add + sign with axes XYZ and runtime in program

boy777 wrote:

But the issue I faced is how to add + sign with axes while they are not in negative position

Currently only in the Master (development) version:
github.com/LinuxCNC/linuxcnc/commit/7253...8871356afee182a1633e

boy777 wrote:

didnt found any help about auto running program from stop point,

You can't do that automatically. And, in fact, you can't do it at all without editing the G-code.

You can start from a particular G-code line, and I guess that, in theory, you could log the pin motion.program-line to file to make it clear where the machine had been stopped.

boy777 wrote:

My idea is , there should be some temporary file attach with every program that run,

That's actually slightly harder than it sounds, for interesting reasons.
The actual motion of the machine in LinuxCNC is done by code running in realtime. This is kernel-module code, and kernel modules have no access to the file system. So the only code that _really_ knows where the machine currently is can't write that data to a file.

It's not as terrible as it sounds, because user-space code can see the HAL pins and can query the state, but with some unknown delays (measured in a few tens of milliseconds normally, but can be longer).

It is interesting to wonder why (as far as I know) nobody has asked for this before. And I think it comes down to how most people view linuxCNC, as part of a machine tool and not as a computer application. If you want to come back to a job on a manual lathe or a mill, you leave the part in the machine. In the case of a classic CNC lathe or mill you would probably leave the part in the machine, and keep the machine powered up to retain the reference points.

How often do you intend to leave a job in the machine half-finished and to quit LinuxCNC? It can't work at all unless you have very accurate axis homing.

The way i do this is:
Add the "last position.txt." to the ini and a blank file with that same name in the config folder. That will remember the last position the machine was at shut down.
When starting the machine again, i scroll to that position in the AXIS screen where the gcode is and highlight the line corresponding to that position. After that i jog back to 0 on all axis , slowing the jog speed so i can set it to within 0.0xxxmm, home all axis and do a run from here from the highlighted line.
Not the best solution, but it sure gets the job done, always.
In your case, having backlash can pose some accuracy issues, but even that can be managed moving past zero and backing slowly to 0 again.
This method is usable where there is no need for extreme accuracy, as that is very dependent on the overall accuracy of the machine. I would not recommend using it on metal mills or lathes, as the tolerances for that kind of work are tight and a slight error in homing can produce unusable parts.

tommylight wrote:

The way i do this is:
Add the "last position.txt." to the ini and a blank file with that same name in the config folder. That will remember the last position the machine was at shut down.

I had forgotten about that. It is part of the way to what is being requested.
linuxcnc.org/docs/2.7/html/config/ini-config.html#_traj_section
POSITION_FILE
Though it is intended for slightly different purposes

I have to use that a lot as the electricity here can go off without any reason or warning. It has saved a lot of material !