Справочник Пользователя для National Instruments NI PCI-6111
Chapter 4
Connecting Signals
4-28
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WFTRIG Signal
Any PFI pin can externally input the WFTRIG signal, which is available as
an output on the PFI6/WFTRIG pin.
an output on the PFI6/WFTRIG pin.
As an input, WFTRIG 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 WFTRIG
starts the waveform generation for the DACs. The update interval counter
(UI) is started if you select internally generated UPDATE*.
select any PFI pin as the source for WFTRIG and configure the polarity
selection for either rising or falling edge. The selected edge of WFTRIG
starts the waveform generation for the DACs. The update interval counter
(UI) is started if you select internally generated UPDATE*.
As an output, WFTRIG reflects the trigger that initiates waveform
generation, even if the waveform generation is being externally triggered
by another PFI. The output is an active high pulse with a pulse width of
25 to 50 ns. This output is set to high-impedance at startup.
generation, even if the waveform generation is being externally triggered
by another PFI. The output is an active high pulse with a pulse width of
25 to 50 ns. This output is set to high-impedance at startup.
Figures 4-22 and 4-23 show the timing requirements for WFTRIG.
Figure 4-22. WFTRIG Input Signal Timing
Figure 4-23. WFTRIG Output Signal Timing
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
= 10 ns minimum
t
w
t
w
= 25 to 50 ns
t
w