How to adjust discriminator threshold on BBCAL DAC

From SBS wiki
Jump to: navigation, search

<<SBS Main<< HOW TOs (BigBite Spectrometer)

How to adjust the VME DAC BBCAL discriminator thresholds

  • Log into sbs-onl@adaq1 with the usual sbs-onl password
 ssh sbs-onl@adaq1
  • Navigate to /adaqfs/home/sbs-onl/hcal/GUI.
  • To set the environment variables do:
  • Execute the following command to open the DAC control GUI:

DAC GUI Startup Output.png

  • After executing the command, the a new DAC GUI should pop up which has instructions to load, initialize and save the settings and adjust the thresholds. The terminal in which the command was executed should also print the previous settings of all the channels.

DAC Control GUI.png

  • Click on "Load mpv04Library tab" to load a library
  • Click on "Initialize mpv04" to initialize the library
  • Click on "Save settings" to save the settings
  • Go to the "Enter DAC Output Voltage Setting (V)" and enter the desired output voltage of the DAC channel.
  • Click on "Set Voltage". Note this sets the DAC output voltage which is not equal to the threshold setting. The predicted threshold setting can be seen in the "Predicted Discriminator Threshold (mV)" column and the actual readback for the HCal sum trigger threshold and BBCal Hi Discriminators 1 and 2 can be seen in the "Threshold Readback (mV)" column.
  • Make sure that BBCal Hi Discriminator 1 and BBCal Hi Discriminator 2 have the same readbacks. You might need to tweak the set value in one of them to make sure that the readbacks are equal.
  • It is also possible to query the readbacks on aslow@adaqsc using:
 caget SBSDaqPi1:thresh1 - for HCAL threshold
 caget SBSDaqPi1:thresh2 - for BBCAL DISC HI1
 caget SBSDaqPi1:thresh3 - for BBCAL DISC HI2
  • For problems/questions with this GUI contact Scott Barcus (