© National Instruments
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3-9
Sample Clock
With Sample Clock timing, on each active edge of the sample clock, the device stores one
measurement. The one measurement is the high and low pulse times of the most recent full pulse
to occur before the sample clock. Figure 3-10 shows an example using Sample Clock timing.
Figure 3-10.
Pulse Measurement: Sample Clock Timing
To use Sample Clock timing, use the DAQmx Timing (Sample Clock) VI or function.
Trigger Settings
By default, the counter begins measuring when software calls DAQmx Start Task. You can
change this behavior by setting DAQmx Trigger properties.
To have the counter begin counting in response to a hardware trigger, use an Arm Start Trigger.
1.
Set ArmStart.TrigType to Digital Edge.
2.
Set ArmStart.DigEdge.Src to select which signal to use as an ArmStartTrigger.
3.
Set ArmStart.DigEdge.Edge to select the rising or falling edge of the signal.
Figure 3-11 shows an example of a count edge task using an Arm Start Trigger.
Figure 3-11.
Pulse Measurement: Using Arm Start Trigger
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