User's Manual

Telit TRIZIUM Product Description
80264ST10007a Rev. 4– 09/09/04
Reproduction forbidden without DAI Telecom written authorization – All Right reserved – Right of modification reserved page 169 of 202
- In data traffic mode (Socket Mode, SKTM), the client can send/receive a raw data stream which will be
encapsulated in the previously configured TCP / IP packets which will be sent to the other side of the network and
viceversa. Control plane of ongoing socket connection is deployed internally to the module.
5.8.2.1 Configuring the GPRS access
The GPRS access configuration is done by setting:
- the GPRS context number 1 parameters (see +CGDCONT command)
- the Authentication parameters: User Name and Password (see commands #USERID, #PASSW)
5.8.2.2 Configuring the embedded TCP/IP stack
The TCP/IP stack behaviour must be configured by setting:
- the packetizer default packet size (see command #PKTSZ)
- the data sending timeout (see command #DSTO)
- the socket inactivity timeout (see command #SKTTO)
5.8.2.3 Defining the Internet peer to be contacted
As last setting definition, the host to be contacted and on which port/protocol must be set :
- the socket definition (see command #SKTSET)
This command permits also to specify the host name instead of its IP address, if a host name is given to the set
command, then the module stores it as a host nick name. It is care of the module user to guarantee that the host nick
name provided corresponds to an existing internet peer.
If an host nick name has been given then, while opening the connection in response to the AT#SKTOP command, the
module will autonomously activate a GPRS connection and query its DNS to obtain the IP address relative to the host
nick name provided. This process of context activation and DNS query may require a bit more time and requires that the
GPRS network coverage is good enough to permit data transfers.
5.8.2.4 Open the connection with the internet host
With the AT#SKTOP all the process required to connect with the internet host starts:
- TRIZIUM activates the first context
- TRIZIUM proceeds to the authentication with the parameters specified on par. 5.8.2.1
- Eventually does the DNS query to resolve the IP address of the host name internet peer
- TRIZIUM establishes a TCP/UDP (depending on the parameter request) connection with the given internet host
- Once the connection is up the module reports the code: CONNECT
From this moment the data incoming in the serial port is packet and sent to the Internet host, while the data received
from the host is serialised and flushed to the Terminal Equipment.
5.8.2.5 Close the Socket and deactivate the context
The connection can be closed because of:
- remote host TCP connection close
- socket inactivity timeout
- Terminal Equipment by issuing the escape sequence "+++"
- Network deactivation
Note: if in the raw data to be sent there's an escape sequence, then the TE must work it out and sent it in a different
fashion to guarantee that the connection is not closed.
The pause time is defined in the parameter S12.
On the reception of an escape sequence the TRIZIUM closes the connection, deactivates the GPRS context returning to
command mode and issuing the NO CARRIER code.
5.8.3 Known limitations