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Each historical value can have its own history depth configured. The D2000 Archive process Archiv process periodically deletes values older than the history depth every few hours in such a way that at least one value older than the history depth history depth always remains.
In addition, it is possible to configure in the D2000 Archiv process the so-called depository databases that provide time-unlimited archiving for those historical values that have the Depository option enabled.
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- By opening a graph - the D2000 HI process automatically generates requests to read all the values displayed in the graph.
- By opening a picture in history mode.
- By actions for reading from the archive: GETARCHVAL, GETARCHARR, GETARCHARR_TO_CNT, GETARCHROW, GETARCHCOL, and GETARCHSTRUCT.
- By requesting historical values from outside the D2000 system:
- Reading via the D2000 Gateway from another D2000 system as a response to the GETOLDVAL command.
- Reading via D2000 Kom process (server protocols, e.g. IEC 870-5-104 Server).
- Reading via D2000 OBJApi function GetArchivData.
- Reading via D2000 VBApi (from Microsoft Visual Basic or Microsoft Excel programs) with functions VBApiGetArchData (simple historical value) or VBApiGetArchDataItem (item of a structured historical value).
- Reading via D2000 Java API.
- Reading via D2000 ODBC driver,
- Reading via D2000 REST API.
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