Use Case:  Set M2 Focus Position

Description:  Set M2 focus position. This case is used during telescope alignment procedure at begining of the night and/or whenever required by VLTICS-ISS/INS.

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

Priority: Critical

Performance: 1 second

Frequency:  Asynchronous, mainly during normal operations but also for optical alignement procedure, up to a couple of times per minute.

Package Assignment:  M2 Subsystem.

Preconditions: 

• M2 is ONLINE

Basic Course: 

• Send command SETFPOS <F> to set M2 focus at given focus position F
  Exception Course: Illegal focus position
  Exception Course: Command failed
• ATCS sends the command to M2 sub-system

  Interface:  Focusing.SetAbs,  Focusing.SetRel

  Exception Course: Command failed
• ATCS returns OK reply

Exception Course: Illegal focus position

• Focus position out of range (|F| > 1 mm)
  ATCS returns ERROR reply

Exception Course: Command failed

• ATCS returns ERROR reply

Postconditions: 

• M2 at given focus position

Issues to be Determined or Resolved: 

Notes:  At INIT time, the mirror is moved at the configured focus position, configurable in the OLDB (in mm)

Last modified: Tue Jun 4 15:12:15 UTC 2002