Mysterious Z axis errors

[A_Camera]

May have an issue

G540 manual
the pulse polarity for the step and direction signals are ACTIVE HIGH.


UCCNC manual
Dir port & pin: Which is the physical output pin on the UC100 device for the step signal. The
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signal can be configured active low or active high selecting or unselecting a checkbox next to the
field. Changing the active polarity of the signal reverses the axis running direction.

Can this be the cause? How do I reverse the polarity while keeping the active high set?

I don't understand the question. In UCCNC you can select active high or active low for each outputs. Set active high for both the step and the direction pins in UCCNC ( i.e. uncheck the box )and you should be fine. Once set up right UCCNC will send step pulses as active high pulses. DIR pin does not actually matter since what is happening depends on how your motors are installed, so if the axis would rotate in the wrong direction if all the DIR pins are set to active high you just change that to active low. This is actually happening with my Y axis because the motor is placed where it is placed, so my X and Z are set to active high and the the Y to active low. UCCNC takes care of that.