HP LD4220tm and LD4720tm Digital Signage Touch Displays

Acknowledgement
[p][][Set ID][][OK/NG][Data][x]
[Data] 0: Lamp Fault
1: Lamp OK
2: N/A(DPM/Power Off)
33. Auto volume (Command: d u)
Automatically adjust the volume level.
Transmission
[d][u][][Set ID][][Data][x]
[Data] 0: Off
1: On
Acknowledgement
[u][][Set ID][][OK/NG][Data][x]
ENWW Transmission/Receiving Protocol 81