National Instruments PCI-6251 User Manual page 42

Signal Name
D GND
P0.<0..31>
APFI <0,1>
+5 V
PFI <0..7>/
P1.<0..7>
Table 3-1. I/O Connector Signals (Continued)
Reference Direction
— —
D GND Input or
Output
AO GND Input
or AI GND
D GND Output
D GND Input or
Output
Description
Digital Ground—D GND supplies the reference
for P0.<0..31>, PFI <0..15>/P1/P2, and +5 V. All
three ground references—AI GND, AO GND,
and D GND—are connected on the device. Refer
Connecting Digital I/O Signals
to the
Digital I/O.
Chapter 6,
Port 0 Digital I/O Channels—You can
individually configure each signal as an input or
Connecting Digital I/O
output. Refer to the
Signals
section of Chapter 6,
Analog Programmable Function Interface
Channels—Each APFI signal can be used as
AO external reference inputs for AO <0..3>,
AO external offset input, or as an analog trigger
input. APFI <0,1> are referenced to AI GND
when they are used as analog trigger inputs.
APFI <0,1> are referenced to AO GND when they
are used as AO external offset or reference inputs.
These functions are not available on all devices;
refer to the specifications for your device. Refer to
APFI <0,1> Terminals
the
Triggering.
+5 V Power Source—These terminals provide a
fused +5 V power source. Refer to the
Source
section for more information.
Programmable Function Interface or Port 1
Digital I/O Channels—Each of these terminals
can be individually configured as a PFI terminal or
a digital I/O terminal.
As an input, each PFI terminal can be used to
supply an external source for AI, AO, DI, and
DO timing signals or counter/timer inputs.
As a PFI output, you can route many different
internal AI, AO, DI, or DO timing signals to each
PFI terminal. You also can route the counter/timer
outputs to each PFI terminal.
As a Port 1 digital I/O signal, you can individually
configure each signal as an input or output.
Connecting Digital I/O Signals
Refer to the
Digital
section of Chapter 6,
PFI.
© National Instruments | 3-3
M Series User Manual
section of
Digital I/O.
section of Chapter 11,
+5 V Power
I/O, or to Chapter 8,