Chapter 4
Signal Connections
4-24
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As an input, the TRIG1 signal is configured in the edge-detection mode.
You can select any PFI pin as the source for TRIG1 and configure the
polarity selection for either rising or falling edge. The selected edge of the
TRIG1 signal starts the data acquisition sequence for both posttriggered
and pretriggered acquisitions.
As an output, the TRIG1 signal reflects the action that initiates a DAQ
sequence. This is true even if the acquisition is being externally triggered
by another PFI. The output is an active high pulse with a pulse width of 50
to 100 ns. This output is set to tri-state at startup.
Figures 4-15 and 4-16
show the input and output timing requirements for
the TRIG1 signal.
Figure 4-15.
TRIG1 Input Signal Timing
Figure 4-16.
TRIG1 Output Signal Timing
The device also uses the TRIG1 signal to initiate pretriggered DAQ
operations. In most pretriggered applications, the TRIG1 signal is
generated by a software trigger. Refer to the TRIG2 signal description for
a complete description of the use of TRIG1 and TRIG2 in a pretriggered
DAQ operation.
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
t
w
= 10 ns minimum
t
w
t
w
= 50-100 ns
