I will try to write an UDP application using WIPStack 3.01 and AT-commands on my Q24Plus modem.
UDP connection setup is good and data transmission is OK every time. character bound the datagramm.
Problem reached while I try to close the UDP “socket”.
Before socket is closed modem sent the frame which consist of three characters “+++”.
<an gprs stack activate commands omited> AT+WIPCREATE=1,1,555,"220.127.116.11",555 OK +WIPREADY: 1,1 AT+WIPDATA=1,1,1 CONNECT 400758050D007319817684A19D00F6B98F8924AE84<ETX> <pause 1 sec>+++ OK AT+WIPCLOSE=1,1 OK
At the UDP-server side (port 555 receive) we got the sequence like this:
<open-port>400758050D007319817684A19D00F6B98F8924AE84<pause 1 s>+++<close-port>
Additional, each datagramm has own headers (about 64 bytes for each UDP datagramm). Then Q24Plus has to transmit 64 bytes of headers\IP protocol for 20 bytes of application data and 64 bytes for “+++” datagramm ~160 bytes in summary. The best case is 64+20 bytes – it is ~90 bytes in summary…
I don’t want to send any data after my datagramm.
How can I close UDP socket without additional “+++” data sending?
Simply pay calculation for 1000 objects:
1440 UDP sessions per day take about 126kb for each device in the best case or 225kb in real using Q24Plus WIPsoft3.01.
For 1000 devices (126kb*1000) * $1/1Mb = $126 per day, but in reality we must pay $225 per day.
Thus we have to pay $99 everyday for this “small mistake”.