Use Case:  Set M2 Pupil Beacon Light Level

Description: This UseCase allow the setting of the light intensity (from 0 to 100%) of the pupil beacon currently switched on.

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 sub-system is ONLINE
• Coudé Sensor Unit is protected for saturation (FSS ND filter)
  (Check not automatic)
• Nasmyth wheel on position HOLE
  (in operation only this position makes sense; in any other wheel position, switching on the pupil beacon has little effect).

Basic Course: 

• Send command SETPBLV <intensity> to set the Pupil beacon light source level
  Exception Course: Command failed
• ATCS sends the command to M2 sub-system

  Interface:  IfPupilBeacon

  Exception Course: Command failed
  
• ATCS returns OK reply

Exception Course: Command failed

• ATCS returns ERROR reply

Postconditions: 

• Pupil beacon light source intensity to given value in percent.

Issues to be Determined or Resolved: 

Notes:

• The intensity shall not be zero.
• The command GETPBCN returns the status of the pupil beacon:
  On/Off state and Intensity in % if On

Last modified: Fri Nov 23 11:55:17 UTC 2001