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6-5
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:
•
DI Sample Clock (di/SampleClock)
•
DO Sample Clock (do/SampleClock)
•
AI Sample Clock (ai/SampleClock)
•
AI Convert Clock (ai/ConvertClock)
•
AO Sample Clock (ao/SampleClock)
•
Counter
n
Sample Clock
•
Counter
n
Internal Output
•
Frequency Output
•
DI Change Detection output
Several other internal signals can be routed to DI Sample Clock through internal routes. Refer
to
Device Routing in MAX
in the
NI-DAQmx Help
or the
LabVIEW Help
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>
•
PXI_STAR
•
PXIe_DSTAR<A,B>
•
Analog Comparison Event (an analog trigger)
You can sample data on the rising or falling edge of DI Sample Clock.
Routing DI Sample Clock to an Output Terminal
You can route DI Sample Clock out to any PFI <0..15> terminal. The PFI circuitry inverts the
polarity of DI Sample Clock before driving the PFI terminal.
Other Timing Requirements
Your DAQ device only acquires data during an acquisition. The device ignores DI Sample Clock
when a measurement acquisition is not in progress. During a measurement acquisition, you can
cause your DAQ device to ignore DI Sample Clock using the DI Pause Trigger signal.
The DI timing engine on your device internally generates DI Sample Clock unless you select an
external source. DI Start Trigger starts the timing engine and either software or hardware can
Содержание DAQ X NI 634 Series
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