Chapter4 ConnectingSignals
©NationalInstruments Corporation 4-33 NI6013/6014 User Manual
Figure4-27. UPDATE*Output Signal Timing
The DACsare updated within 100 ns of the leading edge. Separate the
UPDATE*pulseswith enough time that new data can be written to the DAC
latches.
Thedevice UI counter normally generates the UPDATE*signal unless you
select some externalso urce. The UI counter is started by the WFTRIG
signaland can be stopped by software or the internal Buffer Counter (BC).
D/A conversionsgenerated by either an internal or external UPDATE*
signald o not occur when gated bythe software command register gate.
UISOURCE Signal
Any PFIpin can ext ernally input the UISOURCE signal, which is not
available as an output on the I/O connector. The UI counter uses
UISOURCE as a clock to time the generationof t he UPDATE* signal.
You must configure the PFI pin you select as the source for UISOURCE
in thel evel-detection mode. You can configure the polarity selection for
the PFI pin for either active high or active low. Figure 4-28 shows the
timing requirements for UISOURCE.
Figure4-28. UISOURCESignal Timing
t
w
=300 to 350 ns
t
w
t
p
=50 ns minimum
t
w
=23 ns minimum
t
w
t
w
t
p