As in other manager views, when you click the Bacnet History Import Manager goes to “Learn mode,” split into two panes, and a Trend Logs discover job occurs (Figure 54). The figure below shows three Trend Logs already imported in the station.
To import Trend Logs (or Trend Log Multiples), you select them in the top Discovered pane, and then click , producing the Add dialog (Figure 55). This dialog shows some of a BacnetHistoryImport component’s properties.
Fields in the Add (and Edit) dialog for a history import descriptor in the Bacnet History Import Manager are as follows:
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Name
The BACnet Trend Log (or Trend Log Multiple) object’s name.
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Object Id
The BACnet object type, either Trend Log or Trend Log Multiple, and its instance number for that type, unique within the device.
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Execution Time
The frequency at which data is imported from the remote Trend Log (or Trend Log Multiple) into the Niagara history (or histories). Default is daily, at 2:00 AM.
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Enabled
Must be true (default) to import Trend Log or Trend Log Multiple data into the Niagara history.
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Capacity
Capacity of the imported Niagara history or histories, defaulting to unlimited.
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Full Policy
Niagara policy when history or histories reaches capacity.
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Time Zone
Specifies the “best guess” time zone offset, taking daylight savings time in consideration.
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Local History Name Format
Allows “BFormat” (Baja Format) syntax to specify the name of the Niagara history initially created and populated by the Trend Log data. The default value is
%name%, which recreates the BACnet name of the Trend Log object. You can modify this with other BFormat scripting, for example:%parent.parent.displayName% %name%, which typically would be the name of the Niagara BACnetDevice component and the BACnet Trend Log object name, e.g.J7Bnet BldgA_VAV1_FanOr, you can enter static text for the history name—or, some combination of static text and valid BFormat scripting text.
Note in the case of Trend Log Multiple import descriptor (BacnetTrendLogMultipleImport), the default
%name%value results in histories named using the BACnet name of the Trend Log Multiple object, with underscore delimiters adding the BACnet names of each _object_property record. See Figure 60 for an example.
Note that after adding, you can access additional BacnetHistoryImport properties from the property sheet of any BacnetHistoryImport or BacnetTrendLogMultipleImport. Also the following right-click actions are available:
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Execute
Like an from the manager, this updates the Niagara history from the Trend Log data.
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Clear Records in Device
Produces a confirmation dialog. If answered “
Yes,” the attempts to clear all records in the source BACnet Trend Log object. However, note that records in the imported Niagara history remain.
Also see the next section, About histories imported from Trend Logs.
Niagara histories imported from BACnet Trend Logs (and Trend Log Multiples) have additional fields in each record, namely “Sequence Number” and “Log Event,” which reflect BACnet-required items. These fields do not affect “History Chart” views of these histories, but do require slightly more storage space.
The concept of sequence number was introduced with Addendum B to the 2001 edition of the specification. Trend Logs that were
implemented against earlier editions (which includes logs from R2 Niagara stations, and Niagara AX histories that were collected
with a non-BacnetTrendLogExt) will not have sequence number in their log data, so Niagara has to access the records by time
only.
Figure 56 shows a History Table view of an example history created by a BacnetHistoryImport.
