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POE for ME9210

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The ME9210 has two pins VETH+ and VETH-, but the manual is silent on how they are connected to the network socket. Two related questions:

1. Are there bridge rectifiers internally, so that the stated output polarity is always observed?
2. If so, are there rectifiers on both the unused network pins and the transformer centre taps?
asked Jan 4, 2016 in Embedded Devices by steved2 Seasoned Professional (151 points)

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1 Answer

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Digi support page: http://www.digi.com/support/productdetail?pid=3510&type=documentation links to hardware reference manual: http://ftp1.digi.com/support/documentation/90001247_C.pdf

Page 9 module connector pin#1 = VETH+, pin#2 = VETH-
Page 58/59 has a sample schematics for PoE support.
Page 20 lists -48V DC input on P13, and 12V DC output on P14

See also development board schematics: http://ftp1.digi.com/support/documentation/30006001-06revA.pdf page 3.

VETH+ is directly connected to pin 4+5 of the RJ45 Ethernetmagnetics, VETH- directly to pin 7+8. There is no on module rectifier, signals are just passed through from RJ45 to module pins.
answered Jan 8, 2016 by User143 Community Contributor (102 points)
Thanks for the reply; however I think your information refers to the original ME, and not to the ME9210.
I've just done some measurements on an ME9210, and they are consistent with there being two bridge rectifiers internally - one on pins 4+5, 7+8, and the other on the remaining two pairs, presumably from the centre taps of the transformers; the outputs of these bridges then being connected in parallel and available on VETH+ and VETH-.
Certainly its not as simple as you describe; if nothing else, whatever voltage polarities  I fed into the network connection, VETH+ was always more positive than VETH-.
(I did find some information elsewhere suggesting that the ME and the ME9210 were different in this area, but have been unable to substantiate it with any Digi-derived source)
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