National Instruments Data Acquisition Device E Series - Manual (Page 134)

Chapter 10 Triggering
© National Instruments Corporation 10-5 E Series User Manual
Level Triggering with Hysteresis
Hysteresis adds a programmable window above or below the trigger level
that a valid trigger signal must pass through and is often used to reduce
false triggering due to noise or jitter in the signal.
When using Hysteresis with a rising slope, the trigger asserts when the
signal starts below Level and then crosses above Level. The trigger
deasserts when the signal crosses below Level minus hysteresis as shown
in Figure 10-5.
Figure 10-5. High Hysteresis
When using Hysteresis with a falling slope, the trigger asserts when the
signal starts above Level and then crosses below Level. The trigger
deasserts when the signal crosses above Level plus hysteresis, as shown in
Figure 10-6.
Figure 10-6. Low Hysteresis
Window Triggering
A window trigger occurs when an analog signal either passes into (enters)
or passes out of (leaves) a window defined by two voltage levels. Specify
the levels by setting the window Top value and the window Bottom value.
Level
Analog Comparison Event
Hysteresis
Level
Analog Comparison Event
Hysteresis