The timebase number, is relates to the sample interval for the exact model picoscope being using.
Information related to can be found in the programmers guides, normally under the timebase section.
For 3405DMSO see page 8 of https://www.picotech.com/download/manuals/PicoScope3000SeriesAApiProgrammersGuide.pdf
The timebase calculations are normally a formula apart from the first few timebase values starting at '0' are different.
The other way to get the sample interval in your code is call ps3000aGetTimebase function. Most of our drivers have ps3000aGetTimebase type function.
Picoscope 6 software chooses the timebase number based on the time/division selected. Also in picoscope you can request the number samples.
This is the same as setting the number of pre and post trigger sample using the driver in labview.
In picoscope you can view the actual sample interval and samples captured by opening the view properties panel. ('view' menu - view properties)
The graphs used in our labview examples is 'Waveform Graph' type. The waveform graph plots points evenly distributed along the x-axis.
You would need to create your own vi to setup something similar to the way picoscope has a time/division setting and graph output.
Picoscope software uses downsampling to reduce all the samples being downloaded for each capture. As you normally don't need all the data points to draw the shape of the waveform.
Picoscope software only request all the data points if you save the data to file or zoom in on a area of the waveform. The downsample mode that picoscope uses is aggregated.
under the Aggregation section at the bottom of the page.