National Instruments DAQ X NI 634 Series, Руководство пользователя

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11-5
X Series User Manual
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
– 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
An a log Comp a ri s on Event
Hy s tere s i s
High thre s hold
(Level)
Low thre s hold
(Level – Hy s tere s i s )
Fir s t s ign a l m us t go
b elow low thre s hold.
Then s ign a l m us t
go ab ove high thre s hold b efore
An a log Comp a ri s on Event ass ert s .
An a log Comp a ri s on Event
Hy s tere s i s
High thre s hold
(Level + Hy s tere s i s )
Low thre s hold
(Level)
Fir s t s ign a l m us t go
ab ove high thre s hold.
Then s ign a l m us t go b elow low thre s hold
b efore An a log Comp a ri s on Event ass ert s .