Support #12140

Need to create a computed device for PXIMPS

Added by Richard Neswold about 5 years ago. Updated over 2 years ago.

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We wish to add a device to the machine protection front-end at CMTF (PXIMPS) which shows correctly scaled units for the integrated gate and train inputs.

Through measurements, it was determined that the value of P:GATE1 is inversely proportional to the pulse width (P:L20M0H). Unfortunately, the pulse width device is located on another system than P:GATE1, so PXIMPS will read this parameter at 10 Hz to keep the scaling up to date. Fortunately, the pulse width device isn't adjusted often so, if there are network problems, our copy of its value will probably be correct throughout the outage.

Scaling P:GATE1

We're using the linear transform:

P:GATE1 = (c1 / c2) x + c3


x is the hardware reading of P:GATE1
c1 is 100
c2 is P:L20M0H x 12594
c3 is 74.028 / 12594

This transform is presented in the form used by the control system's scaling library (rather than the traditional "y = mx + b".) We are actually changing both of the device's controls system transforms to identity transform. The scaling is done in the driver.

Scaling P:TRAIN1

The scaling for P:TRAIN is still being determined.


#1 Updated by Richard Neswold almost 5 years ago

  • Priority changed from Normal to High

Mark as a high-priority task.

#2 Updated by Richard Neswold almost 5 years ago

  • Status changed from Assigned to Feedback

This feature is now in the driver. The next few things that need to be done (in addition to making sure the driver is scaling this new parameter properly):

  • Need to update PXIMPS's startup script to load additional modules.
  • Create a new device, P:GATE1S perhaps, that is the same as P:GATE1 except the subcode in the last word of the SSDN is 5 instead of 3. The scaling also needs to be changed to accept a IEEE float.

commit vme-blm|d237c9de

#3 Updated by Richard Neswold over 2 years ago

  • Priority changed from High to Low

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