DRV-28 inverter
s Communication protocol
-263-
RTU master command (transmitted by the master to the inverter)
START
T1-T2-T3-T4 (transmission time of 3.5 bytes)
ADDR (address)
01H
CMD (command code)
03H
Most significant byte (MSB) of
the start address
00H
Least significant byte (LSB) of
the start address
04H
MSB of data quantity
00H
LSB of data quantity
02H
LSB of CRC
85H
MSB of CRC
CAH
END
T1-T2-T3-T4 (transmission time of 3.5 bytes)
The value in START and END is "T1-T2-T3-T4 (transmission time of 3.5 bytes)", indicating that the
RS485 needs to stay idle for at least the transmission time of 3.5 bytes. An idle time is required to
distinguish on message from another to ensure that the two messages are not regarded as one.
The value of ADDR is 01H, indicating that the command is transmitted to the inverter whose address
is 01H. The ADDR information occupies one byte.
The value of CMD is 03H, indicating that the command is used to read data from the inverter. 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 quantity" indicates the quantity of data to be read (unit: word).
The value of "Start address" is 0004H, and that of "Data quantity" 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.
RTU slave response (transmitted by the inverter to the master)
START
T1-T2-T3-T4 (transmission time of 3.5
bytes)
ADDR
01H
CMD
03H
Number of bytes
04H
MSB of data in 0004H
13H
LSB of data in 0004H
88H
MSB of data in 0005H
00H
LSB of data in 0005H
00H
LSB of CRC
7EH
