INVT GD20-004G-2-EU, Operation Manual

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Goodrive20-EU series VFD Communication protocol
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The meaning of the response is that:
ADDR = 01H means the command message is sent to the VFD with the address of 01H and
ADDR occupies one byte
CMD =03H means the message is received from the VFD to the master for the response of
reading command and CMD occupies one byte
"Byte number" means all byte number from the byte (excluding the byte) to CRC byte
(excluding the byte). 04 means there are 4 byte of data from the "byte number" to "CRC CHK
low bit", which are "digital address 0004H high bit", "digital address 0004H low bit", "digital
address 0005H high bit" and "digital address 0005H low bit".
There are 2 bytes stored in one data with the fact that the high bit is in the front and the low bit
is in the behind of the message, the data of data address 0004H is 1388H, and the data of
data address 0005H is 0000H.
CRC occupies 2 bytes with the fact that the high bit is in the front and the low bit is in the
behind.
7.3.1.2 Command code: 06H
06H (correspond to binary 0000 0110) is used to write one word. This command means the
master writes data to the VFD and one command can write one data only. It is used to change
the parameter and working mode of the VFD.
For example, write 5000 (1388H) to 0004H from the VFD with the address of 02H, the frame
structure is as follows:
RTU master command message (from the master to the VFD)
START T1-T2-T3-T4
ADDR 02H
CMD 06H
High bit of writing data address 00H
Low bit of writing data address 04H
High bit of data content
13H
Low bit of data content
88H
CRC CHK low bit C5H
CRC CHK high bit 6EH
END T1-T2-T3-T4
RTU slave response message (from the VFD to the master)
START T1-T2-T3-T4
ADDR 02H
CMD 06H