Line 0 following error

When i set my maximum velocity over 75 mm /min . i get this error message.

how do i rectify this?
thanks in advance
vallab

Its a bit difficult to answer that question because you are not providing any background information.

Assuming you mean "joint following error" and also assuming you have a step/dir machine
this error often means you don't have the required headroom in the stepgen maxvel setting
(it should be about 25% greater than the machine max velocity for each axis)

It may also be that you have run in to the maximum velocity limits of your current step-time and step-space settings.

yes it is joint following error.
i am using servo run by step and direction using pico univ stepper controller.

will try this and update
thanks

I changed the following settings in ini configuration file.
still getting the same joint 0 following error.


& i couldnt find the stepgen_max_vel setting in the ini configuration.
where do i find that setting?

DEFAULT_VELOCITY=0.0167 (unchanged)
MAX_VELOCITY=25.20 (old value = 1.20)
DEFAULT_ACCELERATION =15.0(unchanged)
MAX_ACCELERATION =20.0 (unchaged)

AXIS 0
MAX_VELOCITY=15.20 (old value =1.20)
MAX_ACCELERATION=20.0 (unchanged)
PID_MAX_VEL=20.20 (old value = 1.25)

My max motor speed is 3000RPM, I set my scale as 1 rpm = 1mm linear movement.
so my max velocity = rpm directly.
i couldnt move the motor over 430 rpm

skvallab wrote:

yes it is joint following error.
i am using servo run by step and direction using pico univ stepper controller.

will try this and update
thanks

Oh, that gets a bit more complex. The universal stepper controller in the open-loop mode
is an all electronic servo, where the encoder counter function is fed the step pulses, and
the PID component adjusts the step rate to zero out the error. If you are running in
open-loop mode (DIP switches 1-4 are OFF) then you may need to adjust the
P term in the .ini file to help the loop keep up. You can use Halscope to observe
signals ppmc.0.encoder.00.velocity and pid.0.error and see how your adjustments
improve the response. The calibration menu allows you to adjust the parameters
while LinuxCNC is running. If you have problems, I can run your settings here
and then send you back optimized values.

If you are reading your encoders back to the USC (switches 1-4 would be ON)
then you are having your servo motors lag behind your commanded position.
Again, Halscope is the tool you need to see what is happening. I have a Wiki
page that can be helpful in tuning the servo response.

Jon

thank you so much jon for your offer.

i am attaching my univstep.ini file with this post
and pics of error messages.
and servo pulse input screenshot

regards
vallab

skvallab wrote:

thank you so much jon for your offer.

i am attaching my univstep.ini file with this post

here are some PID settings that looked very good.
P = 2000
I = 1
D = 0.25
FF1 = 0.98
FF2 = 0.0002
Deadband = 0.00005

These are for a scale of 10000, the numbers might have to change if you change that scale
factor.

Jon

Getting joint 3 following error. I am not using that axis.
what might be the reason. i suspect EMI problem.

If i set P =2000
i am getting the joint following error at the start.

reduced it to 200 it is working ok.

getting occasional errors though.

regards
vallab

skvallab wrote:

Getting joint 3 following error. I am not using that axis.
what might be the reason. i suspect EMI problem.

If you are not using the A axis, then you ought to remove it from the configuration.
You would have to go through all the .hal files and remove anything that refers
to the 4th axis. But, a quick fix would be to set the MIN_FERROR on that axis
to a large number, like 1000.

If i set P =2000
i am getting the joint following error at the start.

reduced it to 200 it is working ok.

You need to learn how to use Halscope to view what is happening as you move the axes.
You can also turn up the value of MIN_FERROR, it is currently set to .001, which is
pretty small in mm units.

getting occasional errors though.

regards
vallab