Header Block Format (Fixed Length) - Mitsubishi Electric RS232/485/LAN Serial Communication Control Manual

4.1 Header block format (fixed length)

Reserved
SOH
'0'
st nd
1 2
st
1 byte) SOH: Start of Header
ASCII SOH (01h)
nd
2 byte) Reserved: Reserved for future extensions.
MDT652S must be ASCII '0'(30h)
rd
3 byte) Destination: Destination equipment ID. (Receiver)
Specify a command's receiver's address.
If the command should be sent to certain monitor only, the either of character 'A'(41h) to 'Z'(5Ah)
which is corresponding to monitor ID from No1 to No.26 should be set to this portion. If it
is a broad cast command(only "set command" is available), then the '*'(2Ah)should be applied.
th
4 byte) Source: Source equipment ID. (Sender)
Specify a sender address.
The controller must be '0'(30h).
th
5 byte) Message Type: (Case sensitive.)
Refer to section 4.2 "Message block format" for more details.
ASCII 'A' (41h): Command
ASCII 'B' (42h): Command reply.
ASCII 'C' (43h): Get current parameter from a monitor.
ASCII 'D' (44h): "Get parameter" reply.
ASCII 'E' (45h): Set parameter.
ASCII 'F' (46h): "Set parameter" reply.
th th
6 -7 bytes) Message Length:
Specify the length of the message (that follows the header) from STX to ETX.
This length includes STX and ETX.
The byte data must be encoded to ASCII characters.
Ex.) The byte data 3Ah must be encoded to ASCII characters '3' and 'A' (33h and 41h).
The byte data 0Bh must be encoded to ASCII characters '0' and 'B' (30h and 42h).
Destination
Source
'A'
rd th
3 4
(9/56)
Header Message Check code
Message Message
Type Length
th th th
5 6 -7
Delimiter