POE question

[Phil.g00]

I am considering an external 13W IR illuminator. The supply voltage is listed at 12 -32Vdc or 24 Vac.
Can this be fed directly from POE, or do I need a POE 12V splitter?
I guess what I am asking is, with POE, is there some handshaking protocol that needs to be manipulated by the user device to deliver, or is it just a power source on two wires that can be tapped into by any suitable load?

 

[DsineR]

You will need a POE splitter. That illuminator is rated for 12vdc @ 8w.
Standard POE power is rated at 44-55vdc, most POE splittlers breakout this power - feeding 12vdc to the 'power lead' and keep the 44vdc on the 'RJ45 lead' of the adapter.
Just keep the max watts within the POE req's.
There is a handshake on the ethernet side of the splitter, but not on the power side.

 

[Phil.g00]

You will need a POE splitter. That illuminator is rated for 12vdc @ 8w.
Standard POE power is rated at 44-55vdc, most POE splittlers breakout this power - feeding 12vdc to the 'power lead' and keep the 44vdc on the 'RJ45 lead' of the adapter.

Sorry, this forum automatically inserts a hyperlink, so " That illuminator" is not the illuminator to which I was referring.
However, you have answered my question, standard POE voltage is too high.
Would a passive POE switch at 24V avoid splitters?

 

[DsineR]

Passive POE switch? Not sure what that is, but sounds a lot like a power supply
POE is a standard @ 48-55vdc.
POE splitters are cheap and will do the job for you.

 

[tangent]

You don't need PoE necessarily, you could just hook wires in the cable up to a power supply just make sure it's fused / add another fuse. Just make sure to use more multiple wires.

IF you use actual PoE, just use a splitter. Passive PoE is kind of like a power supply, 802.3af and 802.3at are more complicated and there is sort of a negotiating process to get power.

 

[Phil.g00]

My understanding of passive POE (which may be wrong) is that the PSU voltage supplied to the switch is the voltage that appears on the ethernet cable.
But, Yes, I have heard of a "negotiating process". (POE or POE+ or POE++) There are protocol standards, not just power capabilities, so it appears something is talking to something.
What? I don't know.
These days, I use the wrong PSU for my laptop, and the laptop knows the PSU specs.
I use a a different brand PSU, of the correct voltage and it is incompatible.
It is still just the two power supply wires, though, no data wiring.
So, something is going on data-wise on those two wires. It isn't just a dumb power supply.
If anyone can be definitive, I'm listening.

 

[Starglow]

My understanding of passive POE (which may be wrong) is that the PSU voltage supplied to the switch is the voltage that appears on the ethernet cable.
But, Yes, I have heard of a "negotiating process". (POE or POE+ or POE++) There are protocol standards, not just power capabilities, so it appears something is talking to something.
What? I don't know.
These days, I use the wrong PSU for my laptop, and the laptop knows the PSU specs.
I use a a different brand PSU, of the correct voltage and it is incompatible.
It is still just the two power supply wires, though, no data wiring.
So, something is going on data-wise on those two wires. It isn't just a dumb power supply.
If anyone can be definitive, I'm listening.

It's not the PoE voltage, but the power CURRENT load. Some PoE devices operate at a fixed power current load, say 15 watts...think of the IR illuminator as a light bulb. Other PoE devices have fluctuating power current requirements depending on their operational state. These devices have onboard firmware that negotiates PoE power current requirements with the switch based on how much current the device needs. They may power up drawing 15-watts of current power but once boot-up completes they may need 30-watts of power to operate which is then negotiated with the switch via the firmware functions. The total current wattage draw of all connected PoE devices cannot exceed the total current wattage that the switch can support otherwise some connected PoE devices will not work because the PoE power current budget is maxed out.

 

[TonyR]

Just in case you want to know more or can't fall asleep one night, lots of good POE info here:

Power over Ethernet - Wikipedia

en.wikipedia.org

 

[Phil.g00]

Just in case you want to know more or can't fall asleep one night, lots of good POE info here:

Power over Ethernet - Wikipedia

en.wikipedia.org

This a very useful write-up, so with typical POE, there is a negotiation process about the power levels ( which my particular illuminator won't satisfy) at specific voltage levels that are too high for my illuminator's supply anyway. So typical POE, POE+ & POE++ is out.

So my options are a 12 v splitter or passive POE. With passive POE, there is no negotiation process. You get the voltage applied (24Vdc seems a typical option), and the device will determine the power needed (within reason).

Why would one select one over the other?
Well, the way I see it, a splitter might be cheaper for a single illuminator, but for multiple local illuminators, a passive POE injecting switch might be more cost-effective.

 

[biggen]

This a very useful write-up, so with typical POE, there is a negotiation process about the power levels ( which my particular illuminator won't satisfy) at specific voltage levels that are too high for my illuminator's supply anyway. So typical POE, POE+ & POE++ is out.

So my options are a 12 v splitter or passive POE. With passive POE, there is no negotiation process. You get the voltage applied (24Vdc seems a typical option), and the device will determine the power needed (within reason).

Why would one select one over the other?
Well, the way I see it, a splitter might be cheaper for a single illuminator, but for multiple local illuminators, a passive POE injecting switch might be more cost-effective.

You have got it. Passive PoE is not a standard. It’s whatever the manufacturer wants to do and whatever voltage he wants to send down the pipe. if the passive switch/injector sends 24 v then your end device better be able to handle the voltage or the blue smoke will appear.

I like to use 802.3af and .at devices only. So all my switches run on those standards. That way I don’t have to worry about non-standard devices being fed non standard power on my network

 

[goneracin]

i stumbled into this, and it seems pretty informative

 

[goneracin]

FWIW, I use the Fing app on my smartphone; been using it several years now and it works great for me; find open ports, too.

somehow i put this in the wrong thread.......

 

[TonyR]

somehow i put this in the wrong thread.......

It's no biggie....I'll delete mine if you want to delete yours.....or not.

 

[goneracin]

It's no biggie....I'll delete mine if you want to delete yours.....or not.

na, i figure any information that is available to newbies like myself is a good thing
i know how to get around in my computer, just the it aspect of it is over my head, so im searching all over for info