User's Manual

Table Of Contents
SerialNET Theory of Operation
AT+i Programmer‘s Manual Version 8.32 29-3
Once the socket connection is established, iChip transmits the buffered data collected
during the connection period. The MBTB parameter dictates the maximum number of
bytes to buffer. If additional bytes are received on the serial port before the connection is
established, they are discarded.
iChip will dial-up the ISP to establish an Internet connection before attempting to open
the server socket.
iChip closes its listening socket (if one is defined by the LPRT parameter) to avoid
remote client devices from connecting during this session.
The remote server‘s IP and port are part of the SerialNET mode configuration
parameters. Once a data connection is established, data can flow freely between the local
client device and the remote server. If a connection cannot be obtained, eventually the
client device‘s data will be discarded (similar to the case of a device transmitting serial
data without a serial cable connected). Data continues to flow until a predefined activity
termination event is triggered, upon which the remote connection is dropped.
29.5 Automatic SerialNET Server Wake-Up Procedure
A SerialNET client may be configured to wake up a remote SerialNET server provided it
has its phone number. The
SPN parameter is used to store this wakeup number.
When SPN contains a phone number and no Host Server Name and/or IP are defined, the
SerialNET client tries to retrieve them from the registration e-mail of a remote SerialNET
server. When characters are received from the host port, the SerialNET client dials the
SerialNET server and then hangs up, causing the server to connect to its ISP, send a
registration e-mail containing its IP address and local port, and open a listening socket on
that port.
The client, after waking up the server, connects to its ISP and starts polling the predefined
mailbox for the server‘s registration e-mail. Once this e-mail arrives, the client opens a
socket to the IP address and port defined in the e-mail. The
SWT (SerialNET Wakeup
Timeout) parameter defines how long iChip will wait for this procedure to conclude
before stopping. Data then flows until a predefined activity termination event is triggered,
upon which the remote connection is dropped.
29.6 Transmit Packets
Data originating in the local device is buffered, packetized, and transmitted to the remote
system over the network. Packets are formed as a result of meeting at least one of the
following criteria:
A predetermined number of bytes has been received from the local link (
MCBF).
The TCP/IP connection MTU was met.
A predetermined flush character has been received (FCHR).
A predetermined inactivity timeout event was triggered (MTTF).
Until one of these events occurs, data is buffered in the iChip. When an event occurs, a
packet is transmitted. The event parameters are configured by setting AT+i parameters
prior to initiating SerialNET mode. When a UDP connection is used, data packets are