[CUWiN-Dev] power+serial+ethernet over cat-5 ?

[David Young]

It would be nice if we could run RS-232 Tx/Rx signals to our rooftop
nodes on the same Cat-5 cable we use for power and ethernet, and that
way get console access from inside the subscriber's building.  If we
already had this in place, it would let us "rescue" at least two nodes
without a climb.

Right now, I don't think we have any spare pairs on our PoE cable.
I could be mistaken, but I think there is an ethernet transmit pair,
an ethernet receive pair, a pair with +48V on it, and a fourth pair is
the power "return."

My (possibly naive) idea is to inject/tap the RS-232 Tx signal on the +48V
pair inductively, using a signal transformer and other electronics fu.
Ditto the Rx signal on the return pair.  Will this work at all?  Will it
work over 75 feet of Cat-5?  Would it be expensive to design, build,
and test an RS-232 over PoE injector/tap?

It looks like Falco Electronics carries some of the requisite parts,
and they may supply free samples.

Dave

-- 
David Young             OJC Technologies
dyoung at ojctech.com      Urbana, IL * (217) 278-3933