Change acceleration on the fly?

Hi all!

I'm doing something a little odd with the machine I'm working on, and I'm wondering if there's a way I can change the acceleration of a specific axis/joint or even the whole machine temporarily, then revert it? Obviously you can change it in the INI file, but I want to change and revert it without closing LinuxCNC, i.e. within the scope of a custom M-code or something.

Is there any existing facility for that, or am I out of luck for now? I did notice the motion.axis/joint.N.jog-accel-fraction pins, but I assume those can't change the acceleration for moves made by the trajectory planner.

Thanks in advance!

You can change acceleration when LinuxCNC is running and the interpreter is idle, via the ini.xxxx pins

Thanks, PCW! I'll give that a spin.

There is a module called sim_pin you can load in your ini file that opens a new window allowing you to control hal pin settings. I have used it on live confiigs.

linuxcnc.org/docs/html/man/man1/sim_pin.1.html

In case anyone else out there is looking for a solution, I got this working.

For the project I'm working on, I have a prox switch input which indicates whether the Z axis is carrying an extra load; when that input is high, I want the Z axis to run at a lower acceleration. The machine can pick up and drop off this extra load mid-program with some custom M-codes, thus the need to change the acceleration on the fly.

Here's what I added to my HAL file:
And this in my postgui HAL file (for some reason the ini component doesn't load before the rest of my HAL file?):
A word of caution: If you accidentally set the ini.*.max_acceleration pin to 0 you get some, uh... interesting behaviour. Namely, the interpreter skips moves which include the axis that has 0 accel. This had me very confused for a while this afternoon before I figured out what I had done.