Chapter 6
Digital I/O
©
National Instruments
6-19
X Series User Manual
•
PXI_STAR
•
PXIe-DSTAR<A,B>
•
Analog Comparison Event (an analog trigger)
DO Sample Clock Timebase is not available as an o
u
tp
u
t on the I/O
connector.
Yo
u
might
u
se DO Sample Clock Timebase if yo
u
want to
u
se an external
sample clock signal, b
u
t need to divide the signal down. If yo
u
want to
u
se
an external sample clock signal, b
u
t do not need to divide the signal, then
yo
u
sho
u
ld
u
se DO Sample Clock rather than DO Sample Clock Timebase.
DO Start Trigger Signal
Use the DO Start Trigger (do/StartTrigger) signal to initiate a waveform
generation. If yo
u
do not
u
se triggers, yo
u
can begin a generation with a
software command.
Retriggerable DO
The DO Start Trigger can also be config
u
red to be retriggerable. The timing
engine will generate the sample clocks for the config
u
red generation in
response to each p
u
lse on a DO Start Trigger signal.
The timing engine ignores the DO Start Trigger signal while the clock
generation is in progress. After the clock generation is finished, the timing
engine waits for another start trigger to begin another clock generation.
Fig
u
re 6-8 shows a retriggerable DO of fo
u
r samples.
Figure 6-8.
Retriggerable DO
DO
S
t
a
rt Trigger
DO
Sa
mple Clock
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