Difficulties in probing

Jflesburg wrote:

I'm using (for better or worse) a mesa 7i96

I cant think of better hardware than Mesa, so I'd say it's for the better.

I then followed the instructions to set up plasmac, after unsuccessfully attempting to integrate toma_thc into my earlier configurations.

I think even Tommy would say toma_thc is pretty dated, it was "replaced" by PlasmaC, which has now been replaced by QtPlasmaC. PlasmaC certainly works, but it's not receiving any updates short of critical bug fixes.

When I try to set up probing (following along in 5.2 of the manual), it mentions manually jogging z down until it stops at the Z axis MINIMUM_LIMIT, then click Touch Off with the z axis selected and 0 offset.  I don't have a Z axis MINIMUM_LIMIT switch.  Do I need one?

Nope, if you have one at the top of travel, that's plenty. LinuxCNC will stop machine motion when it reaches the Min Limit provided that you have everything set right and it doesn't mechanically bottom out first. This is referred to as a "soft limit".

When I do the "Probe Test", I set the "Probe Height" until I just make the limit switch and it holds there, but it does not lift back up to "Pierce Height".  I've tried increasing the values of "Pierce Height" and also the "Float Travel", but so far it doesn't move up off the float switch.

Without pictures of your setup, seeing your config files, etc., it's difficult to say. However, you might benefit from checking out the diagram that was recently added to the following section of the QtPlasmaC user guide as it applies to PlasmaC as well.

linuxcnc.org/docs/devel/html/plasma/qtpl...tml#qt_initial-setup

The following verbiage was also added to make the purpose of the touch off more apparent:

Jflesburg wrote:

It would seem that several are migrating toward QTplasmaC. Should I be looking into changing to that?

I think so, but I am probably pretty biased.

I am not sure what distribution of Linux you're running, but it might also be a good time to change if you are running the regular buster distribution .iso.

I put together an installation guide that should make it pretty easy for you to have something a little easier to work with as well as walk you through the necessary steps: forum.linuxcnc.org/9-installing-linuxcnc...indows-users?start=0

Not sure what is going on but when the float switch trips the torch/probe should stop and move up, not down?????

It may be easier for us to help you with some video of what’s going on.  

It may also be helpful if you posted a backup of your config.

The float switch is not wired properly/not in the input set in hal/not properly connected in hal !
Check the float LED on screen while moving the torch by hand up and down, it should go on and off, i bet it is not.