Interactive Programming

Summary: The creation of this content was supported in some part by NSF grant 0538934.

The heart of interactive programming in G is the while loop. Any input control within the while loop can be modified from the Front Panel window at run time to provide seamless interaction with the G program.

Figure 1: Creating Interactive Programs

In the Front Panel window, from the Functions >> Modern >> Numeric select the vertical pointer slide. From the Functions >> Modern >> Graph select Waveform Chart.

Figure 2: Vertical Pointer Slide and Waveform Chart

Figure 3: Vertical Pointer Slide and Waveform Chart

Re-label the vertical pointer slide as Amplitude and the waveform chart as Sine Wave. Re-arrange to GUI to look like the figure below.

Figure 4: Slide & Waveform Chart in Front Panel window

Right click on Sine Wave and select Properties from the pop-up menu.

Figure 5: Selecting Chart Properties

Select the Scales tab and change Maximum to 1023. Sine Wave will display 1024 samples.

Figure 6: X-Axis Maximum

Click on the down arrow located to the right of Time (X-Axis) and select Amplitude (Y-Axis).

Figure 7: Selecting Y-Axis

De-select Autoscale and change the Minimum and Maximum values to -10 and 10. Click OK.

Figure 8: De-Selecting Autoscale

Rearrange Amplitude and Sine Wave terminals and finish the program as shown in Figure 9.

Scroll the mouse pointer over the Loop Control…

Figure 9: Interactive Sine Wave Diagram

Figure 10: Loop Condition

And right click on the Loop Control and from the pop-up menu select Create Control.

A stop terminal is created.

Figure 11

Figure 12: Interactive G Program

With the corresponding stop Boolean input control. Save the G program as Interactivity.vi.

Figure 13: Interactive Program

Run the G program.

Figure 14: Interactive Program

While the program is running, change the Amplitude and watch the graph update to reflect the interactive changes.

Figure 15: Interactive Program

To end the G program, simply click on the stop button.

Figure 16: Interactive Program

Congratulations. You have successfully completed and executed your first interactive G program.

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