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AI Sample Clock Signal
© National Instruments Corporation
example, four. The value decrements with each pulse on ai/SampleClock,
until the value reaches zero. The sample counter is then loaded with the
number of posttriggered samples, in this example, three.
ai/StartTrigger
ai/ReferenceTrigger
ai/SampleClock
ai/ConvertClock
Scan Counter
Figure 4-10. Pretriggered Data Acquisition Example
If an ai/ReferenceTrigger pulse occurs before the specified number of
pretrigger samples are acquired, the trigger pulse is ignored. Otherwise,
when the ai/ReferenceTrigger pulse occurs, the sample counter value
decrements until the specified number of posttrigger samples have been
acquired.
NI 6238/6239 devices feature the following analog input timing signals.
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AI Sample Clock Signal
•
AI Sample Clock Timebase Signal
•
AI Convert Clock Signal
•
AI Convert Clock Timebase Signal
•
AI Hold Complete Event Signal
•
AI Start Trigger Signal
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AI Reference Trigger Signal
•
AI Pause Trigger Signal
Use the AI Sample Clock (ai/SampleClock) signal to initiate a set of
measurements. Your M Series device samples the AI signals of every
channel in the task once for every ai/SampleClock. A measurement
acquisition consists of one or more samples.
n/a
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2
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4-15
Chapter 4
Analog Input
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NI 6238/6239 User Manual
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