Using An Internal Source; Using An External Source; Routing Ai Sample Clock Signal To An Output Terminal - National Instruments PXI-6238 User Manual

Chapter 4 Analog Input
You can specify an internal or external source for ai/SampleClock. You also
can specify whether the measurement sample begins on the rising edge or
falling edge of ai/SampleClock.

Using an Internal Source

One of the following internal signals can drive ai/SampleClock.
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•
•
A programmable internal counter divides down the sample clock timebase.
Several other internal signals can be routed to ai/SampleClock through
RTSI. Refer to Device Routing in MAX in the NI-DAQmx Help or the
LabVIEW 8.x Help for more information.

Using an External Source

Use one of the following external signals as the source of ai/SampleClock:
•
•
•
Note Refer to the NI 6238/6239 Specifications for the minimum allowable pulse width
and the propagation delay of PFI <0..5>.
Routing AI Sample Clock Signal to an Output
Terminal
You can route ai/SampleClock out to any output PFI <6..9> or RTSI <0..7>
terminal. This pulse is always active high.
You can specify the output to have one of two behaviors. With the pulse
behavior, your DAQ device briefly pulses the PFI terminal once for every
occurrence of ai/SampleClock.
With level behavior, your DAQ device drives the PFI terminal high during
the entire sample.
PFI <0..5> terminals are fixed inputs. PFI <6..9> terminals are fixed
outputs.
NI 6238/6239 User Manual
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Counter n Internal Output
AI Sample Clock Timebase (divided down)
A pulse initiated by host software
Input PFI <0..5>
RTSI <0..7>
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