Ray: Now I'm more confused. If the communications are the same then why does the SS have to close the probe in the hardware?
Are you saying that MACH reads the parallel input signals one at a time (serially)?
I know you can look at any pin on any port but using an external dll you have to operate within MACH's time slice to run external programs. Can I get better response talking back across USB and through some API interface to MACH that is faster than the 40 CPS loop?
If the input gets there at a different rate/time does that not effect the point at which it "sees" the condition? Are there any numbers on the repeatability of the Homing; how close to the same point does it stop over multiple home (ref) moves? Maybe I am just concerned over something that has a value so small it can be ignored.
The THC logic functions in MACH are as close to a true feedback loop (closed loop) as you can get. The overall "loop" timing is critical (i.e Software has to know where hardware is so correction moves don't cause massive over/under shoot in the motion).
Once again for desktop mills it's a non-issue.
I apologize for posting in the wrong forum. (wrong)
TOM Caudle
www.CandCNC.com