TEST_SPEED macro issues GET_POSITION while robot in motion

[KevinOConnor]

Hi,

It was reported that recent changes to Klipper have broken the TEST_SPEED macro defined at https://ellis3dp.com/Print-Tuning-Guide/articles/determining_max_speeds_accels.html and https://github.com/AndrewEllis93/Print-Tuning-Guide/blob/main/macros/TEST_SPEED.cfg . This was reported at https://klipper.discourse.group/t/regression-in-step-accuracy/24895 .

The macro seems to be using the sequence:

        G28 X Y
        G0 X{printer.toolhead.axis_maximum.x-1} Y{printer.toolhead.axis_maximum.y-1} F{30*60}
        G4 P1000 
        GET_POSITION

to report the "mcu position" of a stepper to the user.

Unfortunately, the GET_POSITION command doesn't produce consistent reports for "mcu position" if the robot is in motion at the time the command is issued, and the G4 P1000 does not ensure the robot is not in motion. ( https://www.klipper3d.org/Code_Overview.html#coordinate-systems ). I suspect the following would provide better results:

        G28 X Y
        G0 X{printer.toolhead.axis_maximum.x-1} Y{printer.toolhead.axis_maximum.y-1} F{30*60}
        M400
        GET_POSITION

as M400 does ensure all moves are completed prior to the next command running. (That is, a GET_POSITION command after M400 ensures the robot is not in motion at the time the command is issued.)

The behavior of Klipper did change recently with Klipper3d/klipper#7038 , however using just a G4 P1000 could cause inconsistencies even before that PR.

Thanks for working on this,
-Kevin

[stablestud]

@Anonoei @thetic @AdamLay, I quote you here as you are the main forces of the klipper_auto_speed plugin and thus should have the most insight :)

I wonder if this issue described here from Kevin (Klipper Inventor) also affects the klipper_auto_speed plugin as its based on elli's TEST_SPEED.

Could you please advise if thats the case? Thank you

[Anonoei]

@stablestud
KLIPPER_AUTO_SPEED shouldn't be affected, it calls the Python binding for M400 before it measures steppers positions, here: https://github.com/Anonoei/klipper_auto_speed/blob/main/autospeed/main.py#L603