© National Instruments | 3-3
X Series User Manual
AI SENSE, 
AI SENSE 2, 
AI SENSE 3,
AI SENSE 4
— Input Analog Input Sense—In NRSE mode, the reference 
for each AI <0..15> signal is AI SENSE; the 
reference for each AI <16..31> signal is 
AI SENSE 2; the reference for each AI <80..143> is 
AI SENSE 3; and the reference for each 
AI <144..207> is AI SENSE 4. Also refer to the 
Connecting Ground-Referenced Signal Sources 
section of Chapter 4, 
Analog Input.
AO <0..3> AO GND Output Analog Output Channels 0 to 3—These terminals 
supply the voltage output of AO channels 0 to 3.
AO GND — — Analog Output Ground—AO GND is the 
reference for AO <0..3>. All three ground 
references—AI GND, AO GND, and D GND—are 
connected on the device.
*
D GND — — 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.
*
P0.<0..31> D GND Input or 
Output
Port 0 Digital I/O Channels 0 to 31—You can 
individually configure each signal as an input or 
output.
APFI <0,1> AO GND 
or AI GND
Input Analog Programmable Function Interface 
Channels 0to1—Each APFI signal can be used as 
AO external reference inputs for AO <0..3>, 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 device specifications.
+5 V D GND Output +5 V Power Source—These terminals provide a 
fused +5 V power source. Refer to the 
+5 V Power 
Source
 section for more information.
Table 3-1.  I/O Connector Signals (Continued)
Signal Name Reference Direction Description