Background and live history charting provides a Live History Chart view that is similar to the static History Chart view. The key feature of the Live History Chart view is that it combines the historical plot of the History Chart with a continuing live plot that updates according to a configurable sample rate.
The live history chart view plots the data of the selected history log along x and y axes. This is the default view of the HistoryPointList component, so if you double-click on a HistoryPointList in the NiagaraAX-3.3 (or later) workbench nav sidebar, the Live History Chart view displays. An example of the Live History Chart view is shown in Live_History_Chart_view, below, which highlights the features that are only available in the Live History Chart view.
The Live History Chart view contains the standard chart controls and options to help you customize and view the data. However, in addition to these controls and options (described in Chart controls and options) this view has the following additional features:
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Item List pane
This pane displays all the points that are linked to the chart view. You can click to select or de-select each item to display or remove the associated item plot from the chart. You can always resize the pane by dragging the left border to widen or narrow the pane in the view.
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Toggle Item List button
Click this button to display or collapse the Item List pane.
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Continuously updating view
As new data is plotted the view continues to update. When the chart area is filled, the screen scrolls to keep showing the latest data.
You can display the Live History Chart view as either a view of a history extension or as a view of the HistoryChartList component, as shown in the following two illustrations:
You can use relative paths to point to history extension ords when using a HistoryPointListItem component. This allows you
to create a HistoryPointList under a typical device (Air Handling Unit, VAV, or other) and then copy the device (with HistoryPointList)
to other locations without having to edit the ords for each new location. In the example shown in Figure 149, the HistoryPointList and the proxy points (zoneTemp1, 2, 3, and so on) with their history extensions are placed at the same
level (in the same folder). The HistoryPointList component takes care of resolving the ord path for each HistoryPointListItem,
so the relative starting point is the HistoryPointList and not the HistoryPointListItem. In this example, the History Extension
path needs to step up one level using the “../” then includes the folder name (“zoneTemp1/numericInterval”) to designate the history extension.
You can also embed the History Chart view of a “relativized” history extension ord into a Px view. This allows you to use
a single Px view for multiple HistoryPointList (and associated Live History Chart view) locations.