Z Axis Both Limit & Home switch is ignored - X & Y fine

Evening all

I've just signed up to the forum in hope that someone can help with my issue. I've been using LinuxCNC for a few weeks now on my converted Proxxon MF70 without too many major issues. I've made some parts and I'm happy with the progress I am making as a noob to machining.

Anyway, I've just finished installing home/limit switches on the xyz axis and I am encountering an issue with the z axis. The x & y behave as expected. When clicking home axis, the table moves in the correct direction, hits the limit switch, backs away, finds the switch again and moves to home position of +1.0 for both x and y.

The issue is with the z axis which is totally ignoring the switch even if I manually press it. I have it wired exactly the same as the other axis and I have step conf configured the same. I have re-checked my wiring and continuity tested from the driver board through to the switch. De-pressing the NC switch breaks continuity so I know i have it wired correctly.

The only thing I can think of is having the travel set to -80 to 0 so that zero is at top of Z travel and -80 is at bottom near table.

I am using linuxcnc image version 2.7 with a Cobra driver board. I've attached a picture of my custom built enclosure. Hopefully you'll see I am meticulous with wiring using heat shrink on all joints and careful layout of cable routes etc...





Thanks in advance for any help.

Luke

LukeH wrote: The only thing I can think of is having the travel set to -80 to 0 so that zero is at top of Z travel and -80 is at bottom near table.

That's perfectly normal.

Are you using the Axis interface? If you are[1], then look under "Machine" and "Halmeter"

Now start by checking that parport.0.pin-11-in changes state when you press the button.
You can look at the signal both-home-z and the axis.3.home-sw-in too, but they are almost guaranteed to be the same, as the HAL connects them properly.

Then check the other parport inputs, in case you are in the wrong terminal. Then check other things, like that the screw terminal isn't on to the insulation etc.

[1] If you are using something else, then look at the menus in that. If you can't see it, then open a terminal and type "halcmd loadusr halmeter" instead.

Hi

Thanks to your suggestion to use the Halmeter I was able to identify the problem as a loose connection within the aviation style connector plugs I am using. I changed it for a new one and problem solved.

I wasn't aware of the halmeter nor how to use it so thanks for the tip.

Luke.

LukeH wrote: I wasn't aware of the halmeter nor how to use it so thanks for the tip.

Halscope is even better.