LabVIEW stores a number of data points that have appeared on a chart in a buffer—the chart history. You can change the size of this history to change the amount of data that the chart remembers.

Notice Large chart history values can be memory intensive.

Unlike graphs, charts keep the history of data previously written. When a chart runs continuously, its history grows and requires additional memory space until the chart history is full. When the chart history is full, LabVIEW stops taking additional memory.

To adjust the chart history length and view previously collected data, complete the following steps.

  1. Right-click the chart on the front panel and select Chart History Length....
  2. Enter the number of data points you want the chart to maintain in its history buffer and click OK.
  3. Use the chart scroll bar to view previously collected data on the chart. If the chart does not have a scroll bar, right-click the chart and select Visible Items » X Scrollbar to display a scroll bar.
  4. Optional: To clear the chart history continually in a program:
    1. Go to the block diagram for your VI.
    2. Within a While loop, write empty arrays to the History Data attribute node for the chart.
    LabVIEW does not automatically clear chart history when a VI restarts. Clear the chart history to reduce memory demands.
    For an example of bulding a block diagram to clear chart history, see the Clearing Waveform Charts.vi example in the labview\examples\Controls and Indicators\Graphs and Charts\Waveform Graphs and Charts directory.