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GiovanniG
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I need to clear PoE 802.3af if should work with 2 pairs only

Tue May 30, 2023 7:13 pm

Hi, I'm asking your experience, thanks for replies
when a device is defined af, should it work with 2 pairs only?
What about the "at"?

In particular, I've a 4 pairs UTP cable where is connected a Dahua PFT1300 and after it 2 cameras, all by 4 pairs UTP, I need to add another camera, it's very complicated to lay till there a new cable, can I use the 2 spare pairs 5-6 / 7-8?
If PFT1300 can support the af yes, but it is an input "at", and I can't find anywhere the difference between those. May somebody help me?

I do believe that 2 af cameras can ne connected to one 4 pairs cable splitting the 2 pairs
 
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mkx
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Re: I need to clear PoE 802.3af if should work with 2 pairs only

Tue May 30, 2023 10:07 pm

Wikipedia article on PoE says that "alternative A" uses same pairs of wires as are used as data pairs in 10Base-T and 100Base-Tx ... which use pins (1,2) and (3,6). Article about MT PoE support details some particular combinations and it seems that most equipment supports "alternative A".

BTW, af and at use same wiring.
 
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rextended
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Re: I need to clear PoE 802.3af if should work with 2 pairs only  [SOLVED]

Tue May 30, 2023 10:22 pm

The Dahua PFT1300 (PoE Extender) is PASSIVE POE, so use 4,5,7,8 for power AND provide 802.3af/at to the "Camera" port...
 
GiovanniG
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Re: I need to clear PoE 802.3af if should work with 2 pairs only

Tue May 30, 2023 11:13 pm

The Dahua PFT1300 (PoE Extender) is PASSIVE POE, so use 4,5,7,8 for power AND provide 802.3af/at to the "Camera" port...
Thank you for your kind answer, this is really precious info. Are you sure abotu that? Have you tested it? (cut 5-6 and 7-8 pairs).
Searching deeper for info looks you are right and it has sense, in this way is not possible to connect 2 of them in cascade, it should be a real PoE switch before connected.


mkx: thank you, now it's more clear, all starting with "a" menas 2 pairs, all starting with "b" means 4 pairs

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