Query on sample rate, no. and time calculation

[SSR_Nicholas]

I'm using NI9233 to acquire signals. Since the node 'DAQ assistant' only have inputs of no. of samples and sample rate. I thought the sample period equals to no. of samples/sample rate but couldn't always get the correct acquisition time. So what's the quantitive correlation of no. of samples and sample rate? How could I calculate the acquisition time once I set these two parameters?

Thanks a lot.  

[RavensFan]

Can you post a VI that shows your issue?  What are your sample rate and no. of samples., and how do you know the time you are getting is wrong?

[SSR_Nicholas]

Hi. The one I used is the node 'DAQ Assist' to get the analog voltage. There are only two input parameters, number of samples and sampling rate.  Actually what I care for further use are only sampling rate and sampling time. So I do the calculation as time=no./rate.. ... but if you go to the property of the 'DAQ assist' node, you run the testing, the acquisition time you get may not always be the same as the calculated result.  (btw, the acquisition mode I used is 'N Samples'.)

[RavensFan]

I know what the DAQ assistant is.  I asked for you to post your VI so we can see how the properties are setup.

You say the acquisition time you get doesn't match the calculation.  How are you "getting" the acquisition time?  Can you give an example of the acquistion time you are "getting" vs. the calculation?  How "wrong" is it?

[Meadow]

Hello Nicholas,

In 9233, you only have a set of sampling rate that you can do. Could it be the sampling rate that you put into the field isn't supported sampling rate, hence the discrepancies that you saw happen because the card is acquiring at higher speed or at lower speed that supported by 9233. May be you would like to share with us about the how you calculate to get the correct acquisition time.

Please refer to the specification of 9233 to find out more about the supported data rates.

Regards,

James