The sampling rate is not as what I set

[Jaseon]

 In my DAQmx, I set the sampling rate at 20 kHZ (Picture 1 ), but the data I acquired was sampled at 10Hz rate (Picture 2).

Who can help me? Thank you.

My VI is attached.

[crossrulz]

The Rate is in Samples per Channel per Second.  So since you have 2 channels, your sample rate for each channel is cut in half, resulting in a 10kHz sample rate.

[Jaseon]

HI, the sampling rate is 10Hz instead of 10KHz

[Henrik_Volkers]

Just guessing:

You sample 5k samples with 20kS/s , but your indexing of the array seems to be wrong, so you pic (and mix) both channels instead of 2 times 5k samples you save 2 times 2 samples.

5k with 20kS/s each 1/4s * 2   ..... do you have 10Hz or 8Hz samplerate in your  data??

[Jaseon]

I think you are right. You said my indexing of the array seems to be wrong. How chould I change the indexing of the array.

Thank you!

[Henrik_Volkers]

Reading the help of the index array function would be a starting point 😉

[Aaron_W.]

Jaseon,

I think the issue is that you are getting columns (samples) of data back when you index your array and not rows (channels) like what you want. I believe this is what Henrik is mentioning. Change the VI as shown in the picture below:

Wire the 0 and 1 constants into the Row inputs (not the column) of the Index Array VI. You should also right-click on the Build Array function and make sure that Concatenate Inputs is disabled.

[Dennis_Knutson]

Any discussion of sample rate rate with a DBL array is meaningless. There is no timing associated with the samples.