I have your document specifying the RS232 control spec for the P4800. I am not completely clear on the Volume Control parameters.
Can you please email me example commands to set the Input Volume on Input 1 to -30, 0, and +30?
Multiply the control setting by 2 and then logically AND that product with 7Fh.
So, if you want the setting to be -30, follow the instructions.
1) -30 * 2 = -60
2) Convert -60 to hex: C4
3) Logically AND C4 with 7F: 44h
So, to set the volume control to -30, the string would be:
F0h 00h 01h 00h <Device ID> 0Ah 69h 00h 00h 00h 44h F7h
To set the volume control to 0, the string would be:
F0h 00h 01h 00h <Device ID> 0Ah 69h 00h 00h 00h 00h F7h
To set the volume control to 30, the string would be:
F0h 00h 01h 00h <Device ID> 0Ah 69h 00h 00h 00h 3Ch F7h
Note, in AMX and Crestron programming, you do not need to do a manual conversion between decimal and hex. These systems automatically convert. The programming for AMX or Crestron would only be two commands. (1) Multiply the setting by 2. (2) Logically AND that product with 7Fh.