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Topic: compatible with the POE standard in 1 gigabits (Read 1 time) previous topic - next topic

richardpub

I bought an Arduino etherten card with an ethernet POE port .... Unfortunately after testing and searching the net, I discovered that this POE port does not work with my network with a 500 series Cisco switch because it is not compatible with the POE standard in 1 gigabits .... are there Ethernet shields compatible with the latest POE standards ????
In advance thank you for the answer ...
Best regards JLR

westfw

The Cisco should be backward-compatible with the 802.11af PoE that the arduino supports, I think.
Do you have a pointer to documents explaining why it's not?

richardpub

Sorry I did not receive notification of your answer ...
I no longer have the link saying why it does not work, but the reason is that the Gigabit bit rate is too fast for the Arduino processor, so the ethernet shields for the Arduino only go up at 100 mbits ... So as the Cisco switch does not see Gbits, it does not communicate with the POE of the card ...
Since then I bought an Arduino Mega and an Ethernet shield, and that does not work either
cordially

westfw

Quote
the reason is that the Gigabit bit rate is too fast for the Arduino processor, so the ethernet shields for the Arduino only go up at 100 mbits ... So as the Cisco switch does not see Gbits, it does not communicate with the POE of the card ...
Well, that's completely wrong...
PoE is fiddled with entirely separately from data communications, and the cisco-500 supports speeds down to 10baseT (MOST switches invisibly handle speed conversion on the data side of things.)

Since this is a feak'n Cisco you're talking about, it has about a billion commands to modify, show, and debug PoE behavior, so a bit of debugging from the switch side might be useful (this may be difficult if the switch is controlled by the IT department and not you :-( )   For example, there is a "power inline legacy support disable" command...
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/troubleshooting/g_power_over_ethernet.html

richardpub

the Cisco 500 series switch is installed at home and I am the administrator even if my skills are limited to a switch with so many possibilities.
On the other hand I do not understand why my switch supplies PoE a gatekeeper Mobotix T25, without I do nothing else than connect to the Ethernet network ...
Before I start touching the parameters of the switch, I'd like to understand why none of the 2 Arduino Ethernet shield I bought, does not work spontaneously.
in which direction should I use the command "power inline legacy support disable"
can it be managed by separate ethernet line.

westfw

I would start with the show and debug Cisco commands mentioned on the page I linked.
I'm not really familiar with the details, but I've looked at PoE enough to say that both the cisco and the PoE module used on the arduino are well-known and should be compatible.

richardpub

Thank you for your answer ... I will look into the subject ... I will keep you informed of my results ....
cordially....

richardpub

I put a screenshot showing that my Cisco 500 switch feeds my Ethernet PoE shield, moreover without power supply it is turned on, however it does not pass anything from the Arduino board to the browser on the PC and when I reconnect power all the recordings are gone. The program is well distributed to zero

westfw

Quote
my Cisco 500 switch feeds my Ethernet PoE shield, moreover without power supply it is turned on, however it does not pass anything from the Arduino board to the browser on the PC
So ... does your Arduino not get power at all, or does it just not connect to your browser?  Based on the title, I was assuming "no power."  "No connection" is an entirely different set of possible problems and possible debugging paths.

richardpub

when the arduino is powered by the poe is not by the USB port, the arduino is lit but ethernet does not work, the ping is impossible ...

westfw

But the same arduino, with the same ethernet cable and switch port DOES work if powered from the USB port?
Weird...


richardpub

Yes he work when he is powered from the USB port... but not whiteout

westfw

Do you have any serial port debugging in your code?  (though I guess it's a bit annoying to monitor the serial lines without also providing USB power...)

From the schematic, it seems that the PoE device provides Vin for the attached board (rather than 5V), so an arduino with odd Vin wiring or bad regulator might result in not working over PoE while being OK when powered by USB.
Do you have a voltmeter?  I'd start by confirming the Vout of the PoE module, then trace that though Vin and +5V on the Arduino board, and then +5V on the ethernet shield, and then start poking at the SW.

richardpub

I don't have any serial port debugging in my code.

I also have an Arduino Etherten board that should work in POE directly even without code ...
What I could read on a forum, but I do not know which it is, that the feeding in POEGigabits is done on the son 1,2, and 7,8 contrary to the mbits which is done only by 2 sons....
Currently measured on the breadboard, the Vout is 4.9V ...

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