Technical information

SerialNET Theory of Operation
2-88 AT+i Commands Reference Manual May 31, 2008
Completing a SerialNET Session
A SerialNET session is completed when one of the following occurs:
• The local device transmitted the disconnection string, as defined in the DSTR parameter.
• Following an inactivity timeout, as defined in the IATO parameter.
In a modem environment the W24 goes offline when the SerialNET session is terminated.
In a WLAN environment, the W24 reopens the SerialNET listening socket defined in the LPRT
parameter (if it is non-zero) to service future remote client connections.
SerialNET Failed Connection
If the W24 fails to establish a SerialNET connection, SerialNET mode is deactivated for a delay
period defined in the SNRD parameter.
Local Serial Port Configuration
Prior to entering SerialNET mode, W24's local serial port can be configured to comply with a
wide range of devices by assigning a value to the SNSI parameter.
Serial port configuration entails settings to:
Activation Command
The W24 is forced into SerialNET mode by issuing the following command:
AT+i[!| @]SN MD
If the minimal SerialNET parameters are defined, W24 replies with I/OK followed by I/DONE
or I/ONLINE or I/OFFLINE.
If the W24 is online at the time this command is issued, it closes the Internet session in an orderly
manner. This includes closing all open sockets and disconnecting from the ISP in a modem
environment.
When W24 boots up in SerialNET mode, it sets the host serial channel to the fixed baud rate and
serial interface parameters defined in the SNSI parameter. W24 in WLAN mode opens the
SerialNET listening socket (if it is defined in the LPRT parameter) and, if defined, launches the
web server.
In a W24 dial-up environment, the modem is polled for the RING string. If the ring-response
destination e-mail parameter (RRMA) or ring-response server parameter (RRSV) contain values,
W24 waits for the RING strings to subside and connects to the Internet. Once online, it sends an
Baud rate: 300, 1200, 2400, 4800, 9600, 19200, 38400, 56K or 115K
Bits/byte: 7 or 8
Parity: None, Even, or Odd
Stop Bit: Must be 1
Flow Control: None (0) or Hardware (1)