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[sim548c] How to give back IP, and take another in GPRS connection.

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namlooc

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[GSM sim548c] How to give back IP, and take another in GPRS connection.

Hi!

I'm sending data like this:

AT+CREG=1 --> answer: ok
AT+CSNS=4 --> answer: ok
AT+CSTT="INTERNET","INTERNET","INTERNET" --> answer: ok
AT+CIICR -->answer: ok
AT+CIFSR --> answer: ip adres
AT+CIPSTART="tcp","193.200.51.2","8000" --> answer:eek:k
AT+CIPSEND
> HELLOW WORLD <ctrl+z> -->answer: send ok
AT+CIPCLOSE -->answer: close ok
AT+CIPSHUT -->answer: shut ok
AT+CIPSTATUS -->answer: ip initial

Everything till this point is ok. Modem is sending "HELLOW WORLD" correctly to my PC.

After a while, i want to send more data. The same way i did it before:

AT+CREG=1 --> answer: ok
AT+CSNS=4 --> answer: ok
AT+CSTT="INTERNET","INTERNET","INTERNET" --> answer: ok
AT+CIICR -->answer: ERROR !!
AT+CIFSR --> answer: ERROR !!
AT+CIPSTART="tcp","193.200.51.2","8000" --> answer:eek:k
AT+CIPSEND
> HELLOW WORLD <ctrl+z> -->answer: send ok
AT+CIPCLOSE -->answer: close ok
AT+CIPSHUT -->answer: shut ok
AT+CIPSTATUS -->answer: ip initial

Modem is sending "HELLOW WORLD" correctly to my PC, but i can't get another IP adress.

My question: How to get rid of current IP address, and get another ?
or When i will be known about taking away my ip address?
and When a new IP address expires and i will need to get a new one?

I have found in the sim548c datasheet that AT+CIICR works only when STATE is IP START:
**broken link removed**

ciicr.th.jpg[/IMG][/URL]
..but i have IP INITIAL :/
 
Last edited:

Try this:
AT+CGATT=0 ' detach from gprs,
AT+CGATT=1' attach again
AT+CIICR -->answer: ERROR !!
Click to expand...
You get this error because you have already launched a wireless application on modem.
If you only need to send more stuff on the PC without changing IP addresses, try this:
First time:

Code: 
AT+CREG=1 --> answer: ok
AT+CSNS=4 --> answer: ok
AT+CSTT="INTERNET","INTERNET","INTERNET" --> answer: ok
AT+CIICR -->answer: ok
AT+CIFSR --> answer: ip adres
AT+CIPSTART="tcp","193.200.51.2","8000" --> answer:ok
AT+CIPSEND
> HELLOW WORLD <ctrl+z> -->answer: send ok
AT+CIPCLOSE -->answer: close ok
AT+CIPSHUT -->answer: shut ok
AT+CIPSTATUS -->answer: ip initial
2nd, 3rd, etc...

Code: 
AT+CIPSTART="tcp","193.200.51.2","8000" --> answer:ok
AT+CIPSEND
> HELLOW WORLD <ctrl+z> -->answer: send ok
AT+CIPCLOSE -->answer: close ok
AT+CIPSHUT -->answer: shut ok
AT+CIPSTATUS -->answer: ip initial
 

pedja089 said:
Try this:
AT+CGATT=0 ' detach from gprs,
AT+CGATT=1' attach again
Click to expand...
didn't work :/
Only hard reset the GSM modem helps to get another IP address.

pedja089 said:
If you only need to send more stuff on the PC without changing IP addresses, try this:
First time:
Click to expand...
I know that this thing works, but i think it is unreliable. I'm making tracking device on AVR microcontroller and it must by reliable in situations where i lose signal, logout or just want to change IP.

Another thing is that when i pull out the GSM antena plug, and pull in the plug (simulates a bad signal quality in and logout/login fom network) everything goes bad.

Example:
Code: 
AT+CREG=1 --> answer: ok
AT+CSNS=4 --> answer: ok
AT+CSTT="INTERNET","INTERNET","INTERNET" --> answer: ok
AT+CIICR -->answer: ok
AT+CIFSR --> answer: ip adres
AT+CIPSTART="tcp","193.200.51.2","8000" --> answer:ok
AT+CIPSEND
> HELLOW WORLD <ctrl+z> -->answer: send ok
AT+CIPCLOSE -->answer: close ok
AT+CIPSHUT -->answer: shut ok
AT+CIPSTATUS -->answer: ip initial

[B]<pull out the antenna>[/B]
+CREG: 1,0 //LOGOUT
[B]<delay 2sec>[/B]
[B]<pull in the antenna>[/B]
+CREG: 1,1 //LOGIN

AT+CIICR -->ERROR
AT+CIFSR --> nothing happends, no answer
AT+CIPSTART="tcp","193.200.51.2","8000" --> answer:ok, but no connection in PC
AT+CIPCLOSE -->answer: ERROR
AT+CIPSHUT -->answer: OK and STATE: PDP DEACT
AT+CIPSTATUS -->answer: STATE: PDP DEACT

So, after bad signal quality i can't get new ip adress.
Alsow only hard reset helps
What am i doing wrong ?
 

I've done a similar thing with a PIC and SIM900D
I checked whether it is connected to the GPRS, with AT command "AT + CGATT?".
If not connected, then I sent AT + CIPSHUT, and then AT + CSTT ="... etc.
 

I have found another sim548c and everything works perfectly on it :)

The problem seems to be in my copy of sim548c.

How to set factory settings ??
 

AT&F
Maybe is problem in firmware version, try to update firmware.
I have updated the sim900, because some AT commands are not working.
 
I have another question to you.

How much time you're waiting for reply to these questions ?
(In extrem conditions of signal strength,i mean low signal)
Code: 
AT+CIICR
AT+CIFSR
AT+CIPSTART="TCP","IN......
AT+CIPSEND
 

I'm waiting about 120 sec...
I tried 60s, it worked, but only with exelent signal.
 

how do I update the firmware of sim900d? i've got a broken ATE0, everytime I issue this command, my gsm stops from responding, and to think that I issue that using hyperterminal.
 

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