ADLINK PCI-9846 - Manual (Page 51)

Operation Theory 41
3.5.3 Middle-trigger Acquisition
Use middle-trigger acquisition when you want to collect data
before and after the trigger event. The amount of stored data
before and after trigger event can be set individually (M and N
samples), as illustrated in Figure 3-14.
Figure 3-14: Middle-trigger Mode Operation
Please note that trigger event can only accepted when the speci-
fied amount of data has been acquired (M samples). If the sam-
pled data is not enough, the trigger event will be ignored.
3.5.4 Delay-trigger Acquisition
Use delay-trigger acquisition to delay the data collection after the
trigger event, as illustrated in Figure 3-15. The delay time is speci-
fied by a 32-bit counter value so that the maximum delay time is
the period of TIMEBASE X (2
32
- 1), while the minimum delay is
the period of timebase.
Figure 3-15: Delay-trigger Mode Operation
Time
Operation start
Acquisition start
Trigger
Data
Acquisition stop
Begin to transfer data to system
N samples M samples
Trigger event occurs
Time
Operation
start
Trigger
Data
Trigger Event
Occurs
Acquisition stop
Begin to transfer data to
system
N samples
Acquisition start
Delay Time