National Instruments X Series User Manual page 206

For the trigger to assert, the signal must first be below the low threshold, then go above
the high threshold. The trigger stays asserted until the signal returns below the low
threshold. The output of the trigger detection circuitry is the internal Analog
Comparison Event signal, as shown in Figure 11-6.
Figure 11-6. Analog Edge Triggering with Hysteresis Rising Slope Example
Hysteresis
Analog Comparison Event
– Analog Edge Trigger with Hysteresis (Falling Slope)—When using hysteresis with a
falling slope, you specify a trigger level and amount of hysteresis. The low threshold
is the trigger level; the high threshold is the trigger level plus the hysteresis.
For the trigger to assert, the signal must first be above the high threshold, then go
below the low threshold. The trigger stays asserted until the signal returns above the
high threshold. The output of the trigger detection circuitry is the internal Analog
Comparison Event signal, as shown in Figure 11-7.
Figure 11-7. Analog Edge Triggering with Hysteresis Falling Slope Example
Hysteresis
Then signal must go below low threshold
before Analog Comparison Event asserts.
Analog Comparison Event
First signal must go
below low threshold.
First signal must go
above high threshold.
X Series User Manual
Then signal must
go above high threshold before
Analog Comparison Event asserts.
High threshold
(Level)
Low threshold
(Level – Hysteresis)
High threshold
(Level + Hysteresis)
Low threshold
(Level)
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