Discussion in "Embedded GSM Development" started by    mohsin418    May 6, 2014.
Tue May 06 2014, 01:39 pm
Hello, I need to send data strings to a web server using GPRS connected to my PC, I am using huawei GTM900 , please guide me regarding enhanced AT commands for this specific module to access web and deploy data to a webserver.

I tried Different APN's also but no success.
Thu May 08 2014, 05:37 pm
Did you get AT Command manual with this modem? can you post link to its product page?

[Topic moved to Embedded GSM Development Forum]
Fri May 09 2014, 10:48 am
I am facing the same problem I have got the user manual for AT commands for huawei but do not know how to start the TCP connection as in other huawei modules it is ip^init but its nor supported by my module gtm900c, kindly help me to start the TCP connection for huawei gtm900c module.
Fri May 09 2014, 12:56 pm
Chapter 7 explains all the commands related to TCP/IP or GPRS communication. There is another document with name "TCPIP AT Command User Guide" which can give you better idea on how to use these commands with example. However here is a small snippet that you can try out to see if basic GPRS is working. You can make use of a TCP server to receive data for testing.

  1. AT+CGREG? -> check if module is registered to use GPRS, you should get response as 1 or 5 after this is successful try rest of the commands below.
  2. AT+CGDCONT=1,"IP","[APN]" -> set APN (Access point name) for your network, e.g. in case of vodafone its www
  3. AT%ETCPIP -> enable GPRS and TCPIP. If everything is success, you will get a response something like
    %ETCPIP: 1,[ip address],[gateway],[DNS1],[DNS2]
  4. AT%IPOPEN="TCP",IP,PORT -> open a tcp connection, to a server... e.g.
    AT%IPOPEN="TCP","","80" this will open connection to google server and if everything is ok you will get a response "CONNECT" or ERROR if failed
  5. AT%IPSEND="test",4 -> send data to TCP server, response will be %IPSEND:15 --> number can be anything, just make sure its not 0
  6. AT%IPCLOSE -> close current connection

You can try these commands, meanwhile look for the document that I mentioned. It will give you in detail info on how to use TCP/IP on GTM900C
Fri May 09 2014, 02:13 pm
its giving me error 1 on AT%IPOPEN="TCP","","80" , i have tried my area google server ip

how to resolve it
AT+CGDCONT=1,"IP","[APN]" *APN given ok
AT%ETCPIP *given the results
AT%IPOPEN="TCP","","80 *Error 1

now how to resolve it, im in trouble

Fri May 09 2014, 03:21 pm
ok, now its giving error 20, The cache for transmitting TCP data is full.

how to clear cache?
Fri May 09 2014, 03:26 pm
you dont have to send following

all above commands are automatically sent when enabling TCP

you cannot manually set CGREG, coz its set internally by modem depending on your registration status with network.

Error 1 means: not logged into network. please make sure you have inserted card properly and network is registered.
Check signal strength: AT+CSQ
check network registration: at+creg?
and gprs registration: at+cgreg?

after you get success on all these commands, only then try to enable tcp. dont do it before you get CREG and CGREG as 1 or 5. again you cannot set these commands they are set automatically.
Fri May 09 2014, 04:23 pm
AT+CGREG? ..... 1,1
AT+CSQ ...........12,99
AT+CREG ............... 0,1
AT+CGDCONT=1,"IP","Telenor" ... OK
AT%ETCIP? ..... %ETCPIP:1"",,"",""
... ERROR : 1

now where lies the problem?

Fri May 09 2014, 04:53 pm
>> AT%ETCIP? ..... %ETCPIP:1"",,"",""
this shows your TCP/IP stack is up and running fine.


looks like wrong IP to me.. 1522?? it should not be more than 255
 sanaaaa like this.
Fri May 09 2014, 05:02 pm
sorry it was a typo mistake am using 152

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