SIM300 based Question

[financecatalyst]

I am having a very strange problem with my SIM300 modem. It takes 1-2 messages and then stops responding. I mean there is no indication of new messages from the MODEM. So my PIC sends AT+CMGR=1,1 and module keeps replying with OK.

Only first 1-2 messages go through after that have to restart the modem, Could this problem be related to modem settings? or Network?

 

[salmanliaquat]

there is no indication of new messages from the MODEM

Are you sure about it.? because the description that you gave shows that your PIC detects a new sms indication (AT+CMTI) and then issues read sms command.
Could be a problem in your firmware.
I would recommend connecting the module directly to pc and monitor the status on hyper terminal (or any other serial port monitor).
If problem still exist ...then try AT&F command to configure module for factory defined configuration......Hope this would resolve the problem.

Regards,
Salman

 

[financecatalyst]

I have the PC connected parallel to PIN2 of modem (MODEM TX). Nothing comes out with regards the new message. My code is slightly different, it does not wait for +CMTI.

After certain number of seconds it repeats the CMGR command to see if any new message is there.

 

[salmanliaquat]

Did you tried AT&F ..?
Try checking the module's registration status i.e AT+CREG? command. Make sure you module doesn't loose registration to network after receiving 1-2 messages. Also keep checking signal quality using AT+CSQ command.
If the module remains registered and signal quality is also good, then make sure that your SIM is not already full with messages. Try AT+CMGD="ALL" to delete all existing messages and empty the SIM's memory.
I still the problem persists, then i would say module's faulty. Order a new one rather then wasting more time on it.

Regrads,
Salman Liaquat.

 

[techlady]

Hi
I have connectedmy Sim300 module using rs232 to my pc serial port
Then i have done the following
accessories- communicayion- hyper terminal- baud:115200, flow: none
Then after creating this new connection, when I type AT nothing happens!!!
I mean ok msg is not displayed

what do i do?:|

 

[salmanliaquat]

when I type AT nothing happens!!!

You mean when you type AT( and hit enter) .. if nothing happens then assuming that your hardware is fine, there could be two possibilities:
1. If your module is brand new then it will be on auto-baud which you need to keep sending AT(enter) for some time(10-15 times) so that module trains itself on that.
2. If your module is not new, then it may be already configured to some other baudrate. You should try all the baudrates from 4800 to 115200.


Regards,
Salman