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Chapter 2 Function Reference — Configure_HW_Analog_Trigger
NI-DAQ FRM for PC Compatibles 2-86
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National Instruments Corporation
• ND_HIGH_HYSTERESIS—The trigger is generated when the signal value is greater than
the highValue, with hysteresis specified by lowValue.
Figure 2-7.
ND_HIGH_HYSTERESIS
• ND_LOW_HYSTERESIS—The trigger is generated when the signal value is less than the
lowValue, with hysteresis specified by highValue.
Figure 2-8.
ND_LOW_HYSTERESIS
Use the trigSource parameter to specify the source of the trigger you want to use. For E Series
devices, the legal values are
ND_PFI_0 and ND_THE_AI_CHANNEL.
Set trigSource to
ND_PFI_0 if you want the trigger to come from the PFI0/TRIG1 pin. You
need to connect the analog signal you want to use for triggering to the PFI0/TRIG1 pin. To
generate triggers based on an analog signal that takes a wide range of values between –10 V
and +10 V, you should use this setting.
You should select
ND_THE_AI_CHANNEL for trigSource only to generate triggers based on a
low-range analog signal, if you are concerned about signal quality and are using a shielded
cable, or if you want the trigger to be based on an analog input channel in the differential
mode. Using this selection is non-trivial.
highValue
Trigger
lowValue
highValue
Trigger
lowValue