NEC RS-232C - Manual (Page 4)

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5
th
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.
6
th
-7
th
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).
4.2 Message block format
“Message block format” is allied to the “Message Type” in the “Header”.
Refer to the section 6 “Message format” for more detail.
1 Get current parameter
The controller sends this message when you want to get the status of the monitor.
For the status that you want to get, specify the “OP code page” and “OP code”,
refer to “Appendix A. Operation code table”.
“Message format” of the “Get current parameter” is as follows,
 Refer to section 5.1 “Get current parameter from a monitor.” for more details.
2 Get Parameter reply
The monitor will reply with the status of the requested item specified by the controller
in the “Get parameter message”.
“Message format” of the “Get parameter reply” is as follows,

Refer to section 5.2 “Get parameter reply” for more details.
3 Set parameter
The controller sends this message to change a setting of the monitor.
Header Message Check code Delimiter
OP code page OP code
STX
Hi Lo Hi Lo
ETX
Result
OP code
page
OP code Type Max value Current Value
STX
Hi Lo Hi Lo Hi Lo Hi Lo MSB LSB MSB LSB
ETX