Insys GPRS 5.0 serial 11-02-01-03-10.014 Manuale Utente

Connection 

 

INSYS GPRS 5.0 serial 

 

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5.2.4.2  Forming data packets 
For a TCP/IP-based transmission such as the “TCP transparent” 
connection, the transmitted amount of data consists not only of 
the sum of all user data of the application and the required TCP/IP 
headers.  
Each TCP/IP message has a protocol overhead of 40 bytes. For each 
message there is also a confirmation message from the remote 
terminal with 40 bytes as well. 
It is important to select the suitable parameters for the application 
to form the TCP packets in the integrated TCP/IP stack. 
The INSYS GPRS 5.0 serial sends a data packet to the remote termi-
nal when: 

¾

  The maximum size of 512 bytes is reached  

¾

  Since the preset waiting time (default: 100 ms) no character 

has been sent via the serial interface, and data is already 
waiting in the send buffer 

 

For a calculation example see Chapter 8.8.3  

Calculation example 

Connections can be terminated as follows: 
Manual termination using the ATH command in online command 
mode 
By DTR drop (for the setting AT&D2) 
If the remote terminal hangs up 
After switching from data mode to online mode, the connection 
will remain established. However, data is no longer transmitted to 
the remote terminal.  The online command mode is also entered by 
DTR drop (setting AT&D1) or by activating the reset input twice 
within 10 seconds. 
Hang up (terminate connection to the other party) 
The connection was terminated