I just started reading about the properties of the TDMS file format, and am getting nervous my data doesn't have timestamps. I have been acquiring data using this format for a week already. Right now I'm working on the code for the viewer executable. I thought for sure that TDMS saved a timestamp for every waveform sample, but after some reading I'm not so sure anymore. It sounds like it is dependent on your code. I'm acquiring my data from a DAQ device. I haven't had much luck using the "Get TDMS property VIs" to see if I have a timestamp for every sample or not. My samples aren't all at the same dt. I'm saving based on time and in the event of an alarm.