Data archiving is defined by the configuration of an object Historical value. Object describes the source of archived values and archiving method. Object of Historical value type allows to archive:
- simple value of object (not structured variable),
- an item of object of Structured variable type,
- a column of object of Structured variable type,
- object of Structured variable type.
Object of Historical value type can be:
- simple historical value - object represents the course of one parameter in time,
- one-column historical value - object represents the courses of R parameters in time, where the parameters are arranged in one column (each parameter is defined by its serial number 1...R down from top),
- structured historical value - object represents the courses of R x S parameters in time, where the parameters are arranged in matrix containing R-columns and S-rows (each parameter is defined by its column and row).
!!! WARNING !!!
When saving the configuration of the object of Historical value type (by means of the processes D2000 CNF), D2000 system is checking whether the object has not been changed within the meaning of the classification mentioned above. If the object has been already changed, the system displays a warning message that contains both the previous and current object statuses. If the operator saves the object configuration in spite of this fact, some of the D2000 system parts will get into inconsistent status.
Example: The object H.Archiv has been changed from structured historical value to simple one then all ESL scripts, containing e.g. the item H.Archiv ^Item, are obviously incorrect. Such situation also occurs everywhere the items of structured historical values are used in configuration.
Defining the same data source for more Historical values allows to a multiple archiving of the same data with the definition of various archiving criteria. For example: a short-term archiving that very precisely stores all value changes and a long-term archiving that stores only significant changes.
The process D2000 Archiv provides value archiving of object of D2000 system into SQL database.