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5. The GSM modem is logged in the selected APN of GPRS network
The blink repetition period and blinks duration are shown on the figure below.
The above sequence of blinks is valid only with successful login onto the GSM/GPRS
network. If such login is not possible, the GSM LED indicates some errors found in the
login process.
The indicated errors are as follows:
1. SIM card error
2. PIN number error
3. Two attempts of entering wrong PIN number were found
The graphical explanation of the
GSM
LED blinks when signaling errors is shown on the
figure below.
One should remember that error number “3” (entering a wrong PIN code twice)
requires the card must be unlocked in an ordinary GSM mobile phone. Details of this
operation are given in the chapter “
Unlocking the SIM card
”.
If you cannot observe the sequences of LED blinks which indicate successful login, it is
important to write down the error blink sequence before applying for a technical help.
Such knowledge will help the service personnel to diagnose the faults.
Generally, the
Status
LED has only two purposes. Firstly, it indicates the stand-by
mode of the module. It seems the module in such state is inactive, but in fact it
executes the program provided for this mode. The blinks help to evaluate the proper
operation of the module without its activation, thus without additional energy
consumption. Secondly, the LED indicates the strength of a GSM signal passing from
the antenna to the module. This strength is indicated by a blink series repeated every 5
seconds when the module is active. The number of blinks is proportional to the
intensity of the signal, so it means, the more blinks the better are chances for a proper
module operation. The lack of blinks during login to the network means that signal
strength is too low and cannot guarantee a correct operation.
