This document describes the basic principles for performing engineering-style troubleshooting of DEIMOS motors. The specific example cited here is troubleshooting motion of the DEIMOS slitmask select stage. The following commands can be run on polo, deimos or keamano:

• Halt the stage as you cannot turn the LEDs on with the stage in motion.

  modify -s deimot slselmod=Halt

  setting slselmod = Halt (wait)

• Turn the LEDs on so the stage knows it is safe to move.

  modify -s deimot slmskfop=on slselfop=on

  setting slmskfop = on (wait)
  	setting slselfop = on (wait)

• Go into engineering jog mode, in which we don't have to be calibrated and we can back out of soft limits.

  modify -s deimot slselmod="Jog ENGR"

  setting slselmod = Jog ENGR (wait)

• Set your speed. The stage should move, one direction for positive SPD and the other for negative. 10000 is moderately fast. 2000 is really slow. 1000 is so slow that an observer has a hard time seeing the movement.

  modify -s deimot slselspd=-2000

  setting slselspd = -2000 (wait)

• Watch the SLSELTOR value with a cshow, and you should see it wobbling around as the screw flexes and the whole assembly judders and hiccups, but it should vary between 0.1 and 0.8 most of the time. If it gets above 1.5 consistently then something's a bit fishy. If it gets to 3.0 the motor power will be cut by the controller.
  Note: if you get an error, like overtorque, the LEDs will most likely turn themselves off and you will have to start over from the top of this incantation in order to try again.
• To stop the stage:

  modify -s deimot slselmod=Halt

  setting slselmod = Halt (wait)

  or set SPD=0, but halt is easy and fast.
• Important: to restore the stage to normal observing functionality:

  modify -s deimot slselmod=Pos

  modify -s deimot slselcal=homed

  and you should be back in biz.