National Instruments DAQPad-6020E User Manual page 65

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Channel 0
Channel 1
The ai/ConvertClock signal controls the convert period, which is
determined by the following equation:
NI-DAQmx chooses the default convert rate to allow for the maximum
settling time between conversions. Typically, this rate is the sampling rate
for the task multiplied by the number of channels in the task.
The sampling rate is the fastest you can acquire data on the device and still
achieve accurate results. For example, if an E Series device has a sampling
rate of 200 kS/s, this sampling rate is aggregate one channel at 200 kS/s or
two channels at 100 kS/s per channel illustrates the relationship.
An acquisition with posttrigger data allows you to view data that is acquired
after a trigger event is received. A typical posttrigger DAQ sequence is
shown in Figure 2-17. The sample counter is loaded with the specified
number of posttrigger samples, in this example, five. The value decrements
with each pulse on ai/SampleClock, until the value reaches zero and all
desired samples have been acquired.
ai/StartTrigger
ai/SampleClock
ai/ConvertClock
Sample Counter
Figure 2-17. Typical Posttrigger Acquisition
Convert Period
Sample Period
Figure 2-16. Interval Sample
1/convert period = convert rate
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Chapter 2 Analog Input
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E Series User Manual