Figure 4-17. trig2 input signal timing, Figure 4-18. trig2 output signal timing – National Instruments AT E Series User Manual
Page 82
Chapter 4
Connecting Signals
© National Instruments Corporation
4-35
before TRIG2 can be recognized. After the scan counter decrements to
zero, it is loaded with the number of posttrigger scans to acquire while the
acquisition continues. The device ignores the TRIG2 signal if it is asserted
prior to the scan counter decrementing to zero. After the selected edge of
TRIG2 is received, the device acquires a fixed number of scans and the
acquisition stops. This mode acquires data both before and after receiving
TRIG2.
As an output, the TRIG2 signal reflects the posttrigger in a pretriggered
acquisition sequence, even if the acquisition is being externally triggered
by another PFI. The TRIG2 signal is not used in posttriggered data
acquisition. The output is an active high pulse with a pulse width of
50 to 100 ns. This output is set to high-impedance at startup.
Figures 4-17 and 4-18 show the input and output timing requirements for
the TRIG2 signal.
Figure 4-17. TRIG2 Input Signal Timing
Figure 4-18. TRIG2 Output Signal Timing
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
= 10 ns minimum
t
w
t
w
= 50 to 100 ns
t
w