Figure 2-13. Analog Edge Triggering With Hysteresis On Rising Slope; Figure 2-14. Analog Edge Triggering With Hysteresis On Falling Slope - National Instruments SC Express Series User Manual

Analog Edge Triggering With Hysteresis
When you add hysteresis to analog edge triggering, you add a window above or below the trigger
level. This trigger often is used to reduce false triggering due to noise or jitter in the signal. For
example, if you add a hysteresis of 1 V to the example in Figure 2-12, which uses a level of
3.2 V, the signal must start at or drop below 2.2 V to arm the trigger. The trigger asserts when
the signal rises above 3.2 V and deasserts when it falls below 2.2 V, as shown in Figure 2-13.

Figure 2-13. Analog Edge Triggering with Hysteresis on Rising Slope

3.2 V
Hysteresis
2.2 V
Analog Comparison
Reference Trigger
When using hysteresis with a falling slope, the trigger is armed when the signal starts above
Level, plus the hysteresis value, and asserts when the signal crosses below Level. For example,
if you add a hysteresis of 1 V to a level of 3.2 V, the signal must start at or rise above 4.2 V to
arm the trigger. The trigger asserts as the signal falls below 3.2 V and deasserts when it rises
above 4.2 V, as shown in Figure 2-14.

Figure 2-14. Analog Edge Triggering with Hysteresis on Falling Slope

4.2 V
3.2 V
Analog Comparison
Reference Trigger
Level
Hysteresis
Level
NI PXIe-4300 User Manual
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