Starting the multiknobs XAL application

Using the "physics" account, on lcls-srv01, type 'knobs'.

[physics@lcls-srv01 ~]$ knobs

Beamline and Model definition.

The beamline and model is defined in the XAL beamline defintion file that Paul is maintaining:
The production model is in:

/u1/lcls/physics/config/model/lcls.xdxf

This is the default "accelerator" 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.
    Hit the "Add a new Group" button, and enter a name for the Group. This is a way to collect knobs by use, for instance "InjectorKnobs" because there can be >1 knob in a group.
  2. Create a Knob.
    Click on the knob you created, and hit the "Add a new knob" button, and enter a knob name.
  3. Add devices:
    1. Do this "by hand" if you know the PV. Eg YCOR:IN20:492:BDES (YC06)
    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.
  4. "knob" your knob with the arrows. There is no "SENSitivity" in the SLC multiknobs sense, but you can choose the digit to vary.
  5. "Zero" means define the present values as zero of the knob, not move devices to zero of the knob.

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(question)

Comparing SLC multiknobs, with the XAL knobs.

Comparing GUI Applications: the SCP's "Multi Device Knobs" panel vs. XAL Knobs GUI: The SCP's panel is all about

  1. Choosing a file from a directory of mkb files, and assigning it to a knob. This is done in XAL knobs by the Open File dialog, which opens a dialog onto the Default Folder. We can also put the files on the Web, accessed through the XAl knobs web page.
  2. Displaying the contents of some knob files directly as a button push. Contents of the file are displayed by the Knobs app.
  3. Organizing mkbs that have a common subject, into groups on a panel or onto different panels. XAL knobs does organization by Knob Groups.

Comparing non-GUI functionality

  1. In XAL knobs, only a single linear coefficient factor is available as the "knob" value factor; ie no power series or sine/cosine factors.
  2. SLC mkbs always "perturb" magnets and klystrons. In XAK knobs, no special action is taken at the level of the GUI, the method is dictated by whatever the PV implements.

Save and Load

  • You can save and reload knobs using the File->Save and File->Open or File->Open Recent.
  • Note that a .knobs file can contain more than one knob! It contains all the "Groups" and "knobs" that were in the application when you saved.
  • So, there are a couple of ways to organize knobs, knobs files, and groups in the knobs files.
  • The knobs files are in: 
    $PHYSICS_DATA/data/Knobs

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 select >1 with shift select) and Delete key, or Edit->Cut.
  2. Help. Click on Help->Contents

To Add

  • Is there any device type specific code, eg for timing (PDU, DUPCD)?
  • What about TDES and BEAM equivalents.
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