history-HistoryConfig

history-HistoryConfig

This component configures a history in the History database.

Figure 21. History Config properties

The History Config component is available in the history palette under LogHistoryService. The following table summarizes the History Config properties.

Property	Value	Description
HistoryConfig		Container for sub-properties used to configure the attributes of the history record stored in the History space.
Id	Text string	Read only value. String results from value configured in history extension’s `History Name` property. An error string here indicates the `History Name` property is incorrectly configured .
Source	ORD	Read only value. Displays the ORD of the active history extension.
Time Zone	Text string	Read only value. Displays the time zone of the active history extension.
Record Type	Text	Read only values. Displays the data that the record holds in terms of: extension type (history) and data type (BooleanTrendRecord, NumericTrendRecord, and so on).
Capacity	Record Count: nnn (500 default), Unlimited	Specifies local storage capacity for histories. In general, 500 (default record count) or less is adequate for a controller station because those records are usually archived (exported) to a Supervisor station. For this reason, a very large number, such as 250,000 is acceptable for Supervisor stations. `Unlimited` is not the wisest choice even for a Supervisor station.
Full Policy	Roll (default), Stop	Applies only if Capacity is set to “Record Count”. Upon specified record count, the oldest records are overwritten by newest records. `Roll` ensures that the latest data are recorded. `Stop` terminates recording when the number of stored records reaches specified history capacity. Full policy has no effect if `Capacity` is `Unlimited`.
Interval	Text string	Read only value. For Interval-based data collection, the cycle time, or how often the history properties are checked. Any time you change this property, a new history is created (or “split-off”) from the original history because histories with different intervals are not compatible.
System Tags	Text	This property allows you to assign additional metadata (the System Tag) to a history extension. This identifier is then available for selective import or export of histories using the Niagara System History Import or Niagara System History Export option (using the System Tag Patterns). Each System Tag is separated by a semicolon. For example: NorthAmerica;Region1;Cities.