I've had the sme issue since always, but learnt to live with it. Basically I unplug my VFD whenever I needed to probe (mostly in the middle of jobs, changing bits)... which is cumbersome and feels unstable, because every once in a while my controller crashes when doing this ... until... I just tried my very same cnc/controller/vfd/probe setup, except this time with my laptop, unplugged from the AC mains and voila! Time to get a USB optoisolator then. edit: BTW, and this might help other diagnose the problem. I had another issue, the trackpad of my cnc computer was unstable too. Didn't give it much thought asuming it was just "airborne" EMI from the VFD. Well, I just changed the laptop power supply's cable to an unearthed one, and problem begone. Time to resucitate my intent of having home swithces too!
I had the same problem with my XYZ probe using an HP SFF PC. When I switched back to an old Surface Pro 3 it had no problems at all. Picked up a USB in-line isolator and everything has been problem-free ever since. Thanks to everyone that contributed to this thread, most of all to Peter for putting up with all of us.
I have an X32 Blackbox that has similar problems. I have been using it for a few months now and it was all working fine. Now my XYZ Plus probe has the green LEDS on any time the ground wire is touching the spindle. I have disconnected everything from the Blackbox except for the Power plug, the Probe plug and the Computer connection to my laptop. If I disconnect the computer cord then the green LEDS go out. Im believing there might be a short in the Blackbox. I have also completely replaced every wire including the wires from the VFD, all the motor wires, all the limit switch wires and the computer connection wire. I had changed nothing from when it was all working and when it started failing. Thanks for any help.
That rather indicates a short through the PC - try a different PC, or if the computer has 2-pin power plug - try flipping it around.
Spindle should be EARTHED DC GND should be a seperate domain Having a short between the two (thats supposed to be isolated from each other - high voltage mains vs low voltage DC) is dangerous. Unplug things one at a time until probe (good test, could use a multimeter too but probe is a quick indicator of a problem) until problem clears up. Could be endstops mounted incorrectly, failing PSU in a desktop PC or Monitor, etc
Unplugging the usb from my laptop turned the probe off. Unplugged each motor limits witch didn't change anything.
Then laptop PSU might have a short. Try on battery only. Try flipping 2-pin plug on laptop PSU in socket (Neutral Earth bonds exists, if plugged in wrong way round it might leak current)
It doesn't come apart at all. With it unplugged it still have the probe lights on. So I'm assuming a usb insulator would be needed. Now. With the vfd grounded to the outlet. Where would the proper place to ground the cnc it's self? Can I go to an outlet ground at well?
Issure resolved. Wasn't my usb. I had 2 limit switch grounding out through the bolt. Added a small plastic spacer and all is good
