Specifications

Chapter 2 – AT Commands Overview
12 Multi-Tech Systems, Inc. CDMA C1 AT Commands Reference Guide
Command-Line Editing
The character defined by the command ATS5, (default: backspace [IA5 0x08]) is intended to be interpreted as a
request from the host application to the modem to delete the previous character.
Any control characters (IA5 0x00 through 0x1F, inclusive) that remain in the command line after receipt of the
termination character are ignored by the modem.
Before checking for other characters, the modem checks characters from the host application to see if they
match the termination character (S3), then it checks to see if they match the editing character (S5). This ensures
that these characters will be properly recognized even if they are set to values that the modem uses for other
purposes. If S3 and S5 are set to the same value, a matching character will be treated as matching S3 (S3 is
checked before S5).
Input Command Syntax
A command line is made up of the following three elements: the prefix, the body, and the termination character.
AT+CFUN=1<CR>
In the example above, AT is the prefix. The modem expects all commands to begin with the letters “AT” or “at”.
If the host application inadvertently begins a command with characters other than “AT” or “at”, the modem will
ignore the characters and will not echo them. The modem will continue to ignore input until the characters “AT”
or “at” are received.
In some power save modes, the modem serial port UART is powered down. See section 19 for sleep related
functionality.
In the example above, the body, +CFUN=1, includes commands and parameters. The termination character
cannot appear in the body.
The termination character may be selected using the ATS3 command. For more information, see Line
Termination Character S3 section. The default value is CR (IA5 0x0D).
In addition, the modem supports multiple AT commands embedded in a single AT command string request.
However We recommend that this feature be used with care. Response from the modem to multiple AT
commands embedded in a single AT command string can be confusing. The modem will only return the status of
the last instructional command of the string.
Other Syntax
Syntax
Definition
< >
Name enclosed in angle brackets is a syntactical element. Do not use the angle brackets when
entering a command line.
[ ]
Square brackets are used to indicate an optional parameter of a command or an optional part of a
response. Do not use the brackets when entering a command.
Note: Commas separating parameters are usually NOT optional when delimiting a list of “optional”
parameters. The commas are necessary to provide parameter matching with the modem parser.
Output Response Syntax
The two characters defined in ATS3 (the terminating character) and ATS4 (Response formatting character) are
used in all responses, reason codes, and result codes. The default values are <CR> (IA5 0x0D) and <LF> (IA5
0x0A) respectively. The following example illustrates how S3 and S4 are used with their default values.