Gaurdall Rascal Super User Manual page 9

Daytime tamper can also be reset via a keyswitch. Proceed as follows.
Insert the key and turn clockwise to the
marking, then back to the marking.
This will silence the buzzer.
To reset the system and silence the two tone
alternating sound and clear the tamper LED turn
the key clockwise to the marking and then
back to the marking. This will
reset the system.