hl wrote:
>
> Hello,
> Can someone offer advise on best way to set up a bus system ,distance up to
> 50 meters
> maximum of 30 devices I will put micro at each device
> each device has on-off function only, but need to address each separately
> 1 device talks to its partner device but all share same bus line
>
> Bruce

I would give a try for RS-485 or RS-422 bus.

Just on/off function? No return info?
Could use just RS-485 receiver in each device and one transmitter in
main controller unit.

Maxim makes good chips http://maxim-ic.com/ up to 10 Mb/s IRC.

J.M. Vehasmaa