Sending Data and power on 2 wires.

[casdsys]

Does anyone know how to, or have data, links on how to send data ( both ways ) as well as power along 2 wires such as RS-485???
We need to set up a master controller hooked up to multiple boxes with only 2 wires.
Many thanks.

[I_Daniel]

I can't give much of a reply but I recall that you do get intercom systems that work on the mains wiring.
Presumable the data could be sent on the voice circuit ?
Satellite dishes also use a DC voltage to power the receiver at the dish end and then a capacitor/filter circuit is used for the TV signal. A similar system is also used for Masthead amplifiers of analogue TV systems.