Hi!
I am making an anemometer station based upon DfRobot wind sensor that needs to be powerd by 9-24 volts. The power to Arduino controller is provided through PoE and I was looking for a way to extract some of the power from PoE module on Arduino Ethernet to supply the wind sensor.
This question is rather important because the only thing I have on my tower is one Ethernet wire.
Can anyone help with that?
Thanks,
Sergei
Can you please provide a link to the Arduino Ethernet controller that you are using ?
UKHeliBob:
Can you please provide a link to the Arduino Ethernet controller that you are using ?
This one, the "original" 
http://www.arduino.cc/en/Main/ArduinoBoardEthernet
Do you actually have the POE module ?
UKHeliBob:
Do you actually have the POE module ?
Yes.
Just an idea:
Search for the pinout of the RJ45 Cable and look for the supplying pin. Check that with a voltmeter.
When u found it, you need some kind of potential divider to get that ~48V of the PoE to the 24V or less for the sensor. Solder it together and here you go.
The left 2 rows (attachment) are probably the pins of the PoE cable, you have to check yourself which is 1, which is 8, can't tell you.
EDIT: I have the feeling the pins I mentioned refer to the module output not directly to the PoE cable, look at page 4 of the datasheet here:
Which means you can get power from these pins, but it's already regulated down 
In PoE Pins 4/5 are plus, pins 7/8 are minus.
The data sheet for the POE module is at POE Datasheet On page 4 the pinouts are detailed and pins 7 and 8 look like they provide the power out which could be connected to the Arduino Raw input and GND.
UKHeliBob:
The data sheet for the POE module is at POE Datasheet On page 4 the pinouts are detailed and pins 7 and 8 look like they provide the power out which could be connected to the Arduino Raw input and GND.
But these two are already divided down to what Arduino needs, +5V. PoE provides 48V and where do I extract those from?
vomus:
But these two are already divided down to what Arduino needs, +5V. PoE provides 48V and where do I extract those from?
I do not seem to be able to find what kind of Ethernet on Arduino is. Is it only 10/100? If it is, it uses only two pairs and the others are free, so I can use them to transmit power...
But these two are already divided down to what Arduino needs, +5V. PoE provides 48V and where do I extract those from?
Testing with a multimeter might produce a point where 48v is available. An arduino can be used in a 10baseT four conductor setup, leaving four cat5 conductors available for power.