Safer Probing Macros

This is a set of modified macros to use with basic_probe that aims to reduce the chances of crashing your probe.

The stock probe routines generally have some G0 and G1 setup moves before, between, and after the actual G38 probe moves. Currently, if your probe makes contact during the G0 or G1 moves, the machine does not stop, and there is a good chance it will break the probe. I found a couple bug reports that would solve this, but they haven't had any action since 2017 (see 371 and 368 ).

As a workaround, I modified the default probe macros, replacing "G0" and "G1" with G38.3 wherever possible. An individual G38.3 move will stop the machine when the probe makes contact. The routine will then continue with the next move. If the next move is another G38.3 or a G38.2 (as is typical), then the probe routine will be aborted with an error like "probe already tripped at beginning of G38 move."

To use these macros, unzip and then move the macros folder into <your_home_directory>/linuxcnc/nc_files/probe/probe_basic/

IIRC (should test) if the probe trips while in G1 moves, linuxcnc will error.
So if you change the G0 to G1 (with hi feed rate) then it will be safer too.
I think it would be nicer if you could use an M code to turn 'error on trip while not probing' on and off...

Wondering if i missed something, i tested on my machine. In MDI F5 mode, feed and rapid moves get aborted when the probe is triped, and an error is displayed. Same behaviour on manual F3 mode and keyboard jogging.
But running a .ngc file, the machine happily continues movement when probe is triped outside of a G38.n

@cmorely, I did test that before modifying the macros, and neither G0 or G1 error out when the probe trips (when called from a g-code file). They do error in MDI and MAN modes as MaHa points out. An M-code such as you mention would be the ideal solution. As far as I know, such an M-code does not exist yet, thus this workaround for the meantime.

@MaHa, I observed the same behavior as you, so I don't think you are missing anything. That is the reason I replaced G0 and G1's with G38's in the macros.

Ahh i see - yes i tested with a MDI based test.
I'd add a feature request or bug fix entry on github for this.

Thanks Chris. Note that there are already a couple relevant github issues. See the links in my original post.

I was trying to figure out where to get the probe macros for use with QTDragon and the search found this thread. From reading it, it sounds like the ones posted above are the best available at the moment. I have a Hallmark ITTP probe on the way. In the meantime I did some VERY crude testing by manually tripping the signal. Looks like I am all set when the probe gets here. The only question I have is where should one normally find the macros?

Thank You
John

probe routine paths in 2.8 are defined in the INI under: [RS274NGC]

In sim screen for instance this is the entry (path is relative to the INI location.)

SUBROUTINE_PATH = ../../../../nc_files/probe/basic_probe/macros

Chris

What I meant was I had to create the ../probe/basic_probe/macros directory but didn't know where to get the files to put in it.

John

Illars posted a zipped file of them above.