Technical information

AT+i Commands Overview
1-2 AT+i Commands Reference Manual May 31, 2008
Characters within the AT+i command line are parsed as commands with associated parameter
values.
The W24 supports editing of command lines by recognizing a backspace character. When ECHO
is enabled, the W24 responds to receipt of a backspace by echoing a backspace character, a space
character, and another backspace. When ECHO is disabled, backspace characters are treated as
data characters without any further processing.
If a syntax error is found anywhere in a command line, the remainder of the line is ignored and
the I/ERROR result code returned.
An AT+i command is accepted by W24 once the previous command has been fully executed,
which is normally indicated by the return of an appropriate result code.
Due to the fact that W24 is intended for Machine-to-Machine applications, only limited parsing is
performed on AT+i commands it receives from the host. The following restrictions apply:
• When setting parameters to values larger than the 65535 limit, the values is accepted as
modulo 65535.
• The validity of input IP addresses is not checked.
• Illegal numbers, for example, 0.5 or 1.5 are not checked for validity.
Escape Code Sequence
While the W24 is in Internet mode attending to Internet communications, it is possible to break
into the communications and abort the Internet mode in an orderly manner. This is achieved by
sending the W24 a sequence of three ASCII '+' characters ('+++') after a half second silence
period. In response to this, the W24:
• Shuts down Internet communications.
• Terminates data transmission to the host.
• Performs a software reset.
• Responds with an I/ERROR(056) message.
• Returns to command mode.
A maximum delay of 10msec may elapse from the time the '+++' escape sequence is sent until
W24 cuts-off transmission to the host. The interrupted Internet activity is not completed.
Nevertheless, this is considered to comprise a session. Thus, parameters set with the '~' character
are restored to their permanent value.
Socket Command Abort
While the W24 is in Internet mode, during a TCP or UDP socket operation, it is possible to
override W24's normal timeout procedure and abort the current socket operation in an orderly
manner. This is achieved by sending the W24 a sequence of three ASCII (-) characters (---)
following a half second silence period. The socket commands to which this applies are: STCP,
SUDP, SSND, and SFSH. When W24 detects the socket abort command, it aborts the last socket
command and returns an I/ERROR following the STCP and SUDP commands, or I/OK during an
SSND or SFSH command.