- 32 -
7 Communication Protocol
(The following data are all hexadecimal)
1
、
RTU mode and format
When the controller communicates on the Modbus bus in RTU mode, each 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 is higher than that of ASCII mode at the same baud rate,
each message must be transmitted continuously.
（
1
）
The format of each byte in RTU mode
Coding system: 8-bit binary, hex 0-9, A-F.
Data bits: 1 start bit, 8 bits of data (lowest bit sent first), 1 stop bit, parity bit can be selected.
(Refer to RTU data frame bit 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
Without Parity check
Start
1
2
3
4
5
6
7
8
Stop
2
、
Reading and writing function code description
：
Function code
Function description
03
Read register
06
Write register
3
、
Parameter address description of communication protocol
：
Function Description
Address
definition
Explanation of data
R/W
Communication control
commands
2000H
0001H
：
Downtime
W
0012H
：
Forward run
0013H
：
Jog forward
0022H
：
Reverse run
0023H
：
Jog reverse
Communication frequency
setting address
2001H
The communication frequency setting
range is -10000
～
10000.
Note: The communication frequency
setting is a percentage relative to the
maximum frequency, and its range is
-100.00%
～
100.00%).
W
Communication control
commands
2002H
0001H
：
External fault input
W
0002H
：
Fault reset
