Multifunction DAQ

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triggering on NI-9215 board

I am using USB 9215 BNC board, and I am programing in VB5.
I know that analog triggering is not supported for this device, but I would like to know is there a chance to do it with software. I have 3 analog signals which I have to start acquire on rising or faling edge of digital signal which I would like to conect to 4th channel. I would also like to measure time beetwen two rising (or faling) edges of that signal so I could calculate frequency and period, and set how many samples per channel to acquire in that period.
Can anyone tell me is that possible, and if it is how
Thank you
Branimir Turković 

Message Edited by Braco on 11-24-2005 03:06 PM

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Hello Branimir,

The way I would recommend going about this is to continuously acquire using the internal clock from all four channels and monitor the trigger signal channel for the rising edge.  When you detect that signal going above a certain level, then save or analyze the data from the other three channels.  Discard the data that you do not need after it is collected. 

Using the same method, you can also determine the time between edges of your trigger signal.  Perhaps the best way to do it would be to utilize the fact that you are acquiring data with a defined time between samples and to count the number of samples that occur between edges.  There are examples that install with the driver for VB6 that you may want to take a look at if you can at C:\Program Files\National Instruments\NI-DAQ\Examples\Visual Basic 6.0\Analog In.  Pay particular attention to "Acq-Int Clk". 

Hope this helps,



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Hello Laura,


I think I will solve my problem with yours tips.





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