POE 24V or 48V

[coreinput]

Hi folks,

I'm a novice with PoE and have luckily stumbled my way through with a PoE multi port injector setup running fine for a few years now. I'd like to redo my setup using a new WS-12-250-AC which is coming soon and currently in the planning / research phase but confused on the 24v vs. 48v options.

I've read several forum pages on the PoE topic and studied the manuals to my devices but the deeper I read the more I'm confused by it all. I even wonder how my current setup is working since the pin layout doesn't match what makes sense to me. So here goes, I have the WS-GPOE-6multi port passive POE injector running in Mode A (PIN 1. 2 V-, PIN 3. 6 V+) which powers:

4x - network switches which can be powered by IEEE 802.3af PSE via Ethernet port1 - the datasheetsays Power consumption is 6W maximum but the tech specs says Max consumption (Watts) is 12.78 Watts if using PoE via port 1. To further complicate things, the power adapter says 12V, 1.0A.
Q. Is it OK to set my Netonix ports that serve these switches as 24V POE Option @ .75A, or should I use 48V, or will POE Smart handle the correct setting?

1x - Wireless radio which can be powered by IEEE 802.3at via Ethernet port - this one has input power of AC Input Voltage 100-240 VAC and Current 0.8A @ 100-240VAC, with 802.3at output power voltage 55VDC, 30W. I read that the an after-market POE injector for this radio has PoE ping assignment and polarity as: 4/5 (+), 7/8 (–) and output voltage at 55Vdc, user power power at 36W
Q. Is it OK to set my Netonix ports that serve these radios at 48V POE Option @ .75A, or should I use 24V, or will POE Smart handle the correct setting?

I appreciate any input from the board members and Netonix staff, I want to avoid any frying of devices or ports by using the wrong settings. The one thing I keep repeating in my head is no 24VH or 48VH as it will cause some serious headaches for me (and my wallet).

Thanks.

[sirhc]

I have the WS-GPOE-6multi port passive POE injector running in Mode A (PIN 1. 2 V-, PIN 3. 6 V+) which powers:

OK first off if you are running MODE A with PINs 1,2 negative and PINs 3,6 positive this is NOT 802.3af/at compatible pin outs.
802.3af polarity PIN out is: PINs 4,5 positive and PINs 7,8 negative.

By using Mode A you are running a NON STANDARD POLARITY PINOUT unless their documentation is wrong..WHICH I THINK IT IS???

I am hoping that they have poor documentation and MODE A really means that PINs 1,2 are positive and PINs 3,6 are negative which would make more sense as they speak of using a Y cable and one power supply to activate all PINs to match 802.3at POE standard which is PINs 1,2,4,5 positive and PINs 3,6,7,8 negative.

4x - Netgear ProSAFE 8 network switches which can be powered by IEEE 802.3af PSE via Ethernet port1.

OK, the only reason I can think of that you are not frying these Netgear ProSAFE 8 switches is they have a bridge rectifier circuit on the POE IN on Port 1 which corrects an incorrect polarity the same as our WS-6-MINI has because Mode A is NOT 802.3af polarity PIN OUT, but then again as I mentioned above maybe they have poor documentation and MODE A is incorrect in their PIN outs.

BUT either way if you are using MODE A you are powering the wrong PINS for most 802.3af devices which uses PINs 4,5 positive and PINs 7,8 negative.

So this tells me that the Netgear ProSAFE 8 is possibly looking at all 8 PINs which is 802.3at and they have a Bridge Rectifier circuit in there that is correcting the "possibly" incorrect polarity or the documentation on the POE injector is crap.

1x - Wireless radio which can be powered by IEEE 802.3at via Ethernet port - this one has input power of AC Input Voltage 100-240 VAC and Current 0.8A @ 100-240VAC, with 802.3at output power voltage 55VDC, 30W. I read that the an after-market POE injector for this radio has PoE ping assignment and polarity as: 4/5 (+), 7/8 (–) and output voltage at 55Vdc, user power power at 36W

Q. Is it OK to set my Netonix ports that serve these radios at 48V POE Option @ .75A, or should I use 24V, or will POE Smart handle the correct setting?

Answer: Yes, 48V is correct but I would prefer to know the radio model to see if it can use power on all 4 pair and if it can I would then use 48VH.

I appreciate any input from the board members and Netonix staff, I want to avoid any frying of devices or ports by using the wrong settings. The one thing I keep repeating in my head is no 24VH or 48VH as it will cause some serious headaches for me (and my wallet).

YES - 24VH and 48VH are only for special devices that expect power on all 4 pair:
PINS 1 ,2 ,4 ,5 (+) Positive
PINS 3, 6, 7, 8 (-) Negative

The only devices that I am aware of that can use 24VH is the following:
Ubiquiti AFX radios but they also support 24V, 48V, and 48VH

Ignite Metrolink but will also run on our 24V


Look, Read our PDF page 17: http://www.netonix.com/media/wysiwyg/ws-specsheet.pdf
And read the Wiki: https://en.wikipedia.org/wiki/Power_over_Ethernet

They Discuss Mode A and Mode B

MODE A:
PINs 1,2 POSITIVE
PINs 3,6 NEGATIVE

MODE B:
PINs 4,5 POSITIVE
PINs 7,8 NEGATIVE

Basically our VH POE options activates MODE A & B at the same time.
I think your confusion is from their incorrect documentation.

CLICK IMAGE TO VIEW FULL SIZE

[lligetfa]

Chris is right about Mode A and polarity.
https://en.wikipedia.org/wiki/Power_ove ... et#Pinouts

[coreinput]

Thank you both for replies.

I ended up contacting the POE injector vendor asking about the PIN layout / documentation. They replied that their device uses a diode bridge allowing either polarity also pointing me to Wikipedia, where I found this reference

Mode A has two alternate configurations (MDI and MDI-X), using the same pairs but with different polarities. In mode A, pins 1 and 2 (pair #2 in T568B wiring) form one side of the 48 V DC, and pins 3 and 6 (pair #3 in T568B) form the other side. These are the same two pairs used for data transmission in 10BASE-T and 100BASE-TX, allowing the provision of both power and data over only two pairs in such networks. The free polarity allows PoE to accommodate for crossover cables, patch cables and auto-MDIX.

In summary Mode A defines polarity differently for the type of cable termination,

568A expects + voltage on 12, - on 36
568B expects + voltage on 36, - on 12

My devices were probably saved by diode bridges and bridge rectifiers which Interestingly enough is the same thing. The documentation could have been clearer as it incorrectly assumes one specific type of cable termination. Then again I think POE could be simplified for the layman like myself.

Thanks again for your replies, it should be smooth sailing now once the Netonix arrives!

[sirhc]

REMEMBER TO UPGRADE FIRMWARE ON SWITCH BEFORE YOU DO ANYTHING.