GRBL Error when powering off Dewalt Router

Ok when I’m changing bits in the middle of a job or when I’m completed the job, but when I power off the Dewalt Router I get the error. It happens exactly when I power it off. That is only time that it happens when I power it off, not sure how this is happening since its not connected to the machine anywhere but it does happen. Anyone else have this problem? a Fix?

This is caused by EMI. A couple of things specific to this to try:

  • plug the router into a separate surge protector from anything else
  • turn the router down to low before powering off or on
  • turn the router off using a separate switch such as on a router control block or the surge protector mentioned above

and a good quality USB cable with ferrite beads — also add ferrite beads to the router power cable (what seems to be one on the Dewalt is (in my experience) an anti-theft device).

If those things don’t help, the community has worked up a long list of things:


Awesome thanks Will I’ll get started on fixing it this weekend.

Check how your cables are run as well. Try to keep the router cable away from the USB cable. When I relocated my machine to a different area of my room I had to unplug all the cables. When I hooked everything back up I started getting the same problem. I found my USB cable was running paralell to a 120 volt cable for not more than 3" to 4". That’s all it took to cause the exact problem you are describing. EMI at work for sure!

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To add onto @Bjohnes comment above, proximity matters. In my noise mitigation exercises with a CM v2.2 controller I’ve induced disconnect with router shutoff by having the router power cable on the machine extrusions and/or in proximity to stepper and limit switch cabling

I’ve since isolated my router AC power source and cable routing, added ferrite cores, and run a usb isolator. With that I’ve mitigated all CM disconnects and I’m happily running v2.2 and v2.3 PCB versions.


I’ll third that. I had one disconnect when I accidentally looped the router cord down the wrong side of the enclosure right next tot he usb cord. moving it to the other side of the box cured it… ps I have 2.4d board.

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