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Chapter 2
Using the NI PXIe-4300
Figure 2-5.
Typical Pretriggered DAQ Sequence
If an AI Reference Trigger (ai/ReferenceTrigger) pulse occurs before the specified number of
pretrigger samples are acquired, the trigger pulse is ignored. Otherwise, when the AI Reference
Trigger pulse occurs, the sample counter value decrements until the specified number of
posttrigger samples have been acquired. For more information about start and reference triggers,
refer to the
NI PXIe-4300 modules feature the following analog input timing signals:
•
AI Sample Clock Signal
•
AI Sample Clock Timebase Signal
•
AI Start Trigger Signal
•
AI Reference Trigger Signal
•
AI Pause Trigger Signal
Aggregate versus Single Channel Sample Rates
NI PXIe-4300 modules have one ADC per channel so the single channel maximum sample rate
can be achieved on each channel. The maximum single channel rate is the fastest you can acquire
data on the device from a single or multiple channels and still achieve accurate results.
The total aggregate determines the maximum bus bandwidth used by the device. The total
aggregate sample rate is the product of the maximum sample rate for a single channel multiplied
by the number of AI channels that the device support.
Table 2-4 shows the single channels and total aggregate rates for NI PXIe-4300 modules.
Table 2-4.
Analog Input Rates for NI PXIe-4300 Modules
Single Channel
Total Aggregate
250 kS/s
2 MS/s
Don't Care
0
1
2
3
1
0
2
2
2
AI Start Trigger
AI Reference Trigger
AI Sample Clock
Sample Counter
