User's Manual

Chapter 2 Function Reference — Lab_ISCAN_Op
© National Instruments Corporation 2-269 NI-DAQ FRM for PC Compatibles
Note If you have selected external start triggering of the data acquisition operation, a
low-to-high edge at the EXTTRIG of the Lab and 1200 Series device I/O connector
input initiates the operation. Be aware that if you do not apply the start trigger,
Lab_ISCAN_Op does not return control to your application. Otherwise,
Lab_ISCAN_Op issues a software trigger to initiate the data acquisition operation.
If you have enabled pretrigger mode, the sample counter does not begin counting acquisitions
until you apply a signal at the stop trigger input. Until you apply this signal, the acquisition
remains in a cyclical mode, continually overwriting old data in the buffer with new data.
Again, if the stop trigger is not applied,
Lab_ISCAN_Op does not return control to your
application.
In any case, you can use
Timeout_Config to establish a maximum length of time for
Lab_ISCAN_Op to execute.