peabrain
You are correct in needing another brain for enable and disable, the brain that Vital Systems supplied is just for axis selection and jog increments only, I am surprised they are not able to get you up and running as they are still selling the Mach 3 license, and still have the Mach 3 file download. My guess is they never got the MPG to work properly in Mach 3 before jumping onto the Mach 4 program hoping everyone would be switching over.
Check out the VistaCNC pendants, they are plug and play and work well, just another option.
cv580