Ideally I am thinking of a token ring. i.e one fibre only around the whole network. The reason for this this device has to be able to withstand variouse amounts of interference and noise. I have already implemented a 485 drop bus for this device, but this is only as a secondary form of communication.

The main problem I am having at the minute is the one bit delay between RX -> TX messages. As if I use the standard serial port the minimum delay is one byte, which if there are many nodes on the network makes full ring comms quite slow.

I hope this has helped

Dan