From: Tony Denault

   Subject: How to take calibration data for array focus stage.

      Date: 01/13/00


1. login to littledogm as spex
   It also helps to be able to see the voltage on channel 04 (Afoc A/D).
   Use the Spex XUI or littledog's ldog_show program.

2. Run the test stepper program
    % testStepper

3. Run this command to initialize program's motor parameters.
      Enter Command: io
      IO%  au pa hl st ln ac25000; vl5000;

4. Obtain calibration data:

   a. Center mechanism it is as close to 0 volts as you can get. You can
      do this my hand, or use IO mode and run motor commands, ie:

      au lp0;         <- lp to load position.
      au ma5000; go   <- example move absolute command.
      au mr5000; go   <- example move relative command.
      au rp           <- report position.
      au st           <- stop

   b. execute the 'AfocData' command. This is the procedure to measure
      steps vs volt.

   c. You should run this 2 times:

        From 0 to max positive steps.
            BegPos = 0
            EndPos = 350000
            Skip   = 5000

        From 0 to max negative steps.
            BegPos = 0
            EndPos = -350000
            Skip   = -5000

      The end position are out of range so you can measure the full & find where
      the limit trigger.

 d. If you hit a limit, the should report and error and abort further measurement.
    To the following:
   
    1. Go into IO mode.

    2. Issue 'au rp' to report the current position. This is the step position where
       the limit was triggered.

    3. To move back to step 0: au ma0; go

5. Notes:

   Positive hardware limit trigger at:  313106
   Negative hardware limit trigger at: -296261