LG M3704CJ Owner's Manual page 84

RS-232C
Transmission / Receiving Protocol
47. logo Indicator (Command : f p)
To set the LED for Power Indicator
Transmission
Data 0 : Off
1: On
Acknowledgement
48. Serial no.Check (Command : f y)
To read the serial numbers
Transmission
Data FF (to read the serial numbers)
Acknowledgement
* The data format is ASCII Code.
Controlling the Multiple Product
A29