hi frieds,
I am doing interfacing gsm modem with my com port through vc++ application. we have three majore function 1) check signal strength 2) read sms using at+cmgl="ALL" 3) send sms using at+cmgs
it run perfect but after few days it creates problem in reading sms virtually it has sms in sim memory but when i check for command that time it shows "ok" response from modem .so it shows that there is no sms in sim memory but when we restart modem than it start working fine
so please guide me about this problem.
Are you using VC++ (M$ Visual C++) to build programs for a '51 processor?
Have you tried to delete SMS messages after reading them?
Your question is off-topic, as it has nothing to do with any Keil product - nor even any target system supported by any Keil product!
See: http://www.keil.com/forum/
However, the GSM modem neither knows nor cares what is connected to it - so everything that's already been said about GSM modems here is equally applicable to your situation. So, use the 'Search' facility and see what's already been said...
The first thing you need to try is sending the commands manually from Hypoterminal or similar - if this works, then the problem lies in your software; if it doesn't work, then you have a more fundamental issue with the modem and/or its connection to the PC.
Remember, once the SIM (or other selected storage) is full, the modem cannot receive any further SMS messages until you delete some messages...