Keywords: pdbi-trouble

Next: Synchronisation Up: The Real Time system Previous: The Tasks and Programs Contents

## 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 (`ACQUIS`ition common locked) (CLEARED)
  This semaphore is used to lobck/unlock the acquisition common.

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