The 1D to 2D conversion at the output of the for loop is called "autoindexing." For loops will create an array of whatever is wired out of them. Since you have a 1D array going into the tunnel, you get a 2D array coming out. A scalar in produces a 1D array out. This can be disabled by popping up the context menu on the tunnel and disabling indexing. Look at the help files for more information.
You could use the Get Time functions to generate the t0 for build waveform.
If you need timestamping with less than 1 ms resolution, you need to be a bit creative. The computer time functions (Time of Day and Tick Count) do not have resolution better than 1 ms. If you have a hardware sampling clock in the data acquisition system, the intervals between samples will be at 1/fs to the accuracy of the DAQ clock. Using the time of day for t0 and the delta t from the hardware clock will allow you to calculate the time of any sample. If you need absolute timing accuracy beyond this level, you may need to have a GPS clock or other precise timekeeper which gets acquired along with the data.
Lynn
