Chapter 4 Signal Connections
National Instruments Corporation
4-35
VXI-MIO Series User Manual
As an input, the WFTRIG signal is configured in the edge-detection
mode. You can select any PFI pin as the source for WFTRIG and
configure the polarity selection for either rising or falling edge. The
selected edge of the WFTRIG signal starts the waveform generation for
the DACs. The update interval (UI) counter is started if you select
internally generated UPDATE*.
As an output, the WFTRIG signal reflects the trigger that initiates
waveform generation. This is true even if the waveform generation is
being externally triggered by another PFI. The output is an active high
pulse with a pulse width of 50 to 100 ns. This signal is set to input
(High-Z) at startup.
Figures 4-24 and 4-25 show the input and output timing requirements
for the WFTRIG signal.
Figure 4-24.
WFTRIG Input Signal Timing
Figure 4-25.
WFTRIG Output Signal Timing
Rising-edge
polarity
Falling-edge
polarity
t
w
t
w
= 10 ns minimum
t
w
t
w
= 50-100 ns
