Talk Notes on Multiknob and Bump Requirements

Beamline and Model definition.

The beamline and model is defined in the XAL beamline defintion file that Paul is maintaining:
http://www.slac.stanford.edu/cgi-wrap/cvsweb/physics/config/model/lcls.xdxf?rev=1.1&content-type=text/x-cvsweb-markup&cvsroot=LCLS
The default "accelerator" is loaded at startup. If you want to load a test model, Use Accelerator->Load Accelerator...

Create a multiknob

To create a knob, just do the following:

1. Optionally, create a group .
2. Create a knob
3. Add devices:
   1. Do this "by hand" if you know the PV. Eg YCOR:IN20:492:BDES
   2. Do this by "drilldown" (which uses physics name). In the Editor:
      1. Select a model sequence: Eg BXG TO BX01. Note that sequences are in alphabetical order. That is on the fix list.
      2. Select a device "type". Note that the type names given are:
         1) SNS type names, which themselves use >1 name eg hcorr == dch == horrzcorr => X correctors.
         2) and also flattened hierarchy of types, eg type "dipole" includes hcorr and vcorr.
      3. Select a device name, by "physics name".
      4. Select FieldSet (not FieldRB). (issue: FieldRB should not be offered).
   3. Or calculate bump knobs
      1. Select a section of contiguous sequence of sections (a "combo sequence") Accelerator->Sequences
         BXG TO BX01 - BX01 to BX02 works.
      2. Knobs->(Make Horizontal Bumps | Make vertical bumps) Make Horizontal Bumps (Make Vertical Doesn't work, since it seems so many of our correctors are SLC!)
      3. For Horizontal Bumps: These setups were tested.
         1. Design Offset 3 (default) magnets - works (4 magnet doesn't work!)
         2. Design Angle 5 (default) magnets - works
         3. Live Offset 3 - works
         4. Live Angle 5 works - works
      4. For Vertical Bumps, select sections BXG to BX01 - QM15 to FV2
         1. Design Offset 3 (default) magnets - works, but they're mostly SLC magnets, so you can't connect and can't set them.

Coefficient setting options

1. Fill Down. Set all the coefficients' values to the value of the first.
2. Proportional. Set all the coefficients to their devices' value, and set the knob factor to 1 (ie, no change)
   So good for moving all to 0 slowly.
3. Magic. What's that

Problems and Issues

1. Knobs app can't set non-EPICS devices (eg correctors), so;
   1. In "drilldown" mode it offers you devices to set that it can't in fact set (eg having selected BX02 TO QM15, you select Y corrector YC21303 (which is in fact an SLC CS corrector), select FieldSet (which you shouldn't have been able to do) and then it can't connect.
      WORK AROUND: Be conscious of what's SLC and what EPICS. See resources 0,1.
   2. It makes bumps using correctors it can't set!
      Eg: Select sequence indexes 2,3,4,5. Make Vertical design offset knobs. The first knob created is BPM21301. This contains 3 correctors, all SLC! Eg YXC21303 - YCOR:LI21:303. So, knob can't be implemented. This problem seems particularly acute for Vertical bumps! Are more of our horizontal correctors EPICS?
      NO work around. *Will have to fix so that that elements which are not settable="true" in the xdxf file, are not included.
2. Knobs->"Proprotional Coefficients" spelt wrongly.
3. Knobs Editor uses SNS type names, which themselves use >1 name eg hcorr == dch == horrzcorr => X correctors.

Misc.

1. Deleting a knob: To delete knobs - select (can sect >1 with shift select) and Delete key.
2. Help. Click on Help->Contents