May,
The DAQ device has two available internal timebases, 20 MHz and 100 kHz. When an internal scan clock (STARTSCAN) is used, the actual clock is derived by dividing-down one of these timebases. An external scan clock can also be provided (for example, from PFI 7). Additionally, an external scan clock timebase (SISOURCE) can be provided to derive the scan clock. The following KnowledgeBase discusses the use of an external timebase in greater detail:
How Do I Use SISOURCE as the External Timebase for the STARTSCAN Signal?So, the difference between the two programs you have referenced is that one uses an external scan clock and the other u
ses an external scan clock timebase.
Good luck with your application.
Spencer S.