Goodrive18 series two-in-one VFD Communication
-120-
CMD=03H means the command message is sent to read data from the VFD and CMD
occupies one byte.
"Start address" means reading data from the address and it occupies two bytes with the MSB
on the left and LSB on the right.
"Data count" indicates the count of data to be read (unit: word).
"Start address" is "0004H" and "Data count" is 0002H, indicating that data is to be read from
the data addresses of 0004H and 0005H.
CRC check occupies two bytes with the MSB on the left and LSB on the right.
The response information is described as follows:
"ADDR" is "01H", indicating that the message is sent by the VFD whose address is 01H. The
ADDR information occupies one byte.
"CMD" is "03H", indicating that the message is a response of the VFD to the 03H command of
the master for reading data. The CMD information occupies one byte.
"Number of bytes" indicates the number of bytes between a byte (not included) and the CRC
byte (not included). The value "04" indicates that there are four bytes of data between
"Number of bytes" and "CRC CHK LSB", that is, "MSB of data in 0004H", "LSB of data in
0004H", "MSB of data in 0005H", and "LSB of data in 0005H".
A piece of data contains two bytes, with the MSB on the left and LSB on the right. From the
response, the data in 0004H is 1388H, and that in 0005H is 0000H.
CRC check occupies two bytes, with the LSB on the left and MSB on the right.
7.3.1.2 Command word 06H (0000 0110), writing a word
This command is used by the master to write data to the VFD. One command can be used to
write only one piece of data. It is used to modify the parameters and running mode of the VFD.
For example, to write 5000 (1388H) to 0004H of the VFD whose address is 02H, the frame
structure is as follows.
RTU master command (from the master to
the VFD)
RTU slave response (from the VFD to the
master)
MSB of data writing
address
MSB of data writing
address
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