## Commons

All real-time tasks interact through global commons:

- GENERAL is for general parameters,
- ANTENNA for antenna related parameters,
- RECEIVER for receiver related parameters,
- ACQUIS for continuum detector and correlator parameter and results,
- OBSRED and ACTIVE are shared between OBS and the acquisition program RDI.

A set of semaphores are used for synchronisation.

- S_ANT (ANTENNA common locked) (CLEARED)
  This semaphore is blocked (set) whenever a task uses the antenna common and released (cleared) when the operation if finished. The next task requesting the common can grab it, and so on...
- S_GENERAL (GENERAL common locked) (CLEARED)
  This semaphore is used to lock/unlock the general common.
- S_ACQUIS (ACQUISition common locked) (CLEARED)
  This semaphore is used to lobck/unlock the acquisition common.

This scheme is used to avoid conflicting actions from several tasks.