Mitsubishi Electric FR-A720-0.4K Instruction Manual page 347

Error response
An error response is returned if the query message received from the master has an illegal function, address or
data. No response is returned for a parity, CRC, overrun, framing or busy error.
CAUTION
No response message is sent in the case of broadcast communication also.
Error response (Response message)
1) Slave Address 2) Function
H80 + Function
(8bit)
Message
1) Slave address
2) Function
3) Exception code
Error code list
Code Error Item
ILLEGAL FUNCTION
01
(Function code illegal)
ILLEGAL DATA ADDRESS
02
(Address illegal)
ILLEGAL DATA VALUE
03
(Data illegal)
*1 An error will not occur in the following cases.
1) Function code H03 (Read Holding Register Data )
When the No. of Points is 1 or more and there is one or more holding registers from which data can be read
2) Function code H10 (Write Multiple Holding Register Data)
When the No. of Points is 1 or more and there is 1 or more holding registers to which data can be written
Namely, when the function code H03 or H10 is used to access multiple holding registers, an error will not occur if a non-existing holding
register or read disabled or write disabled holding register is accessed.
REMARKS
An error will occur if all accessed holding registers do not exist.
Data read from a non-existing holding register is 0, and data written there is invalid.
⋅ Message data mistake detection
To detect the mistakes of message data from the master, they are checked for the following errors. If an error
is detected, an alarm stop will not occur.
Error check item
Error Item
The data received by the inverter differs from the
Parity error
specified parity (Pr. 334 setting).
The data received by the inverter differs from the
Framing error
specified stop bit length (Pr. 333).
The following data was sent from the master before
Overrun error
the inverter completes data receiving.
The message frame data length is checked, and the
Message frame
received data length of less than 4 bytes is regarded
error
as an error.
A mismatch found by CRC check between the
CRC check error message frame data and calculation result is
regarded as an error.
3) Exception Code
(8bit)
(8bit)
Set the address received from the master.
The master-requested function code + H80 is set.
The code in the following table is set.
The set function code in the query message from the master cannot be
handled by the slave.
The set register address in the query message from the master cannot be
*1
handled by the inverter.
(No parameter, parameter read disabled, parameter write disabled)
The set data in the query message from the master cannot be handled by
the inverter.
(Out of parameter write range, mode specified, other error)
Error Definition
Communication operation and setting
CRC Check
L H
(8bit) (8bit)
Setting Description
Error Definition
Inverter Side Operation
1) Pr. 343 is increased by 1 at error
occurrence.
2) The terminal LF is output at error
occurrence.
4
337