Telit EZ10-GPRS/-PCS
Product Description
80269ST10014a, Rev. 3 – 26/09/05
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Page 32 of 74
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3.1.2 EASY GPRS definition
The EASY GPRS feature provides a way to replace the need of an Internet TCP/IP stack at the
terminal equipment side. The steps that will be required to obtain a virtual serial connection (that is
actually a socket) to the Internet peer are:
a) configuring the GPRS Access
b) configuring the embedded TCP/IP stack behaviour
c) defining the Internet Peer to be contacted
d) request the GPRS and socket connections to be opened (host is connected)
e) exchange raw data
f) close the socket and GPRS context
All these steps are achieved through AT commands.
As for common modem interface, two logical status are involved: command mode and data traffic
mode.
-
In Command Mode (CM), some AT commands are provided to configure the Data Module
Internet stack and to start up the data traffic.
- 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.
3.1.2.1 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)
3.1.2.2 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)
3.1.2.3 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