Sorry that I didn't think about these issues.

The amount of data to be transmitted will be very small - about 24 bits at a time. Any device will transmit at any time and there could be as many as 20 messages per second. The bit rate would then be about 480 bps.

Having a master device would be OK. All messages will be going to either the master device or from the master device. All other devices won't be communicating with each other.

The entire length of the bus will be 20ft max. if populated with 20-40 devices. And I don't have a need for hot-swapping.

I plan on coding the comm. protocol myself or locating something pre-written so of course I hope to have it as simple as possible. All devices will be based on some 8052 derived mcu.

Thank you for your interest already. I appreciate any advice you can offer.