by cncdrive » Thu Mar 07, 2019 4:15 pm
Step/dir interface works like that the controller sends a step pulse and the direction signal in the meantime is high or low and depending on if it is high or low the motor will step one step to CW or CCW.
The direction signal should be valid at the time when the step signal is sent or earlier. (not later).
One possible problem can be if the step signal active low setting is incorrect and so the signal is read by the drive inverted and then it is no more guaranteed that the direction signal is valid on the active edge of the step signal, because when is setup to be the active edge in the UCCNC is not the active edge for the drive. For example the UCCNC sending out active high step signals, so the step signals low to high transition edges are to what the dir signals are synronised to by the software, but the drive is reading the active low edges which is the high to low transition and at that time the dir signal can be incorrect, because the dir signal is sync-ed to the other edge of the signal.
This usually causes some lost steps time to time is what the usualy symptom is for the user.
There is an active low setting in the UCCNC and also in the drive, you can change it on both sides.
(Edit: I see you using Mach3 and I wrote UCCNC, and I'm tired to correct the text now, will not do it, but it works the same with Mach3 or any other software with step/dir interface, so what I wrote is valid for mach3 too.)