Chapter 8
PFI
X Series User Manual
8-4
ni.com
Using PFI Terminals as Static Digital I/Os
Each PFI can be individ
u
ally config
u
red as a static digital inp
u
t or a static
digital o
u
tp
u
t. When a terminal is
u
sed as a static digital inp
u
t or o
u
tp
u
t,
it is called P1.
x
or P2.
x
. On the I/O connector, each terminal is labeled
PFI
x
/P1.
x
or PFI
x
/P2.
x
.
In addition, X Series devices have
u
p to 32 lines of bidirectional DIO
signals.
Using PFI Terminals to Digital Detection Events
Each PFI can be config
u
red to detect digital changes. The val
u
es on the PFI
lines cannot be read in a hardware-timed task, b
u
t they can be
u
sed to fire
the change detection event. For example, if yo
u
wanted to do change
detection on eight timed DIO lines b
u
t wanted to ens
u
re that the val
u
e of
the lines was
u
pdated every second independent of the eight lines changing
yo
u
co
u
ld set a PFI line
u
p for change detection and connect a 1 Hz signal
to it.
Connecting PFI Input Signals
All PFI inp
u
t connections are referenced to D GND. Fig
u
re 8-2 shows this
reference, and how to connect an external PFI 0 so
u
rce and an external
PFI 2 so
u
rce to two PFI terminals.
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