MPG Still Skipping Steps...

[safeairone]

I know I read that the previous software version (3.46) was having issues with the Masso pendant MPG skipping steps when jogging and that the new release (3.48) was supposed to address this, but I can't seem to find that thread using the search.

The 3.48 release notes say:

• Lathe, Mill and Plasma: Bug fixes to issue that was causing the system to ignore external JOG/RAPID command. This issue was affecting controllers up to 4 axis but 5 axis version was not affected.
  

I have a 5 axis controller (mill G3-6047) and it definitely was affected with the old software release and is still being affected with the new release, albeit a lot less.

When I jog using release 3.48, the axis will move on every click of the MPG and then, randomly, there will be a sequence of clicks with no movement. On the setup screen, the A and B channels for the MPG don't always change state with every click of the handwheel.

Continuous jogging using the Jog screen produces nice, smooth axis movement.



Anyone else still getting missed steps with the MPG on the pendant?

 

[zombieengineer]

Quote from safeairone on November 28, 2020, 4:18 pm

On the setup screen, the A and B channels for the MPG don't always change state with every click of the handwheel.

That sounds like a hardware fault.

Are you able the go back and forwards over the same dial location and have the same issue? (A/B channels don't always change).

With each click the one of the A/B channels should change followed by the other channel on the next click.

How long have you had the pendant for? (<12 months?)

I can check my pendant to see if it has a similar issue.

 

[zombieengineer]

Checked my MPG pendant and I was expecting quadrature style pulses - what I found instead was both A & B pulsing on each click (4 phases per click).

From the F1 screen you need to turn the dial very slowly to see the A/B pulse sequence. The pulses are fast enough that there is a potential that pulses are missed

 

[safeairone]

Thanks, ZombieEngineer. I think you've set me on the right track; Going click-by-click on the MPG on the setup screen won't show every state change on channel A & B--you need to drag it slowly through the clicks to see them.

So everything seems to be working correctly on the setup screen then. When I crank the MPG at a fair speed, the axis moves except for the random intermittent hesitation. When I go click-by-click through spots where there was hesitation, everything moves perfectly, so I suspect something downstream (servo, encoder, Gecko servo controller) isn't keeping up with rapid clicks when I really crank the MPG.



I'm not getting an "out of position" indication on the servo controller at any point, but now I have a place to look and I know it's not software-related.

\

 

[safeairone]

Well, I think I have this solved... it looks like it s a matter of tuning the encoders, servo controllers and Masso settings. I still haven t calibrated everything yet as I m still finishing up the machine build, but I was able to make adjustments so that the axis I was testing would move without skipping IF I CRANKED THE HANDWHEEL AT A SLOWER SPEED and used the jog screen for large rapid moves.

This is in contrast to the Haas machines I normally use where you can crank the handwheel at a high RPM and get the machine to (essentially) rapid flawlessly for full-travel moves at .100 /click.

Unfortunately, during troubleshooting I turned the servo controller up to full gain for testing, which, in the brief few seconds I had it powered up, vibrated the Ruland beam coupling between the servomotor and the ballscrew to its untimely death. ?