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Appendix A Modbus Communication Protocol
117
Examples for abnormal codes:
Abnormal
code
Definition
Abnormal
code
Definition
0x01
Illegal function code
0x20
Frame error: frame length error,
check error
0x02
Illegal data address
0x21
Parameters are unchangeable.
0x03
Illegal data, data beyond
upper/lower limits
0x22
Unchangeable upon operation
of parameters
0x04
Slave operation failure, the
data is within the range of
upper/lower limits, but it is
invalid.
0x23
Password protected for
parameters
0x05
Order valid, in process, mainly
occurs upon storing data into
EEPROM
0x24
Non
−
host computer equipment
control, invalid host computer
command
0x06
Slave busy, mainly occurs
upon storing data into
EEPROM
4. Function Interpretation
Function 0x03 reads parameters and status words of multiple function code parameters of the inverter.
PDU Part Contents
Data Length (Byte)
Range
Request:
Function code
1
0x03
Initial address of
register
2
0x0000 ~ 0xFFFF
Number of registers
2
0x0001 ~ 0x0010
Response:
Function code
1
0x03
Read bytes
1
2*Number of registers
Read contents
2*Number of registers
Function 0x06(0x41) rewrites single function code or control parameter of the inverter and save it upon
power failure (not save).
PDU Part Contents
Data Length (Byte)
Range
Request:
Function code
1
0x06(0x41)
Register address
2
0x0000 ~ 0xFFFF
Register data
2
0x0000 ~ 0xFFFF
Response:
Function code
1
0x06(0x41)
Register address
2
0x0000~ 0xFFFF
Register data
2
0x0000 ~ 0xFFFF
