POE baseboard ?

08 Mar 2011

I have a very simple requirement for effectively an mbed with Ethernet socket and powered using POE (power over Ethernet). A simple variant of the existing mbed must surely have some significant market ?

Failing that does anyone offer a baseboard ... small prototyping / pad area and/or parallel pin headers for exiting mbed pins a bonus... will be adding a single RS232

K

09 Mar 2011

Seen this? http://www.coolcomponents.co.uk/catalog/product_info.php?products_id=608&currency=USD

Power over ethernet... simple way to do this is not PoE per 802.3af, but use a power inserter ($5) that places a wall wart transformer's output, say, 5VDC, on the unused pairs. At the mBed end, do the reverse, same power inserter hardware but it is doing a power un-insert, then those wires go to a plug or other means to connect where the power is needed. Mind the I*R drop in the cat5 cable - the source may need to be a bit more than X volts.

Inserter/un-inserter (there are many sorts of these to be found) http://www.amazon.com/Shielded-Inserter-Power-Current-LEDS/dp/B004EHUQEA

09 Mar 2011

steve childress wrote:

Inserter/un-inserter (there are many sorts of these to be found) http://www.amazon.com/Shielded-Inserter-Power-Current-LEDS/dp/B004EHUQEA

Can you simply replace the female DC jack with a male one to create the "uninserter"?

09 Mar 2011

Yes. Or shop and find one with a male.

09 Mar 2011

steve childress wrote:

Seen this? http://www.coolcomponents.co.uk/catalog/product_info.php?products_id=608&currency=USD

Power over ethernet... simple way to do this is not PoE per 802.3af,

Yes - that's the baseboard I use currently but I wanted one with on board POE - and it should (must) be 802.3af as the network switches provide the power this way. The unused pair is not a viable option for me - and also has concerns when people attach standard devices to cable runs powered this way. An RS232 port or two on the baseboard would be a nice bonus.

K

13 Mar 2011

If you have a baseboard where the magnetics are not in the RJ45 connector, then you could get to the needed signals. With this, I've done as steve childress mentioned, creating a non-standardized poe.

To work within standardized POE, I've seen these POE modules that you could design in. I have not used them before, so offer no comment on that.

Take note that most of the RJ45 connectors with internal magnetics may not let you tap into the circuit on the cable side.