VEGA INSYS Modem GPRS 5.0 - Manual (Page 45)

INSYS GPRS 5.0 serial Connection
45
For a TCP/IP-based transmission such as the
“TCP transparent” connection, the transmit-
ted 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 over-
head of 40 bytes. For each message there is
also a confirmation message from the re-
mote terminal with 40 bytes as well.
A selection of parameters, adjusted to the
application, for forming TCP packets in the
integrated TCP/IP stack helps prevent un-
necessary high costs for the data transmis-
sion.
The INSYS GPRS 5.0 serial sends a data
packet to the remote terminal when:
The maximum set value (default: 512
byte) has been reached
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
(see Chapter 8.8)
AT**TCPBLOCK=
<block-size>
AT**TCPAGG=<agg-time>
5.2.9 Termination
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 estab-
lished. However, data is no longer transmit-
ted to the remote terminal. The online
command mode is also activated by DTR
drop with the setting AT&D1, or by activat-
ing the reset input twice within 10 seconds. Data traffic
<1 Sec.
Pause>
+++
<1 Sec. Pause>
ATH
The connection was terminated Ok