10
III Communication protocol
1. RTU mode and format
When the controller communicates on Modbus in RTU mode, every 8-bit byte in the information is divided into two
4-bit hexadecimal characters. The main advantage of this mode is that the density of characters transmitted by it is
higher than that of ASCII mode at the same baud rate, and each information must be continuously transmitted.
(1) The format of each byte in 1)RTU mode
Coding system: 8-bit binary, hexadecimal 0-9, A-F.
Data bit: 1-bit start bit, 8-bit data (lower bit first sent), 1-bit stop bit, and optional parity bit. (Refer to RTU data frame
as sequence diagram)
Error check area: cyclic redundancy check (CRC).
(2) RTU data frame bit sequence diagram
With parity check
Start
1
2
3
4
5
6
7
8
Par
Stop
No parity check
Start
1
2
3
4
5
6
7
8
Stop
2. Description of reading and writing function code:
Function code
Functional Description
03
Read register
06
Write register
3. Register address
（
2
）
Register Map
Address
Control command input
2000H
Monitoring parameter reading (D-00
～
D-30)
1000H
～
001EH
Communication Frequency setting
2001H
User parameter setting (00.00
～
08.06)
0000H
～
0806H
Factory parameter setting (09.00
～
09.10)
0900H
～
090AH
4. Description of parameter address of communication protocol:
Functional Description
address
definition
Explanation of data meaning
R/W
Communication control
command
2000H
0001H: Stop
W
0012H: Forward running
0013H:Forward jog operation
0022H: Reverse operation
0023H: Reverse jog operation
Communication setting
frequency address
2001H
The set frequency range of communication is-10000
～
10000.
Note: the communication set frequency is a percentage of
W
