Number of samples and rate

Hi,

I am acquiring data from a triaxial accelerometer (so 3 channels: X,Y,Z axis). 

So far I wrote a very simple code using DAQ Assistant:

I am acquiring using "N samples" acquisition mode but I don't understand the relationship between number of samples (Ns) and rate...

I mean Ns is how many samples I want in a single acquisition while the second is how often a sample is taken. 

I ran the code using as an example Ns=1000; rate=1000Hz and print data as time series.  I would expect to have 1000 samples in 1 second (time=Ns/rate) instead I have 1000 samples in 0.6s.

Or again I tried with Ns=1000; rate=100Hz with an expected time of 10s instead it is 0.6s again.

I don't understand the relationship between the two values