Start And Stop Trigger - National Instruments 653X User Manual

Chapter 2 Using Your 653X
653X User Manual
The three types of trigger signals available are the start trigger, the stop
trigger, or the start and stop trigger.
Start Trigger
A start trigger is a trigger that initiates a pattern I/O upon receipt of a
hardware trigger on the ACK (STARTTRIG) pin.
ACK (STARTTRIG)
REQ
Figure 2-16. Starting Data Transfer Using a Trigger
Stop Trigger
When using a stop trigger, transfer starts upon a software command. 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 an error will return in software.
STOPTRIG
REQ
Figure 2-17. Stopping Data Transfer Using a Trigger

Start and Stop Trigger

When using a start and stop trigger, 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 a stop
trigger is received before a start trigger, it is ignored. If the stop trigger
arrives before all the pretrigger data is acquired an error will return in
software.
Pretrigger Data
2-28
Posttrigger Data
Posttrigger Data
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