Table 5.   Signal Descriptions Signal

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NI USB-6001/6002/6003 User Guide

AO GND

—

—

Analog Output Ground—The reference point 

for analog output.

AO <0, 1>

AO GND

Output

Analog Output Channels 0 and 1—Supplies 

the voltage output of the AO channels. Refer to 

the 

Analog Output

 section for more information.

P0.<0..7>

D GND

Input or 

Output

Port 0 Digital I/O Channels 0 to 7—You can 

configure each signal individually as an input or 

output. Refer to the 

Digital I/O

 section for more 

information.

P1.<0..3>

D GND

Input or 

Output

Port 1 Digital I/O Channels 0 to 3—You can 

configure each signal individually as an input or 

output. Refer to the

Digital I/O

 section for more 

information.

P2.0

D GND

Input or 

Output

Port 2 Digital I/O Channel 0—You can 

configure each signal individually as an input or 

output. Refer to the 

Digital I/O

 section for more 

information.

PFI 0, 1

D GND

Input

Programmable Function Interface or Digital 

I/O Channels—An edge counter input or digital 

trigger input. Refer to the 

PFI 0 and PFI 1

 

section for more information. 

D GND

—

—

Digital Ground—The reference point for digital 

signals.

+5 V

D GND

Output

+5 V Power Source—Provides +5 V power up 

to 150 mA. Refer to the 

+5 V Power Source

 

section for more information.

Table 5.  

Signal Descriptions (Continued)

Signal 

Name

Reference

Direction

Description

NI USB-6001/6002/6003 User Guide

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© National Instruments

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11

Analog Input

The NI USB-6001/6002/6003 has eight analog input channels that you can use for four 

differential analog input measurements or eight single-ended analog input measurements. 

Figure 5 shows the analog input circuitry of the NI DAQ device.

Figure 5.  

NI USB-6001/6002/6003 Analog Input Circuitry

The main blocks featured in the analog input circuitry are as follows:

•

MUX—The multiplexer (MUX) routes one AI channel at a time to the mode selector 

multiplexer (DIFF/RSE MUX).

•

DIFF/RSE MUX—The mode selector multiplexer selects between differential mode 

(DIFF) and referenced single-ended (RSE) measurement mode.

•

IA— The instrumentation amplifier (IA) removes the common mode signal and buffers the 

analog input signal before it is sampled by the analog-to-digital converter (ADC).

•

ADC—The analog-to-digital converter (ADC) digitizes the AI signal by converting the 

analog voltage into digital code.

•

AI FIFO—The NI DAQ device can perform both single and multiple analog-to-digital 

conversions of a fixed or infinite number of samples. A first-in-first-out (FIFO) buffer 

holds data during AI acquisitions to ensure no data is lost.

•

ADC Control—The ADC control circuitry sets the conversion rate of the ADC, sets the 

input configuration, drives the scanning sequence, and starts acquisitions synchronous with 

PFI 0 or PFI 1.

AI Data

AI Sampling Clock

AI Start Trigger

16-Position

Screw Terminal

Plug

I/O Connector

AI FIFO

IA

ADC

ADC

Control

MUX

DIFF

RSE

MUX

AI 0

AI 7

AI GND

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NI USB-6001/6002/6003 User Guide

Analog Input Modes

You can configure the analog input channels on the NI DAQ device to take up to four differential 

(DIFF) or eight referenced single-ended (RSE) measurements. 

•

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