3COM CORPORATION

US ROBOTICS 28,800 EXTERNAL

Modem Type

Data (synchronous/asynchronous)/Fax

Maximum Data Rate

28.8Kbps

Maximum Fax Rate

14.4Kbps

Data Bus

External

Fax Class

Class I & II

Data Modulation Protocol

Bell 103A/212A

ITU-T V.22, V.22bis, V.23, V.32, V.32bis, V.25

Fax Modulation Protocol

ITU-T V.17, V.21CH2, V.27ter, V.29

Error Correction/Compression

MNP5, V.42, V.42bis

CONNECTIONS

Purpose

Location

Purpose

Location

Line out

CN3

DC power

CN1

Line in

CN4

Volume

R1

RS-232/422

CN2

Power switch

SW2

DTR SIGNAL

Setting

SW1/1

í DTR normal

Off

DTR forced high

On

RESULT CODES

Setting

SW1/2

í Verbal result codes enabled

Off

Numeric result codes enabled

On

RESULT CODES DISPLAY

Setting

SW1/3

í Enabled

On

Disabled

Off

ECHO DISPLAY

Setting

SW1/4

í Enabled

Off

Disabled

On

AUTO ANSWER

Setting

SW1/5

í Disabled

On

Enabled

Off

CARRIER DETECT

Setting

SW1/6

í CD normal

Off

CD forced high

On

SOFTWARE RESET

Setting

SW1/7

í CD normal

Off

CD forced high

On

AT COMMAND SET

Setting

SW1/8

Enabled

On

Disabled

Off

DIAGNOSTIC LED(S)

LED

Color

Status

Mode

Condition

AA

Red

On

Answer

Auto-answer enabled

AA

Red

Off

N/A

Auto-answer disabled

AA

Red

Blinking

N/A

Phone is ringing

CD

Red

On

N/A

Carrier signal detected

CD

Red

Off

N/A

Carrier signal not detected

RD

Red

Blinking

N/A

Modem is receiving data or sending result codes

RD

Red

Off

N/A

Modem is not receiving data

SD

Red

Blinking

N/A

Modem is transmitting data

SD

Red

Off

N/A

Modem is not transmitting data

TR

Red

On

N/A

DTR signal is high

TR

Red

Off

N/A

DTR signal is low

CS

Red

On

N/A

CTS high

CS

Red

Off

N/A

CTS normal

ARQ/FAX

Red

On

Data

Error control connection established

ARQ/FAX

Red

Blinking

Data

Error control data is being transmitted

ARQ/FAX

Red

Blinking

Fax

Modem is connected in FAX mode

Proprietary AT Command Set

BIT-MAPPED REGISTER S13

Format:

AT [cmds] S13=n [cmds]

Example:

ATS13=13<CR>

Default:

0

Range:

0 - 89

Unit:

Bit-mapped

Description:

Controls DTR reset, DTR dialing, reset dialing, and MNP3.

Bit

Value

Function

0

í 0

1

DTR normal.

Reset on low DTR.

1

í 0

Not used.

2

í 0

Not used.

3

í 0

1

DTR dialing disabled.

DTR dialing enabled.

4

í 0

1

Reset dialing disabled.

Reset dialing enabled.

5

í 0

Not used.

6

í 0

1

MNP 3 enabled.

MNP 3 disabled.

7

í 0

Not used.

BIT-MAPPED REGISTER S15

Format:

AT [cmds] S15=n [cmds]

Example:

ATS15=13<CR>

Default:

0

Range:

0 - 56

Unit:

Bit-mapped

Description:

Controls non-error-correcting mode buffer, MNP4, and BS/DEL switch.

Bit

Value

Function

0

í 0

Not used.

1

í 0

Not used.

2

í 0

Not used.

3

í 0

1

Non-error-correcting mode transmit buffer set to 1.5KB.

Non-error-correcting mode transmit buffer set to 128 bytes.

4

í 0

1

MNP 4 enabled.

MNP 4 disabled.

5

í 0

1

Use backspace key for delete disabled.

Use backspace key for delete enabled.

BIT-MAPPED REGISTER S27

Format:

AT [cmds] S27=n [cmds]

Example:

ATS27=139<CR>

Default:

0

Range:

0 - 191

Unit:

Bit-mapped

Description:

Controls V.21, V.32 encoding and modulation, V.42 answer tone and handshake, and 9600 result codes.

Bit

Value

Function

0

í 0

1

V.21 disabled.

V.21 enabled.

1

í 0

1

V.32 trellis coding disabled.

V.32 trellis coding enabled.

2

í 0

1

V.32 modulation enabled.

V.32 modulation disabled.

3

í 0

1

2100Hz answer tone enabled.

2100Hz answer tone disabled.

5, 4

í 00

01

10

11

V.42 detect, LAPM and MNP enabled.

V.42 detect and LAPM enabled.

MNP enabled.

LAPM enabled.

6

í 0

Not used.

7

í 0

1

Actual result codes displayed.

Force 9600 result codes.

COMPRESSION AND ERROR CORRECTION

Format:

AT [cmds] S51=n [cmds]

Example:

ATS51=3<CR>

Default:

0

Range:

0 - 7

Unit:

Bit-mapped

Description:

Selects compression and error correction for specific modulations.

Bit

Value

Function

0

í 0

1

MNP/V.42 enabled during V.22 operation.

MNP/V.42 disabled during V.22 operation.

1

í 0

1

MNP/V.42 enabled during V.22bis operation.

MNP/V.42 disabled during V.22bis operation.

2

í 0

1

MNP/V.42 enabled during V.32bis operation.

MNP/V.42 disabled during V.32bis operation.

BIT-MAPPED REGISTER S56

Format:

AT [cmds] S56=n [cmds]

Example:

ATS56=139<CR>

Default:

0

Range:

0 - 223

Unit:

Bit-mapped

Description:

Controls non-linearing coding, TX level deviation, pre-emphasis, pre-coding, shaping, V.34, and V.FC.

Bit

Value

Function

0

í 0

1

Non linearing coding enabled.

Non linearing coding disabled.

1

í 0

1

TX level deviation enabled.

TX level deviation disabled.

2

í 0

1

Pre-emphasis enabled.

Pre-emphasis disabled.

3

í 0

1

Pre-coding enabled.

Pre-coding disabled.

4

í 0

1

Shaping enabled.

Shaping disabled.

5

í 0

Not used.

6

í 0

1

V.34 enabled.

V.34 disabled.

7

í 0

1

V.FC enabled.

V.FC disabled.

BREAK LENGTH

Type:

Register

Format:

AT [cmds] S21=n [cmds]

Example:

ATS21=20<CR>

Default:

10

Range:

0-255

Unit:

10 ms

Description:

Sets the length of error correction mode breaks sent from DCE to DTE in ARQ mode.

BREAK TYPE

Type:

Configuration

Format:

AT [cmds] &Yn [cmds]

Example:

AT &Y0<CR>

Description:

Configures action of break signal.

Command

Function

&Y0

Break empties buffer.

í &Y1

Break empties buffer and is sent immediately.

&Y2

Break does not empty buffer and is sent immediately.

CONNECTION SPEED UPPER LIMIT

Type:

Configuration

Format:

AT [cmds] &Nn [cmds]

Example:

AT &N1 DT555-1212<CR>

Description:

Sets required connection speed if &U is set to 0. Otherwise, sets fastest allowed connection speed.

Command

Function

í &N0

Variable.

&N1

300bps

&N2

1200bps

&N3

2400bps

&N4

4800bps

&N5

7200bps

&N6

9600bps

&N7

12Kbps

&N8

14.4Kbps

&N9

16.8Kbps

&N10

19.2Kbps

&N11

21.6Kbps

&N12

24Kbps

&N13

26.4Kbps

&N14

28.8Kbps

CONNECTION SPEED LOWER LIMIT

Type:

Configuration

Format:

AT [cmds] &Un [cmds]

Example:

AT &U1 DT555-1212<CR>

Description:

Sets slowest allowed connection speed if &N is set to 1 or higher.

Command

Function

í &U0

Disabled.

&U1

300bps

&U2

1200bps

&U3

2400bps

&U4

4800bps

&U5

7200bps

&U6

9600bps

&U7

12000bps

&U8

14400bps

&U9

16800bps

&U10

19200bps

&U11

21600bps

&U12

24000bps

&U13

26400bps

&U14

28800bps

ERROR CONTROL MODE

Type:

Configuration

Format:

AT [cmds] &Mn [cmds]

Example:

AT &M1 %C1<CR>

Description:

Selects active error-control protocols.

Command

Function

&M0

Normal mode, error control disabled.

í &M4

Normal/ARQ.

&M5

ARQ mode.

ESCAPE CHARACTER RESPONSE

Type:

Register

Format:

AT [cmds] S14=n [cmds]

Example:

ATS14=0<CR>

Default:

0

Description:

Controls reaction to escape character.

Command

Function

í S14=0

Normal operation.

S14=1

When +++ is received, modem goes on hook, enters command state and sends NO CARRIER result code.

EXTENDED RESULT CODES

Type:

Configuration

Format:

AT [cmds] &An [cmds]

Example:

AT &A1 %C1<CR>

Description:

Selects extended result codes.

Command

Function

&A0

Extended result codes disabled.

&A1

ARQ result codes enabled.

&A2

V.32 result code enabled.

í &A3

Error correction and compression result codes enabled.

FLOW CONTROL CHARACTER - XON

Type:

Register

Format:

AT [cmds] S22=n [cmds]

Example:

ATS22=20<CR>

Default:

17

Range:

0-127

Unit:

ASCII

Description:

Sets the character used to represent XON.

FLOW CONTROL CHARACTER - XOFF

Type:

Register

Format:

AT [cmds] S23=n [cmds]

Example:

ATS23=20<CR>

Default:

19

Range:

0-127

Unit:

ASCII

Description:

Sets the character used to represent XOFF.

FLOW CONTROL PASSTHROUGH

Type:

Configuration

Format:

AT [cmds] &In [cmds]

Example:

AT &I0 &W<CR>

Description:

Allows modem to act on, then transmit XON/XOFF characters.

Command

Function

í &I0

Software flow control disabled.

&I1

XON/XOFF passthrough enabled.

&I2

XON/XOFF passthrough disabled.

FLOW CONTROL TYPE

Type:

Configuration

Format:

AT [cmds] &Hn [cmds]

Example:

AT &H0 A<CR>

Description:

Sets type of flow control used by modem.

Command

Function

&H0

Flow control disabled.

í &H1

CTS/RTS flow control enabled.

&H2

XON/XOFF flow control enabled.

&H3

CTS/RTS and XON/XOFF flow control enabled.

HELP SCREENS

Type:

Immediate

Format:

AT <prefix>$

Example:

AT &$<CR>

Description:

Shows command help screens for all commands beginning with the given prefix, or no prefix if none is given.

Command

Function

$

Shows AT help screen.

&$

Shows AT& help screen.

INACTIVITY TIMER

Type:

Register

Format:

AT [cmds] S19=n [cmds]

Example:

ATS19=20<CR>

Default:

0

Range:

Unidentified

Unit:

1 minute

Description:

Sets the length of time that the modem does not receive information before it disconnects.

LOCK SERIAL PORT

Type:

Configuration

Format:

AT [cmds] &Bn [cmds]

Example:

AT &N9 &B0<CR>

Description:

Sets operation of serial port speed.

Command

Function

&B0

Serial speed follows connect speed.

í &B1

Serial speed locked.

&B2

Serial speed locked in ARQ mode only.

MAPPING

Format:

AT [cmds] S55=n [cmds]

Example:

ATS55=13<CR>

Default:

0

Range:

0 - 15

Unit:

Bit-mapped

Description:

Controls mapping.

Bit

Value

Function

0

í 0

1

8S-2D map enabled.

8S-2D map disabled.

1

í 0

1

16S-4D map enabled.

16S-4D map disabled.

2

í 0

1

32S-2D map enabled.

32S-2D map disabled.

3

í 0

1

64S-4D map enabled.

64S-4D map disabled.

REPORT INFORMATION

Type:

Immediate

Format:

AT [cmds] In [cmds]

Example:

AT I1 O<CR>

Description:

Displays modem properties.

Command

Function

I0

Reports product code.

I1

Reports ROM checksum result.

I2

Reports RAM checksum result.

I3

Reports firmware version.

I4

Reports current command settings.

I5

Reports current NVRAM settings.

I6

Reports current connection’s statistics.

I7

Reports configuration.

BAUD RATE

Format:

AT [cmds] S54=n [cmds]

Example:

ATS54=139<CR>

Default:

0

Range:

0 - 255

Unit:

Bit-mapped

Description:

Controls baud rate.

Bit

Value

Function

0

í 0

1

2400 baud rate enabled.

2400 baud rate disabled.

1

í 0

1

2743 baud rate enabled.

2743 baud rate disabled.

2

í 0

1

2800 baud rate enabled.

2800 baud rate disabled.

3

í 0

1

3000 baud rate enabled.

3000 baud rate disabled.

4

í 0

1

3200 baud rate enabled.

3200 baud rate disabled.

5

í 0

1

3429 baud rate enabled.

3429 baud rate disabled.

6

í 0

1

Call indicate during V.34 operation enabled.

Call indicate during V.34 operation disabled.

7

í 0

1

V.8 during V.34 operation enabled.

V.8 during V.34 operation disabled.

TONE DIALING TEST

Type:

Register

Format:

AT [cmds] S16=n [cmds]

Example:

ATS16=1<CR>

Description:

Selects the tone dialing test

Command

Function

í S16=0

Tone dialing test disabled.

S16=1

Tone dialing test enabled.

V.32 AND V.32bis MODULATIONS

Format:

AT [cmds] S34=n [cmds]

Example:

ATS34=13<CR>

Default:

6

Range:

0 - 15

Unit:

Bit-mapped

Description:

Controls V.32 and V.32bis modulations.

Bit

Value

Function

0

í 0

1

V.32bis enabled.

V.32bis disabled.

1

í 1

Not used.

2

í 1

Not used.

3

í 0

1

V.32 modulation disabled.

V.32 modulation enabled.

V.32 HANDSHAKE TIME

Type:

Register

Format:

AT [cmds] S28=n [cmds]

Example:

ATS28=20<CR>

Default:

8

Range:

0-255

Unit:

.1 second

Description:

Sets length of V.32 handshake.