3Com PC Card User Manual - page 32

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C

HAPTER

 5: U

SING

THE

 M

ODEM

Attaching this information to faxes is known as fax branding. Refer to your fax 

communication software documentation for details on how to comply with the 

fax-branding requirement.

AT Commands

AT commands are set at the factory (factory settings are called defaults) to 

perform specific modem functions in preselected ways. They can be used to 

display call status or send and receive data with communications software such as 

HyperTerminal.

Entering AT Commands

AT commands are instructions typed at the command line of any communications 

application. A communications application is in command mode when the 

application is started but the modem has not yet dialed. When your application is 

in command mode, the AT commands you type are sent directly to the modem.

The most common way to enter AT commands is from terminal mode in your 

communications software. The basic rules for entering AT commands are:

■

All AT command lines must begin with the prefix AT. 

■

Spaces between command characters (and option characters) are ignored. 

■

Command line parameters cannot exceed 255 characters. 

■

Use a carriage return [Enter] to enter a command line. Commands take effect 

as soon as they are received.

■

Type commands in either upper or lower case, not a combination.

■

If you leave the number off a command, zero is assumed. For example, if you 

type 

ATE

, 

ATE0

 is assumed.

A: Answer Mode

Causes the modem to attempt a handshake in answer mode.

D: Dial Number

Instructs the modem to go off-hook and execute the dial string which follows the 

D. Commands which may be part of the dial string are listed below. Any 

unrecognized character in the dial string is ignored. Once dialing is complete, the 

modem attempts a handshake in originate mode (unless the R parameter is given).

.

0-9 Any number simply dials that number.

A, B, C, D, # or * (tone dial only) dials the indicated symbol.

P

Causes subsequent numbers to be pulse dialed.

T

Causes subsequent numbers to be tone dialed. 

R

Forces the modem to dial a call in answer mode. 

W

Causes the modem to wait for a dial tone using S7 as a time out.