Z Axis limit (homing) switch jumpers no longer working

[S. Ronin McGowan]

Morning all,

I'm trying to resolve the last issue that came up while dealing with the Z Axis DRV8825 burning out due to free movement (falling under the weight of the DW611). I was reconnecting everything today after installing the new DRV8825 for the Z axis, and everything works great. Well, everything other than the Z homing limit switch. No matter what I do (including literally shorting across the pins on Z- and then Z+ in another test), I cannot get any indication that the switch circuit has been closed. Note that I have a laser installed, and therefore (IIRC) I had to update the firmware (worked fine after). Here's the steps I've already performed, just so we all save ourselves a bunch of ask and answer rounds ;-)

1. Tested all limit switches in software with manual closing of the switches. (Z axis failure)
2. Continuity and resistance check across all limit switches (all ok)
3. Continuity and resistance check across all limit switch signalling wires (all ok).
   
4. Swapped Z axis switch signal from Z+ to Z- and retested. (same results)
   
5. Swapped Z axis switch signal to X axis and retested (wires and switch performed properly).

Can anyone think of another test that I might have missed? If not, I'll move on to my hypothesis...

Could it be that something happened and somehow the Z- and Z+ portion of the limit signalling circuit got fried?

If anyone can help, I'd be ever grateful, there's enough going on already in my projects and learning CNC on my own but DEFINITELY don't want to have to manually home and reset zero, etc, every time I go to start a new setup.

Thanks in advance, and cheers!

[Bruce]

If you just installed a laser then you are using the PWM 0-5vdc signal at Z+ which moves the Z limit switch to Spindle Enable (SpnEn)

[S. Ronin McGowan]

Ah Bruce, you just made my day! I could have sworn that Z- was the location I needed to move the limit switch to. I knew I had to move it after updating the firmware so that the laser could use Z+, and unfortunately I convinced myself that I had the right spot. Thank you for correcting me! I've had more than your average bear's concussions (participated in a chronic traumatic encephalopathy related study wherein they performed FMRI scans of my brain) and other head trauma and so my memory gets wonky sometimes.

Cheers all, and stay safe!