Chapter 4
Analog Input
©
National Instruments Corporation
4-15
Several other internal signals can be routed to AI 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
Use one of the following external signals as the source of AI Sample Clock:
•
PFI <0..15>
•
RTSI <0..7>
•
PXI_STAR
•
Analog Comparison Event (an analog trigger)
Routing AI Sample Clock Signal to an Output
Terminal
You can route AI Sample Clock out to any PFI <0..15> 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 Sample Clock.
With level behavior, your DAQ device drives the PFI terminal high during
the entire sample.
All PFI terminals are configured as inputs by default.
Other Timing Requirements
A counter on your device internally generates AI Sample Clock unless you
select some external source. AI Start Trigger starts this counter and either
software or hardware can stop it once a finite acquisition completes. When
using an internally generated AI Sample Clock, you also can specify a
configurable delay from AI Start Trigger to the first AI Sample Clock
pulse. By default, this delay is set to two ticks of the AI Sample Clock
Timebase signal.
