History import and export
Under the NiagaraNetwork and the BacnetNetwork, local data logging provides the ability to use the HistoryDeviceExt. This device-level extension serves as the parent container for history descriptors--components that specify how history-type collections (log data) are imported or exported. The HistoryDeviceExt property sheet, shown in Figure 4-13, has the following properties that you can use to adjust history-related communications:
Retry Trigger
Refer to "Retry Trigger," page 4-14 for details.
Retry Interval
The retry interval property also includes the ability to schedule “retries” at specific times or manually. This allows you to consider when and how often to allow import and export attempts across the network.
Figure 4-13 HistoryDeviceExt
Creating history import and history export descriptors is how you save a history to a different location (station) from where it originated. In a typical application, this is considered “archiving.” For example, an originating history (with a limited record count) may be in a JACE station. If imported to a supervisor station, its history import descriptor can be configured such that the imported history in the supervisor has “unlimited” record capacity. The JACE history can run collecting only the last 500 records, while the imported history in the supervisor will collect all (unlimited) records. These settings affect the size of the history logs that are archived over the network.
History import
History import provides some controls that allow you to limit or expand the size of the files that are archived to the local station. These properties are shown in Figure 4-14 and described as follows:
Figure 4-14 Selected history device extension parameters
Enabled
Refer to "Common control properties", for details.
Trigger Mode
Refer to "Common control properties", for details.
Config Overrides:
This component allows you to specify a number for Capacity and Full Policy. These parameters allow you to control the number of records that you pull in on an import (Capacity) and (if a capacity number is set) to specify what to do when that number is reached (Full Policy).
These “override” options provide a way to limit import file size and bandwidth and are called “overrides” because they take priority over the values that are specified in the remote station under a point’s individual History Ext, History Config properties.
History export
History export provides controls that allow you archive history files at defined times and intervals. To limit or expand the size of the files that are archived to the local station. These properties are shown in Figure 4-15 and described as follows:
Figure 4-15 Selected history device extension parameters
Enabled
Refer to "Common control properties", for details.
Trigger Mode
Refer to "Common control properties", for details.