3COM CORPORATION

US ROBOTICS 1200

Modem Type

Data (synchronous/asynchronous)

Maximum Data Rate

1200bps

Data Bus

External

Data Modulation Protocol

Bell 103A/212A

CONNECTIONS

Purpose

Location

Purpose

Location

Line out

CN1

Power

CN4

Line in

CN2

Volume

SW3

RS-232/422

CN3

Power

SW2

DIAGNOSTIC LED(S)

LED

Color

Status

Condition

LED1

Red

On

Analog loopback self test mode

LED1

Green

On

Data mode

LED2

Red

Blinking

Modem is transmitting/receiving data

LED2

Green

On

Carrier signal detected

DTR SIGNAL

Setting

SW1/1

» On

DTR forced high

Off

DTR normal

RESULT CODES

Setting

SW1/2

» Verbose result codes enabled

On

Numeric result codes enabled

Off

RESULT CODES DISPLAY

Setting

SW1/3

» Display enabled

On

Display disabled

Off

ECHO COMMANDS DISPLAY

Setting

SW1/4

» Local echo enabled

Off

Local echo disabled

On

AUTO ANSWER

Setting

SW1/5

» Modem doe not answer on first ring

On

Modem answers on first ring

Off

CARRIER DETECT

Setting

SW1/6

» CD normal

Off

CD forced high

On

MULT-LINE INSTALLATION

Setting

SW1/7

» Single phone connected

Off

Multiple phones connected

On

AT COMMAND SET

Setting

SW1/8

» AT command set recognized

On

AT command set disabled

Off

Proprietary AT Command Set

ANALOG LOOPBACK SELF TEST

Type:

Register

Format:

AT [cmds] S16=n [cmds]

Example:

ATS16=139<CR>

Description:

Selects the tone dialing test

Command

Function

0

Data mode.

1

Analog loopback.