Quote Originally Posted by Ger21 View Post
That info is incorrect. Macros run plenty fast enough, and in fact are used by thousands of people to auto zero there tools. The macro just calls the G31 move, and then retrieves the locations and sets the zero position.
It is correct. Mach 3 macro refresh rate is 10Hz. If you need to detect an input pulse less than 100ms, then it cannot be guaranteed that a macro will detect the change, which is why you had to use PLC for many commercial tool changers.

However, as I'm sure you're well aware, when you call G-code from a macro, that is then handled by the main motion engine, so is not restricted by the 10Hz refresh rate. The macro simply stalls until the motion is complete.