How to completely disable PID on a MESA 5i25 / 7i76 setup...

Hi everyone,

I try to set up a LinuxCNC retrofit of a Deckel FP2NC CNC mill. I use drivers with internal closed loop. The encoders are connected to the drivers (Benezan Speedcube).

I am looking for the correct settings of the PID parameters in the pncconf wizard.
Is it possible to completely disable the internal closed Loop of the LinuxCNC software?

Jan

No, the stepgen uses PID to correct for small timing differences in the hardware and LinuxCNC
If you are not closing the loop back to LinuxCNC (via encoders feedback to LinuxCNC)
then the PID settings are preset correctly (FF1=1.00, P = 1000, everything else = 0)

Thanks a lot for your quick response. I will try the settings as soon as I am back home in the workshop.

Jan

I got confused in this exchange. As I believe I'm in the same situation, and have wondering the same thing.

Jan said the encoders are connected to the drivers.

Is that not the same as "If you are not closing the loop back to LinuxCNC (via encoders feedback to LinuxCNC)"

Coming up with the parameters and thus double loop correction has me lost.

In the step/direction configuration, there is no need to come up with
PID parameters (pncconf's default parameters are fine), and there is
no double loop (there is no external feedback coming to LinuxCNC)

Only in the rather special case where you have step/direction drives and have encoder
feedback to LinuxCNC need the PID loop be tuned

I still had Problems with my MESA-Setup, because it looked like I didn´t disable the PID-controller.
The reason for my servo-drivers showing error as soon as the motors startet moving was something else:

The scale calculation of the stepconf-wizard is obviously faulty. I entered my data in the fields so the result should be 12.000 steps per revolution for my test setup.

The wizard enters a value of 5.000.000 in the .ini-file as the steper scale. This is why the motors start moving with acceleration parameters far beyond the possible limits.


Can someone crosscheck this with his machine?

Jan

The scale calculation pop-up works on my system (LinuxCNC 2.7.11)
It both calculates the proper value (12000) and transfers it to the main screen
if I hit the apply button in the popup.

Hi Jan,

this is a bug in the PncConf Wizard. I had the same problem the last days if I enter my values into the wizard the saved calculation was a mess. The reason is if you linux cnc installation has german language setting. The wizard can not work with the differenze between dot "." and comma ",".

I changed my language to english and the problem was gone.

I'm not sure where I can report this? I think this problem occurred many times if the user setup an german language.

Have fun
Ferdl

What version of linuxcnc are you using? There has been some work on this problem not sure if it's released yet though.

Chris M