Bug #24579

Two cavity operation at CMTF

Added by Shrividhyaa Sankar Raman 9 days ago. Updated 1 day ago.

Start date:
Due date:
% Done:


Estimated time:
Spent time:


  • Unable to control cavity 4 parameters – using controller 2 in the control 1 position.
  • Stopped and started LV when switched to cavity B.
  • Tried connecting to the HWR dev controller in the lab to check this and found the same problems.
  • Ran cavity B in CW mode and applied a FF value of 0.5 and looked at the waveform for control out I and Q.
  • This displays the constant value for FF I and Q seen by the controller.
  • It does not display the entered value for cavity B but the value for cavity A.


#1 Updated by Shrividhyaa Sankar Raman 9 days ago

  • Priority changed from Normal to Urgent
  • Searched through the firmware files for possible error locations based on the output observed from DACs 1 and 3.
  • Checked to make sure the registers being written to are the right registers, by comparing the Debug output from the ARM code, the spreadsheet and the firmware.
  • Checked to make sure the right signals were received on the DACs (using the scope) upon changing the values on LabVIEW.
  • Noticed value of Magnitude on Cavity A is mimicked by value of Magnitude on Cavity B. This change takes effect only when the phase value is changed.
  • TODO:Check to see if this is a LabVIEW issue.

#2 Updated by Shrividhyaa Sankar Raman 9 days ago

  • % Done changed from 0 to 100
  • Labview checked but processing of parameter in question was not made for that parameter but for a derived parameter.
  • Checked for callback function of the derived parameter from the spreadsheet.
  • Callback parameter CHANGE_cb_CB_ff_magphase converts the Mag and Phase to I and Q.
  • Code computed using wrong variable.
  • Correction was made and tested with Labview.
  • Issue was corrected!

#3 Updated by Shrividhyaa Sankar Raman 9 days ago

  • Status changed from New to Closed

#4 Updated by Shrividhyaa Sankar Raman 1 day ago

Once the issue was corrected and tested at the lab, the code was taken to the CMTF facility and tested there and was found to work.

Also available in: Atom PDF