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

[Haudy Kazemi]

At 02:01 AM 9/18/2005 -0500, you wrote:
>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

There may be an easier solution for you...put the RS-232 signals over TCP/IP:
http://www.lantronix.com/device-networking/embedded-device-servers/xport.html

Jesse Brown (aka wolf on the Sveasoft devteam) has put together a board
using this Lantronix Xport specifically meant to be used in Linksys
WRT54G/GS routers, so that the RS232 console output can viewed remotely
over an IP connection:
http://www.theforestnetworking.com/hardware.php
http://www.theforestnetworking.com/tfnxpt-pics.php

In the case of the WRT54G, after installing an Xport, a short CAT5 patch
cable can be connected to one of the WRT54G's switch ports.  This way there
is no need to run an extra CAT5 cable down a tower.  (I'm assuming that the
CAT5 cable serving as the backbone connection is connected to one of the
switch ports, and that the WAN port is unused.)

Other WRT54G serial port mods:
http://www.rwhitby.net/wrt54gs/serial.html
http://jdc.parodius.com/wrt54g/serial.html

-hk