Hardware Description

National Instruments USB-9421, USB-9472, and USB-9481 are data

acquisition modules with integrated signal conditioning. They

provide plug-and-play connectivity via USB for faster setup and

measurements, offering four or eight digital input or output channels

specifically designed for monitoring and control applications. The

NI USB-9421 digital input module accepts high-voltage levels

between 11 and 30 V for direct connection to 24 V systems. The

NI USB-9472 can source up to 30 V externally powered at 0.75 A of

current per channel, and the NI USB-9481 uses electromechanical

relays that can switch 2 A at 30 VDC and 1 A at 60 VDC. In addition,

these modules include channel-to-earth ground isolation for safety,

noise immunity and high common-mode voltage range.

Software Description

The USB-9421, USB-9472, and USB-9481 all use NI-DAQmx

high-performance, multithreaded driver software for interactive

configuration and data acquisition on Windows OSs. Use

NI-DAQmx to test channels, generate code, and apply custom

functionality to any of your measurements. All NI data acquisition

devices shipped with NI-DAQmx also include VI Logger Lite

configuration-based data-logging software.

Recommended Accessories

The USB-9421, USB-9472, and USB-9481 all have built-in screw-

terminal connectivity, so no additional accessories are required. The

USB-9421 and USB-9472 are also available with D-Sub connector

options that connect to the NI 9934 strain relief accessory, or any

other standard 25-pin D-Sub connector.

Common Applications

The USB-9421, USB-9472, and USB-9481 are ideal for monitoring

and control applications where easy connectivity and portability are

essential, such as:

• Portable industrial monitoring and controlling motors, fans,

pumps, relays, and limit switches

• Data logging

• Small form-factor applications

• Embedded OEM applications

• In-vehicle data acquisition

• Academic lab use

Information for OEM Customers

For information on special configurations and pricing, please

Portable USB-Based

High-Voltage Digital I/O

• Small, portable devices

(12.1 by 8.6 by 2.5 cm)

• 4 or 8 channels with 24 V

logic levels

• High current-switching capacity

ground isolation

• Plug-and-play connectivity

via USBs

• Screw-terminal and D-Sub

connectors for direct wiring to

industrial sensors and actuators

Operating Systems

• Windows 2000/XP

Recommended Software

• LabVIEW

• LabWindows/CVI

Measurement Services

Software (included)

• NI-DAQmx driver software

• VI Logger Lite data-logging

software

NI USB-9421

Screw Terminals ........................................................779451-01

D-Sub Connector......................................................779452-01

NI USB-9472

Screw Terminals ........................................................779449-01

D-Sub Connector......................................................779450-01

NI USB-9481 ................................................................779453-01

Accessories

NI 9934 ......................................................................779104-01

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For complete product specifications, pricing, and accessory

Ordering Information

Product

Bus

Input Lines

Output Lines

Isolation

Signal Levels

Output Current per Channel

Connector

USB-9421

USB

8 sink

–

Bank

11 to 30 V

–

Screw Terminal, D-Sub

NI-DAQmx

USB-9472

USB

–

8 source

Bank

6 to 30 V

0.75 A

Screw Terminal, D-Sub

NI-DAQmx

USB-9481

USB

–

4 Form A Relay

Bank

60 VDC

250 VAC/VDC

2 A (30 VDC)

1 A (60 VDC)

Screw Terminal

NI-DAQmx

Table 1. Portable USB DAQ for High-Voltage Digital I/O Selection Guide