Cross Triggering in WaveForms (Under Construction)

This guide explores the use of cross-triggering between different instruments within WaveForms. Note that there are many applications and approaches to cross triggering beyond what will be covered in this guide.

• A Digilent Test & Measurement Device with Analog I/O and/or Digital I/O
  • Note: Users without a device may still find this guide informative
• A Computer with WaveForms Installed

In the general sense, cross triggering describes systems where multiple instruments - often different devices - share trigger events. This can mean that either both instruments capture the signal containing the trigger event, or that when one of the instruments detects the trigger event, it generates a signal to trigger the other instrument.

This guide demonstrates how to perform cross triggering between multiple WaveForms instruments with a single Digilent Test & Measurement device.

This example demonstrates how using cross triggering makes it easier to change trigger sources across multiple instruments.

If needed, power your Digilent Test and Measurement Device and turn it on, then connect the device to your computer.

Connect the analog input channel 1 positive pin (1+, orange cable) to the waveform generator output channel 1 pin (W1, yellow cable). Then connect the analog input channel 1 negative pin (1-, orange and white cable) to ground (down arrow, black cable). Lastly, connect the external trigger 1 pin (TRIG 1, grey cable) to the digital input/output pin 0 (DIO 0, pink cable).

The circuit achieved by these connections is a simple loopback, allowing the test and measurement device's waveform generator to provide a stimulus for its own oscilloscope, and to generate an external trigger with its digital I/O.

Launch WaveForms, then open the following instruments and apply the following changes to their settings:

1. Open a new Wavegen instrument.
   • Set the Channel Synchronization to Independent
   • Set the Trigger source to Manual
   • Set the Wait time to none
   • Set the Run time to 1 ms
   • Set the Repeat count to infinite
   • Leave all other settings as their defaults
   • Click Channel 1's Run button
2. Open a new Scope instrument.
   • Set the Trigger Mode to Repeated and Normal
   • Set the Trigger Source to Wavegen 1
   • Set the Time Position to 0 s
   • Set the Time Base to 1 ms/div
   • Disable Channel 2 by unchecking its box
   • Leave all other settings as their defaults
   • Click the Run button
3. Open a new StaticIO instrument.
   • Configure DIO 0 to be a button that outputs 0 when released, and 1 when pressed

More information on how to use each of the instruments used in this example can be found in their respective “Using the …” guides, linked above.

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Once the workspace is set up, you can now begin experimenting with the resulting system:

Click the Manual Trigger button in the bottom left-hand corner of the WaveForms application to trigger the Wavegen instrument to output a signal once. The signal plays back so quickly that you will not see the Wavegen's state go from Armed to Running back to Armed. You will see the Scope's state go from Armed to Trig'd back to Armed, and the captured event will be displayed in the Scope's plot.

Next, try modifying the Wavegen Trigger's Wait time field. Any value will work. Click the Manual Trigger button again. You will see the scope take a capture. Despite the changes, the captured signal will be placed at the same point in the plot. Modifying the Wavegen trigger's wait time also affects the Scope trigger: both instruments wait for that amount of time after the Manual Trigger to capture/generate the signal.

Next, change the Wavegen Trigger's Source field to External 1. In the StaticIO instrument, click the button corresponding to DIO 0. You will observe that this button has the same behavior as the Manual Trigger.

In conclusion, note that through each of these changes to the trigger configuration, the Scope trigger did not need to be reconfigured at all!

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