Use Case:  Switch On/Off M2 Pupil Beacon Light Source

Description:  Switch On/Off M2 Pupil Beacon light source. This action is dedicated to optical alignment procedures and is therefore not foreseen to be used during normal operation. Only one beacon can be switched on at a time. This constraint applies as well for the Nasmyth beacons (NFD sub-system).

Role(s)/Actor(s): 
Primary: Operator,Maintenance
Secondary: M2

Priority: Desirable.

Performance: 1 second

Frequency: Asynchronous, typically while alignment procedure.

Package Assignment:  M2 Subsystem.

Preconditions: 

• M2 is ONLINE
• Coudé Sensor Unit is protected for saturation (FSS Neutral Density filter)
  (no automatic check: this pre-condition shall be checked using a dialog box from the engineering panel, or an acknowledge from osf scripts).
• Nasmyth wheel on Free Hole position
  (in operation only this position makes sense; in any other wheel position, switching on the pupil beacon has little effect)

  Interface:  IfNasmythWheel.Encoder.PositionReadout

Basic Course: 

• Send command SETPBCN <ON|OFF> to switch ON/OFF M2 beacon light source
  Exception Course: Command failed
• ATCS sends the command to M2 sub-system

  Interface:  IfPupilBeacon

  Exception Course: Command failed
  Postcondition: M2 beacon light source switched ON/OFF

  Interface:  IfPupilBeacon

• ATCS returns OK reply

Exception Course: Command failed

• ATCS returns ERROR reply

Postconditions: 

• M2 pupil beacon light source is switched Off or On with the default intensity (configurable in the database).

Issues to be Determined or Resolved:  Check preconditions

Notes:

• The pupil beacon is an halogen source giving white light.
• The command GETPBCN returns the status of the pupil beacon:
  On/Off state and Intensity in % if On

Last modified: Fri Nov 23 11:48:29 UTC 2001