Hi Larry,
I believe that John is referring to the DAQmx create event. You can find this special type of event structure under Measurement I/O pallette->NI-DAQmx->Advanced->DAQmx Events->Create Event. You can set the register for events property node for "Every N Samples Acquired into the Buffer." You may also reference the detailed help here http://zone.ni.com/reference/en-XX/help/370469AA-01/lvdaqmx/mxcreateevent/
Regards
Doug W
Applications Engineer
National Instruments