Archiving
History import and export descriptors save a history to a different location (station) from where it originated. In a typical application, this is considered archiving. For example, in the originating controller station, a history may contain a limited number of records. In the Supervisor station the same history may have unlimited record capacity. This topic provides information that is unique to histories under a NiagaraNetwork.
History features:
Upon a join command, export tags in a controller station automatically add pre-configured history import descriptors to the NiagaraStation under the Supervisor station’s NiagaraNetwork and import the histories from the controller station to the Supervisor station. This is one of many functions provided by export tags.
The Niagara History Import Manager and History Export Manager view support folders under the to better organize history import and export descriptors. Each folder provides these manager views.
The Device Histories View on a NiagaraStation Histories extension provides shortcuts to histories. Although not unique to the NiagaraNetwork, this feature may be useful, especially in a Supervisor station.
On-demand polling for both local histories and imported histories makes it possible to poll for live data when viewing a history chart or history table view. The Live Updates button (play icon) toggles this feature.
You can import and export histories based upon system tag text patterns rather than by using explicit History Ids, that is, using a discovery job in the History Import (or Export) Manager you can select specific histories to add. This utilizes a System Tags property in the history extensions.
The last two features above have associated properties in history import and history export descriptors with values available in the corresponding manager views. In addition, the on-demand polling feature has an associated On Demand Poll Scheduler component under the NiagaraNetwork’s history network extension (History Policies).