U.S. ROBOTICS, INC.

VARMODEM 2400

Modem Type

Data (synchronous/asynchronous)

Maximum Data Rate

2400bps

Data Bus

8-bit ISA

Data Modulation Protocol

Bell 103A/212A

ITU-T V.21, V.22, V.22bis, V.23

CONNECTIONS

Purpose

Location

Purpose

Location

Line out

CN1

Volume

SW2

Line in

CN2

   

BASE I/O ADDRESS SELECTION

Port

J3

J4

» COM1: (3F8h)

Off

Pins 2 & 3 closed

COM2: (2F8h)

On

Pins 2 & 3 closed

COM3: (3E8h)

Off

Pins 1 & 2 closed

COM4: (2E8h)

On

Pins 1 & 2 closed

INTERRUPT SELECTION

IRQ

J5

» 4

Pins 1 & 2 closed

3

Pins 2 & 3 closed

DTR SIGNAL

Setting

SW1/1

» On

DTR forced high

Off

DTR normal

RESULT CODES

Setting

SW1/2

» Off

Verbal result codes enabled

On

Numeric result codes enabled

RESULT CODES DISPLAY

Setting

SW1/3

Off

Display disabled

» On

Display enabled

ECHO COMMANDS DISPLAY

Setting

SW1/4

» Off

Local echo enabled

On

Local echo disabled

AUTO ANSWER

Setting

SW1/5

» On

Modem does not answer on first ring

Off

Modem answers on first ring

CARRIER DETECT

Setting

SW1/6

» Off

CD normal

On

CD forced high

MULTI-LINE INSTALLATION

Setting

SW1/7

» Off

Single phone connected

On

Multiple phones connected

AT COMMAND SET

Setting

SW1/8

» On

AT command set recognized

Off

AT command set disabled

ESCAPE CODE

Setting

SW1/9

» On

Go to command mode and display OK result code when escape character is received

Off

Disconnect, go to command mode and display NO CARRIER when escape character is received

VOLUME CONTROL

Setting

SW1/10

» Off

High volume

On

Low volume

Proprietary AT Command Set

See document V1254 for a full command summary.