Chapter 8
Programmable Function Interfaces (PFI)
8-2
ni.com
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.
PFI Circuitry on Non-Isolated S Series Devices
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
NI 6124 Specifications
.
PFI for Isolated Devices
(NI 6154 Only)
Isolated S Series devices have 10 Programmable Function
Interface (PFI) signals—six input signals and four output signals.
Each PFI <0..5>/P0.<0..5> can be configured as a timing input signal for
AI or counter/timer functions or a static digital input. Each PFI input also
has a programmable debouncing filter.
Timing
S
ign
a
l
s
Direction Control
S
t
a
tic DI
I/O Protection
We
a
k P
u
ll-Down
PFI
x
/P1 or
PFI
x
/P2
S
t
a
tic DO
B
u
ffer
To Inp
u
t Timing
S
ign
a
l
S
elector
s
PFI
Filter
s
