Specifications

Cascade Modem Manual

Page 16

3.3. Basic AT Commands

The XE5690SM uses “AT” commands for configuration and control. This section describes the AT command format

and lists the commands, registers and result codes.

Command Mode: The XE5690SM enters command mode on power-up, reset, a lost connection, or receipt of the

escape code. In command mode the modem accepts commands from the host on transmit data. Appropriate

result codes are returned on received data.

Command Line Format

AT commands follow a strict format. Each command line, except A/, begins with the prefix AT. The “A” and “T”

may be both uppercase or both lowercase but cannot be of different cases. The modem determines data rate of the

host equipment by measuring the width of the incoming bits of the “A” and “T”.

Multiple commands may be combined into a single command line of up to 48 characters. Commands are executed

in the sequence they appear upon receipt of a carriage return. Spaces inserted into the command line are not

placed in the buffer.

The command line can be edited with a backspace before it is executed. The backspace erases the previous

character in the command line. Register ‘S5’ allows the user to select a character other than backspace to edit the

command line.

If the command buffer overflows, the modem issues an “ERROR” result code, and the command line is not executed.

Re-Execute Last Command – The A/ command causes the modem to re-execute the last command line. This is the

only command which does not require the “AT” prefix.

Omitted Parameters – Most commands include a parameter which determines how the functions will be set.

When the command parameter is omitted from the command string, it is assumed to be a ‘0’.

Escape Characters – A 3 character escape sequence may be entered to switch the modem into command mode

while on line. The escape character, set by Register ‘S2’, must be entered 3 times in succession to execute the

escape. An ‘AT’ command must then be entered within the period defined by S12 to enter command mode. The

default escape sequence is ‘+++’.

Result Codes – The modem issues a result code after each action. Result codes may be sent as full words, one, two

or three digit numeric codes, or may be disabled all together. Each result code ends with a carriage return when

numeric result codes are chosen. When full word result codes are chosen, a Line Feed and Carriage Return precede

and follow each result code.