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Send Trigger Message

Use visatrigger Function

You can execute a trigger with the visatrigger function. This function is only for VISA-GPIB and VISA-VXI interfaces. It is equivalent to the viAssertTrigger operation, as described in the VISA Specifications found at IVI Specifications. For an instrument connected with the VISA-GPIB interface, this function sends the GPIB GET (Group Execute Trigger) command.

Refer to your instrument documentation to learn how to use its triggering capabilities.

Execute Trigger

This example illustrates VISA-GPIB triggering using a Keysight™ 33120A function generator. The output of the function generator is displayed with an oscilloscope so that you can observe the trigger.

  1. Create a VISA-GPIB object — Create the VISA-GPIB object g associated with a National Instruments® GPIB controller with board index 0 and an instrument with primary address 1.

    g = visadev("GPIB0::1::0::INSTR");
  2. Write and read data — Configure the function generator to produce a 5000 Hz sine wave, with 6 volts peak-to-peak.

    writeline(g,"Func:Shape Sin")
    writeline(g,"Volt 3")
    writeline(g,"Freq 5000")

    Configure the burst of the trigger to display the sine wave for 5 seconds, configure the function generator to expect the trigger from the GPIB board, and enable the burst mode.

    writeline(g,"BM:NCycles 25000")
    writeline(g,"Trigger:Source Bus")
    writeline(g,"BM:State On")

    Trigger the instrument.

    visatrigger(g)

    Disable the burst mode.

    writeline(g,"BM:State Off")

    While the function generator is triggered, the sine wave is saved to the Ref A memory location of the oscilloscope. The saved waveform is shown in the following figure.

    Image of an oscilloscope screen displaying a sine wave in a MATLAB figure window

  3. Disconnect and clean up — Use clear to disconnect the instrument from the VISA-GPIB object g and to clear it from the MATLAB® workspace when you are done working with it.

    clear g

See Also

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