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XE3314B

Low-Cost, Embeddable 33,600 BPS Modem Module

Unspecified 

XE3314B AT Commands

Modes of Operation

The XE3314B uses "AT" commands for control and

configuration. The XE3314B operates in three modes;

Command Mode, Fax Mode and Data Mode. Exten-

sions to the AT command set support fax operation.

Data Mode: The modem enters data mode after it es-

tablishes a link and issues a "CONNECT" result code.

In Data Mode the modem modulates all signals on

Transmit Data, Pin 13, and sends them to the remote

modem. The modem demodulates the signal from the

remote modem and places it onto Received Data, Pin 3,

for the host equipment. When the modem exits data

mode, it issues a "NO CARRIER" result code.

Command Line - A command line may include mul-

tiple commands. The modem executes the commands

in the sequence they appear in the command line.

Spaces, inserted to improve legibility, do not fill space

in the command buffer. A carriage return terminates the

command line and causes the commands to be ex-

ecuted. Register S3 allows the user to select a character

other than a carriage return to terminate the command

line.

Command Buffer - The command buffer holds 40

characters, including the AT prefix. If it overflows, the

modem issues an "ERROR" result code and commands

are not executed.

Command Mode: The XE3314B enters command

mode on application of power, reset, loss of the con-

nection, or receipt of the escape sequence. In com-

mand mode the modem accepts commands from the

host on Transmit Data. Appropriate result codes are re-

turned on Received Data at the same speed and parity

as the commands.

Fax Mode: The modem enters fax mode on receipt of

the AT+FCLASS=1 command. Fax commands and re-

sponses are issued at 19,200 bits per second; the char-

acter format is 8 bits no parity. The modem accepts

Class 1 Fax commands only in fax mode. The A/,

ATO, AT&T and escape commands are not valid in fax

mode.

Commands

The modem is configured and controlled with AT com-

mands. AT commands follow a strict format. The

command line is stored in the command buffer and ex-

ecuted upon receipt of a carriage return. Until ex-

ecuted, the command line can be edited with the back-

space key.

Command Format - Each command, except A/, begins

with the AT prefix. The "A" and "T" may be both up-

per case or both lower case but cannot be of different

cases. The modem uses the prefix to identify the host's

speed and parity. The modem determines speed by

measuring the width of the incoming bits and parity by

comparing the parity bits of the "A" and "T." The mo-

dem then returns result codes at the host's speed and

parity.

Command Line Editing - A backspace can be used to

edit the command any time before it is executed. The

backspace character, Control and H simultaneously on

some systems, erases the previous character in the

command line. Any character except for the "A" and

"T" can be erased. Register S5 allows the user to se-

lect a character other than a backspace to edit the com-

mand line.

Re-Execute Last Command - The A/ command

causes the modem to re-execute the command line

stored in the command buffer. This is the only com-

mand which does not require the "AT" prefix.

Omitted Parameters - Most commands include a pa-

rameter which determines the command function.

When the parameter is omitted from the command

string, it is assumed to be a 0.

Escape Characters - A three character escape se-

quence, entered while in data mode, will switch the mo-

dem into command mode while remaining on line. The

escape character, set by Register S2, is entered 3 times

in succession to execute the escape. The default es-

cape sequence is "+++."

Result Codes - The modem issues a result code after

each action. Result codes may be provided as full

words, numeric codes or may be disabled. Each result

code ends with a carriage return when numeric result

codes are chosen. When full word result codes are cho-

sen, a Line Feed and Carriage Return precede and fol-

low each result code.

XECOM

(6)

XE3314B

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