Chapter 4
Analog Input
4-22
ni.com
Using a Digital Source
To
u
se AI Reference Trigger with a digital so
u
rce, specify a so
u
rce and an
edge. The so
u
rce can be any inp
u
t PFI signal.
The so
u
rce also can be one of several internal signals on yo
u
r DAQ device.
Refer to
Device Routing in MAX
in the
NI-DAQmx Help
or the
LabVIEW
Help
in version 8.0 or later for more information.
Yo
u
also can specify whether the meas
u
rement acq
u
isition stops on the
rising edge or falling edge of AI Reference Trigger.
Routing AI Reference Trigger to an Output Terminal
Yo
u
can ro
u
te AI Reference Trigger o
u
t to any o
u
tp
u
t PFI terminal.
AI Pause Trigger Signal
Yo
u
can
u
se the AI Pa
u
se Trigger (ai/Pa
u
seTrigger) signal to pa
u
se and
res
u
me a meas
u
rement acq
u
isition. The internal sample clock pa
u
ses while
the external trigger signal is active and res
u
mes when the signal is inactive.
Yo
u
can program the active level of the pa
u
se trigger to be high or low.
Using a Digital Source
To
u
se AI Sample Clock, specify a so
u
rce and a polarity. The so
u
rce can
be any inp
u
t PFI signal.
The so
u
rce also can be one of several other internal signals on yo
u
r DAQ
device. Refer to
Device Routing in MAX
in the
NI-DAQmx Help
or the
LabVIEW Help
in version 8.0 or later for more information.
Getting Started with AI Applications in Software
Yo
u
can
u
se the USB-621
x
device in the following analog inp
u
t
applications:
•
Single-point analog inp
u
t
•
Finite analog inp
u
t
•
Contin
u
o
u
s analog inp
u
t
Yo
u
can perform these applications thro
u
gh DMA, interr
u
pt, or
programmed I/O data transfer mechanisms. Some of the applications
also
u
se start, reference, and pa
u
se triggers.
