ISTR you can fit one or more PICs as required.

I'm getting to understand your assembly code
Congratulation John - that's more than I ever did :LOL:

From memory, the Txsyn timing is a simple grab a slot when ready affair with a different delay based on chip position to help prevent collisions.
(i.e. if Txsyn = hi, delay X.Y,Z or W recheck Txsyn if hi, pull txsyn low and transmit)

Is the vernier being switched into fast mode correctly? Different makes/types of scale have different clk/data line switching sequences so some don't work with out mod'ing the code


Are you powering the scales from the interface or the on-board cell? (I replaced the cells with a ~1uF SM cap) What voltage are you ghetting across the PSU red-led?

The serial port is running at 115,200 baud, so screening and good earthing is advisable. And, it derives its -Ve from the PC so, just check that's working OK.