AX58100

So you are still working on this? Great to see.

There can be a few reasons behind this.
Let's think. The motion component generates the wanted position in joint.0.motor-pos-cmd, sends that off to the EtherCAT device and receives the actual position, as the stepper driver sees it, in joint.0.motor-pos-fb. The difference between them is the following error. Which also happens to be available as joint.0.f-error.
I am thinking along the lines of either a scaling issue or you are asking the stepper driver to make steps at a higher rate than it can generate.

Let's first verify the behavior of the following error. Start halscope and record the signals joint.0.motor-pos-cmd, joint.0.motor-pos-fb and joint.0.f-error when you run the axis at below the critical speed and above the critical speed. One wants to see how those signals develop up to and including the following error stop. If you post screen dumps of halscope for those two situations I can help to take next step.

The pins joint.0.motor-pos-cmd and joint.0.motor-pos-fb do not exist, the ones that do appear are join.0.motor-pos-cmd and join.0.motor-pos.fb, are those the ones I have to check with halscope? I have never used halscope, I will have to learn how to use it.

They should definitely be called joint.0 if they don't there might be bigger problems. The "0" of course refers to the number of the joint that gives the following error.
You find the pin names here
linuxcnc.org/docs/html/man/man9/motion.9.html#JOINT%20PINS
motor-pos-cmd
motor-pos-fb
f-error
are the interesting ones.

There are tutorials on halscope out there. It's a good tool to know how to handle. Basically select the three pins in the fields down below, adjust scaling and offset (can be done later as well). Set to record every millisecond, as long as possible. Manual trigger, and trigger when you get get the following error. It keeps a buffer of recorded data so you won't miss it even if you trigger slightly afterwards. Then adjust the curves with the same scaling for motor-pos-cmd and motor-pos-fb so they can be compared, and put up f-error as well, with a proper scaling so one can see it develop.

Hi, any progress?
In the software there is not so much to change, but there is the MAX_ACCELERATION setting. It will restrict the acceleration if set lower in the ini file.
You can have a look and see what you have there. The last lines in StepGen3.h
 

I haven't had time to use halscope, I'll look at your recommendation for modifying the firmware.

In the firmware the stepgen scale JOINT_1_SCALE is defined at 100. I put that value in STEP_SCALE in the ini file and the speed is no longer limited nor does it give me a following error. I don't know if I'm wrong but the value of STEP_SCALE in the ini file is determined by the value programmed in StepGen3.h. Or I don't understand what the value JOINT_X_SCALE refers to.