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DAQ assistant triggers only at second signal

Dear all,

I'm a newbie in Labview and I am struggling with the DAQ assistant.

 

I generate a signal using NI9263 at AO0.

The generated signal at AO0 is a pulse-like train between -10 and 10V. Meaning it is always 0V, but then goes to +10V for a short time, then to 0V for a short time, then to -10V for a short time and back to 0 V. I can generate this pulse-train using a front panel button. Every time I press the button, a single pulse-train is generated. That works fine.

 

I want to read this signal back using NI9205 at AI0. Therefor I use the DAQ assistant in analog trigger mode on AI0, level 5V.

I set the triggering to wait infinitely. I placed this code in an infinite while loop.

 

When I run the code, I first press the front panel button to generate the signal and I see this is happening on an oscilloscope.

But, the triggering does NOT occur. When I press a second time the front panel button to generate the signal, THEN a trigger occurs.

Triggering seems to work only after I twice generate the pulse-train. So triggering happens on the 2nd press, on the 4th press, 6th, ...

 

Why does it not trigger on all the events?

 

Thanks!

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Hard to tell without seeing the code, but my guess is you've got a problem in the dataflow.  Make sure things are happening in the order you expect them to.

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Hi Claude,

 

Were you finally able to find a solution?

If still needed, and as SnowMule suggested already, if you share your code someone will probably be able to help you...

 

Kind regards,

Cédric | NI Belgium
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