I finally finished my digital I/O cape! It only took about two and a half hours to hand solder all of the components. It is fully tested and ready to go.
It has an isolated DC to DC converter, 16 optically isolated digital inputs and 16 optically isolated digital outputs, a 4 wire RS-422 port, and an optically isolated 2 wire RS-485 port.
I have released the Eagle 6.5 project files, for my older v1.0 board (v2.0 is in the photo), on GitHub: https://github.com/compeoree/bb-dio-cape.
Now back to Qt 5.....