Nexxt NVR ports don't turn on (green LED) for Dahua Poe cameras

[jimmi heiserman]

I have a Nexxt NVR unit (Xpy 1280-HD) with 8-channels and it comes packaged with 4 PoE cameras. Used it for a few months.

Now I bought 4 more PoE cameras from Dahua (a totally different company/brand). model: Dahua IPC-HFW2439S-SA-LED-S2: IPC-HFW2439S-SA-LED-S2

They don't seem to power on at all. The Nexxt NVR LED in the front doesn't light up (green) for any of the Dahua cameras. Is this an under-powered problem? I thought I could mix PoE with other brand's NVRs. I have gone through what I think are all of the trial and error steps. I have reduced it to not even needing to connect the NVR to any other router. Just plug it in for power, isolated, to see what cameras and lights turn on, one camera at a time to avoid any stupid conflicts. Nothing. Swapped cables, short cables, long, home-crimped, store bought, swapped ports... The 4 Nexxt Cameras turn on and light up the port's LEDs as green, while the 4 Dahua cameras don't appear to have any power and the port LEDs on the NVR don't turn on at all.

Thanks for any help.

 

[sebastiantombs]

Sounds like the Nexxt isn't using PoE that complies with the industry standards. Try powering one of the Dahua cameras with a 12 volt DC wall wart to see if that is, indeed, the problem.

 

[alastairstevenson]

Sounds like the Nexxt isn't using PoE that complies with the industry standards.

I think you are correct.
No mention in the product spec of the specific PoE standard supported, and non-standard is also implied by the use of a 19v PSU.
Invariably a standard PoE NVR uses a 48v PSU.

 

[jimmi heiserman]

Yes, I agree that sounds like the next test. Neither of these 8 camera (two different brands) came with a wall plug (but that's fine, I should be able to go buy one). But what I also find odd is how the Nexxt camera (black cables) uses the second plug as a RESET button, while the Dahua uses the extra plug for what appears to be a wall unit plug? Why the difference? Everything seems really wonky with these cameras, but I don't know which brand is the wonky one yet.



Here is a pic of the power supply that the Nexxt NVR uses.

 

[alastairstevenson]

I don't know which brand is the wonky one yet.

Not the Dahua brand - it's widely used, well engineered and manufactured, reliable, and works well, conforms to recognised standards so is quite interoperable with other brands.

Here is a pic of the power supply that the Nexxt NVR uses.

Yes, that's 19v.
Lends credibility to the thought that the Nexxt NVR uses a non-standard form of PoE.

 

[alastairstevenson]

By the way - in the Nexxt NVR user manual it does say that cameras wired to the LAN (eg if you were to power up the Dahua camera with 12v and connect to the LAN) cannot be connected.
That's at variance with what is usually the case with an NVR, they can usually do both.
Whether the NVR will connect to the camera if you power with 12v and connect to the NVR PoE port might be an interesting, and a little risky, experiment.

 

[sebastiantombs]

Given that Dahua using a blocking diode on the 12VDC input line that should, note I say should, provide isolation. Generally, non standard PoE is so far from spec that they use the blue and brown pairs for power. It might be interesting, and eliminate some more risk, to use a DVM and check out which pins on the Nexxt cables are carrying the 12VDC supply voltage and even if it's actually 12VDC and not some other voltage. If it turns up on the orange and green pairs then I wouldn't even think about connecting a Dahua camera to the NVR.

 

[jimmi heiserman]

Thank you everyone! well-read and researched people here.

While I do want to know definitively what this problem was, and I do believe it is the underpower issue everyone suggested here, I am not an electrical guy and will have to enlist friend to dig deeper with me. But what are the cheapest paths to get back to where I should be with 8 working cameras?

I think the best step forward is to buy another 4-port sufficiently-powered PoE switch. Then connect my 4 better Dahua cameras into that, and connect that PoE switch into one of the ports of my 8-port NVR. So I will only be using 5 of the 8 ports in the NVR, but still maxing out the cam allotment.
[Green is new purchase in my diagram]


Is this the best step forward? Probably cheaper than a new 8-port NVR. Or can I just get some PoE injectors for the 4 good cameras and connect that near the NVR storage area?

 

[sebastiantombs]

Injectors for the Nexxt cameras probably won't work since they are not standard. Before using a four port switch for them you need to confirm that the NVR will accept an ethernet signal only on the ports. It is possible, although not likely, that it detects cameras based on PoE loading. No PoE needed on a port and the port won't activate.

If you unplug the Nexxt cameras do the Dahua cameras work with the NVR if the Nexxt cameras are not plugged in? I would be very cautious about doing that simply because the Nexxt isn't standard PoE apparently.

 

[jimmi heiserman]

[First of all, I made an idiotic mistake in my diagram. I added a diagram to help people understand what I was thinking, and I had which cameras were going were backwards in the diagram. I fixed it in the diagram in my post above. Sorry. Nexxt Cameras go directly into Nexxt NVR, because they already work there.]

I want an injector to give power to these Dahua cameras that are probably not powered enough. I think I hear what you are saying about putting a data-only camera (powered further down the line) on a port that may be expecting a PoE camera.




For your last question, I tried just putting a single Dahua camera in there. Still doesn't work. But thanks for thinking through these hurdles with me. Now that I corrected my diagram, do you think a PoE injector on the Dahua cameras have a better chance of working? This is my next step to solve this riddle.

 

[sebastiantombs]

Doing it that way will protect the cameras from the non-standard PoE. Alternately you could try a single port PoE injector first. If you can get a switch with a non PoE uplink port that would be the best thing to try. Worst case if it doesn't work you end up with a spare 4 port PoE switch. Keep in mind too that NVRs do have limits on the bandwidth, total amount of megapixels, that they can process.

 

[pozzello]

How about trying to use passive PoE splitters for the Dahua cams? usually sold in injector + splitter pairs, you may just need the splitters...

won't cost much to try: for example,

https://www.amazon.com/Ethernet-Splitter-Injector-Waterproof-Surveillance/dp/B07QSTNDNY

unless Nexxt does something totally stupidly non-standard like Zmodo does (do the Nexxt cable have 8 wires in em at least?), which measuring voltages on the pins could confirm...