I need to add ethernet communication to an arduino (Uno and Mega). Since I'm doing that, I figured I'd also like to have PoE powering it. So, I started researching. What a confusing mess this topic is, just about everywhere.
As best as I can tell, the official ethernet shields are all discontinued. I also came across this arduino, which I think is also discontinued:
But even though it's seemingly called "Arduino Ethernet Rev3 with PoE". It doesn't actually have PoE. That part of the name requires an optional "poe module". Though there's no indication as to what that part might be. I'll need this to be on a mega, for more I/O, so this isn't really an option for this project. But still, it's a confusing product.
There's also this shield... again "With PoE"...
But it says " NB: the Power over Ethernet module is proprietary hardware not made by Arduino, it is a third party accessory." and then immediately follows that by saying "The Shield does not come with a built in PoE module". So, umm... it does, or it doesn't?
There's also the choice of 5100, 5200, 5500 ethernet shields and modules. Though I think this part I've at least come to a conclusion on... that the 5500 is faster and perhaps better. The shields I see connect easily, nothing to guess about it seems. But, the module versions, its not clear how those connect. I suppse once I narrow down what one might be the best option it'll be easier to find connection info.
Discontiued or not, these and others are available. But, it's not really clear how to get actual PoE power from the ethernet connection on the shiled/module with any of these options. As I mentioned even devices that mention that they have PoE oboard, don't actually have PoE onboard. Though I suspect I can likely find a specialized Arduino that has all of that onboard for real... at a high price. I'd like to keep this on the low cost end as best as possible.
The simplest approach seems to be using a PoE splitter with just an ethernet shield (without PoE). Plug the power connector part of the splitter to the arduino's power ocnnector. Plug the ethernet part to the shield's ethernet port. But, even that isn't well explained. Should it be a 5V, 9V, 12V splitter, how many amps should it provide? Should it be active or passive, does it matter?
Here there are a variety of options for a splitter (though there are likely similar cheaper sources):
The to PoE or not to Poe part comes in here. Amongst the confusion is that I see people posting about two issues... it not being possible to use an assigned IP (only DHCP works), or that they can't connect the ethernet to a network switch, only to a router, or only to certain brands/models. I will need to use this with a PoE network switch, and there won't be DHCP available no router). So I will need to assign an IP to the device in code. Does this mean I can't use these PoE shields/modules?
