Use Case:  Set Nasmyth Beacon Light Level

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

Role(s)/Actor(s): 
Primary: Operator,Maintenance
Secondary: Nasmyth sub-system

Priority: Desirable.

Performance: <1 second

Frequency: Asynchronous, typically while alignment procedure.

Package Assignment:  Nasmyth Focus Device Subsystem.

Preconditions: 

• Nasmyth sub-system is ONLINE
• Coudé Sensor Unit is protected for saturation (FSS ND filter)
  (Check not automatic)
• Nasmyth wheel on position 3 or 4 (TOOL #1 or #2)
  (in operation only these 2 positions make sense; in the other 2 wheel positions, switching on the Nasmyth beacon has little effect).

Basic Course: 

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

  Interface:  IfNasmythBeacon.No1On/Off,  IfNasmythBeacon.No2On/Off

  Exception Course: Command failed
  
• ATCS returns OK reply

Exception Course: Command failed

• ATCS returns ERROR reply

Postconditions: 

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

Issues to be Determined or Resolved: 

Notes:

• The intensity shall not be zero.
• The command GETNBCN returns the status of the 2 Nasmyth beacons:
  On/Off state and Intensity in % if On

Last modified: Fri Nov 23 08:01:04 UTC 2001