AC90 TENSION CONTROL FREQUENCY INVERTER MANUAL BASIC OPERATION AND TRIAL RUN
180
can begin.
There is at lowest
3.5 bytes vacancy at
beginning
RTU DATA FRAME FORMAT
MODBUS MESSAGE
slave machine
address
function
code
data
checking
There is at lowest
3.5 bytes vacancy at
ending
●
Command code and communication data description
For example
：
The frequency inverter whose slave machine address is 01H, memory initial address is 2100H [(C-00]),
read continuously 3 words, then the structure of that frame is described as follows:
RTU host machine command information
START
Transmission time of 3.5 bytes
Slave machine address
01H
Command code
03H
Start address high-order
21H
Start address low-order
00H
Data number high-order
00H
Data number low-order
03H
CRC CHK low-order
0FH
CRC CHK high-order
F7H
END
Transmission time of 3.5 bytes
RTU Slave machine responding information
（
normal
）
START
Transmission time of 3.5 bytes
Slave machine address
01H
Command code
03H
Byte number low-order
06H
Data address 2100H high-order
13H
Data address 2100H low-order
88H
Data address 2101H high-order
00H
Data address 2101H low-order
00H
Data address 2102H high-order
00H
Data address 21021H low-order
00H
CRC CHK low-order
90H
CRC CHK high-order
A6H
END
Transmission time of 3.5 bytes
Slave machine responding information
（
abnormal
）
START
Transmission time of 3.5 bytes
Slave machine address
01H
Command code
03H
Error code
04H
CRC CHK low-order
21H
CRC CHK high-order
33H
END
Transmission time of 3.5 bytes
