Using An Analog Source; Ai Sample Clock Signal; Using An Internal Source; Using An External Source - National Instruments DAQPad-6020E User Manual

Note Pause triggers are only sensitive to the level of the source, not the edge.

AI Sample Clock Signal

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Using an Analog Source

When you use an analog trigger source, the internal sample clock pauses
when the Analog Comparison Event signal is low and resumes when the
signal goes high (or vice versa). Refer to Chapter 10, Triggering, for more
information on analog triggering.
You can use the AI Sample Clock (ai/SampleClock) signal to initiate a set
of measurements. Your E Series device samples the AI signals of every
channel in the scan list once for every ai/SampleClock. A measurement
acquisition consists of one or more samples.
The source of the ai/SampleClock signal can be internal or external. You
specify whether the measurement sample begins on the rising edge or
falling edge of the ai/SampleClock signal.

Using an Internal Source

By default, ai/SampleClock is created internally by dividing down the
ai/SampleClockTimebase. Refer to the
section for more information.
Several other internal signals can be routed to the sample clock. Refer to
Device Routing in MAX in the NI-DAQmx Help or the LabVIEW 8.x Help
for more information.

Using an External Source

You can use a signal connected to any PFI or RTSI <0..6> pin as the source
of ai/SampleClock. Figure 2-24 shows the timing requirements of the
ai/SampleClock source.
AI Sample Clock Timebase Signal
2-37
Chapter 2 Analog Input
E Series User Manual