Test Panel - inop - no function?

Hello - question from a newbie...

LinuxCNC setup just first time now installed, so absolutely inexperienced...
RT Kernal installed..
Mesa 5i25 inserted , and as I got just a 7i75 to play with (no intelligence on it) ... used firmware PROB_RFx2 for the 5i25
... Stepper (Leadshine DM556) are working... with some unexpected...

Questions:
PNCConf - Test Panel "Launch test panel" in I/O Connector 2 for Mesa inop ... or at least no response when pressed...
I found in a 2014 y post, in the forum, that inop... but guess 6y later should be solved?!?

Testing the Axis... "Test / Tune Axis" function in PNCCONF.. (changed Step On-Time to 4000 (seems was too slow for my Leadshine Driver))
Axis travels 50mm , stops and remains for default 1 sec.. I changed to 10sec ... and moves back 50mm thereafter... thats ok, but..
Unexpected, the Axis moves around while halted a few steps ... 5i25 sends signals (detectable with Oszi) + and - ... and also on this axis test page in PNCCONF , it shows bouncing around a few steps... any idea, as there is no feedback .. no axis encoders, installed...nothing... ?
hm2_5i25.0.stepgen.04.position-fb jumps around a bit ... (in 1/100 .. maybe up to 0.05 )
hm2_5i25.0.stepgen.04.velocity-fb
and HAL-Meter .. default indication "Speed_rpm" also goes +- hundreds
I assume, both should remain steady during the 10 sec break... ?!? Tested X, Y, Z Axis...

As I just downloaded... LinuxCNC V2.7.15 ... should be latest..

I just started with this File generated by PNCCONF .. and yes, I can move my axis ... but ... without manual moving... X indication bounces around maybe 1 mm and the same is visible on the real stepping motor... mhhh ending up in a joint 0 following error...

Any help very welcome

Yours,
Michael

Can you post your hal and ini files?

Sure PCW
Here we are..

You have the P term set too high, the default should be 1/servo thread
period so P=1000 at your 1 mS servo period would is correct.

Hi PCW,
Thanks.. it works...
Just curios why it has an influence on a stopped stepper axis (if no feedback...)

Kr
Michael

Actually most step generator systems do have feedback though it is local to the controller
(LinuxCNC in this case). The way this works with Mesa hardware and LinuxCNC is that
LinuxCNC sets the velocity (steps per second) every servo thread period and checks
the current step position from the step generator. If there is a small deviation from the
expected position, (say because of small time base differences between the hardware
and LinuxCNC) the velocity will have a correction applied so that at the next servo
thread, the error will be reduced or completely corrected.

A P term of 1/servo_thread_period results in this correction being done in one servo period

A P term of more than 2/servo_thread_period will be unstable because the correction
will cause a a position error larger than original error but in the opposite direction