history-LogHistoryService
When enabled, this service maintains a buffered history (LogHistory) of some of the messages seen in the station’s standard
output. When troubleshooting, this log provides a history of recent error messages.
The LogHistoryService is available in the history palette. If it is not already present, drag it from the history palette to the Services node in the Nav tree, as shown here.
Figure 26. Adding the LogHistoryService
You can edit LogHistoryService properties and set configuration properties in the Property Sheet, as shown here.
Figure 27. Log history service properties
To open this Property Sheet expand and double-click LogHistoryService.
Properties
| Property | Value | Description |
|---|---|---|
| Enabled | true or false |
Activates and deactivates use of the component. |
| Minimum Severity | Error (default), Warning., Trace, or Message | Use this property to set the lowest-level station output message that you want to log. Choose the level of output that you want to record. |
| 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 .
|
| Time Zone | display or drop-down list | The time zone is set up using the Set System Date/Time, which you access either using a platform connection and or using one of the station’s PlatformServices views (Platform Service Container plugin or System Date and Time Editor). Otherwise, the time zone is displayed for information only. |
| 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
Unlimited is not the wisest choice even for a
|
| 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 |
| 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. |
| Last Record | Container for read only values for sub-properties that describe attributes of the last recorded change: date/time the last record was made, time zone, and the operation that generated the record, and the user who made the change. |