Hi, I’m Jadon and I’m running Mach4 on a CNC router with an external motion controller, and I’m seeing a strange issue that I haven’t been able to track down. If Mach4 is left idle for more than a few minutes with the machine enabled, the Z axis still jogs and homes normally, but the moment I start a G-code job, Mach4 suddenly reports a motion fault and ignores all Z moves in the program while X and Y continue running. There’s no E-stop triggered and no following error shown, but the DRO for Z freezes at the last jog position and the tool just air-cuts. Restarting Mach4 temporarily fixes it, which makes me suspect some kind of state or buffer problem rather than wiring. I’ve checked soft limits, probe settings, and motor tuning, and nothing stands out. Has anyone run into Mach4 losing axis motion control only after sitting idle, and where should I be looking to diagnose this properly?

the forum probably needs to know your motion controller.

motion controller would help. Also if your using external drives, make sure and turn off the driver sleep function. DM542's have a switch for half-current