How is dt from "Get Waveform Components" calculated?

I am acquiring data, making waveforms, and writing to TDMS.
I physically took data for 2 hours and did timed events.
When I "Get Waveform Components" and determine array size of components I get the following result for data length:
dt = 0.002 sec/sample (500 hz)
Array Size of waveform components = 129350 samples
0.002 x 129350 = 258.7 sec = 4.3 min of total data length
When I view the waveform in Labview, I see an accurate representation of my timed events.
It looks like the full 2 hours of data is captured to some degree.
If I am losing data, does that mean my dt isn't always equal to 0.002 like "Get Waveform Components" says?
Any other ideas?
Thanks!

Waveforms assume a constant dt with each sample occuring every dt. If you are missing data, then the waveform will show a shorter acquisition time and what you actually took. Since you claim your times look right, then it is safe to assume you had no data loss.
DAQmx will give you warnings if you miss data from the DAQ card's buffer (data overwritten). So if you didn't get a warning about that, then you didn't miss any data.
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