POE (Power over Ethernet) Ethernet to RS232/485 Converters

Has anyone tried making a Ethernet to serial converter that is POE compliant?

Would it be nice to have a Ethernet device server that can be installed in-line between the Ethernet Switch and the PLC serial port without need for power supplies.

If this converter is small enough, it could be used like an in-line coupler.

Tibbo, Digi, and Lantronix all have tiny embbeded components that make this possible.

Is this what you mean?
http://www.bb-elec.com/product_family.asp?FamilyId=142&Trail=1&TrailType=Top

That would work

That would work for me.

Thank you much.