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Why Does My LabVIEW Graph Ignore the Initial Timestamp and Time Interval When Displaying My Waveform?



Primary Software: LabVIEW Development Systems
Primary Software Version: 2014 SP1
Primary Software Fixed Version: N/A
Secondary Software: N/A

Problem:
I am using a waveform graph to display a waveform with a specified initial timestamp and time interval. However my graph is ignoring these waveform properties and plots my data beginning at zero on the X-axis.  When graphing waveforms with different initial timestamps, the graph does not show this offset and both waveforms begin at zero on the X-axis. How can I configure the X-axis to use my timestamp data?

Solution:
Waveform graphs ignore the timestamp properties of the input waveform by default. The graph will instead display waveform data with the array index number along the X-axis. This is why the graph displays all waveforms beginning at zero.Waveform graphs ignore the timestamp properties of the input waveform by default. The graph will instead display waveform data with the array index number along the X-axis. This is why the graph displays all waveforms beginning at zero despite different initial timestamps.

While this is convenient for comparing multiple waveforms with different start times, this is not always desirable. To change the behavior of a graph, right-click on the graph and deselect the Ignore Time Stamp option from the menu as seen in the image below.




When this option is deselected, the waveform graph will display the time stamp data along the X-axis using an absolute display format. To change the display format for the timestamps, right-click on the X-axis and select Formatting... to open the menu seen below. Select the Advanced editing mode radio button on that menu to specify a format string. 



These steps will configure a waveform graph to display timestamp information along the X-axis. Multiple waveforms will be displayed with different initial timestamps and show their offset.

Note: The waveform graph is a polymorphic indicator so the source data can be either an array or a waveform. If the data source is a one dimensional array, then the data has no timestamp information and the graph will not display timestamps. The option discussed above to Ignore Time Stamp will not appear in the right-click menu. This setting is only available when a waveform is wired as the data source for the graph.

Related Links:
KnowledgeBase 1W3F9QHE: How Do I Display the Time and Date on the X-axis of a Graph or Chart in LabVIEW to Timestamp My Data?
KnowledgeBase 1H6G9A4S: How Do I Programmatically Format the X-Axis of a LabVIEW Graph to Display Timestamps?
KnowledgeBase 0HLH2GTA: What is the Difference Between Graphs and Charts in LabVIEW?

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Report Date: 10/19/2000
Last Updated: 08/27/2015
Document ID: 22IELSL3

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