displaying a vibratory signal in a waveform on LabVIEW

[Fred19ni]

Hi everybody,

I have cDAQ9171, NI 9230 and an accelerometer. I use element of NI-DAQmx pallete to acquire data and it's work good. But, I have a problem to display the vibratory signal on a waveform graph because it isn't working like a want. I would like to collect data while 1 second with a number of sample (2560k per example for sample rate = 2560Ks/s). Then, display it on my waveform every second.

Please somebody can help me ?

[GerdW · Accepted solution]

Hi Fred,

But, I have a problem to display the vibratory signal on a waveform graph because it isn't working like a want.

Then most often the problem is with the way the VI is created… 😄

I would like to collect data while 1 second with a number of sample (2560k per example for sample rate = 2560Ks/s). Then, display it on my waveform every second.

Ok, that's a nice description.

But why do you read just one sample each 100ms, when you want to read 2.56MS/s?

Why do you set a sample rate of 1kS/s, when you want to read samples faster?

Why do you read just one sample per DAQmxRead?

Why do you set a "sample per channel" of 100k? Did you read the help for the DAQmxTrigger function?

[Fred19ni]

Thanks GerdW for your reply,

But why do you read just one sample each 100ms, when you want to read 2.56MS/s? it was only an example.

Why do you set a sample rate of 1kS/s, when you want to read samples faster? about sample rate is it rate in LabVIEW ? and what is the description of sample per channel.

Why do you read just one sample per DAQmxRead? wrong configuration

Why do you set a "sample per channel" of 100k? Did you read the help for the DAQmxTrigger function? no, I read it right away.

thanks for yours questions.

[Bob_Schor]

Your sampling rate seems exceedingly high.  When I think of "vibration", I think of sound, so I expect signals in the range 1Hz-50KHz, maybe even narrower, but certainly not 2MHz!

Have you tried using MAX to look at your device and run some Test Panels to get MAX to acquire (and show you) some data?  Were you able to acquire data at 2MHz?  Does it look "reasonable" to you?

Once you have a reasonable Task that works in MAX, it is fairly simple to "translate" that into equivalent LabVIEW DAQmx code.  I recommend you do a Web search for a paper whose title is something like "Learn 10 Functions in NI-DAQmx and Solve 80% of your Data Acquisition Tasks".

Bob Schor