POE for my Smartthings Hub

[Benji]

Okay, ST v2 hub powered by PoE, it works

So I was just going to dump this all in and let you all fend for yourselves but in the interests of you not blowing up your hub I feel I should do a little bit of an explanation. Usual disclaimers apply, this is NOT supported and there are no guarantees it will work at all. I’m NOT responsible for any loss or damage to any property or data. At this point I have openly admitted to ST that I have used a power supply other than the one they give you with the hub and I accept that in all likely hood that if I have any issues with my hub, ST will tell me to go and pound sand and they have every right too. If you choose to attempt this as well you MUST accept this risk.

Firstly there are a couple of ways people do PoE and they are what I will call ‘the proper way’ and ‘faking it’ -

Faking It (PoE):

With this method, people use some sort of device that merely takes whatever power supply you have, and electrically connects it directly to the unused pairs of wires in an Ethernet cable when running at 100Mb.

There is no intelligence going on, no conformity to any legitimate PoE protocols and will inject whatever voltage your power supply has onto those wires. You may find that the voltage will drop by the time you reach the end of the cable if doing long runs and also, if you plug the other end into a device without splitting the power back out, you’ll probably fry whatever is on the other end.

I’m not a fan of doing it this way so I’m not going to go into any detail about it.

The Proper Way:

Welcome to IEEE 802.3af/at, have a read:

Power over Ethernet

Now, at this point there are a couple of ways you can do this properly and it’s all to do with how you are supplying the ‘power’.

The first way is if you have a PoE switch (which is how I am doing it) it’s stupidly simple and I HIGHLY recommend the TP-Link stuff (in either setup) for a couple of reasons:

1. It’s one of the few that can support Gigabit Ethernet even when using PoE if it’s needed, though if the ST hub starts pushing that kind of throughput I’m going to be asking some questions!

2. It’s CHEAP. Like, it’s almost certainly cheaper than ones that don’t support Gigabit Ethernet anyway so you might as well get these.

So, if you have a PoE switch that supports 802.3af/at, all you need is a TP-Link TP-POE10R which is the splitter -

It comes with the power cable and an extra Ethernet cable for about $14! How cool is that!

Amazon.com: TP-Link Gigabit Ethernet PoE Splitter Adapter (TL-PoE10R):...

So once you tear that bad boy open, what I want you to do is pay extra extreme attention to the voltage switch on it. You’ll note on the picture I posted above it can support three different output voltages and will list the current it can supply at those different voltages:

• 12V / 1A
• 9V / 1A
• 5V / 2A

So the first thing we need to do is set the correct voltage and how do we do that? Well… what does the power supply say that comes with the ST hub? There are two important bits of information here:

The first being that it outputs 5V and can supply UP to 2A. Can our PoE splitter match that? Yes it can output 5V (so go ahead and switch it to 5V NOW) and it too can supply UP to 2A, remember with current the device draws whatever current it needs from the power supply, not the other way round, so as long as whatever splitter you use can supply 2 amps or more at 5V then you’re okay, if the splitter can only supply say 1A @ 5V then we’d have a problem in this instance and you should not even try.

Voltage on the other hand is ‘supplied’ by the power supply regardless, if you get the voltage switch wrong, it’s highly likely you’ll kill whatever it is you’re plugging it into. Now the second piece of important information is the little diagram on the right, this indicates that the center part is + (positive) and the outer part is - (negative) which must also match what the splitter outputs (and in this case does) otherwise you might kill something again.

Now that we’ve got that out of the way, let’s plug everything in:

1. Connect the Ethernet cable that ST supplies into the port on splitter that as labelled something like ‘DATA ONLY OUT’ and then into the Ethernet port on the hub.

2. Next we’ll connect the black power cable that came with the splitter into the ‘POWER ONLY OUT’ from the splitter and into the power in on the ST Hub (you’ve set the voltage to 5V… RIGHT?).

3. Finally, I plug an Ethernet cable into my switch (all of my ports are PoE, yours may vary) and then the other end into the splitter that is labeled something along the lines of ‘Power+Data IN’.

Before you lot jump on me, yes, I know, it’s a mess… I know I should be ashamed of myself especially since I used to work in a datacenter and now I’m a networking guy… Believe me, there’s a plan, there’s a 12U rack sitting right behind me where I took this picture but we’re currently decorating and the things that are currently ‘needed’ are just thrown together…

Anyway… Green lights!

Now, if you DON’T have a PoE switch but you still for some reason want to power the ST hub via PoE then I would probably say this ‘kit’ is your best bet:

http://www.tp-link.com/en/products/details/cat-4794_TL-POE200.html

It seems to only support 100Mb for some reason, not that’s an issue for the ST hub but most importantly comes with the appropriate 48V power supply to inject PoE properly. If you have your own 48V / 0.5A power supply you can probably just get the injector instead:

http://www.tp-link.com/en/products/details/cat-4794_TL-POE150S.html

And use it with the splitter above. Now, one last time, HAVE YOU SET IT TO 5V? Any questions?