User Manual of A90 Series Inverter
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address, frame error, etc.), no response will be returned. This will be regarded as
a timeout by the slave station.
If the slave station receives a request without communication error but cannot
process the request (e.g. a request to read the non-existent register), the slave
station will return an exception response and the master station will be informed
of the actual error.
The exception response message has two fields different from those of the normal
response:
Function code field: In the normal response, the slave station copies the
function code of the original request in the corresponding function code field.
The MSB values of all function codes are 0. In the exception response, the MSB
of the function code is set to 1 by the slave station. That is,
the exception
response function code = normal response function code + 0x80
.
Data field: The slave station can return the data from the data field in the normal
response and exception code in the exception response. For the defined
exception codes, see Table 0-4 Definitions of Exception CodesTable 0-4.
Table 0-4 Definitions of Exception Codes
Exception
code
Item
Meaning
01H
Illegal function
The function code received by the slave station (inverter) is
beyond the configured range (see 12.3.3 Function code).
02H
Illegal data
address
The data address received by the slave station (inverter) is not
allowed. In particular, the combination of the start address of
the register and the transmission length is invalid (see 12.3.4
Register address distribution).
03H
Illegal data
frame
The slave station (inverter) has detected the incorrect query
data frame length or CRC check.
04H
Slave failure
When the slave station (inverter) tries to execute a requested
operation, an unrecoverable error occurs. This may be caused
by the logic error, failure to write to the EEPROM, etc.
05H
Data over-range
The data received by the slave station (inverter) is not
between the minimum and maximum values of the
corresponding register.
06H
Parameter
read-only
The current register is read-only and cannot be written.
07H
Unchangeable
When the inverter is in the running status, the current register
