Anyway to get digital line passing to work with Digi pro 900 xbee units unsung digimesh firmware?
No, and I’ve not heard of any plans to add it to Digimesh or Zigbee. You’ll need an external PIC or micro to act as your I/O info forwarder.
One problem is the ‘solution’ is harder than it seems & on the S1 Xbee which supports it, many people asked for better features. You need watchdog timers to detect when the remote/source of your output has gone away, plus many people want an N x M solution, so this bt #1 goes to that #5, but #4 over there should come from #2 of a third node. Plus with the S1 you’ll find you cannot mix I/O line passing and direct setting by remote software, which was another common complaint.