ADLINK PCIe-9852 - Manual (Page 29)

Operations 19
PXIe-9852
ger event, a time delay is implemented before commencing acqui-
sition. The delay is specified by a 16-bit counter value such that a
maximum thereof is the period of TIMEBASE X (2
16
), and the min-
imum is the Timebase period.
Figure 3-6: Delayed Trigger Mode Acquisition
3.4.3 Pre-Trigger Mode
Collects data before the trigger event, starting once specified func-
tion calls are executed to begin the pre-trigger operation, and
stopping when the trigger event occurs. If the trigger event occurs
after the specified amount of data has been acquired, the system
stores only data preceding the trigger event by a specified
amount, as follows.
Figure 3-7: Pre-Trigger Mode Acquisition
Time
Operation start
Acquisition start
Trigger
Data
Trigger Event Occurs
Acquisition stop
Data transfer to system begins
N samples
X samples have been acquired
before trigger occurs, where X<N
Trigger signals occuring before the specified
amount of data has been acquired are ignored