Thanks, DFGray. It definitely seems you're the expert regarding hdf5/NI-HWS/high-speed/large data set acquisition on these forums!
It looks like in the datasets I'm saving there's only 4 subgroups under wfm_group0 (i.e. no 'vector' group) when I open them in Matlab. (perhaps it's because I'm only passing it a vector of I8s --see below-- and not a true waveform) But the hardlink under axis1 does the trick.
So you say the HWS automatically saves t0, dt, gain & offset? How does it know this information if all it's being passed is a 1D vector of I8s? Perhaps it doesn't and that's why I don't have the vectors subgroup? The niScope VI passes out a vector of data and a 'waveform info' in a separate data entity, but unless I combine them into a waveform data type (which adds seemingly unnecessary overhead and copying in memory) I guess I don't see how HWS can keep track of those entities unless I manually add them to the file.
So, if manually adding them to the file is the way to go, are there any VIs under HWS (I don't have access to my development computer atm) that allow you to insert the data directly?
Right now it's not too big of a problem since I'm only using t0, dt, gain & offset to display the data in LabVIEW. Once it gets opened in Matlab all they care about is that 1D vector of data.