User manual

605M-D1 GPRS Modem User Manual
man_605M-D1_1.5.doc Page 32
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 a 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.
Open the Connection with the Internet Host
With the AT#SKTOP all the process required to connect with the internet host starts:
• ELPRO 605M-D1activates the first context
• ELPRO 605M-D1proceeds to the authentication
• Eventually does the DNS query to resolve the IP address of the host name internet peer
• ELPRO 605M-D1establishes 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 serialized and flushed to the Terminal Equipment.
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 ELPRO 605M-D1closes the connection, deactivates the GPRS context
returning to command mode and issuing the NO CARRIER code.
4.2.6 EASY GPRS Outgoing Connection
The EASY GPRS feature provides a way to place outgoing TCP/UDP connections and keep the same IP address
after a connection, leaving the GPRS context active.
The steps that will be required open a socket and close it without closing the GRPS context are:
• configuring the GPRS Access
• configuring the embedded TCP/IP stack behaviour
• defining the Internet Peer to be contacted
• request the GPRS context to be activated
• request the socket connection to be opened
• exchange data
• close the TCP connection while keeping the GPRS active