Serial Comms over Cat5

I came across a really interesting hack to power, control and run a wireless access point, all from one piece of Cat5 cable. It relies on the way 100 meg ethernet only uses two pairs in the cable, leaving two other pairs unused (a fact exploited by some network admins who need to run more machines than they have cable runs for by using a splitter).

I don’t have a wireless access point on my roof that needs power, serial and data comms. However it got me thinking. Currently my serial terminal is sat on a table next to my server, which is a bit pointless. It’d be much more useful downstairs. I don’t want to run a long serial cable around my house though, the place has enough wire creatively hidden as it is.

So what I plan on doing is creating two ’splitter’ boxes; one end will have a standard RJ45 socket for a long piece of ethernet cable, the other end will have a short ethernet cable with plug, and a short serial cable with plug. Two of these devices, one on each end of a regular ethernet cable, will allow me to squirt serial and ethernet down a single cable run.

I’ll have to use software flow control though, and probably lower the baud rate to overcome any interference, but it should be good enough for a text terminal. If it works, I may build another pair to send serial comms into my office to hook my A1500 up to my server for file transfers.

Tags: blog365, cat5, communication, ethernet, Hardware, serial