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AUTO DIAL 21A

U.S. ROBOTICS, INC.

AUTO DIAL 21A

Card Type

Modem (asynchronous)

Chip Set

U.S. Robotics

Maximum Data Rate

1200bps

Data Bus

External

Data Modulation Protocol

Bell 212A

V2252

CONNECTIONS

Function

Label

Function

Label

Line out/in - unidentified

CN1

DC power

CN4

Line in/out - unidentified

CN2

Power switch

SW1

RS-232/422

CN3

Analog loopback switch

SW2

USER CONFIGURABLE SETTINGS

Setting

Label

Position

Auto answer disabled

SW3/A

Off

Auto answer enabled

SW3/A

On

CD normal

SW3/B

On

CD forced high

SW3/B

Off

Equalize for dial-up phone lines

SW3/C

Off

Equalize for dedicated phone lines

SW3/C

On

DTR normal

SW3/D

Off

DTR forced high

SW3/D

On

RS232C

Setting

SW4/A

SW4/B

SW4/C

SW4/D

Pin 2 receive/Pin 3 send

On

On

Off

Off

Pin 2 send/Pin 3 receive

Off

Off

On

On

MISCELLANEOUS TECHNICAL NOTES

Note: Diagram not available.

DIAGNOSTIC LED(S)

LED

Color

Status

Condition

CD

Red

On

Carrier signal detected

CD

Red

Off

Carrier signal not detected

HS

Red

On

Modem is operating at 1200bps

HS

Red

Off

Modem is operating at slower than 1200bps

OH

Red

On

Modem is off-hook

OH

Red

Off

Modem is on-hook

TR

Red

On

DTR signal is high

TR

Red

Off

DTR signal is low

RD

Red

On

Modem is receiving data

RD

Red

Off

Modem is not receiving data

AN

Red

On

Auto-answer enabled

AN

Red

Off

Auto-answer disabled

SD

Red

On

Modem is transmitting data

SD

Red

Off

Modem is not transmitting data

AL

Red

On

Modem is in analog loopback test mode

AL

Red

Off

Modem is not in analog loopback test mode

ON

Red

On

Power is on

ON

Red

Off

Power is off

Proprietary AT Command Set

ABORT

Type:

Immediate

Format:

Any key

Description:

Aborts dialing command issued; modem hangs up.

ANSWER

Type:

Immediate

Format:

AT [cmds] A

Description:

Enables answer mode, the modem goes off-hook.

ATTENTION

Type:

Immediate

Format:

AT [cmds]

Description:

Tells the modem that a command follows or use alone to test OK result code

DIAL

Type:

Immediate

Format:

AT [cmds] D<#> [cmds]

Example:

ATDT 443-3388,,,1111;

Description:

Dials telephone number according to any modifiers included in the string

Note:

Any combination of modifiers can be used to produce the desired dial functions in sequence.

Command

Function

í P

Pulse dialing enabled

T

Tone dialing enabled

,

Dialing paused for 2 seconds

ECHO

Type:

Configuration

Format:

AT [cmds] En [cmds]

Description:

Controls echo function; display keyboard commands when enabled.

Command

Function

í E0

Echo function disabled

E1

Echo function enabled

ECHO - ON-LINE

Type:

Configuration

Format:

AT [cmds] Fn [cmds]

Description:

Selects whether commands sent while in data mode are echoed

Command

Function

F0

Local echo enabled

í F1

Local echo disabled

ESCAPE SEQUENCE

Type:

Immediate

Format:

+++AT [cmds] <CR>

Description:

Initiates the escape sequence and returns the modem to the on-line command state if it receives three escape characters set in S2 within the time allotted by S12.

Note: Do not precede this command with AT.

PULSE DIALING

Type:

Configuration

Format:

AT [cmds] P [cmds]

Description:

Enables pulse dialing

Note: This command can be duplicated with the P modifier in the D (Dial) command.

REPEAT PREVIOUS COMMAND

Type:

Immediate

Format:

A/

Description:

Repeats previous command, mainly used for redial

Note: Do not precede this command with AT, or follow it with <CR>.

RESET

Type:

Immediate

Format:

AT [cmds] Z [cmds]

Description:

Resets the modem and clears all registers to default values

RESULT CODES

Type:

Configuration

Format:

AT [cmds] Qn [cmds]

Description:

Enables modem to send result codes to the DTE

Command

Function

í Q0

Result code sending enabled

Q1

Result code sending disabled

RESULT CODE FORMAT

Type:

Configuration

Format:

AT [cmds] Vn [cmds]

Description:

Selects word or numeric format for information-text and result codes

Command

Function

V0

Numeric format enabled

í V1

Verbose (word) format enabled

SELECT CALL PROGRESS RESULT CODES

Type:

Configuration

Format:

AT [cmds] Xn [cmds]

Description:

Enables selection of tone detection and associated result code format options

Command

Function

í X0

Extended result codes disabled; result codes 0-4 enabled.

X1

Extended result codes enabled; result codes 0-5 enabled

SPEAKER MODE

Type:

Configuration

Format:

AT [cmds] Mn [cmds]

Description:

Selects various speaker options

Command

Function

M0

Speaker disabled

í M1

Speaker enabled until carrier signal detected

M2

Speaker enabled

STATUS-REGISTER

Type:

Configuration

Format:

AT [cmds] Sn=x [cmds]

Description:

Writes to a specified register, values ranging from 0-255.

Command

Function

S0=x

Sets the number of rings allowed before the modem automatically goes off-hook.

S0=0 will disable auto-answer.

S2=x

Selects a character used for the escape sequence.

Default = 43

S7=x

Maximum wait time in seconds the modem uses after dialing to detect a carrier signal from the remote modem for both originating and answering calls.

Default = 30

TONE DIALING

Type:

Configuration

Format:

AT [cmds] T [cmds]

Description:

Enables tone dialing mode

Note: This command can be duplicated with the T modifier in the D (Dial) command.