VEGA INSYS Modem GPRS 5.0 - Manual (Page 93)

INSYS GPRS 5.0 serial GPRS General
93
8.8.2.2 Transmission of user data with user data acknowledge of the remote terminal
Application
/
GPRS modem
control center
Data: 15
TCP/IP PUSH: 40
Data: 0
TCP/IP ACK
: 40
Data ACK: 2
TCP/IP PUS
H: 40
Data: 0
TCP/IP ACK: 40
Total: 177 byte
8.8.2.3 TCP Keep Alive
Some GPRS providers terminate the connections when they are inactive. Voda-
fone, for example, terminates the connection after approximately 30 minutes
without data transfers. For this reason, applications that exchange data in larger
intervals should consider a Keep Alive timer. The TCP stack generates an empty
TCP message in adjustable intervals which the TCP remote terminal responds to.
This will satisfy the expectations of the provider regarding the amount of data.
The INSYS GPRS 5.0 serial will provide this function.
The application will not notice this action.
Application
/
GPRS modem
control center
Data: 0
TCP/IP PUSH: 40
Data: 0
TCP/IP NAC
K: 40
Total: 80 byte