4. SOFTWARE
CONFIGURATION
4.1 Introduction to AT Commands
A command line is a string of characters sent from a DTE to the modem (DCE) while the
modem is in command mode. A command line has a prefix, a body, and a terminator. Each
command line must begin with the AT character sequence and must be terminated by a carriage
return. Commands entered in upper or lower case are accepted, but no combination is allowed.
Characters that precede the AT prefix are ignored.
The AT command body contains printable ASCII characters (32-126). The terminator is ASCII
<CR> character. The command line interpretation begins upon receipt of the carriage return
character. Empty AT command containing no characters but AT and <CR> is used as an
indication that modem is in command state and works correctly. Modem answers with
<CR><LF>OK<CR><LF>. <CR> and <LF> are control characters that precede and follow
every modem response message, so they will be omitted in following text.
The modem recognizes a backspace character (ASCII 08) after AT sequence. It clears
previously typed character from modem command buffer, allowing correction of wrong entered
command with no consequence.
If syntax error, invalid range or nonexistent command is detected in entered command line,
modem responds with “ERROR” message. Entered command is accepted only if previous AT
command is executed and acknowledged with corresponding message.
Advice:
Since modem doesn’t support character echoing in command mode, it is
advised to activate local echo in terminal application (Telix, HyperTerminal,
etc.) used for AT setting. Local echo will help to insure which characters were
typed and sent to modem.
4.2 Entering Command Mode
By default, modem is in data mode. In data mode modem performs its basic function
transmitting data over preset channels. While modem is in data mode it is not allowed to
perform any setting procedures. To enter command mode perform following procedure:
1.
Connect the communication cable to DIAG RS-232 connector at the modem front
panel. Data transmission and configuration are performed over the different ports. The
configuration adapter is used for firmware boot loading only.
2.
a) If modem is turned off, push the SET button, turn on the modem by connecting its
power supply and keep the SET button pushed approximately for 1 second.
b) If modem is already turned on, push the SET button, then push and release the
RESET button while keeping the SET button pushed approximately for 1 second.
3.
Modem will respond with its introductory message “
IG202T-R38
vx.x” indicating
command mode and firmware version.
Important:
For proper modem configuration 8N1data format at 1200b/s needs to be
selected in terminal application.
IG202T-R38 User Manual v1.3
, Rev. date: 16 November, 2009
8