Communication Procedure; Command Format - Planar VM55LX-X User Manual

4.

Communication Procedure

Send control commands from a host controller via the RS232 connection. Do not send a new
command until the previous command is acknowledged. However, if a response is not received
within 500 milliseconds, a retry may be triggered. Every valid command receives an ACK. A
command that is valid, but not supported in the current implementation, will be responded to
with NAV (Not Available). If the command buffer is corrupt, (transmission errors) the command
will be responded to with NAK. The display operates according to the received command. If the
command is a valid "Get" command, the display responds with the requested info. If the
command is a valid "Set" command allowed, the display performs the requested operation.
Note: For LAN control, the port number is 5000
5.

Command Format

The RS232 packet format:
Header Monitor ID
In Detail:
Number of Field
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
Byte 8 ~ Byte 44
Last Byte
VM Series Displays RS232 User Guide
020-1359-00A
Category Code0 Code1
Name of Field
Header
Monitor ID
Category
Code0 (Page)
Code1 (Function)
Length
Data Control
Data[0] ~ Data[N]
Checksum
Data
Length Data[0]
Control
Description
Header = 0xA6
Monitor ID
Range: 1 ~ 255
Signal Mode: Display Address range from 1 to 255
Broadcast Mode: Display Address is 0, so no ACK
or Report is expected
0x00
0x00
0x00
Length has to be calculated in the following
way: Length = N + 3
Data Control = 0x01 (fixed)
This field can be also empty.
If not empty then the range of Data Size, N = 0 to
36.
Checksum
Range = 0 to 255 (0xFF).
Algorithm: The EXCLUSIVE-OR (XOR) of all bytes
in the message except the checksum itself.
Checksum = [Header] XOR [Monitor ID] XOR ...
DATA[0] ... XOR DATA[N]
Command Packet Format
...
Data[N] Checksum
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