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TECHNICAL MANUAL
Telit GM862-GPS
Quad Band GPS Data Terminal Module
Pag.27 of 79
Rev. 0
NOTE: this command differently from the AT#SKTOP DOES NOT automate all the
process of activating the GPRS, if no GPRS is active the command reports ERROR;
therefore before issuing this command the GPRS shall be activated with AT#GPRS=1
command.
In the same manner, when disconnecting the #SKTD command does not close the GPRS
context, leaving it active for next connections until an AT#GPRS=0 command is issued or
the network requests a context closing.
3.10.8.6
Close the Socket without deactivating 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 if the socket was opened with the AT#SKTD
command, the GM862-GPS closes the connection, does not deactivate the GPRS context
and returns to command mode issuing the NO CARRIER code.
3.10.9 Enhanced Easy GPRS Incoming Connection
The New Enhanced Easy GPRS feature provides a way to accept incoming TCP/UDP
connections and keep the same IP address after a connection, leaving the GPRS context
active.
The steps that will be required to open a socket in listen, waiting for connection requests
from remote hosts and accept these request connections only from a selected set of hosts,
then close it without closing the GRPS context are:
a) configuring the GPRS Access
b) configuring the embedded TCP/IP stack behaviour;
c) defining the Internet Peer that can contact this device (firewall settings)
d) request the GPRS context to be activated
e) request the socket connection to be opened in listen
f) receive connection requests
g) exchange data
h) close the TCP connection while keeping the GPRS active.
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