Figure 4-26. wftrig input signal timing, Figure 4-27. wftrig output signal timing, Update* signal – National Instruments AT E Series User Manual
Page 89: Update* signal -42
Chapter 4
Connecting Signals
4-42
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Figures 4-26 and 4-27 show the input and output timing requirements for
the WFTRIG signal.
Figure 4-26. WFTRIG Input Signal Timing
Figure 4-27. WFTRIG Output Signal Timing
UPDATE* Signal
Any PFI pin can externally input the UPDATE* signal, which is available
as an output on the PFI5/UPDATE* pin.
As an input, the UPDATE* signal is configured in the edge-detection mode.
You can select any PFI pin as the source for UPDATE* and configure the
polarity selection for either rising or falling edge. The selected edge of
the UPDATE* signal updates the outputs of the DACs. In order to use
UPDATE*, you must set the DACs to posted-update mode.
As an output, the UPDATE* signal reflects the actual update pulse that is
connected to the DACs, even if the updates are being externally generated
by another PFI. The output is an active low pulse with a pulse width of
300 to 350 ns. This output is set to high-impedance at startup.
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
= 10 ns minimum
t
w
t
w
= 50 to 100 ns
t
w