I have been following the discussion about the various methods of
implementing a PIC network with interest and wondered if anyone had
considered using time domain multiplexing of the communication media.
If  the frame period is long enough relative to the clock of the lowest
processor speed of a node, then each node could self calibrate itself on
power up by timing the period between the frame synchronisation pulses sent
by the master controller.
Just toying with the idea at the moment but I thought I'd toss it into the
pot to gauge reaction.

Stuart Broad.