V&T Technologies Co., Ltd.
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Appendix A Modbus Communication Protocol
123
7. Case Study of Modbus Communication Control
Start No.1 inverter to perform forward rotation, and set the rotation velocity to 50.00Hz (indicating 5,000 internally) as
per the following commands:
Address
Function
code
Register
Address
Number
Bytes
Register
Contents
Check Sum
Request
0x01
0x10
0x8000
0x0002
0x04
0x0001,0x1388
0xCEFF
Response
0x01
0x10
0x8000
0x0004
None
None
0xE80A
Read the operating frequency of No.1 inverter and the response operating frequency of the inverter is 50.00Hz:
Address
Function
code
Register
Address
Number
Bytes
Register
Contents
Request
0x01
0x03
0x8136
0x0001
None
0x4C38
Response
0x01
0x03
None
0x02
0x1388
0xB512
No.1 inverter stops in the default mode:
Address
Function
code
Register
Address
Register Contents
Check Sum
Request
0x01
0x06
0x8000
0x0000
0xA00A
Response
0x01
0x06
0x8000
0x0000
0xA00A
Note:
It needs to set P0.06 to 2 firstly.
8. Communication Network Construction
Connecting one inverter to the computer
Computer
Converter RS232-485
RS232 cable
Maximum 15
meters
Site No.1
GND 485+ 485-
Twisted pair with shielded
GND
Attached Fig.3 Connecting One Inverter to the Computer