Triggers to move tags into store-forward state

If the normal data collection algorithm detects a bad quality and connection loss (10) detail in the queried data, then the tag is put into a store-forward queue. Additionally, all tags are marked as in store-forward if the Wonderware Historian SDK HistorianConnectionStatus ConnectedToServerStorage property is false. A false ConnectedToServerStorage occurs in the following Wonderware Historian states:

1. The Wonderware Historian is in a stopped state

2. The Wonderware Historian is in a shutdown state

In both of the above cases, all the tags are moved into store-forward state. To lessen the impact on the Wonderware Historian and to allow some of the store-forward data to arrive in the historian, a delay is added after the ConnectedToServerStorage is set to true. The delay represents approximately one-third of the total time that the ConnectedToServerStorage flag was false. After this delay, the same store-forward algorithm described earlier is used on the tags. Initially, both Wonderware Historian states might appear to represent the same store-forward states, but observation of the data reveals something different.

For stopped historian state, a bad quality and Connection Loss (10) are not seen immediately or are never seen at all. The wait for the First-Store-Forward data value (248) helps delay the algorithm long enough for the historized data to catch up in the historian. Without the wait for the First-Store-Forward data value the algorithm exits too quickly.

The shutdown state has most of the same markers as a data source store-forward event with the bad quality and Connection Loss (10) detail, but in rare cases has been observed (rarely) to behave like the stopped state with the Connection Loss delaying its appearance or not at all. A shutdown state also causes a loss of connection to the Wonderware Historian server. The algorithm accounts for this by attempting to reconnect to the server before proceeding with the store-forward data collection.