Use the digital waveform graph to display digital data, especially when you work with timing diagrams or logic analyzers.

The digital waveform graph accepts the following data types as input:

By default, the digital waveform graph displays data as digital lines and buses in the plot area. Customize the digital waveform graph to display digital buses, digital lines, or a combination of digital buses and lines.

If you wire an array of digital data where each array element represents a bus, the digital waveform graph plots each element of the array as a different line in the order that the array elements draw to the graph.

To expand and contract digital buses in the tree view of the plot legend, click the expand/contract symbol to the left of the digital bus. Expanding and contracting digital buses in the tree view of the plot legend also expands and contracts the bus in the plot area of the graph. To expand and contract digital buses when the plot legend is in standard view, right-click the digital waveform graph and select Y Scale » Expand Digital Buses from the shortcut menu.

Note Y Scale » Expand Digital Buses is available only if you both disable Show Buses With Lines and use standard view for the plot legend. To disable Show Buses With Lines, change the plot legend to the standard view, right-click the digital waveform graph, and select Show Buses With Lines from the shortcut menu to remove the checkmark next to the menu item.

The digital waveform graph in Figure 10. Digital Waveform Graph plots digital data as a bus. The VI for this front panel does the following:

  • Converts the numbers in the Numbers array to digital data
  • Displays the binary representations of the numbers in the Binary Representations digital data indicator

In the digital graph, the number 0 appears without a top line to symbolize that all the bit values are zero. The number 255 appears without a bottom line to symbolize that all the bit values are 1.

Figure 10. Digital Waveform Graph

Front panel showing digital waveform graph and binary representations of numbers.

To plot each sample of digital data, right-click the y-scale and select Expand Digital Buses. Each plot represents a different bit in the digital pattern. You can customize the appearance of data plotted on a digital waveform graph.

The digital waveform graph in the following front panel displays the six numbers in the Numbers array:


Front panel with digital waveform graph and binary numbers.

The Binary Representations digital data indicator displays the binary representations of the numbers. Each column in the table represents a bit. For example, the number 89 requires 7 bits of memory (the 0 in column 7 indicates an unused bit). Point 3 on the digital waveform graph plots the 7 bits necessary to represent the number 89 and a value of 0 to represent the unused eighth bit on plot 7. Notice that the data is read from right to left.

The VI block diagram does the following:

  • Converts an array of numbers to digital data
  • Uses the Build Waveform function to assemble the start time, delta t, and the numbers entered in a digital data control
  • Displays the digital data

LabVIEW block diagram showing conversion of numbers to digital waveform.
For examples of the digital waveform graph, refer to labview\examples\Controls and Indicators\Graphs and Charts\Digital Waveform Graph\Digital Waveform Graph.lvproj.