National Instruments VXI-MIO Series - Manual (Page 74)

Chapter 4 Signal Connections
VXI-MIO Series User Manual 4-28  National Instruments Corporation
Figure 4-15. TRIG1 Input Signal Timing
Figure 4-16. TRIG1 Output Signal Timing
The module also uses the TRIG1 signal to initiate pretriggered data
acquisition operations. In most pretriggered applications, the
acquisition is started by a software trigger. Refer to the TRIG2 signal
description for a complete description of the use of TRIG1 and TRIG2
in a pretriggered data acquisition operation.
TRIG2 Signal
Any PFI pin can externally input the TRIG2 signal, which is available
as an output on the PFI1/TRIG2 pin.
Refer to Figure 4-12 for the relationship of TRIG2 to the data
acquisition sequence.
As an input, the TRIG2 signal is configured in the edge-detection mode.
You can select any PFI pin as the source for TRIG2 and configure the
polarity selection for either rising or falling edge. The selected edge of
the TRIG2 signal initiates the posttriggered phase of a pretriggered
acquisition sequence. In pretriggered mode, the TRIG1 signal initiates
the data acquisition. The scan counter indicates the minimum number of
Rising-edge
polarity
Falling-edge
polarity
t
w
t
w
= 10 ns minimum
t
w
t
w
= 50-100 ns