GS105PE POE Pass Thru Limits

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gdurniak wrote:

In the Tech Specs,  I did miss the "7.9W Limit" on af,  but still one camera should run

 

While Spec'd at 12W, the cameras run below 6W

No, and no.

It's not about what it's spec'd, and it's not what drawing under whatever condition.

It's about the fact that the camera does request Class 0  - this i the only spec applicable (there are some resistors soldered in, and some pulsing do the negotiation - in newer/higher IEEE PoE+/++ standards also makes use of LLDP) - this makes the switch reserving the power for a class 0 device. If not available == no power.

For a reason, the specs are on 6W - I guess again it's about processing and/or IR LEDs. If the camera would operate under all conditions below 6W, they could have defined it to be a Class 2 device (read max 7W from the PSE, 6.49W max at the PD). And now it would get powered.

Obviously they have chosen Class 0 - either because the camera can draw more then these 6W, or by laziness - because this low cost NVR/camera combo maker never had the idea that a more granular specs could be required. Simply because their design intention is on NVR port, one camera. Problem solved for the NVR/camera maker going to market.

There are PoE+/++ devices which are lowering capabilities if the higher product class power isn't available, e.g. acess points operating on lower power of the last few watts are absent.

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gdurniak wrote:

And even an "at" supply allows only one Class 0 device.  This detail is very well hidden

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Just adding the info that info might not be sufficient - because the IEEE PoE design details and class levels are not commonly known and it isn't commodity know-how for many newcomers.

We can argue with Netgear that the content of the troubleshooting document (especially the tables) should be made available direct on the product specs page. I have done that btw. a long time ago...I'm not Netgear.

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gdurniak wrote:

I'm not the only one.  Many others here are equally surprised.

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Hey you are not alone - I've hit the similar questions scratching my head when planning and testing the GS105PE capabilities for the first time.

Most of the confusion is coming because we're humans having troubles and are mis-matching electrics lessons 1..3 basics with what is IEEE PoE, device classes, and the guaranteed power design.