Joint 3 Following error is driving me crazy (2.7 to 2.8 update)

Hello,
I'm trying to update LinuxCNC from 2.7 version to 2.8.1 (Debian Buster) version.

i'm running an standard Gantry XXYZ machine with a Mesa 5i25 and a g540 Geckodrive.

I've passed a day configuring .ini file to get the machine homed (I was getting Joint 3 Following error on homing), so I tuned speeds, and now it's homing is OK. (hm2-g540-stepper_2.8.1.hal and 5i25-g540_2.8.1.ini)

When I launched a cutting program again I've got Joint 3 Following error again, with same speeds as in 2.7 version.

Maybe you can help me with configs (I attached 2.7 and 2.8 versions) so I could keep 2.8.1 install.

Thank you very much.

Christian

Stepgen_max_velocity and stepgen_max_acceleration
Must be 25% higher than max_velocity and max_acceleration, they are mostly wrong on both ini files.

Thank you Tommylight!
I corrected .ini file in all axis/joints as you said, with no luck :

[AXIS_X]
MIN_LIMIT = -1.0
MAX_LIMIT = 1240.0
MAX_VELOCITY = 100
MAX_ACCELERATION = 40
[JOINT_0]
TYPE = LINEAR
MAX_VELOCITY = 100
MAX_ACCELERATION = 40
STEPGEN_MAX_VEL = 125
STEPGEN_MAX_ACC = 50
BACKLASH = 0.000
SCALE = 22.2222222
...
[JOINT_3]
TYPE = LINEAR
MAX_VELOCITY = 100
MAX_ACCELERATION = 40
STEPGEN_MAX_VEL = 125
STEPGEN_MAX_ACC = 50
BACKLASH = 0.000
SCALE = 22.2222222

I've also lowered speed and accel to from 80% to 20%, no changes.

After homing I run the LinuxCNC axis.ngc file, axis Z moves OK, and then "Joint 3 following error"

I don't understand why it's homing OK, and not moving OK
and why It was working with those speeds on 2.7 and now not working...

Thankyou

Your ferror limits in the ini file are too narrow:
FERROR = 0.005
MIN_FERROR = 0.005

Try changing these to

FERROR = 0.1
MIN_FERROR = 0.01

Thankyou PCW!

I've changed FERROR = 0.1 and MIN_FERROR = 0.01 on all JOINTS :
I get the same "Joint 3 following error"
I include the .ini file.

I will reinstall 2.7 version so I can mill some jobs.

Christian

You must umcomment these lines or a joint 3 following error is guaranteed:

# net motor.03.pos-fb <= hm2_[HOSTMOT2](BOARD).0.stepgen.03.position-fb
# net motor.03.pos-fb => joint.3.motor-pos-fb

Thanks PCW!

After uncommenting those lines and I can't Jog the X axis machine, no Homing neither.
I get directly a "Joint 3 following error" when I try to move the axis, or homing.

I appreciate your help.

I think what has happened is that the automatic script for updating 2.7 configurations
to 2.8 has failed for your gantry configuration. In fact for a 2.8 configuration, joint 3 hardware
should be driven by LinuxCNCs joint 3 commanded position, not Joint 0 (which is a leftover
from a 2.7 gantry configuration):

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

There are probably more changes needed so beware that you may get bad behaviour
(including racking) before all the needed 2.7 --> 2.8 changes are in place

Can you post the current 2.8 hal and ini files?

Thanks PCW!

Yes, maybe is better to restart a new config from a working gantry 2.8 file.
I confirm the 2.7 version is working without problems.

It's a pitty a software update can break a working configuration.

I share the 2.8 configs.

Christian

Can you try with:

# X2 position command from Joint 3
net emcmot.03.pos-cmd <= joint.3.motor-pos-cmd
net emcmot.03.pos-cmd => hm2_[HOSTMOT2](BOARD).0.stepgen.03.position-cmd