Value history
The DemoApplication uses the actual WinCC OA HistoryDB for storing the value history (see also History DB). This data is always saved on an event basis and thus constitutes a complete picture of the history. In addition to the common data types such as float and integer, the WinCC OA history database can also save other data point element data types such as strings, Bit32 and a wide range of dynamic array types (see Data types of History DB).
Several autonomous archives
Several autonomous archives can exist in parallel. Parameters can be set specifically for each archive for changing records, back-up times, archiving times or delete cycles. In this way, it is possible to store highly dynamic data points in the system online without restrictions or compression and for a defined period of time. Statistical data calculated from this information, compressed values or merely less dynamic data point elements are simply stored in other archives and can then remain accessible for considerably longer periods of time. By this means, it is possible to achieve really long-term archiving over many years without having to make compromises in the highly dynamic online area.
The archives are completely maintenance free and have automated administration.
Setting parameters
The parameters for each of the archives are set via the Database configuration button behind the Database tab in the System management panel (see also System management).
The six archives programmed for the DemoApplication can be seen in the console (see also Starting and Stopping the DemoApplication) as processes to be run, as well as in the corresponding panels in System management.
The function of an archive should be obvious from its name.
Figure: Panel for setting Parameters for the Value Archives
