DIY Bitsetter w/ CNCJS triggering "Alarm 4"

I have a strange issue that started happening today. When I try and initialize my DIY Bitsetter in CNCJS (using the neilferreri macro) the program triggers Alarm 4 when it gets to G38.2.

Here’s why this is strange:

  • This exact setup was functioning a week ago as intended. I’ve made no changes to the hardware or software of my machine or controller (I did install an enclosure on the machine, but I didn’t touch any of the wiring).
  • Probing XYZ and just Z using Neil’s macros works just fine
  • This would imply my DIY Bitsetter is at fault (it’s just a momentary NO button connected to the standard probe block), but when I test it with or without the probe installed on it, it works as intended with no shorts.

I’m at a complete loss what could be causing the issue. Initially I thought it was because I’d zeroed my Z axis so close to global zero (tall stock), but I even after restarting the whole setup multiple times, rehoming, and zeroing XYZ and just Z on the wasteboard, it still errors out at the same place in the macro.

DIY Bitsetter is based on this one:

Anyone got any ideas? I’d upload proof my DIY Bitsetter button is working (tested w/ a multimeter), but the Youtube app crashes every time I try to upload a video :rage:

Send a ? through the console with and without the connections at the diy bit setter. What does grbl return?


Neil, thanks, I knew there had to be a a way to interrogate the status of the sensors, but my googlefu was failing me (I was looking for an LED on the board).

I discovered there was a chip that was shorting the block of my XYZ probe to the chassis of the enclosure (steel).

I’d also like to take this opportunity to say thank you for your CNCJS macros, they are fantastic!

edit: In case anyone has this issue and find this thread via searching, when I used the “?” command in the console, it returned Pn:P at the end which disappeared when I removed the touch probe from the holder. This let me know that the simple act of having the probe installed in the holder was causing an issue, when I removed the holder I noticed that a chip was shorting between a scratch in the paint on my enclosure and one of the screws. The issue was fixed by gluing a piece of wood to the bottom of the touch probe bracket in order to make sure chips couldn’t touch both the enclosure and the contacts on the bit setter. If I were to 3d print this again, I would make sure it had a solid bottom and the change the screw holes to blind.