Passive POE
 

Has anyone thought about using passive POE injectors to power the new Radio? Anyone have a favorite model?

I personally prefer RJ45s to barrel jacks any day, so I'm very interested in eliminating them if possible.

Re: Passive POE
 

We just bought a set of these. This is the official injector sold by the company that makes the radio.

We'll report in once we test the injector.

Re: Passive POE
 

I didn't really understand the box. Open Mesh makes and supports the ideal device that you can't use. It's only one item to add and reduces the connections at the radio. A great idea, but can't be used.

It's possible to use the extra wires in the cable with the work around adapters posted above. I've used similar ones (mine come from Adafruit for $5.95+shipping with good success in non-mobile applications. But only needing one end would be good.

Any ideas why the GDC decided to not allow the Open Mesh device?

Re: Passive POE
 

http://www.flyteccomputers.com/detai...fBoCL n_w_wcB

This is powered from a battery (12V), and outputs the required 48V (802.3af)
Poe. If using this, the only connection to the OM5P-AN is the ethernet cable. :D

Re: Passive POE
 

That will burn the radio up, it does not work on 48 volts. And its against the blue box note about injectors.

Re: Passive POE
 

Also, 48 volt circuitry is not legal at all.

Re: Passive POE
 

For the record, all PoE is 44v or greater - the radio will absolutely work on 48v IF THE 48V IS BEING SUPPLIED BY A POE INJECTOR INTO A POE-COMPATIBLE ETHERNET PORT. This is in no way suggests that putting 48v into the standard power connector will result in anything but a crisped radio, but plugging a PoE injector into the radio will work just peachy. It is, however, specifically outlawed in the rules - since there isn't a 48v source on the robot, you need an active power converter, so even if you take a DC/DC converter and strip the Ethernet cable to give 48v to the radio, all you will have done is created your very own custom injector, which is illegal.

Re: Passive POE
 

Wrong. 802.3af POE perhaps, but as the acronym stands for Power over Ethernet, any power provided by an Ethernet cable qualifies, hence the labeling on one port of the radio "18-24V POE".

Re: Passive POE
 

Hello!

The argument is primary a semantic one, and I doubt I'll convince you otherwise, but its implications are important enough I think I'll disagree with you.

PoE is an acronym, certainly, but it alway, ALWAYS, refers to 802.3af. That's how standards work.'Passive 12-24v PoE' is not a standard, it's a proprietary interface developed by OpenMesh and Ubiquiti that allows for power over ethernet, but, and this is important, it's not PoE, despite meeting the definition. When something says it supports PoE, it means it supports af, end of story. For the record, I've worked as an engineer in wifi testing and have contacts in the networking industry - I'm hip to the lingo.

https://www.open-mesh.com/poe/

Sparks

Re: Passive POE
 

802.3af is an industry standard that uses ~48vdc, supplies 15.4w, and uses as a minimum cat3 cable

802.3at is an industry standard that uses ~52vdc, supplies 30w, and uses a minimum cat5 cable.

"18-24v POE" is non standard. It will only work with devices specifically designed for it and will probably burn up if used with standard PoE. Use at your own risk.

Back to the OPs post: I would not use PoE on a mobile robot because the RJ45 connector is not robust enough for the vibration our robots see.

Re: Passive POE
 

I agree, but I still believe it's better than a standard barrel jack connector. Also, using passive injectors seems to be much easier than dealing with the af standard. The cable length we're talking about here is ~5 ft max which equates to ~0.4 V drop @ 1 A load. Passive injection is perfectly suited for this.

Re: Passive POE
 

I am just a software guy, but don't we already depend on an RJ45 connector for the very vital connection between the RobotRIO and the radio, so how would using it for power make it worse? Do the RJ45 cables bounce more than the barrel connector and arc inside the housing? (genuinely curious, I had previously thought it would be a win)

Re: Passive POE
 

RJ45 is a loose fit connector and is a standard failure point during shock and vibe testing (bounce causes the contacts to come apart). I don't really like it for the radio connection, but we have little choice here.

I'd prefer a connector like the Cannon / Amphenol MS3112E12-10P connector.

Standard barrel connectors have 360 degree connection so vibe failures are minimized and the only common failure point is if the connector totally pulls out of the socket.

Re: Passive POE
 

Out in the the real world there are a plethora of devices using nonstandard voltages for PoE. The devices are marketed as POE devices. I sympathize with you only wanting to call only 802.3af devices POE, but be aware that others don't follow your desires.

The blue box is strangely worded, but it does appear to allow you to supply the radio power from the VRM to radio thru the Ethernet cable.

Re: Passive POE
 

Just pointing this out, but it seems that this has never been illegal to begin with! Passive POE is, and has been, legal because the passive injectors are basically cable splices with nice housings around them. There is no rule against splicing ethernet cable or adding additional connectors to your wiring. The only difference this year is that the radio has the ability to eliminate one of the splices.