Chapter 6
Digital I/O
6-4
ni.com
You can configure each DIO line to be an output, a static input, or a digital
waveform acquisition input.
DI Sample Clock Signal
(NI 6124 Only)
Use the DI Sample Clock (di/SampleClock) signal to sample
the P0.<0..7> terminals and store the result in the DI waveform acquisition
FIFO. These S Series devices do not have the ability to divide down a
timebase to produce an internal DI Sample Clock for digital waveform
acquisition. Therefore, you must route an external signal or one of many
internal signals from another subsystem to be the DI Sample Clock. For
example, you can correlate digital and analog samples in time by sharing
your AI Sample Clock or AO Sample Clock as the source of your
DI Sample Clock. To sample a digital signal independent of an AI, AO,
or DO operation, you can configure a counter to generate the desired
DI Sample Clock or use an external signal as the source of the clock.
If the DAQ device receives a DI Sample Clock when the FIFO is full,
it reports an overflow error to the host software.
Using an Internal Source
To use DI Sample Clock with an internal source, specify the signal source
and the polarity of the signal. The source can be any of the following
signals:
•
AI Sample Clock (ai/SampleClock)
•
AI Convert Clock (ai/ConvertClock)
•
AO Sample Clock (ao/SampleClock)
•
Counter
n
Internal Output
•
Frequency Output
•
DI Change Detection Output
Several other internal signals can be routed to DI Sample Clock through
RTSI. Refer to
Device Routing in MAX
in the
NI-DAQmx Help
or the
LabVIEW Help
in version 8.0 or later for more information.
Using an External Source
You can route any of the following signals as DI Sample Clock:
•
PFI <0..15>
•
RTSI <0..7>
