Bosch B9512G Owner's Manual page 19

Control Panels Warning displays and tones | en 19
5.5.1 Invalid entry (error tone)
The invalid entry tone follows the keypress tone when the
keypress completes an invalid entry.
Some entries require one keypress. Other entries require a series
of two or more keypresses.
Bosch Security Systems, Inc. 2015.01 | 02 | F.01U.307.371