I used a $6 Video/Audio/Power Balun on CAT5e for my PTZ which is 24v. I went to an electronics shop and got some RCA socket connectors ($1 each or less) and connected a short length of electric cable (about 3 inches or about 70mm) to the +/- on the DVR's RS232 (RS485 would also work) and the other end to the RCA socket being sure to keep in mind the +/- was connected to on the socket. I then connected the Audio RCA connector on the balun into that socket coming out of the DVR. Then on the PTZ, I connected it's RS232 cables +/- in the same location on another RCA socket as was done with the DVR before. I then simply plugged in the balun's audio connector in and, voila! Done! Very clean solution to do power/ptz/video on the one cable and one set of baluns without loss. Was about 30 meter cat5e run.
I used the same baluns for all 7 of my cameras, two of which are PTZ the rest are fixed. I use Geovision on a PC as my DVR and the RS232 are the GV-NET IO card.