Measurement Computing Data Acquisition Systems rev.10.4 - Manual (Page 77)

DaamNShotRearm -- Once triggered, this mode continues the acquisition for the specified post-trigger count,
then re-arms the acquisition with the same acquisition configuration parameters as before. The automatic re-
arming of the acquisition may be disabled at any time by issuing the daqAdcDisarm function. Other than the
re-arming feature, this mode works like DaamNShot. Upon re-arming, data collection will only be reinitiated
when the trigger event re-occurs after the previous acquisition post-trigger count has been satisfied.
The DaamNShotRearm command can only be used with WaveBooks.
DaamInfinitePost -- Once triggered, this mode begins continuous acquisition until explicitly terminated
by the daqAdcDisarm function.
DaamPrePost -- This mode begins collecting the specified number of pre-trigger scans immediately upon
issuance of the daqAdcArm function. The trigger will not be enabled until the specified number of pre-trigger
scans has been collected. Once triggered, the acquisition will continue collecting post-trigger data until the
post-trigger count has been satisfied. Once the post-trigger count has been satisfied, the acquisition will
automatically disarm itself and terminate.
Daq 2000 Series devices, DaqBoard/1000 Series devices, and WaveBooks
[with WBK 30’s] in cycle mode both return the exact pre-trigger amount of
data specifies. Other devices record data from before the pre-trigger event
(i.e., all scans from arming to disarming). See daqAdcBufferRotate for more
details.
Relationship to Trigger Start/Stop Events
The daqAdcSetAcq function sets the style or mode of the acquisition. However, it does not specify trigger
start events, nor does it specify trigger stop events--although it does specify stop conditions (if those stop
conditions are scan counts or infinite). Specific trigger start and stop events are defined by other functions:
Trigger start events (EventA) can be defined using daqAdcSetTrigEnhanced and
daqSetTriggerEvent
.
Trigger stop events (EventB) - can be defined using the daqSetTriggerEvent.
The following table shows the relationship between trigger event definition and acquisition mode parameter
settings for possible acquisition configurations:
Desired Acquisition
Without Pre-Trigger Scans
mode preTrigCount postTrigCount
Trigger acq on EventA and stop on scan n
after trigger
DaamNShot Ignored n
Trigger acq on EventA and continue
indefinitely until disarmed by application
(daqAdcDisarm)
DaamInfinitePost Ignored Ignored
Trigger acq on EventA, stop on scan n
after trigger, then re-arm to trigger on
EventA (repeat until disarmed) ( Note 1)
DaamNShotRearm Ignored Ignored
Trigger acq on EventA and stop on
EventB *
DaamInfinitePost Ignored Ignored
With Pre-Trigger Scans mode preTrigCount postTrigCount
Take m pretrigger scans, start acq on
EventA, and stop on scan n after trigger
DaamPrePost m n
Take m pretrigger scans, start acq on
EventA, and stop on EventB ( Note 2)
DaamPrePost m Ignored
Note 1: WaveBook products only.
Note 2: Applies to DaqBook/2000 Series, DaqLab/2000 Series, DaqScan/2000 Series, DaqBoard/2000 Series,
DaqBoard/1000 Series, and DaqBoard/500.
Programmer’s Manual 908594 Daq API Command Reference 4.2-21