send ok sim300
I can send UDP data from the SIM300 to a server using the following commands:
AT+CIPSTATUS
STATE: IP INITIAL
OK
AT+CIPSPRT=1
OK
AT+CDNSORIP=0
OK
AT+CIPSRIP=1
OK
AT+CIPHEAD=1
OK
AT+CGDCONT=1,"IP","apn"
OK
AT+CSTT="apn","username","password"
OK
AT+CIICR
OK
AT+CIPSTATUS
STATE: IP GPRSACT
OK
AT+CIFSR
1xx.18.108.49
AT+CIPSTATUS
STATE: IP STATUS
OK
AT+CIPSTART="UDP","2xx.23.12.123","4000"
CONNECT OK
OK
AT+CIPSEND
> Test Message
SEND OK
The only thing that changes between UDP and TCP is the AT+CIPSTART command.
If you are getting a SEND OK back from the modem it probably means that the modem is sending the data to the GPRS network and it is getting lost somewhere else.
Because UDP is connectionless there won't be any indication that the packet has been lost or dropped.
You should probably check that:
a) Your GPRS network supports UDP traffic. Some operators only allow TCP.
b) Your servers firewall is allowing UDP connections through. Try sending UDP packets from a computer to your server.
To send UDP data to a server you can try this program:
http://sockettest.sourceforge.net/
It allows you to send/receive TCP and UDP data.