POE Splitter Loses Power

R

RugenNixie

Weaksauce
Joined
Aug 29, 2004
Messages
123
I set up a security camera using POE, and I also installed a separate infared light for night recording. To power the infared light, I installed a TrendNet TPE-104S POE splitter.

The path to the camera and IR light is:
  • POE switch to ethernet splitter
  • 1 leg from the ethernet splitter goes to the camera
  • Other leg from ethernet splitter goes into the POE splitter
  • Data out from the POE splitter is left empty
  • Power out from the POE splitter is connected to the IR light
The problem I'm having is that after extended power outages, the POE splitter is dead (LED power light is off). Also the POE switch shows no connection on the ethernet to the camera (no link light). If I cycle power on the switch, nothing changes. The only way I can find to get the system working again is to pull and then reconnect the ethernet line feeding into the POE splitter. Doing this immediately restores power to the POE splitter (as evidenced by the LED power light on the splitter), and it also restores the connection to the switch (as evidenced by the switch link light).

I can't make sense of this, and therefore don't understand how to fix it. At first I thought it might be the POE splitter, but switching it to a similar DLink splitter resulted the same. I could understand if only the IR light stopped working, but both the camera and IR light are dead until I pull & replug the cable into the POE splitter.

I don't have the option of powering the IR light independently.

Any ideas?
 
Is the switch a managed switch? If so, have you checked the logs for the switch port?

If it is a Cisco switch I am betting there would be an error on the port that a simple shut/no shut would correct.
 
If it's a manged switch, you need to look at the wattage draw output and make sure the port isn't maxed out. They only have a certain wattage they can output.
 
Wait... your "path" first says Ethernet splitter... which then goes to a PoE splitter. What kind of "Ethernet splitter" are we talking about here?

803.2af PoE only allows for one device feeding from a single PoE switch port up to a max of 15 watts. The connected device has to negotiate with the switch to enable full power, which is why only one power drawing device can be connected.

Are you trying to power both the camera and the IR light from a single PoE switch port?
 
stevewm said:
Wait... your "path" first says Ethernet splitter... which then goes to a PoE splitter. What kind of "Ethernet splitter" are we talking about here?
Click to expand...

The ethernet splitter is just like a phone jack splitter, except made for ethernet. It's not a hub/switch of any sorts.

803.2af PoE only allows for one device feeding from a single PoE switch port up to a max of 15 watts. The connected device has to negotiate with the switch to enable full power, which is why only one power drawing device can be connected.

Are you trying to power both the camera and the IR light from a single PoE switch port?
Click to expand...

I am trying to power both the camera and IR light from a single POE switch port. The combined wattage is 10 watts (4 watts for the camera and 6 watts for the light), but you've got me wondering if the initial current after the power outage might be exceeding the 15 watts. The problem has only occurred after power outages.
 
The switch is not a managed switch. Just a basic 8-port switch, with 4 ports being POE.
 
I agree with stevewm, I don't really see how 2 devices can be powered through a splitter with POE unless it somehow negotiates power sufficient for 2 devices. I'd guess the wattage draw is higher than the splitter can handle.

I think your best bet would be to replace the camera with one that has an integrated infrared light.
 
green91 said:
I agree with stevewm, I don't really see how 2 devices can be powered through a splitter with POE unless it somehow negotiates power sufficient for 2 devices. I'd guess the wattage draw is higher than the splitter can handle.

I think your best bet would be to replace the camera with one that has an integrated infrared light.
Click to expand...

Yes, I'm trying to make something work that shouldn't. The camera was installed first and then I tried to add the IR light. It works except occasionally after power outages. The camera is too expensive to replace. Pulling a second ethernet cable might be possible.
 
I didn't realize that there was a negotiation with the switch for the power draw. I assumed that the power draw was similar to household wiring in that the power is available to be drawn as long as you don't exceed the maximum. I thought that having 1 data device (camera) and 2 power drawing devices (camera & light) would work as long as the maximum wattage wasn't exceeded.
 
803.2af PoE devices do in fact indicate to PoE switches they are standards compliant, the switch then decides which mode to deliver power in and tells the device this. The device can optionally specify its power "class" which is how much power it will need. There are some "passive" devices that just use straight power off a set pair of wires, however generally when a device is advertised as being PoE compatible, it is using the 803.2af standard as dictated here: http://en.wikipedia.org/wiki/Power_over_Ethernet

When you say ethernet splitter, are you using a device such as the one shown on the first picture here on this page?: http://www.pakwheels.com/forums/non-wheels-discussions/122342-change-modem-use-splitter

I just cannot get past that part, because the only Ethernet splitter device I know of is a device such as linked above. It takes advantage of the fact that 100Mbit ethernet only uses 2 pairs of a 4 pair cable. These splitter devices take 2 connections from a switch and shift the signals around so that each connection uses 2 of the pairs in the 4 pair CAT5 cable. You need another splitter on the end of the cable to separate them back out.

If you are using a single ethernet splitter, It is sheer luck your setup even works at all.

If you where to get another ethernet splitter, and plug it into 2 ports on the PoE switch, it would be OK. The PoE switch will sense that only 2 pairs are connected in the wiring and use the correct power mode.

With that in mind, your setup should be:

1. PoE Swtich
2. Ethernet splitter plugged into 2 PoE ports on the PoE switch.
3. cable running to the cam/IR connected to the single output side of the splitter
4. On the other end, another ethernet splitter connected to the single cable
5. One connection from the ehternet splitter goes off to the camera, the other off to the PoE splitter.

Each device will negotiate with the switch separately which is the correct way and should function without problems.
 
stevewm said:
803.2af PoE devices do in fact indicate to PoE switches they are standards compliant, the switch then decides which mode to deliver power in and tells the device this. The device can optionally specify its power "class" which is how much power it will need. There are some "passive" devices that just use straight power off a set pair of wires, however generally when a device is advertised as being PoE compatible, it is using the 803.2af standard as dictated here: http://en.wikipedia.org/wiki/Power_over_Ethernet

When you say ethernet splitter, are you using a device such as the one shown on the first picture here on this page?: http://www.pakwheels.com/forums/non-wheels-discussions/122342-change-modem-use-splitter

I just cannot get past that part, because the only Ethernet splitter device I know of is a device such as linked above. It takes advantage of the fact that 100Mbit ethernet only uses 2 pairs of a 4 pair cable. These splitter devices take 2 connections from a switch and shift the signals around so that each connection uses 2 of the pairs in the 4 pair CAT5 cable. You need another splitter on the end of the cable to separate them back out.

If you are using a single ethernet splitter, It is sheer luck your setup even works at all.

If you where to get another ethernet splitter, and plug it into 2 ports on the PoE switch, it would be OK. The PoE switch will sense that only 2 pairs are connected in the wiring and use the correct power mode.

With that in mind, your setup should be:

1. PoE Swtich
2. Ethernet splitter plugged into 2 PoE ports on the PoE switch.
3. cable running to the cam/IR connected to the single output side of the splitter
4. On the other end, another ethernet splitter connected to the single cable
5. One connection from the ehternet splitter goes off to the camera, the other off to the PoE splitter.

Each device will negotiate with the switch separately which is the correct way and should function without problems.
Click to expand...

Agreed

That is the only type of ethernet "splitter" I have seen as well and have seen them misused many times. I have a pair of them in the basement in fact that I picked up from someone misusing them!
 
Get one of these, this will fix it.
ethernetkiller.jpg


/s

Seriously though, you need to run another cable and have each device on it's own port. It is strange that it is even working as it is.
 
I've attached a crudely drawn image to show the proper use of Ethernet splitters and how your setup should be hooked up.


EXPrL.jpg
 
stevewm said:
803.2af PoE devices do in fact indicate to PoE switches they are standards compliant, the switch then decides which mode to deliver power in and tells the device this. The device can optionally specify its power "class" which is how much power it will need. There are some "passive" devices that just use straight power off a set pair of wires, however generally when a device is advertised as being PoE compatible, it is using the 803.2af standard as dictated here: http://en.wikipedia.org/wiki/Power_over_Ethernet

When you say ethernet splitter, are you using a device such as the one shown on the first picture here on this page?: http://www.pakwheels.com/forums/non-wheels-discussions/122342-change-modem-use-splitter
Click to expand...

That is what I am using.

I just cannot get past that part, because the only Ethernet splitter device I know of is a device such as linked above. It takes advantage of the fact that 100Mbit ethernet only uses 2 pairs of a 4 pair cable. These splitter devices take 2 connections from a switch and shift the signals around so that each connection uses 2 of the pairs in the 4 pair CAT5 cable. You need another splitter on the end of the cable to separate them back out.

If you are using a single ethernet splitter, It is sheer luck your setup even works at all.

If you where to get another ethernet splitter, and plug it into 2 ports on the PoE switch, it would be OK. The PoE switch will sense that only 2 pairs are connected in the wiring and use the correct power mode.

With that in mind, your setup should be:

1. PoE Swtich
2. Ethernet splitter plugged into 2 PoE ports on the PoE switch.
3. cable running to the cam/IR connected to the single output side of the splitter
4. On the other end, another ethernet splitter connected to the single cable
5. One connection from the ehternet splitter goes off to the camera, the other off to the PoE splitter.

Each device will negotiate with the switch separately which is the correct way and should function without problems.
Click to expand...

I'll give that a try. That will be a lot easier than trying to run a second cable.

Thanks for your help!
 
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