Chapter 3
Connecting the Signals
©
National Instruments Corporation
3-27
DAQPad-MIO-16XE-50 User Manual
Figure 3-14.
TRIG1 and TRIG2 Input Signal Timing
Figure 3-15.
TRIG1 and TRIG2 Output Signal Timing
TRIG2 Signal
Any PFI signal can externally input TRIG2, which is available as an output
on the PFI1/TRIG2 screw terminal.
Refer to Figure 3-13 for the relationship of TRIG2 to the DAQ sequence.
As an input, the TRIG2 signal is configured in the edge-detection mode.
You can select any PFI signal 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 scans 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 board 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 board acquires a fixed number of scans and the acquisition
stops. This mode acquires data both before and after TRIG2 is received.
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
= 10 ns minimum
t
w
t
w
= 50 to 100 ns
t
w
