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Using an Internal Source
To use do/SampleClock with an internal source without making any external connections,
specify the signal source and the polarity of the signal. The source can be one of the following
signals:
•
AO Sample Clock
•
Counter 0 Out
Program the DAQ device to update the DIO pins on the rising edge or falling edge of
do/SampleClock.
Using an External Source
You can use a signal connected to any RTSI <0..6> pin as the source of do/SampleClock. You
can generate samples on the rising or falling edge of do/SampleClock.
Any PFI line that can be routed to RTSI can also be used as the clock source. Refer to
Device Routing in MAX in the NI-DAQmx Help or the LabVIEW Help for more information.
You must ensure that the time between two active edges of the do/SampleClock is not too short.
If the time is too short, the DO waveform generation FIFO is not able to read the next sample
fast enough.
Digital Waveform Acquisition
(NI 6731/6733 Only)
The NI 6731/6733 can acquire digital waveforms. This behavior is also referred to as correlated
digital I/O because there is no dedicated clock source for the digital operation. Refer to the
Sample Clock Signal (NI 6731/6733 Only)
The DI waveform acquisition FIFO stores the digital samples. The NI 6731/6733 can use DMA
transfers to move data from the DI waveform acquisition FIFO to system memory. The DAQ
device samples the DIO lines on each rising or falling edge of a clock signal, di/SampleClock.
For more information on DMA transfers, refer to the
Bus
Interface.
Chapter 9,
You can configure each DIO line to be an output, a static input, or a digital waveform acquisition
input.
TitleShort-Hidden (cross reference text)
section for a list of possible sources.
Direct Memory Access (DMA)
section of
© National Instruments | 4-3
DI
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