Many moons ago I used that board and had missing step issues. I put it down to the speed of the opto isolators, but couldn't say for certain.I then used a board from CNC4YOU which was a lot better and worked ok in Mach3 and had 10v PWM for the VFD.

I finally got fed up with Mach3 and bought the AXBB and wouldn't go back. I can now run my toolpaths without babysitting the machine and hovering over the emergency stop button. Very confident with UCCNC.

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