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Trigger with adjustable threshold

Does a function exist that allows me to adjust the threshold of a software based trigger at run-time? The express VI "Trigger and Gate" is a start but I can only configure the VI using the Wizard. There's the "Manual Tigger" input which means I can build my own logic, but I was hoping to avoid this additional step seeing that an adjustable threshold seems like a obvious feature.

 

Thanks,

Craig

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Craig,

 

Try right-clicking on the Express VI and selecting Open Front Panel.  Select Convert when the dialog box appears.  This will convert the Express VI into a regular VI and should give you programatic access to the threshold settings.  Remember to click Save As and save them under new names so that the code for the original express VI remains unaltered.

Regards,

Jared R.
Precision DC Product Support Engineer
National Instruments
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If you right click on the Express vi and select 'Open Front Panel' this will convert the Express vi into a standard vi. Use this as a sub vi and you should be able to change the levels at run time.

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I would like to pick up this issue as a newbie. So now we can make adjustable vis out of express vis. In the Trigger and Gate vi the issue is rather the fact that the amplitude threshold is hidden in a 'condition'-object/bundle of the type def triggerCluster which is initialised in the configure_trigger_and_gate.vi and passed on to the subroutines of the express vi. I would just like to get an extra handle outside of the Trigger_and_Gate.vi to alter the threshold dynamically. Any suggestions - that do not involve passing an extra variable through the whole chain as then one needs to change also the subroutines.

 

Cheers

 

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Hello avoverlo,

 

Welcome to the forum! 

 

What version of LabVIEW are you using, and for what OS? I've checked back to LabVIEW 2011 on Windows, and after converting the Trigger and Gate express VI to a standard VI, the Start and Stop Trigger clusters are accessible from the front panel of the top-level VI generated (Trigger and Gate.vi).  You should be able to wire these clusters to the connector pane of the top-level VI, and based on the implementation it appears that you should be able to configure these parameters between calls to the subVI. 

 

Are you attempting to dynamically adjust the trigger levels based on the data in the provided waveform while it is being processed?  That is a trickier proposition.

 

If the above recommendation doesn't help, could you post the portion of your code you are attempting to modify and point out specifically where you're encountering issues?

 

Regards,

Tom L.
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