Start And Stop Trigger - National Instruments 653 Series User Manual

Chapter 2 Using Your NI 653X
ACK (STARTTRIG)
REQ
Posttrigger Data
Figure 2-3. Starting Data Transfer Using a Trigger
Stop Trigger
When you use a stop trigger, data transfer starts upon a software command.
Then, once a hardware trigger is received on the STOPTRIG pin, a
predetermined amount of pretrigger and posttrigger data is saved in the
buffer. Once this data is in the buffer, transfer stops. If the stop trigger
arrives before all the pretrigger data is acquired, NI-DAQ returns an error.
STOPTRIG
REQ
Posttrigger Data
Pretrigger Data
Figure 2-4. Stopping Data Transfer Using a Trigger

Start and Stop Trigger

When you use a start and stop trigger, data transfer starts upon receiving a
trigger on the start trigger line (ACK/STARTTRIG pin) and ends upon
receiving a trigger on the stop trigger line (STOPTRIG pin), and a
predetermined amount of pretrigger and posttrigger data is saved in the
buffer. If the device receives a stop trigger before a start trigger, the stop
trigger is ignored. If the stop trigger arrives before all the pretrigger data is
acquired, NI-DAQ returns an error.
© National Instruments Corporation 2-9 NI 653X User Manual