Patrick Hanson wrote:
>
> I am hoping somebody out there in PIC land may be able to help me.
> I am currently working on a simple home automation system using multiple
> 16C84's (max of 10) fitted with rs232 trancievers as slaves and a PC as
> the master controller. I am not sure how to go about connecting all the TXD
> lines on the slaves to the PC without causing possible conflicts. It is
> intended to be a multi-drop system with each slave having a unique node
> address and only responding when polled.
>
> Thanks
>
> Pat Hanson
> University of Western Sydney, Hawkesbury
> Australia

You sure got some assistance on this one Patrick. :)
If it's for home automation, the RS-232 will do fine over short lengths
if you daisy chain the whole thing. That is: TX to RX to TX to RX etc.,
right back to the PC.
Every PIC passes the data through and checks to see if the command is
for it. If it isn't it passes the data stream on.

Check:
http://www.labyrinth.net.au/~donmck/picex.html
for a full command summary of what I did to achieve this.

Sure it can be done with RS-485 and multi-drop, but 232 is fine for a
complete daisy chain cct that stretches right back to your PC, and saves
you having a convertor box or cct at your PC serial port.

Don McKenzie donmck@labyrinth.net.au
DonTronics Tullamarine, Australia
http://www.labyrinth.net.au/~donmck

EASY PIC'n Beginners Guide to using PIC 16/17 MicroChip products.
Picosaurus(tm) 40 pin FED Basic with 8 channels of A-D, and real Uart.
MEL PicBasic Compiler. Programmers from 15 USD.  Pic-Axe(tm) A New Tool.