gigabyte091
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Re: hEX PoE (RB960PGS)

Sat Apr 20, 2024 8:47 pm

Agree with @jaclaz here. When I know that my device needs to power other PoE devices then I power that device with dedicated PSU.

At my office I have several switches on desks that are powered from central PoE switch. 7 desks, 7 switches. That's a lot power bricks...and space that is saved. But those switches don't provide power to other devices.
 
Nukleari
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Re: hEX PoE (RB960PGS)

Sat Apr 20, 2024 11:25 pm

Well in that case I might want to use something else, I only planned to power 1 device with it (and plug in some other devices that are not poe), but I would rather not force poe on on the RB5009 ports.
The hEX S supports standard 802.3af/at on its input, and I could power that 1 device with it's usb port (it uses around 5W so 1 port on the RB5009 should be able to handle it).
Just out of curiosity, would an 802.3af device work plugged in the hEX S passive poe out port? (assuming I power it via RB5009 48v peo and that device is only using around 5w and expects 44-56v)
Last edited by Nukleari on Sat Apr 20, 2024 11:39 pm, edited 1 time in total.
 
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mkx
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Re: hEX PoE (RB960PGS)

Sat Apr 20, 2024 11:37 pm

Just out of curiosity, would an 802.3af device work plugged in the hEX S passive poe out port?

Probably yes. The power negotiation phase (which is the basic difference between passive PoE and 802.3 PoE) in 802.3 af/at is there for PSE (PoE out device) to make sure that power can safely be enabled on the port (and optionally to learn power requirements if device, connected to that port). And that happens before full 48V is output.
If PSE outputs 48V without the power negotiation, then vast majority of powered devices will gladly use it and won't insist on negotiating power. But voltage being output has to fall into standard voltage range, which is around 48V (depending on standard revision it can be between 44V and 57V). MT's passive PoE does a very basic check of connected equipment when poe out is set to "auto". Which may or may not work when powered device is 802.3 af/at. In this case it may be necessary to set poe out to "forced on" (make sure that connected device can survive 48V on ethernet port).
 
Nukleari
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Re: hEX PoE (RB960PGS)

Sat Apr 20, 2024 11:43 pm

Just out of curiosity, would an 802.3af device work plugged in the hEX S passive poe out port?

Probably yes. The power negotiation phase (which is the basic difference between passive PoE and 802.3 PoE) in 802.3 af/at is there for PSE (PoE out device) to make sure that power can safely be enabled on the port (and optionally to learn power requirements if device, connected to that port). And that happens before full 48V is output.
If PSE outputs 48V without the power negotiation, then vast majority of powered devices will gladly use it and won't insist on negotiating power. But voltage being output has to fall into standard voltage range, which is around 48V (depending on standard revision it can be between 44V and 57V).
Thanx, just edited the my post with the voltages as you were answering.
So I think the hEX S would be perfect for my use case. (I could even power my device with it's port, and only worry about not plugging anything else in that port)
 
jaclaz
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Re: hEX PoE (RB960PGS)

Sat Apr 20, 2024 11:56 pm

@Nukleari
It is the other way round:
https://mikrotik.com/product/RB960PGS#f ... ifications
It has passive PoE in and passive or 802.3af/at out (if powered in the 44-57 V range).
So you won't have issues to power a 802.3af device, a 802.3at is debatable because of the current limitation.
As a side note, remember that the Mikrotik Is mode B, and while in theory a compliant to 802.3af/at device should be compatible with both mode A and mode B, I would double and triple check before risking to send 48 V on the wrong pairs. (this is essentially why the negotiating of the protocol is a smart thing, as opposed to passive)
 
Nukleari
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Re: hEX PoE (RB960PGS)

Sun Apr 21, 2024 12:19 am

@Nukleari
It is the other way round:
https://mikrotik.com/product/RB960PGS#f ... ifications
It has passive PoE in and passive or 802.3af/at out (if powered in the 44-57 V range).
So you won't have issues to power a 802.3af device, a 802.3at is debatable because of the current limitation.
As a side note, remember that the Mikrotik Is mode B, and while in theory a compliant to 802.3af/at device should be compatible with both mode A and mode B, I would double and triple check before risking to send 48 V on the wrong pairs. (this is essentially why the negotiating of the protocol is a smart thing, as opposed to passive)
Yes the hEX PoE is as you described, but in one of my posts I was asking about the hEX S, that is the other way around. Because I would rather not force poe on on any port of the RB5009 to avoid acidentally plugging in something else in that port (the RB5009 is in a central location in the house with a patch panel and cables going to a lot of places, the ports on the router are only labeled with some really small numbers, so its relatively high risk in my opinion).
On the hEX S, I wouldn't mind the poe port being basically forced on because I would connect devices directly to it, and the poe out port on it is clearly labeled.
 
jaclaz
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Re: hEX PoE (RB960PGS)

Sun Apr 21, 2024 12:41 am

Ahh, I see now.
Yes, the Hex S has 802.3af/at PoE in and passive PoE out.
The side note about mode A and mode B still applies, be careful and make some tests.
Personally I would anyway use a splitter to power a device from passive PoE at 48 V.
There are splitters that are compatible with both modes.
In case, first test the end device with the 802.3af out of the RB5009. If after the negotiating the device powers on, it should mean that It Is mode B compatible, and thus you can safely connect it to the passive power out of the Hex S, in the worst case it won't power on, but you won't risk frying it.
Better be safe than sorry.
 
Nukleari
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Re: hEX PoE (RB960PGS)

Sun Apr 21, 2024 3:48 pm

Ahh, I see now.
Yes, the Hex S has 802.3af/at PoE in and passive PoE out.
The side note about mode A and mode B still applies, be careful and make some tests.
Personally I would anyway use a splitter to power a device from passive PoE at 48 V.
There are splitters that are compatible with both modes.
In case, first test the end device with the 802.3af out of the RB5009. If after the negotiating the device powers on, it should mean that It Is mode B compatible, and thus you can safely connect it to the passive power out of the Hex S, in the worst case it won't power on, but you won't risk frying it.
Better be safe than sorry.
Just tested it with the RB5009 and its working. I also checked the power usage and it's less than 4W.

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