SECRET CODE FOR SWITCHING ON SIREN

At the time of switching on, the BC generates a random code which it sends to the siren with the switch-on command.

The siren memorises the random code.

When the switching off of the alarm system is requested, the BC sends the switch-off command to the siren together with the random code: the siren compares the code with its memorised code and is only switched off if the comparison is positive.

In this way the system is protected from intrusion attempts aimed at deactivating the siren.

In addition at each switch-on the BC memorises in EEPROM:

• code used
• any excluded external modules
• condition of entry points (doors, boot), so as to have this information available even after an undesired reset of the system