Specifications

Chapter 2 – AT Commands Overview
Multi-Tech Systems, Inc. CDMA C1 AT Commands Reference Guide 11
Terminology
Command Types
Terminology used to describe AT command communication
Term
Definition
AT Command
This is referred to as a command from the host application to modem with a
request to perform a service.
Result Code
This is an immediate response to a command, informing the host application
whether the execution of the command succeeded or failed. The strings “OK” or
“ERROR” are the only two Result Codes available. A result code is always returned
after an AT command has been sent to the modem.
Extended Reason Code
If enabled, (see AT+CMEE), the modem may respond with a result code of either
+CME ERROR: or +CMS ERROR followed by a reason code rather than a result
code of ERROR.
Response
A response contains data that has been requested via an AT command. A
response is returned before the result code of the command. A response is
provided only when the result code is OK.
Unsolicited Response
An unsolicited response is sent by modem when a specific event occurs. Some
unsolicited responses can be turned on and off via AT commands. Some
unsolicited responses are always enabled or turned on.
AT Commands Types
Command Type
Definition
Action Command
Action commands are used to perform a function. Typically, action commands are used
to change the value of a setting in modem, send data, or perform advanced queries
that require input data.
Read Command
Read commands typically end with a “?”. Most read commands do not have any input
parameters; however, in some cases an input parameter provides options for the
response format. The read commands are used for reading values of certain settings in
the modem.
Test Command
Test commands are not supported in the C1 modem.
Command Format and Syntax
Alphabet
The T.50 International Alphabet 5 (IA5) is used in this manual. Only the low-order seven bits of each character
are significant to modem. Any eighth or higher-order bit(s) are ignored for the purpose of identifying commands
and parameters. Lower-case characters (IA5 values from 0x61 to 0x7A) are considered identical to their upper-
case equivalents (IA5 values from 0x41 to 0x5A) when received by modem from the host application. Result
codes from the modem shall be in upper case.
All commands must begin with the characters A and T. If the A and T are not received by the software, the
remaining characters will not be processed. This is important; should the A or T be lost in communication or not
supplied, none of the characters sent to the modem will be echoed back until an AT sequence is observed.