Use Case:  ATCS Stop

Description:  The telescope is stopped at the current position, the brakes are engaged, the control loops disabled, and the sub-systems are put in a STANDBY safe state, but most functions are left switched on in order to resume quickly the operational state.
Each required sub-system used during observation is brought in state STANDBY.
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 ONLINE or STANDBY (for example STANDBY, substate ERROR).

Basic Course: 

• Send command STOP to Stop ATCS
  Exception Course: Command failed
• ATCS puts in STANDBY all required and not ignored subsystems used in observation mode

  by using Standard Command.

  Control loops are disabled and brakes engaged.

  Interface:  IfAltDrive,  IfAzDrive

  Exception Course: Command failed
  Postcondition: all required and not ignored subsystems are in STANDBY
• ATCS global system state update
  Postcondition: ATCS in state STANDBY, substate IDLE
• ATCS sends final OK reply

Exception Course:  Command failed

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

Postconditions: 

• ATCS is in state STANDBY substate IDLE
• All required and not ignored ATS subsystems used in observation mode are in STANDBY
  (control loops are disabled and brakes engaged).

Issues to be Determined or Resolved: 

Notes:

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