DIY 3020 CNC I/O Board

[EddyCurrent]

Les, You say you have a version of this that works well, so by making the changes to it's own supply and using opto-isolation surely this one will work fine too ?
Using pull up resistors is good, that last thing you want is an input that's floating about and susceptible to induced voltages so it needs to be tied to one leg or the other.
This is only one board so are you going to show how it fits into the complete system ?
If you notice, things like stepper motors, limit switches, spindle to some extent, are all wired in more or less the same way so it's the emergency stop circuit that interests me most.
Correct me if I'm wrong but you are using Mach3 on this job ? are you going to use the charge pump feature ?