NEC RS-232C - Manual (Page 7)

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5. Message type
5.1 Get current Parameter from a monitor.
Send this message when you want to get the status of a monitor.
For the status that you want to get, specify the “OP code page” the “OP code”, refer to “Appendix
A. Operation code table ”.
1
st
byte) STX: Start of Message
ASCII STX (02h)
2 nd -3 rd bytes) OP code page: Operation code page.
Specify the “OP code page” for the control which you want to get the status.
Refer to “Appendix A Operation code table” for each item.
OP code page data must be encoded to ASCII characters.
Ex.) The byte data 02h must be encoded to ASCII characters '0' and '2' (30h and 32h).
OP code page 02h -> OP code page (Hi) = ASCII '0' (30h)
OP code page (Lo) = ASCII '2' (32h)
Refer to Operation code table. (Appendix A)
4 th –5 th bytes) OP code: Operation code
Refer to “Appendix A Operation code table” for each item.
OP code data must be encoded to ASCII characters.
Ex.) The byte data 3Ah must be encoded to ASCII characters '3' and 'A' (33h and 41h).
OP code 3Ah -> OP code (Hi) = ASCII '3' (33h)
OP code (Lo) = ASCII 'A' (41h)
Refer to Operation code table.
6
th
byte) ETX: End of Message
ASCII ETX (03h)
5.2 "Get parameter" reply
The monitor replies with a current value and the status of the requested item (operation code).
1 st byte) STX: Start of Message
ASCII STX (02h)
2
nd
-3
rd
bytes) Result code.
OP code page OP code
STX
Hi Lo Hi Lo
ETX
1 st 2 nd -3 rd 4 th –5 th 6 th
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
1 st 2 nd -3 rd 4 th –5 th 6 th –7 th 8 th -9 th 10 th -13 th 14 th -17 th 18 th