116
Num
ber
Name Function
2
Com
mand
code
QD200 series frequency inverter supports part of
command codes of Modbus protocol.
All slaves execute command code and the matching
slave responses code include:
(1) 03H:Read one word (2 bytes)
(2) 06H:Write one word (2 bytes)
During error response, the feedback command code
of the slave = the request command code of the master
+ 80H.
3
Data
This part is the main content of communication and
the core of data exchange. Its content and length vary
with the variation of the command codes. See the
following concrete descriptions of every command code.
4
CRC
code
Cyclical redundancy check (CRC) code is used for
error detection of received data done by the receiving
equipment and for judging whether the received data
are correct. Please refer to “A2.3 Cyclical redundancy
check (CRC)” for generation of CRC code.
Note: CRC code first sends low bytes then high bytes.
Except this, all messages of Modbus-RTU adopt the
transmission sequence of “high bytes first - then low bytes”.
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General