Data and power over 2 lines

[ecoli-557]

Greetings to All-
I have searched some of this site (would take a month to do it all!) with various keywords and have not gotten the inspiration needed .
I would like feedback on what others may consider as the best way to commumicate between several PICs over the DC (could be AC) wires. I would like to only use a single pair for both data and power.
I was thinking about 1 wire commands between the PICs but any serial protocol could do such as SNAP.
No real restriction the voltage as I would plan on regulators so the DC could be AC and as high as 24 VDC (or AC).
The lengths of wires could be as long as 500 feet or as short as 100.
Curious if anyone else has attempted this?
Regards!

[mackrackit]

Here are a couple of threads, nothing but ideas though.
http://www.picbasic.co.uk/forum/show...ghlight=design
http://www.picbasic.co.uk/forum/showthread.php?t=9559

[ecoli-557]

Dave-
The second is similar to what I am thinking of, I have also just considered capacitively coupling DC squarewave output from the USART onto the DC lines, but that seems too simple.
Am I making this harder than it needs to be?
-Steve

[mackrackit]

I think the answer is in the first link, post 29 and 31. But I have not tried it.
Being that you want to use the lines to power the PICs, have a filter at each PIC and send / receive the modulation between the filters.

But I am having one of those days where every LED I pick up is backwards. So just ideas.

[ecoli-557]

I just turned up this interesting ref on something that may work.
http://www.interfacebus.com/Design_C...or_MI_Bus.html
I could use this as an interface between PICs and use PICBASIC PRO and use 1-wire or some other protocol?
Anyone have any thoughts?

[Archangel]

I just turned up this interesting ref on something that may work.
http://www.interfacebus.com/Design_C...or_MI_Bus.html
I could use this as an interface between PICs and use PICBASIC PRO and use 1-wire or some other protocol?
Anyone have any thoughts?

This was commonly done, before cable/satalite TV, people used to put preamplifiers on the antenna mast, and power it from a wall wart on the ground using only the coax / twin lead cables. Remember chokes pass DC and block AC, Capacitors pass AC and block DC.

[aratti]

Intersil has several dc and ac transceiver which will surely solve your problem!