SIM900 and TCP/UDP streaming

[gianluca.alberico]

Hi all,

I need to develop a project with Arduino Due and SIM900 module. After some testing, I managed to establish a connection between the SIM900 module, acting as a TCP client, and a PC listening to a specific port, so acting as a TCP server. My need is to have a streaming as much fast as possible, that is, I can't obviously expect high speeds but I have to understand if this module can fit my needs and in which conditions and limitations. I have a problem regarding the streaming of data, in particular, I can't make more of one send at a time. For example, if I send 64 bytes to the server in a first time, and then I send other 64 bytes in a second time, the server only receives the first 64 bytes. This happens with both transparent and not-transparent mode. It seems that, after the established TCP connection, the module can send only once some data.
The following is the list of AT commands I send to the SIM900 module in transparent mode:

AT+CPIN=xxxx
AT+IFC=2,2
AT+CREG?
AT+CGATT?
AT+CIPMUX=0
AT+CIPMODE=1
AT+CIPCCFG=3,2,1024,1
AT+CSTT="mobile.vodafone.it","",""
AT+CIICR
AT+CIFSR
AT+CIPSTART="TCP","...hostname...","...portnumber..."

After this commands, since the transparent mode is enabled, I try to send some data as said before, just by transmitting to the serial port established between Arduino and SIM900. In the first send it works, but the module got stuck and doesn't send any other data.
Am I missing something?

Thank you in advance.