Datalogic Gryphon I GM440 Series Product Reference Manual page 54

Enter/Exit Programming Mode
Beep On Not on File
This option enables/disables the action of the reader to sound a three beep
sequence upon receiving a Not-On-File (NOF) host command.
$CBPNF00(CR)
Beep On Not On File = Disable
$CBPNF01(CR)
DEFAULT
Beep On Not On File = Enable
44 Gryphon™ I GD44XX/GBT4400/GM440X