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Exported FGen Trigger Pulse is short ...

I'm trying to use the VirtualBench External trigger by exporting my FGen Start to the Trig Output and it seems to work but ...  the trigger is really short.  I measured it using the VirtualBench scope and it was only ~20 ns wide.  I'm trying to use it to trigger a cRIO 9401 input and the 9401 running on my 40 MHz FPGA (cRIO 9068) isn't fast enough to detect the rising edge of the trigger reliably.

 

 Is it possible to make this trigger pulse longer or do I have a setup issue?

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There is nothing wrong with your setup, that is the expected pulse width.

 

Unfortunately, pulse-width does not vary with output frequency, and there is no way to make the pulse wider.

 

Apologies,

 

William Earle

Software Engineer

NI R&D

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Thanks for the info - this was the first case where VirtualBench didn't knock it out of the park for me on my first attempt.  So far it is an awesome tool and I hope the triggering gets updated in the future so that it is able to trigger other NI 'high speed' TTL inputs for testing purposes like this use case.

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@Omar_Mussa wrote:

Thanks for the info - this was the first case where VirtualBench didn't knock it out of the park for me on my first attempt.  So far it is an awesome tool and I hope the triggering gets updated in the future so that it is able to trigger other NI 'high speed' TTL inputs for testing purposes like this use case.


I filed a bug report for you on this behavior - CAR 515747.

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Zach Hindes
NI R&D
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Great, thanks Zach,

 

In the meantime our EE helped us workaround the problem by creating a board for extending the trigger from 20 ns to > 1 usec.  I look forward to getting that board out of my way though.  If a 9401 can reliably detect the trigger than it will work for me in my application use case.

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@Omar_Mussa wrote:

Great, thanks Zach,

 

In the meantime our EE helped us workaround the problem by creating a board for extending the trigger from 20 ns to > 1 usec.  I look forward to getting that board out of my way though.  If a 9401 can reliably detect the trigger than it will work for me in my application use case.


Great workaround!  I'm glad you got something working!  On our end it may be a bit tricky since we support frequencies up to 20MHz.  A longer pulse would be slower than the update of the waveform itself.  We'll look into it, though.

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Zach Hindes
NI R&D
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