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Since historical data is one of the most valuable items in SCADA and MES systems, the archive process is one of the first to be configured as redundant. On two (or more) computers, a pair of watchdog + D2000 Archiv process processes is configured using the SCS Config utility with the parameter /W<name>,<instance> indicating the name and number of the instance (e.g. /WSELF,1 or /WSELF,2) and with the parameter /S, /RD, or /RF specifying the server or redundancy group to which the archive connects (see Starting user processes).
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Historical value filled from a script (value storage) serves as a store of values that are not created by direct archiving of values of another object in the system, statistical calculation, or calculation in a calculated historical value. Filling in values is only possible from the ESL script or manually through the D2000 HI process. The value storage can be variable or periodic. The periodic value storage can have value playback enabled - in real time it publishes the values that were previously inserted by the script (e.g. production planning data).
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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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