Slider (scale) to change stepper acceleration

Hello!
I'm wondering is it possible to change stepper motors ACCELERATION value in real time with the pyVCP scale (SLIDER) component.
Yes  I can change MAX_ACCDLERATION value in INI file but rebooting is not very good solution.
Any HAL code example will be welcomed also.

This solution will help to remove (decrease) mechanical vibration from big router type laser cutter.

You can change them without restarting Linuxcnc but not necessarily in real time (ie durring the exicution of a G-code file.)

For example I made a custom M100 code that would change all of the acceleration settings for each of my axis on a cnc router. The command was M100Pn with n=the new acceleration setting. I had the code for the M100 command written so that if the Pn was omitted then it would reset the accleration settings back to thier original default settings.  Or you can use a hal command to setp the value of  the pin "ini.N.max_acceleration".

The M-code worked reasonably well for me, but I'm not sure I would trust it to actually make those changes on the fly during the execution of a program.  It might work perfectly, or it could give an unpredictable delayed reaction, or it might not effect the change until execution of the G-code file ends.  I only used it as an MDI command between running programs.

If you try to use this M code be sure to edit it to change the default acceleration setting to one that is appropriate for your machine (This one was set to 6in/sec^2)

 

I'm not sure that changing the accelerations via a slider in real time will work. The problem is that the trajectory planner must recalculate the accelerations for a file, and locks those settings durring execution. (I think a loaded g-code file might need to be reloaded or reprocessed before execution after changing the acceleration settings.)

Thank you very much!
It works very well...need yo add only USER_M_PATH =... to INI file and give full permission to execute the M100 file.
You are right, this is not real time... and after entering M100 code all breakout board output jumps a little....but i do not care...it solves my problem

M100 Pxx command works and Hal meter show me the same acceleration value in ini.0.max_acceleration pin...but no changes in motor acceleration...any comments?

Interesting. I have to be honest with you, I set this up a long time ago, and the machines that were using it were (and still are) running Linuxcnc version 2.7.

I just experrimented a bit in a virtual machine and it appears that in the version of Master that I have installed there. if both a max acceleration for the joint and a max acceleration for an axis letter are specified, the max acceleration for the axis letter overrides the joint max acceleration. This seems like a bug to me, I would think that the expected behavior should be that the lowest max acceleration should be the one obeyed if both are specified. Changing the M code to this should work.

A little more experimentation shows that the joint max acceleration is only obeyed in joint mode (such as when homing), and the axis acceleration is what is obeyed in world mode. So both are required.

This behavior works fine in a Cartesian machine, but might give very broken results for a non Cartesian machine (such as a robot arm.) But I haven't really played with one of those.

Hi again!
Final results:
yes, this code is correct:

halcmd setp ini.0.max_acceleration $accel
halcmd setp ini.x.max_acceleration $accel

M100 Pxx codes works well....it contains keyboard arrow/pendant/program acceleration overrides
so...i wrote small part to pyVCP as well

Thank you all! (specially to Todd)