National Instruments NI WLS/ENET-9163 - Manual (Page 19)

© National Instruments Corporation 19 NI WLS/ENET-9163 Carrier User Guide and Specifications
The NI-DAQmx Help is available after installation from Start» Programs»
National Instruments»NI-DAQ»NI-DAQmx Help. To view the
LabVIEW Help, in version 8.0 or later, select Help»Search the LabVIEW
Help in LabVIEW. Alternately, to download the LabVIEW Help, go to
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You also can specify whether the measurement acquisition begins on the
rising edge or falling edge of ai/StartTrigger.
Routing AI Start Trigger to an Output Terminal
You can route ai/StartTrigger to the PFI 0 terminal. The output polarity is
selectable.
AI Reference Trigger Signal
Use a reference trigger (ai/ReferenceTrigger) signal to stop a measurement
acquisition. To use a reference trigger, specify a buffer of finite size and
a number of pretrigger samples (samples that occur before the reference
trigger). The number of posttrigger samples (samples that occur after the
reference trigger) desired is the buffer size minus the number of pretrigger
samples.
When the acquisition begins, the NI WLS/ENET-9000 Series device begins
to fill the buffer. After the specified number of pretrigger samples are
captured, the NI WLS/ENET-9000 Series device begins to look for the
reference trigger condition. If the reference trigger condition occurs before
the NI WLS/ENET-9000 Series device captures the specified number of
pretrigger samples, the NI WLS/ENET-9000 Series device ignores the
condition.
If the buffer becomes full, the NI WLS/ENET-9000 Series device
continuously discards the oldest samples in the buffer to make space for
the next sample. This data can be accessed with some limitations before
the NI WLS/ENET-9000 Series device discards it. Refer to the
KnowledgeBase document, Can a Pretriggered Acquisition be
Continuous?, for more information. To access this KnowledgeBase, go to
ni.com/info and enter the info code rdcanq .