Chapter 6
Digital I/O
X Series User Manual
6-16
ni.com
Digital Output Triggering
Digital o
u
tp
u
t s
u
pports two different triggering actions:
•
Start trigger
•
Pa
u
se trigger
An analog or digital trigger can initiate these actions. All X Series devices
s
u
pport digital triggering, b
u
t some do not s
u
pport analog triggering. To
find yo
u
r device’s triggering options, refer to the specifications doc
u
ment
for yo
u
r device. Refer to the
DO Start Trigger Signal
and
DO Pause
Trigger Signal
sections for more information abo
u
t these triggering
actions.
Digital Waveform Generation
Yo
u
can generate digital waveforms on the Port 0 DIO lines. The DO
waveform generation FIFO stores the digital samples. X Series devices
have a DMA controller dedicated to moving data from the system memory
to the DO waveform generation FIFO. The DAQ device moves samples
from the FIFO to the DIO terminals on each rising or falling edge of a clock
signal, DO Sample Clock. Yo
u
can config
u
re each DIO signal to be an
inp
u
t, a static o
u
tp
u
t, or a digital waveform generation o
u
tp
u
t.
The FIFO s
u
pports a retransmit mode. In the retransmit mode, after all the
samples in the FIFO have been clocked o
u
t, the FIFO begins o
u
tp
u
tting all
of the samples again in the same order. For example, if the FIFO contains
five samples, the pattern generated consists of sample #1, #2, #3, #4, #5,
#1, #2, #3, #4, #5, #1, and so on.
X Series devices feat
u
re the following DO (waveform generation) timing
signals:
•
DO Sample Clock Signal
*
•
DO Sample Clock Timebase Signal
•
DO Start Trigger Signal
*
•
DO Pause Trigger Signal
*
Signals with an
*
s
u
pport digital filtering. Refer to the
PFI Filters
section
of Chapter 8,
PFI
, for more information.
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