5i25 + 7i85s +....

I'm just saying that the PID+velocity stepgen with Mesa hardware gives a
nearly perfect pulse stream. If you are seeing significant position errors
with a local feedback stepgen system, you have a setup issue.


If you are seeing these issues when using a stepgen and encoder feedback, thats
likely a LinuxCNC position loop tuning issue or a drive tuning issue.

Dont get me wrong, im still totally impressed about Linuxcnc!
English is just still not my native language

So i write es short and direct as possible. In the hope, that i dont sound like an 12y old all the time.
This may sound cheeky/rude sometimes.

My tuning atm is capable to manage a acceleration of 1200 with a max following error of about 1mm.
(depending on load)

Just imagine, whats possible if the Drive internal hardware PID gets the control!
But for that you will need a different setup, where Linuxcnc sends coordinates and hardware calculates
the whole movement in Steps.

Look at my Z-Axis and you will understnd my need vor perfeckt movement

If you want to use the drives position PID then just run LinuxCNC/Mesa in stepgen mode
(feedback from the local stepgen counter) and the drive is in full position mode control

At this point you could use the encoder feedback to check how well the drives PID is doing
(by subtracting the commanded position from the feedback position and plotting the result)

You may find the the errors are mainly in the drive...

Thats something i wish to try.

But how does it work?
In Servomode Axis just sends velocitiy/acceleration informations to Mesa and Mesa generates the Steps.
How does Mesa know the correkt Steps. It just listens for the software PIDs information. Or im wrong?

Thats it, when i talked about the difference of Steppermode and Servomode. -> Set of Steps VS regulation.

Yes, it generates steps at the requested rate and there is position feedback
(note that the position feedback is accurate to 1/65536th of a step)

This keeps the actual steps generated equal to the requested position
( to within a _very_ small fraction of a step )

Ok, i better keep that 65536th of a step in mind if i engrave parts for Intel or AMD in the future.

But as i noticed, if i use hm2_5i25.0.stepgen.00.position-fb the PID is still in action.

It shows up, when PID is in a bad setup. -> doesnt reach final position or dfrifting.
But i will test it again. Maybe i missunderstood something.