We don't have a time format that will support milliseconds. However, you can create you own string labels to do this using Value Pairs. Value Pairs allows you to setup values you are plotting like 1,2,3... to specific strings, in your case: 12:00:00:000, 12:00:00:005, etc. You could create these value pairs from the time strings you are reading in and some relative values with:
CWGraph1.Axes.Item(1).ValuePairs.Add.Name = "12:00:00:000"
CWGraph1.Axes.Item(1).ValuePairs.Add.Value = 1
Then plot the Y data point at x=1 for this time.
Best Regards,
Chris Matthews
Measurement Studio Support Manager