Datasheet
Information Regarding GPRS INSYS GPRS 5.0 serial
66 Mai 06
8.8.2.2 Transmission of user data with reference data acknowledge
of the remote terminal
Application
/
GPRS Modem
control centre
r
e
f
e
r
e
n
c
e
da
t
a:
1
5
T
C
P
/
I
P
P
U
S
H
:
4
0
r
e
f
e
r
e
n
c
e
d
a
t
a
:
0
T
C
P
/
I
P
A
C
K
:
4
0
r
e
f
e
r
en
c
e
d
a
t
a
A
C
K
:
2
T
C
P
/
I
P
P
U
S
H
:
4
0
r
e
f
er
e
n
c
e
d
a
t
a
:
0
T
C
P
/
I
P
A
C
K
:
4
0
Total: 177 byte
8.8.2.3 TCP Keep Alive
Some GPRS providers terminate the connections when they are inactive. Vodafone, for
example, terminates the connection after approximately 30 minutes without data trans-
fers. 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 pro-
vider regarding the amount of data. The INSYS GPRS 5.0 serial provides this function.
The application will not notice this action.
Application
/
GPRS Modem
control centre
r
e
fe
r
e
nc
e
d
ata
:
0
T
C
P
/I
P
P
U
S
H:
4
0
r
ef
e
r
e
nc
e
d
ata
:
0
T
C
P
/I
P
N
A
C
K
:
40
Total: 80 byte