If the parameter archIdent is the reference to an object of Historical value type, the action performance is described above. If the parameter is the reference to an object (not of Historical value type) or a structured variable item that is not of Object type, the system is attempting to find an object of Historical value type that archives values of the object (item).
If the parameter archIdent is the reference to a structured variable item that is of Object type, the item "points" to an object in the system. If the object is of Historical value type, the action will read data from it. If it is not, the system is attempting to find an object of Historical value type that archives values of the object.

The reading result (value) is to be assigned to the variable valueIdent_Real. If this identifier is stated, the action will assign to it the value:

• True - data are loaded,
• False - no data.

If the identifier isDataIdent_Bool is not used and there are no data, the action doesn't modify a value of the identifier valueIdent_Real.

I the identifier archFlagsIdent_Int is stated, archive flags for a value, that was read, are saved into the identifier (archive flags are defined as the sum of the following constants):

• 1 - (ArcStart) - value stored into the database at the moment of D2000 Archiv start
• 2 - (ArcStop) - value stored into the database at the moment of D2000 Archiv stop
• 4 - (ArcBlock) - value stored into the database at the beginning of blocking the archiving (by the stop condition of archiving configured in D2000 CNF)
• 8 - (ArcUnBlock) - value stored into the database at the end of blocking the archiving (by the start condition of archiving configured in D2000 CNF)
• 16 - (ArcDeleted) - value from the archive database that was deleted by an user. The action ignores the deleted value (as if it were not in the archive)
• 32 - (ArcUsermodify) - value in the archive that was modified by an user
• 64 - (ArcOldVal) - old value that was read from a communication station
• 128 - (ArcProcessModify) - value that was modified by a process (not by an user: ESL Script, D2000 VBApi, ...)
• 256 (ArcLoadData) - obsolete: value was obtained from OS/2 database SQL Gupta via On-line archive database import
• 512 (ArcMonoTime) - value is stored with monotonous time
• 1024 (ArcK) - value of periodic archive is generated during reading as a copy of previous value

The logical AND (&), that may be also applied into integer operands, is used to test archive flags.
For example: If the condition aflags & 4 = 4 holds, then the flag of a value that was read from the archive database by means of the action GETARCHVAL is ArcBlock (blocking of the archiving).

Value of parameter archivInstance_Int defines the instance of archive which executes the request. If the parameter is not defined (or the value is 0), the active instance of archive will execute the request.

• If the particular archive process is not running, the action generates the error _ERR_ARCHIV_NOT_RUNNING.
• If an an object of Historical value is archived:
  • periodically, reading a value out of the period is unsuccessful
  • according to a filter, value for the required time is to be derived from the last stored value in the archive.

Reading of archived value: