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PC-DMIS 2021.1 SP2 - Possible bug with linear open scans & findnoms?

Aaron Baldauf
When I create a linear open scan with “findnoms”, after I close the command and open it again it changes to “master”.
After I changed it a second time to "findnoms" it keeps that setting.

It doesn’t happen every time and I can’t reproduce it but it happened enough times,
that a coworker and I both noticed it independently on two different CMMs.

Does anybody have the same issue or maybe knows why this could happen?

I will continue to try and reproduce it but I’m happy for your input.
  • I have an update on this issue.

    I can reproduce this when I have the execution controls set to "normal".
    We use this setting when we have scans on on aluminum so it makes individual points and doesn't "drive" along the part. (so we don't have issues with aluminum on the ruby tip)

    Is this the correct behavior of the software or is this a bug?
  • Don Ruggieri

    Do you maybe know if this normal behaviour or if this is a bug?
  • I hope can chime in here with the answer he provided me on the (same) post from the TP forum.


  • This is the conversation I had:

    from
    Hello @Aron Baldauf About PC-DMIS 2021.1 SP2 - Possible bug with linear open scans & findnoms?

    From the post in the forum, I understand that you are trying to create a linear open scan with the "FINDNOMS" option selected from nominal method, after generating the points and creating the scan, the nominal method automatically changes to "Master". Then for the second time when you edit the same command and change the option from "Master" to "FINDNOMS" and create the scan, it keeps "FINDNOMS" in the nominal methods.

    This is as per design, working as expected

    Find Noms
    When the FIND NOMS option is selected, PC-DMIS will pierce the CAD model to find the closest location on a CAD surface to the measured point. It will then set the nominals to the location found on the CAD surface.

    When the Nominal is not found from the CAD, the measured data from the first execution will be considered as the nominal value for the second execution, so first time the nominal method will change to "Master" since the nominal value is not found and for the Second execution it will keep the "FINDNOMS" as nominal method

    If you have some other issue, please provide more details.

    if this clarified your issue, I will comment the same in the forum.

    please feel free to contact me.

    Thank you, have a great day!

    my answer
    Hi Jdevaraj

    Thanks for the answer but I still don't understand completely. I have a part with CAD.

    When I have the execution controls set to "Re-learn" and the nominal method set to "FINDNOMS"
    It already keeps it at "FINDNOMS" after I generate and create the scan.

    Only when I set the execution controls to "Normal" and the nominal method set to "FINDNOMS"
    it changes it to "Master" after I generate and create the scan. (not run just create)

    Why does it change with in "Normal" mode and not in "Re-learn" mode?
    And why does it change at all at "Normal" mode when I have a CAD and select the surfaces?

    Thank you for your time!

    from
    Hi Aaron Baldauf,
    Thanks for sharing the details, I will share the information with the development team to get to a solution
    Thank youSlight smile

    Do you have some other information?
  • Aaron Baldauf No, that's about it, except for your reply of course - which was essential (I was hoping your issue would get some attention for it to be fixed) and judging by the reply from there is an issue.
  • Don Ruggieri

    The last information I have on this, is that a ticket got raised.
    Is there any news on this issue?
  • Sorry for the delay, let me try to clarify a bit more. What JDevaraj said is correct, in fact it came from the team that works on this area.

    FINDNOMS is one way to teach the routine what the nominal locations are. It is designed to be a LEARN mode function only. In other words, it finds the nominals the first time, when you are learning (or teaching, writing) the measurement routine. After that, if you have the execute controls set to NORMAL it will continue to take those same hits, one at a time, in the traditional fashion of a touch trigger probe.

    With FINDNOMS as the Nominals method, but this time you have the EXEC CONTROLS set to DEFINED, it will take those original (found) nominals and scan the surface on a path defined by those nominals. Both the Exec Controls of NORMAL and DEFINED are true execute mode functions.

    The difference here is when you have Nominals Method set to FINDNOMS and the Exec Control set to RELEARN, that is saying that you are "Mastering" the part the first time. Once you've done that, no need to learn those points over again. In fact, the Nominals Method control is pretty much ignored after the first time. There is no need to find the nominal values or vectors as you've already done that, and it is somewhat time consuming. So instead, this control switches to MASTER to basically tell it to look for the values you "found" the first time.

    Admittedly the terms used, and the dialog itself, are not all that intuitive. It has been tweaked a few times over the years to try to make it better but obviously could still benefit from some improvements. For now, I will see if I can get some documentation/help improvements anyway.

    nb: For my own future reference, PCD-218223, PCD-49948
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