GSM/GPRS SIM300CZ problem, please help!

[Hung Mai]

Hi everyone!

I have just bought the GPRS module which using the SIM300CZ.
By following the instruction of Mr "GSM Man" at thread:
it seems that I was able to connect to the google.com.
As the connection has been established, I try to execute the command "AT+CIPSEND", after this command, the modem response to Hyperterminal like this:
> - indicates that it's ready to receive data
But the problem I'm facing with is that after the modem response this notification, the connection is "CLOSED" almost immediately (within 1 or 2 seconds).
One thing I have mentioned is that: After the connection has been established (by this command AT+CIPSTART="TCP","www.google.com","80"), if I don't even type the "AT+CIPSEND", the connection is also closed automatically after a few seconds.
I tried many times, and the issue happens exactly the same. I have no idea if there is something wrong.
Please help!
Thank you.

 

[GSM Man]

Please provide a log of the commands you are sending prior to the "AT+CIPSEND" command and the responses from the module. It may be that you haven't actually established a connect before you are issuing the command.

 

[Hung Mai]

Dear Mr GSM-Man,

Thank you very much for your quick response.
After spending more time on research, I have found that my module is different from yours. And the major difference is: when issuing the send command, my module requires the buffer length while your module does not. As providing the buffer length, everything works smoothly.

Thank you.