PoE Extender to provide connectivity to non-PoE Device?

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coffeebaron

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#3216547 10-Apr-2024 13:50

One of these:

https://www.gowifi.co.nz/mikrotik/gper.html

You just need a 24v PoE injector at start, then set jumper for no PoE out at far end.

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#3216548 10-Apr-2024 13:56

One more quick thought. Futureproofing. What else might you want to put over that side of the building in the future? The fibre option may be smart for that reason.

The most recent warehouse expansion job we touched, a small patch cabinet was added with a PoE switch for WiFi access points and cameras. A fibre link was run from the main patch panel that terminated in SFP modules in the switches at each end.

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richms

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#3216550 10-Apr-2024 14:09

nztim:

I was quoting RRP from CDL, I would never install anything from AliExpress in a commercial environment also that 80M cable will need to be terminated

That was terminated duplex LC fibre, just the plain yellow stuff.

I was more posting it as a statement of how much the locals are bending you over and reaming you with their pricing. NZ computer sellers are pathetic with their sky high prices and always crying about low margins which is why I have probably only bought about 4 things locally that are not monitors over the last year.

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richms

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#3216552 10-Apr-2024 14:13

Paul1977:

@nztim Is it really that terrible a solution? Other than the potential of the extender failing, are there any other drawbacks? Based on the indictive pricing you put up fiber will be well over twice the cost, so if the only issue is one additional point of failure then I would have thought still worth considering?

Only terrible if you forget that it is there and are looking at link lights at one end and assuming that means something is plugged in at the other end.

Some of the cheap POE extenders dont require negotiation to turn power on with the output ports, but the $11 3 port one I got (only 100 megabit) does requre it. The risk to devices is pretty small as power is put between pairs and that should be isolated on any non POE device, but I have seen some where they have centertapped magnetics for POE and bridge them together on the non powered device. That would present a short to the source which should shut it down but who knows with that much impedance in the line if it would have enough current to do that.

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Paul1977

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#3216562 10-Apr-2024 15:37

Thanks guys, for expedience I might stick with the Ethernet this time with the PoE extender and just keep a spare handy. We've had a couple of PoE cameras running with these for several years with no problem, so they seem to be fairly reliable. If I had a little more lead time I'd look more seriously at fibre, but this job needs to be done fairly quickly so a little reluctant to do something I'm not familiar with without time to learn a bit more.

My only real concern was whether you could plug a non-PoE device into a PoE extender (I know non-PoE devices are fine in PoE switches, but couldn't find much at all specifically about PoE extenders). However, I believe the 802.3at standard dictates that it shouldn't send any power to the end device unless it's agreed upon via handshake - and the extender says it's 802.3at so I assume this means it'll be fine?

Paul1977

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#3216563 10-Apr-2024 15:42

richms:

Some of the cheap POE extenders dont require negotiation to turn power on with the output ports, but the $11 3 port one I got (only 100 megabit) does requre it. The risk to devices is pretty small as power is put between pairs and that should be isolated on any non POE device, but I have seen some where they have centertapped magnetics for POE and bridge them together on the non powered device. That would present a short to the source which should shut it down but who knows with that much impedance in the line if it would have enough current to do that.

@richms how would I determine whether a specific extender requires negotiation to turn on power? I'd assumed that if it says it complies with 802.3af/at then it would require negotiation, but is that not the case?

EDIT: The documentation says "Once GP-101ET detects the existence of an IEEE 802.3at / 802.3af device, the “PoE OUT” LED indicator will be steady, ON to shows it is providing power." That would imply that it's negotiating before outputting power wouldn't it?

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nztim

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#3216567 10-Apr-2024 15:52

Paul1977:

My only real concern was whether you could plug a non-PoE device into a PoE extender (I know non-PoE devices are fine in PoE switches, but couldn't find much at all specifically about PoE extenders). However, I believe the 802.3at standard dictates that it shouldn't send any power to the end device unless it's agreed upon via handshake - and the extender says it's 802.3at so I assume this means it'll be fine?

It acts just like a PoE switch, will only supply power if detected the device is PoE

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richms

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#3216569 10-Apr-2024 15:54

Paul1977:

@richms how would I determine whether a specific extender requires negotiation to turn on power? I'd assumed that if it says it complies with 802.3af/at then it would require negotiation, but is that not the case?

EDIT: The documentation says "Once GP-101ET detects the existence of an IEEE 802.3at / 802.3af device, the “PoE OUT” LED indicator will be steady, ON to shows it is providing power." That would imply that it's negotiating before outputting power wouldn't it?

Then that should be fine. The first one I got just had all the outputs on it commoned together to its 48v supply and only signaled on the input to a switch to get power.

It seems quite common for the CCTV industry to take many shortcuts with their gear.

Richard rich.ms

Paul1977

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#3216570 10-Apr-2024 15:55

nztim:

Paul1977:

My only real concern was whether you could plug a non-PoE device into a PoE extender (I know non-PoE devices are fine in PoE switches, but couldn't find much at all specifically about PoE extenders). However, I believe the 802.3at standard dictates that it shouldn't send any power to the end device unless it's agreed upon via handshake - and the extender says it's 802.3at so I assume this means it'll be fine?

It acts just like a PoE switch, will only supply power if detected the device is PoE

Cheers. That's what I thought it should do, I just wasn't positive.

Paul1977

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#3216571 10-Apr-2024 15:56

richms:

Paul1977:

@richms how would I determine whether a specific extender requires negotiation to turn on power? I'd assumed that if it says it complies with 802.3af/at then it would require negotiation, but is that not the case?

EDIT: The documentation says "Once GP-101ET detects the existence of an IEEE 802.3at / 802.3af device, the “PoE OUT” LED indicator will be steady, ON to shows it is providing power." That would imply that it's negotiating before outputting power wouldn't it?

Then that should be fine. The first one I got just had all the outputs on it commoned together to its 48v supply and only signaled on the input to a switch to get power.

It seems quite common for the CCTV industry to take many shortcuts with their gear.

Thanks.

mdooher

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#3217478 12-Apr-2024 17:56

for a printer why not just drop the speed to 10Mb/s... that will work fine over 160m you won't need the POE extender

at 100Mb/s, Even if the odd packet gets a resend it won't matter to a printer

(I know standards and all that but if it works....)

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technician14

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#3219957 18-Apr-2024 19:07

A poe switch or injectors will only power devices if needed they will not send power if they do not need like a desktop or laptop or printer, you don't need a injector half way for that distance, you can also use a ethernet over power for 300m

Is it only a printer your connecting too at 160m?

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