Trend Chart Overview

The trend chart allows you to plot real time data from OPC UA servers and historical data from Historian servers. You can plot the data using the context of a model or browse for a Historian or OPC UA server. You can then add tags to the chart.

The model contains asset types and assets. The assets have properties associated with them, which are, in turn, associated with tags defined in Historian or OPC UA.

The following image shows an example of a trend chart.

The following table describes the tasks that you can perform on a trend chart.
Task Procedure
Access the properties used in a trend chart. The properties used in a trend chart appear in the Legend section.
Show/Hide the plotted data To display this option, select a property from the trend chart legend. Use to show or hide the data on the chart.
Remove a property from the trend chart. To delete plotted data from the trend chart, select the respective property from the legend, then select .
Increase the area of a trend chart.
  • Hide the toolbar by selecting .
  • Hide the Legend section by selecting .
Pause the data flow of a trend chart. This option is available only for the live mode.
  • On the toolbar, select to pause trending.
  • You can resume the data flow by selecting .
View the delta value between two data points. The delta values for the trend is displayed in the Legend section.

On the toolbar, select , and select the two data points whose delta value you want to view.
Display units on the Y-axis If a source tag has engineering units, then the unit information appears on the chart's y-axis, legend, and tooltip.

Units do not appear on a single y-axis. If you opted for a single y-axis configuration, the units appear only on the chart's legend and tooltip.
Drill down a trend chart. On the toolbar, select to drill down or zoom into a trend chart for more granular information. To zoom out, select .

If you want to zoom in or zoom out a single axis, select the axis in the drop-down list box next to .

If you want to enlarge an area on the chart, select , and then select the area on the chart.

Data is re-fetched only in historical mode when zoomed in/out (changes chart start time/duration) of a chart. For example, consider trending 500 samples from 1-2pm, then zoom in to 1:00 - 1:10pm to request 500 samples data for that 10 minute span.
Pan across a trend chart. You must zoom in/out of a chart to be able to pan across a trend chart. The pan icon is enabled when you perform the zoom operation.

The pan icon is visible only in the Live mode.

  • Zoom in/out of a chart.
  • On the toolbar, select , and then drag the icon to the area on the chart that you want to view.
  • Move the icon left/right to pan across the x-axis.
  • Move the icon up/down to pan across the y-axis.

In Historical mode:
Mark a trend chart view as favorite. It is an easy way to view the trend chart for commonly used configuration settings. On the toolbar, select , enter a name for the view, and then select Add.
Important: Special characters ? / \ # ; % are not supported. Do not include them in your favorite name.
To load a favorite view, select the view from the drop-down list box next to .

You can also access the list of saved favorites while creating application pages in Operation Hub. Under Trend Card widget properties, select a favorite chart view from Select Favorite drop-down list. The selected view loads by default when you launch the trend chart at runtime.
View the statistics of tags plotted on a trend chart. On the toolbar, select to show/hide the statistical data for Historian tags used in the trend chart. The statistics appear below the chart.

In historical mode, tag statistics are re-fetched on zooming in/out (changes chart start time/duration) of a chart.
Trend Card This is the default chart type. There are three chart types:
  • Stacked Y-axis
  • Trend Card
  • Tabular View
You can access other chart types from the trend chart toolbar.
Stacked Y-axis On the toolbar, select Stacked Y-Axis to stack multiple charts. For example, if you choose to trend four tags, the chart appears with a common x-axis and a stacked y-axis. With a stacked y-axis, you can:
  • View delta for all the charts in a stack.
  • Mouse-over each chart in a stack to view tooltips.
  • Configure a source tag to change the chart type to line, area, or scatter.
  • Configure a source tag to apply a label name along the y-axis for the chart.
Note:
  • Zooming into Y-axis and X/Y-axis is disabled.
  • It is recommended to use the scroll bar to scroll through the stacked charts. If using any other means of scrolling (mouse scroll wheel, touch pad/screen) to scroll through the charts, the tooltips appear inconsistently when you hover from one tag to other. To fix this, move your mouse pointer out of the chart area, and then mouse-over the tag to view its tooltip.
Tabular View On the toolbar, select Tabular View to display data in a table format.
  • Tags appear as column headers. You can choose a display style for tags. If Tag Name and Description is selected as display style, mouse-over the the column (tag) name to view its description.
  • You can select the number of rows to display per page, whether 50, 100, 200, or 500.
  • Filter data in each column to search for the exact values.
  • Sort the TIMESTAMP column values in an ascending/descending order.
Export the trend chart data. The trend chart data is exported and saved as a CSV file.
On the toolbar, select , then select to export data.
Print a trend chart. On the toolbar, select , then select .
You have the option to provide a title that appears above the trend chart.
Reset the trend chart options. On the toolbar, select , then select . Any changes you have made to the duration, start time, axis preferences, and properties are reverted.
Scroll through the historical data. Select and to move back and forth in the chart, and access historical data. Scrolling back and forth changes the start time for the chart.

For example, if you are currently viewing trends during 1-2pm, you can scroll back in time to view 12:45-1:45pm, then return to current view.

Recommendations While Using a Trend Chart

When you create a trend chart, we recommend that you apply the following guidelines:
  • When you add a trend chart to a page using the page designer, use separate containers for the breadcrumb and the chart. For the trend chart, set the height to 100%.
  • When accessing a trend chart on a mobile device:
    • Use a device with medium to high resolution.
    • Use the device in landscape mode.
    • To print a trend chart using an Android device, use the screen capture feature rather than selecting .
    • Configure the trend chart using a desktop rather than an Android device. This is because when you attempt to search for an asset or a Historian tag on an Android device, the in-built keyboard of the device appears, which may not allow you to enter the search criteria.
    • When you view the delta between two data points, the value may not be clearly readable on a mobile device with low to medium resolution. Therefore, we recommend that you view the delta value on a desktop or a mobile device with high resolution.
    • When you view statistical data, the trend chart area may be limited. To avoid this issue, plot up to two properties on the trend chart.
    • To pan across the trend chart or drill down the trend chart on an iPad, use the Zoom feature of the iPad rather than selecting , , or , respectively.