TI120 Series Variable Frequency Drive
Appendix A
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Appendix A
Modbus communication protocol
1. Support protocol
Support Modbus protocol, RTU format and ASCII code format; the broadcast address is 0, and the
slave address setting values are 1~247, 248~255 reserved.
2. Interface mode
RS485: asynchronous half duplex, least significant bit preferred to send; the high byte precedes
the low byte.
3. Protocol format
The ADU (Application Data Unit) check is the CRC16 check sum of the first three parts of the ADU
obtained by high and low byte exchange.
The exception code indicates the specific cause of the error.
The RTU data frame format is as follows:
Start: at least 3.5
idle characters
Slave
address
Function
code
Data
Check
sum
End: at least 3.5
idle characters
ADU
PDU
Exception codes are listed as follows:
Exception
code
Significance of
exception code
Exception
code
Significance of exception
code
0x01
Illegal function code
0x18
Information frame error
0x02
Illegal register
0x20
Parameters cannot be
modified
0x03
Data error
0x21
Operation cannot be
modified
0x04
Slave operation failed
0x22
Parameters are protected by
password
4. Functional interpretation
Function 0x03 reads multiple register parameters
