One more thing to remember when setting pre-trigger scans. When you set a the number pretrigger scans to something greater than 0 you are setting up a stop trigger and not a start trigger. The minimum number of pretrigger scans that you can set for a stop trigger is 2. You can view the example that ships with LabVIEW in the DAQ triggering section of the examples (I/O interfaces->Data Acquisition->Analog Input->..) to see how to set up triggering. There are additional examples and details on triggering available at www.ni.com/support and use the technical resources search.
