I am admittedly biased as I adore my Saleae, especially because I can have the analogue view side-by-side with the decoded digital side to track down quirks. But your capture I think is exactly what I needed -
From looking at the Sigrok capture there's pretty significant pulse width distortion on the LC II's packets, and where the ImageWriter should be responding I think the signal is so weak the RS422 transceiver is just clipping it (I see like 30 microseconds sometimes between pulses), so no wonder the PIC isn't outputting anything.
Any chance you have an oscilloscope to confirm, or are up for some surface mount soldering?
I have an idea on how to fix it, but it does require some 0603 parts being added hah. If not I'll be picking up a really long phone cable tomorrow and can hopefully repro it too.
From looking at the Sigrok capture there's pretty significant pulse width distortion on the LC II's packets, and where the ImageWriter should be responding I think the signal is so weak the RS422 transceiver is just clipping it (I see like 30 microseconds sometimes between pulses), so no wonder the PIC isn't outputting anything.
Any chance you have an oscilloscope to confirm, or are up for some surface mount soldering?

