Backoff when limit switch is hit

Hi,
how can I set a backoff distance when the limit switch is hit ?
Currently the axis hits the limit switch and gets stuck - no way to move the table, unless I unpower the CNC and manually move the table until the switch is deactivated.

Nothing found in pncconf to set it.
Nothing found by searching the forum/google for 1h.

I assume I can set it in the .ini file, but how ?


 

Put a - in front of the home_latch_velocity or remove it if it is already there.

Nothing like this found in .hal not .ini.

I want to use "Limit-All" on Pin4 of my Mesa 7i92 with DIY breakoutboard.
I want the machine to detect the limit and then backoff by 5mm to release the switch.
I do not want to detect any HOME position. I am homing manually.

The function "Limit All" works and detects the switch, but does not backoff.

After playing with pncconf settings:
- Function "Limit+Home All" did not at all detect (or react) on the switch.

I think I need a little bit more explanation about how to setup the limit+backoff - if this is possible at all.
I did not find any meaningful setting in pncconf.
The documentation also did not enlight me very much.

Can you explain in greater detail if its possible to use "Limit-All" and have a backoff on all axis ?

Edit:  I found the checkbox in AXIS to deactivate limits - this at least lets me move the table back from the limit switch !
I think this is the function I was looking for - its manual, but it enables to release the switch and not get stuck at the limit.

 

Remember that limit switches should never be hit and are just there for safety.
So having a manual process is the correct way so you can resolve whatever went wrong....

Limit + backoff is not possible.
Combined Home/Limit + backoff is possible during homing:
linuxcnc.org/docs/2.8/html/config/ini-ho...witch_example_layout
Soft limits (the ini file MAX_LIMIT & MIN_LIMIT) should be set inside physical limit switches so the limit switch will not normally be hit unless something goes wrong.

Hi
thanks for the clarification and I feel I have to better understand the usage of a HOME position.
So far I was thinking abut limit switches as you describe - never try to hit them.

The HOME position is basically the position where the machine rests when not in use.
But it rarely is the (0,0,0) position of my work-piece at the same time, right ?

I could combine HOME+LIMIT positions and I think this is what I will do.

What I see in my AXIS GUI is only a "Referenzfahrt" (german for reference run) for each axis and this searches for the HOME position by acitvating limits/home switches.

But how can I set the (0,0,0) position on the workpiece ?
This position is different from the HOME position, but I find no button how to set the coordinate system to (0,0,0).

Thanks phillc54 for the link - I will work myself thru this.
When working in the wood-shop I was not able to load those doc-pages, so thought they were offline. But now from the living-area WLNA I cann access it - seem a network issue in the shop.

After homing use the "Touch Off" button to set the work coordinates.

linuxcnc.org/docs/2.8/html/gui/axis.html#cha:axis-gui