I have a working board to gather 1-wire com and sent it to PC via RS232. I would like to modify my board to include a RS485 output. I think I have figured out how to implement the RS485 in full duplex without having to change any of my current code but I have a few of questions.
(1) If I parallel my RC6/TX and RC7/RX from my 16f873 both to the MAX232 and my SN75179B(RS485), will the 16f873 be able to drive both devices or should I place a buffer on the output of the f873? I am not sure how to make that determination.
(2) I am going to use CAT5 wiring to deliver the RS485. I am not clear about the use of each twisted pair to deliver the full duplex signal. One article I found said to use a wire for SN75179 signal “A” in one pair while using a wire for signal “B” in another pair. Does that mean I can use one pair to carry signal “A” & “Y” and another pair to carry “B” & “Z”. I would like to use a third pair to carry a momentary push button signal on the RS485 cable.
(3) Unused wires? Should any unused wire in the CAT5 cable be grounded, and is it a bad idea to run 5V in the same cable? Comments will be appreciated.