Serial Instrument Control

Interfaces for USB

Overview

The National Instruments USB-232 and USB-485 transform your

Universal Serial Bus (USB) port into asynchronous serial ports for

communication with serial devices. The NI USB-232 and USB-485

are available in either 1, 2, or 4-port versions and use standard

RS-232, RS-422, or RS-485 communications. All products include

driver software for Windows 2000/XP. You can install and use the

USB-232 and USB-485 as standard serial ports from your existing

applications or with applications written with NI-VISA.

Additionally, the USB-232 2 and 4-port

versions feature software-selectable

DTE or DCE transceiver modes, as well

as an automatic transceiver detection

mode, or Auto232. The USB-485

features software selectable biasing;

therefore, you can turn biasing on and

off for each port through software.

Development environments, such as

Visual Basic, Visual C++, and Excel, as

well as National Instruments LabVIEW, LabWindows/CVI and

Measurement Studio, can access the serial ports using standard

serial I/O functions.

• Compatible with standard PC

serial port

• 1, 2, and 4-port versions

• Handle RTS/CTS hardware

handshake lines

• 128 B transmit and receive FIFOs

• 5,6,7, or 8 data bits

NI USB-485

• RS-485 or RS-422 interface

• 460.8 kb/s maximum transfer rate

• Communicates with up to

31 devices

• Automatic transceiver-control

mode for 2-wire RS-485 devices

• Software-selectable biasing

• Cable lengths up to 1.2 km

(4,000 ft)

NI USB-232

• RS-232 interface

• 230.4 kb/s maximum transfer rate

• Software-selectable DTE or DCE

transceiver modes (2 and 4-port

models only)

Operating Systems

Windows 2000/XP

Recommended Software

Other Compatible Software

• C/C++

•Visual Basic

• Any package with the

Microsoft serial driver interface

Driver Software (included)

• NI-Serial

INFO CODES

For more information

or to order products

and enter:

usb232

usb485

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Ordering Information

*External 12 VDC power supply included

P = Power Cord Type

0 = U.S. 120 VAC

4 = Universal Euro 240 VAC

2 = Swiss 220 VAC

5 = North American 240 VAC

3 = Australian 240 VAC

6 = United Kingdom 240 VAC

Number

Part

Model

Serial Port

of Ports

Number

NI USB-232

RS-232

1

778472-01

NI USB-232/2

RS-232

2

778473-02

NI USB-232/4

RS-232

4

778473-04

NI USB-485

RS-485/RS-422

1

778475-01

NI USB-485/2

RS-485/RS-422

2

778476-02

NI USB-485/4

RS-485/RS-422

4

778476-P4*

FIFO size ................................................. 128 B

Maximum transfer rate............................ 460.8 kb/s (RS-485); 230.4 kb/s (RS-232)

USB connector (1 port) ............................ captive cable with USB series A plug

USB connector (2 and 4 port) .................. USB standard series B connector

Serial connectors...................................... DB-9

Noise emissions ....................................... Class A

Power Requirements

5 VDC (from USB) ........................................ USB-232 (100 mA typ, 200 mA max),

USB-232/2 (200 mA typ, 500 mA max),

USB-232/4 (300 mA typ, 500 mA max),

USB-485 (175 mA typ, 500 mA max)

USB-485/2 (300 mA typ, 500 mA max),

+12 VDC (from supply furnished)............ USB-485/4 (225 mA typ, 500 mA max)

Operating Environment

Ambient temperature............................... 0 to 70 °C

Relative humidity...................................... 10 to 90%, noncondensing

Storage Environment

Ambient temperature (1 port).................. -40 to 80 °C

Ambient temperature (2 and 4 port)........ -40 to 85 °C

Relative humidity...................................... 10 to 90%, noncondensing

Electrostatic Discharge Protection

Case contact and air discharge................ ±4 kV

RS-232 and RS-435 data lines ................. ±15 kV (HBM)

Specifications

NI USB-232 Series, NI USB-485 Series