What POE mode (A or B) does Dahua PoE NVR use?

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MakeItRain

Pulling my weight
Aug 7, 2017
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Does anyone know what POE mode Dahua uses ? is it alternative A or B?

I'm having a problem where 1 of the cameras that's hardwired to the exterior, it doesn't work when it connects to the Dahua POE NVR.

But when I use a TP-Link PoE injector, it works. When I bring the camera into the house and mount it straight to a the Dahua NVR using a different cable, the camera works. That tells me the RJ45 cable between the NVR and the exterior of the wall is bad somehow. But then why does it work with TP-Link POE injector?

This tells me that both the TP-link POE injector and Dahua NVR *must* be using a different PoE mode...
initial research tells me TP-link uses mode A where the data and power is mixed. The camera, when connected to the suspected bad RJ45 cable and Dahua NVR does not respond, but I can see the infrared LED so it is getting power.
 
MakeItRain said:
Does anyone know what POE mode Dahua uses ? is it alternative A or B?

I'm having a problem where 1 of the cameras that's hardwired to the exterior, it doesn't work when it connects to the Dahua POE NVR.

But when I use a TP-Link PoE injector, it works. When I bring the camera into the house and mount it straight to a the Dahua NVR using a different cable, the camera works. That tells me the RJ45 cable between the NVR and the exterior of the wall is bad somehow. But then why does it work with TP-Link POE injector?

This tells me that both the TP-link POE injector and Dahua NVR *must* be using a different PoE mode...
initial research tells me TP-link uses mode A where the data and power is mixed. The camera, when connected to the suspected bad RJ45 cable and Dahua NVR does not respond, but I can see the infrared LED so it is getting power.
Click to expand...
No idea, but most likely A...we know the tp link uses A, so even if the dahua used B, you would still have issues as B uses all pairs...
there is likely another reason the tp works...
have you tried re-crimping both sides? did you use the 568B standard on both sides?
 
If it helps any I just went through a similar problem. If you build your own cables, on short lengths the color scheme is not critical, only straight pairings. But on longer lengths, like 250 ft plus, I got red power light, but could not find cameras. Once I went back and did standard coloring scheme everything worked, as SNR separation is important.

It will even pass the rj45 tester, but fail to lock for that reason.
Moral of the story' always use standard color scheme when building cables.
 
bluecam said:
If it helps any I just went through a similar problem. If you build your own cables, on short lengths the color scheme is not critical, only straight pairings. But on longer lengths, like 250 ft plus, I got red power light, but could not find cameras. Once I went back and did standard coloring scheme everything worked, as SNR separation is important.

It will even pass the rj45 tester, but fail to lock for that reason.
Moral of the story' always use standard color scheme when building cables.
Click to expand...
it is ALWAYS critical to use the 568 standard...even on short runs..you will drop packets otherwise...it may be less noticeable but its happening.
 
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The camera is required to support both modes. Injectors generally use mode B (power on the spare wires) and switches generally use mode A (power on the data wires), so I'm "assuming" that the nvr's built-in switch is mode A. I doubt that any Dahua specs state this, so the only way to know for sure would be for somebody to measure it. I had a problem just a few days ago where the camera was powered (red lights on) but didn't respond. The problem turned out to be an RJ45 that I hadn't pushed in all the way. The only 2 things I can think of that would cause the combination of what you described are a problem in the wiring, or the wire being just too long. If I was at the end of my rope on this, I'd make up a cable about the same length or longer than the installed cable and how it works.
 
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Look, if you see: (IEEE802.3af/at) than it is type B. Cause type A do not support PoE+ (at)
if you see IEEE802.3af than it can be or type A or type B

For example: NVR5416-16P has IEEE802.3af/at, so it has PoE type B
 
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Roman G said:
Look, if you see: (IEEE802.3af/at) than it is type B. Cause type A do not support PoE+ (at)
if you see IEEE802.3af than it can be or type A or type B

For example: NVR5416-16P has IEEE802.3af/at, so it has PoE type B
Click to expand...
I disagree with this. 802.3at specs maximum 30 watts over 2 pairs (mode A), or 60 watts max over 4 pairs (mode B). It's mentioned at the bottom of page 2 on this document:

https://www.microsemi.com/document-portal/doc_view/24-understanding-ieee802-3at-poeplus
 
I strongly advise to use 568B Color mode for RJ-45 cabling (fabric). That will provide the solution. In general, if a device neeed 802.3af (that is for most of non speed domes) it can be supplied from 802.3af/at.
 
According tolates onformation, type of PoE depend on the model of the NVR. What model do you have?
 
bluecam said:
If it helps any I just went through a similar problem. If you build your own cables, on short lengths the color scheme is not critical, only straight pairings. But on longer lengths, like 250 ft plus, I got red power light, but could not find cameras. Once I went back and did standard coloring scheme everything worked, as SNR separation is important.

It will even pass the rj45 poe tester, but fail to lock for that reason.
Moral of the story' always use standard color scheme when building cables.
Click to expand...

if you see: (IEEE802.3af/at) than it is type B. Because type A don't support PoE+ (at)
if you see IEEE802.3af than it could be or type A or type B

For instance: NVR5416-16P features IEEE802.3af/at, therefore it has Power over ethernet type B
 
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