jastein,
Thanks for looking. Below almost works as I'd like. This is from my previous G100 controller setup. I think Pokey57CNC can probably do something similar without the diodes.
My goals:
1. A physical start button on the machine that must be pressed until the G320s reset (approx 4 secs). This dual button also latches a relay for the motors high voltage. So the
motors and motor power can only turn on with this button. Mach cannot turn on either of these functions, only turn them off.
2. The Mach Enable button must be pressed at the same time after the G320 resets or Mach will become disabled. So you hold the start until you see the motor error LED turn off
or hear the motors singing, then press and release the Enable button. Mach will hold it on from here. If Mach is not enabled or estops for whatever reason the motors will be disabled. The high
voltage to the motors stays on when Mach disables in this way.
3. If a motor errors want to know which one happened first. That's why the diodes. Otherwise 3 switches for start and 3 lines to enable. Maybe since the Pokey57CNC has a motor
enable in each motor connector the diodes on the right aren't needed.

Any motor enable can be used for AX_ENABLE. The resistor value needs optimizing.
I haven't finished evaluating if the Pokey57CNC AX_Enable current limits are satisfied. The AX_Enable pin says it can do 8ma. This sinks ~16ma for a fraction of a second.
I'll post as I get more info and try a few other things.