From OpenSCADAWiki
The service task of the redundancy mechanism is always running and executed at intervals which are set in the appropriate configuration field. The real work on implementing the redundancy is carried out in the presence of at least one redundant station in the list of stations, and means:
- Controlling of the connection with the external stations. In the controlling process the requests to remote stations are made to get the updated information and to check the connection. In the case of loss of connection with the station the repeat of connection to it is made through interval specified in the configuration field "Restore connection timeout". In the "Live" field of the station the current state of communication is displayed. In the "Counter" field the number of requests carried to the remote station, or the time remaining for the next connection attempt to the lost station is displayed.
- Local planning of execution the controller objects in reserve. Planning is carried out in accordance with the station level and preferences of execution of the controller objects.
- Calling the data synchronization function for the local controller objects, working in the mode of data synchronization from the external stations.