I have used SL6087-firmware 7.51 for 1 years and have recently encountered a serious problem. It will be very grateful if anyone can help me.
My application reads data from uart port and sends it to a remote server via GPRS. Everything seems to be fine but after a time running, some devices (about 5% and increasing) lost the connection with the operator. The led does not blink and i cannot call it. However the application was still working because there were still some right messages sent from the uart port.
I logged into flash the state of sim and the result of at+creg. The result respectively is: ADL_SIM_STATE_FULL_INIT and at+creg returns 2 (not registered, ME currently searching for a new operator).
The weird thing is that the device will continue to work if i unplug and plug the power supply.
I don’t know why the device cannot register with the operator even though it is restarted by at+cfun=1 command in the application after 30 minutes polling creg status unsuccessfully
Thanks & Best regards,
Pham Viet Sam