Chapter 7 Modbus Communication Protocol
ACH200 Series High Voltage Variable Frequency Speed Control System Operating Manual
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7.4 Communication Instructions
Read slave parameter command code: 03H, reads N words (Word), and can read up to 20
consecutive words.
For example, if the AC drive with slave address 01H and memory start address 2100H ([C-00])
reads 3 consecutive words, the structure of the frame is described as follows:
RTU Master Command Information:
START
3.5 bytes transmission time
Slave address
01H
Command code
03H
Start address high bit
21H
Start address low bit
00H
Number of data high bit
00H
Number of data low bit
03H
CRC CHK low bit
0FH
CRC CHK high bit
F7H
END
3.5 bytes transmission time
RTU slave response information (when normal):
START
3.5 bytes transmission time
Slave address
01H
Command code
03H
Number of bytes low
06H
Data address 2100H high bit
13H
Data address 2100H low bit
88H
Data address 2101H high bit
00H
Data address 2101H low bit
00H
Data address 2102H high bit
00H
Data address 2102H low bit
00H
CRC CHK low bit
90H
CRC CHK high bit
A6H
END
3.5 bytes transmission time
RTU slave response information (when normal):
START
3.5 bytes transmission time
Slave address
01H
Command code
83H
Error code
04H
CRC CHK low bit
40H
CRC CHK high bit
F3H
END
3.5 bytes transmission time
Write slave parameter command code: 06H, writes a word data (Word) to the specified data
address, which can be used to modify the AC drive parameter value.
For example, write 5000 (1388H) to the 3000H address of the slave address 1 AC drive. Then
the structure of the frame is described as follows:
RTU master command information:
START
3.5 bytes transmission time
