Chapter 2
Using the Module
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National Instruments Corporation
2-31
Analog Edge Triggering
For analog edge triggering, configure the module to detect a certain signal Level and slope,
either rising or falling. Figure 2-20 shows an example of rising edge analog triggering. The
analog comparison becomes true when the signal starts below Level and then crosses above
Level.
Figure 2-20.
Analog Level Trigger on Rising Slope
Analog Edge Triggering With Hysteresis
When you add hysteresis to analog edge triggering, you add a window above or below the
trigger level. This triggering mode often is used to reduce false triggering due to noise or jitter
in the signal. For example, if you add a hysteresis of 1 mV/V to the example in Figure 2-20,
which uses a level of 3.2 mV/V, the signal must start at or drop below 2.2 mV/V to arm the
trigger. The analog comparison becomes true when the signal rises above 3.2 mV/V and
becomes false when it falls below 2.2 mV/V, as shown in Figure 2-21.
Figure 2-21.
Analog Edge Triggering with Hysteresis on Rising Slope
Level and Slope of
Signal Initiates Data Capture
0
3.2 mV/V
Level
Reference Trigger
Analog Comparison
Level
Hysteresis
3.2 mV/V
2.2 mV/V
Analog Comparison
Reference Trigger
