All nodes need to listen at all times.

Without a master, you will need Collision Detection; ie, nodes listen whilst tansmitting, and assume that any coruption must be due to a collision with another node transmitting simultaneously. Then you need some algorithm to back-off & retry later.


You will need some sort of "broadcast" message so that the new unit can announce its presence.

If removal is well-controlled, you could have a similar broadcast "good bye" message; If not, units will have to keep polling to see who's on the bus.