i have never used RS232 and so the information i have has not been verified.

All communications are performed with hexadecimal values and the checksum is the
sum of all values except for the header.
If a value is greater than two digits, such as in 11+FF+01+01=112, the foremost digit
is discarded.
Example) Power On & ID=0
Header Command
ID
Data Length Data 1 Checksu
0xAA 0x11 1 Power m
→
Header Command
0xFF
Data Length Data 1
12
0xAA 0x11 1 1
- If you want to control all devices connected via serial cables at the same time
regardless of their IDs, set the IDs to "0xFE" before sending the command. In this case,
each set or device will execute the command but will not respond with an ACK message.
Table 2-1 RS232 Communications Specifications
Bit Rate 9600 bps
Data Bits 8 bits
Parity None
Stop Bits 1 bit
Flow Control None
No Command Type Command Value Range
1 Status Control 0x00 -
2 Time Control 0x01 -
3 On Time Control 0x02 -
4 Off Time Control 0x03 -
5 Video Control 0x04 -
6 Audio Control 0x05 -
7 RGB Control 0x06 -
8 PIP Status Control 0x07 -
9 Maintenance Control 0x08 -
10 Serial Number Control 0x0B -
11 Display Status Control 0x0D -
12 Software Version Control 0x0E -
13 Model Number Control 0x10 -
14 Power Control 0x11 0 ~ 1
15 Volume Control 0x12 0 ~ 100
16 Mute Control 0x13 0 ~ 1
17 Input Source Control 0x14 -
18 Image Size Control 0x15 -
19 Direct Channel Control 0x16 -
20 Contrast Control 0x24 0 ~ 100
21 Brightness Control 0x25 0 ~ 100
22 Sharpness Control 0x26 0 ~ 100
23 Color Control 0x27 0 ~ 100
24 Tint Control 0x28 0 ~ 100
25 Red Gain Control 0x29 0 ~ 100
26 Green Gain Control 0x2A 0 ~ 100
27 Blue Gain Control 0x2B 0 ~ 100
28 Treble Control 0x2C 0 ~ 100
29 Bass Control 0x2D 0 ~ 100
30 Balance Control 0x2E 0 ~ 100
there is more but i guess if this bit works then i can post the rest.
let me know if it is of help.