Changing INI JOINT SCALE online

Hello everybody,
I have a question. Is it possible to change the scale of one joint while linuxcnc is running?
I tried to find the pin or parameter with the halcmd list, but without any results.
I'm using a mesa 7i76e board.

Thanks in advance
kindly regards
Alessandro

You can do it with a script that set the new scale value
or by adding the scale component but you have to scale
both the feedback position and commanded position at the
same time or you would get a following error

Sorry, Thanks for the feedback. I found the right parameter, "hm2_7i76e.0.stepgen.xx.position-scale". I gave it a very big following error value to test it. Thanks

Hello PCW, how can I scale the feedback position and commanded position at the same time while the program is running?

I tried to put in the INI file this values:

FERROR = 100.0
MIN_FERROR = 25

but as you said, the following error happened anyway, when from 150 I scaled to 140 with this command:

halcmd setp hm2_7i76e.0.stepgen.XX.position-scale 140

Thanks in advance
Kindly regards

Hello,

I added a scale component in the hal file, trying to scale at the same time the position command and the position feedback, but I still didn't solve the issue of the following error because I don't really well know what I am doing.

The scale component requires an FP thread, so I can't add it to a base thread. I'm using stepper motors.
I linked the following lines in this way:

net molt1 scale.1.in <= joint.3.motor-pos-cmd
net emcmot.03.pos-cmd <= scale.1.out
net emcmot.03.pos-cmd => hm2_[HOSTMOT2](BOARD).0.stepgen.03.position-cmd

net molt2 scale.2.in <= hm2_[HOSTMOT2](BOARD).0.stepgen.03.position-fb
net motor.03.pos-fb <= scale.2.out
net motor.03.pos-fb => joint.3.motor-pos-fb

net multipl scale.1.gain scale.2.gain

Still bad results.
Can someone address me, if I'm moving between the right pins please?

Well, bad results are rather expected since you are generating
an instantaneous position step.

Maybe it would be better to step back and ask what you are trying to
accomplish to see if maybe there is a better way

I'm trying to make an "online" calibration about an extrusion flow rate of an extruder screw. As the flow is different according to the pellet size, I need to find the right rate value when I change material supplier.
As I can't understand if the set rate is right from the first layer, but I need to wait some layers to check if It is over extruding or under extruding, is it very tedious to interrupt a print after hours because you need to change the extrusion scale. I can change it that via the servo driver ( it's not closed via linuxcnc ), but I'd rather prefer to find a smart and comfortable online method with a jog wheel in my GUI.
Any suggested option?

In that case I would just use the stepgen in velocity mode without feedback
(so no following errors)

Oh, this could be the right option that I was looking for Thanks, PCW.
The same solution can solve also the problem about starting a program from a line, where till now, the extrusion go crazy forward over the set position and destroy the print?