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XE9601

9600 BPS Data Modem Module

Xecom 

AT Commands

Modes of Operation

The XE9601 has two operating modes; Data mode and

Command mode. Modem setup occurs in Command

Mode; data transfer occurs in Data Mode.

Data Mode: XE9601 enters data mode after it

establishies a modem link and issues the "CONNECT"

result code. In Data Mode all signals on Transmit Data

(TXD) are sent to the remote modem. Demodulated

signals from the remote modem are placed onto

Received Data (RXD). The XE9601 exits data mode

when it loses the link or receives the escape sequence.

Command Mode: XE9601 enters command mode on

power-up, reset, disconnect, or receipt of the escape

sequence. The modem accepts commands from the

host on TXD and issues Result Codes on RX. The

modem ignores signals on TXD which do not conform

to the command format.

Command Line Format

Modem commands follow a specified format. Each

command begins with the "AT" prefix. The modem

stores the command line in its command buffer. The

command is executed upon receipt of a carriage

return. The command line can be edited up until the

time it is executed.

"AT" Prefix - Each command begins with the "AT"

prefix. The "A" and "T" may be both upper or lower

case but cannot be different cases. The prefix

identifies the speed and parity of the host. The

modem measures the width of incoming bits to

calculate speed and compares the parity bits of the

two characters to determine parity.

Command Line - A command line may include a

series of commands. Commands are executed in the

sequence they appear. A carriage return terminates

the command line and triggers the modem to execute

the commands. Register S3 allows the user to select a

character other than a carriage return to terminate the

command line and intitate command execution.

The command buffer holds up to 40 characters

including the "AT" prefix. You may insert spaces to

improve ledgibility; they do not fill space in the

command buffer. If the command buffer overflows, the

modem issues an "ERROR" result code, and the

commands are not executed.

A Backspace can be used to edit the command line.

The command line can only be edited before

execution. The backspace erases the previous

character in the command line. Register S5 allows the

user to select a character other than a backspace to

edit the command line.

Re-Execute Last Command - The A/ command

causes the modem to re-execute the last command

line. This command does not require the "AT" prefix.

A command string remains in the command buffer until

a new command is issued or power is shut-off.

Ommitted Parameters - Most commands require a

parameter to specify the function. When this

parameter is omitted from the command, it is assumed

to be a 0.

Escape Sequence - An escape sequence switches the

modem from data to command mode while maintaining

the modem link. The escape sequence uses an

escape character, set by Register S2, entered 3 times

in succession. The default escape character is "+." A

guard timer before and after the sequence prevents

normal data from triggering an escape.

Result Codes - The modem issues a result code after

each action. Result codes may be full words, numeric

codes or may be disabled. Each numeric result code

ends with a carriage return. Full word result codes

have a Line Feed and Carriage Return before and after

the result code. The XE9601 sends result codes at the

speed and parity determined from the "AT" prefix.

Xecom, Inc.

(4)

XE9601

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