© National Instruments
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8-1
8
PFI
X Series devices have up to 16 Programmable Function Interface (PFI) signals. In addition,
X Series devices have up to 32 lines of bidirectional DIO signals.
Each PFI can be individually configured as the following:
•
A static digital input
•
A static digital output
•
A timing input signal for AI, AO, DI, DO, or counter/timer functions
•
A timing output signal from AI, AO, DI, DO, or counter/timer functions
Each PFI input also has a programmable debouncing filter. Figure 8-1 shows the circuitry of
one PFI line. Each PFI line is similar.
Figure 8-1.
X Series PFI Circuitry
When a terminal is used as a timing input or output signal, it is called PFI
x
(where
x
is an integer
from 0 to 15). When a terminal is used as a static digital input or output, 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
.
The voltage input and output levels and the current drive levels of the PFI signals are listed in
the device specifications
Timing
S
ign
a
l
s
Direction
Control
I/O Protection
We
a
k P
u
ll-Down
PFI
x
/P1/P2
S
t
a
tic DO
B
u
ffer
To Inp
u
t Timing
S
ign
a
l
S
elector
s
PFI
Filter
s
S
t
a
tic DI
PFI
Ch
a
nge
Detection
Содержание 6368
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