Limit3 question.

Hi. I've always wanted to define acceleration on a hal pin, to change it 'live', but it isn't possible in emc2.

Today, reading here: linuxcnc.org/docs/html/man/man9/limit3.9.html , i've learned about limit3.x.maxs and maxa.

If i understood correctly this limits max acceleration (and velocity) for the given movement into limit3.x.in. Is it?

Do you think can i use some way this parameter connected to maybe a Spinbutton into Gladevcp, where i set the limit of acceleration?
this way i can set an initial Hi acceleration, and then slow this into Gladevcp during axis running.

Any ideas?

Thanks, Davide.

I would like to try this way, but sincerely i don't know which pin can I feed limit3 with..
or, better, where can i after plug the output?

Hi

Haven't tried it but would have thought

stepgen.N.maxaccel which is a RW param would be a good place to start

When emc starts, this is set to the MAX_ACCELERATION figure for that axis from the .ini file

Unless you are doing something very clever, would appear to just need a limit1 component to define the bounds within which the acceleration can be adjusted.

regards

ok, i'll try that. it's a stepper machine, so it will not be so important.

but, what if i do a 'setp stepgen.N.maxaccel my_hal_pin'
does it work?
i would like to set maxaccel with the value of a spinbutton, in the moment when i reset the estop (in the same moment i'm setting my_kins_values from other spinbuttons..), but i really don't know how.

while thinking on this i'll try as you suggest, Andy.
Thanks, Davide.

got this error:
...
tgvcp.hal:45: value 'tgvcp.max_acc_out' invalid for float
tgvcp.hal:45: setp failed
Shutting down and cleaning up EMC2...

tried to do this:
# Prova modifica accelerazioni:
setp stepgen.0.maxaccel tgvcp.max_acc_out #this is line 45.
setp stepgen.1.maxaccel tgvcp.max_acc_out
setp stepgen.2.maxaccel tgvcp.max_acc_out
setp stepgen.3.maxaccel tgvcp.max_acc_out

tgvcp.max_acc_out is a out_pin created into python, with the value token from the spinbutton.

andypugh wrote:

dab77 wrote:

setp stepgen.0.maxaccel tgvcp.max_acc_out

You can't do that. setp takes a pin or a parameter and a number.

You can _type_ setp at the command line, but it isn't a way to link a gui control to a parameter. And you can't net a parameter.

without re-writing stepgen you can't change the acceleration on the fly.

I say it again, do it in CAM.

no, i'm sorry, but in CAM is not the way it should be and it would be a real pita..

I think there should be a way!
as you say, i proved i can setp by typing into the command line, so how can i do that from my python file?

p.s. i've tried the limit3 way, but the acceleration doesn't change.

Andy Pugh wrote:

Stepgen-maxaccel is a parameter, it can't be netted. (you can only net pins)

I didn't say anything about connecting it with net

Andy Pugh wrote:

You can't do that. setp takes a pin or a parameter and a number.
You can _type_ setp at the command line, but it isn't a way to link a gui control to a parameter.

You can use setp. One way might be.

Write a handler for the slider or spinbox you set the new max accel with.

From that handler fork halcmd setp stepgen.0.maxaccel [value]

See the Forum discussion under Glade > Label regards writing python event handlers for glade widgets

Another way would be to write a user M code script which does the same thing and call it from your g code at the point
where you want to limit accel to a given value, no pretty gui sliders but can be written in 2 minutes.

regards