Use Case:  ATCS Start

Description:  Each required sub-system used during observation is brought from state STANDBY to state ONLINE, i.e. all sub-systems are completely activated and the telescope is under position control, ready to move at next operative command.
The brakes are disengaged, the control loops closed, A failure will leave the ATCS in state STANDBY substate ERROR.

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

Priority: Major

Performance: A few minutes

Frequency: Whenever necessary.

Package Assignment:  Mode Switching.

Preconditions: 

• ATCS is in state STANDBY

Basic Course: Start automatically

• Send command START to Start ATCS
  Exception Course: Command failed
  
• ATCS puts ONLINE all required and not ignored subsystems used in observation mode

  by using Standard Command

  Control loops are enabled and brakes disengaged.

  (Interface:  IfAltDrive IfAzDrive )

  Exception Course: Some sub-systems failed to go ONLINE
  Postcondition: all required and not ignored subsystems are ONLINE
• ATCS global system state update
  Postcondition: ATCS in state ONLINE, substate IDLE
• ATCS sends final OK reply

Alternate Course: Start manually

• Put ONLINE all required and not ignored sub-systems one by one.

  by using Standard Command from the Control GUI

  Exception Course: Some sub-systems failed to go ONLINE
  Postcondition: all required and not ignored subsystems are initialized and in ONLINE state

Exception Course: Command failed

• ATCS global system state update
  Postcondition: ATCS in state STANDBY, substate ERROR
• ATCS sends final ERROR reply

Exception Course: Some sub-systems failed to go ONLINE

• ATCS global system state update
  Postcondition: ATCS in state STANDBY, substate ERROR
• Ignore sub-systems that failed
  Alternate course: Retry to Start manually for failed sub-systems

Postconditions: 

• ATCS is in state ONLINE substate IDLE
• All required and not ignored ATS subsystems used in observation mode are initialized and ONLINE
  (control loops are enabled and brakes disengaged).

Issues to be Determined or Resolved: 

Notes:

Last modified: Thu Jun 28 13:32:59 UTC 2001