INVT Goodrive350-19 Series Operation Manual page 423

Goodrive350-19 series VFD for crane
"H" indicates a hexadecimal value). One hexadecimal value occupies one byte.
The 03H command is used to read information including the parameters and running status of the
VFD.
For example, starting from the data address of 0004H, to read two contiguous pieces of data (that is,
to read content from the data addresses 0004H and 0005H), the frame structures are described in the
following.
RTU master command (from the master to the VFD)
START
ADDR (address)
CMD (command code)
Start address high-order bits
Start address low-order bits
Data count high-order bits
Data count low-order bits
CRC low-order bits
CRC high-order bits
END
"START" and "END" are "T1-T2-T3-T4 (time gap with a min. length of 3.5 bytes)", indicating that a
time gap with a minimum length of 3.5 bytes must be kept before RS485 communication is executed.
The time gap is used to distinguish one message from another so that the two messages are not
regarded as one message.
"ADDR" is "01H", indicating that the command is sent to the VFD whose address is 01H. The ADDR
information occupies one byte.
"CMD" is "03H", indicating that the command is used to read data from the VFD. The CMD
information occupies one byte.
"Start address" indicates that data reading is started from this address. 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 LSB on the left and MSB on the right.
CRC check occupies two bytes, with the LSB on the left, and MSB on the right.
RTU slave response (from the VFD to the master)
T1-T2-T3-T4 (time gap with a min. length of 3.5 bytes)
T1-T2-T3-T4 (time gap with a min. length of 3.5 bytes)
START
ADDR
01H
03H
00H
04H
00H
02H
85H
CAH
T1-T2-T3-T4 (time gap with a min. length of
-411-
Communication protocol
3.5 bytes)
01H