Mitsubishi Electric fr-e700 series, Instruction Manual

Page: 498 / 608

MODBUS®/TCP (FR-E700 SC ENE) Parameter
6 - 344
Error response
●
An error response is returned if the query message received from the master contains an illegal
function, address or data.
No response is returned for parity, overrun, framing, and busy errors.
●
Error response (Response message)l
●
Error code list
햲
An error response is not returned in the following cases:
– Function code H03 (reading data of holding registers)
When the number of registers is specified as one or more and there are one or more holding
registers from which data can be read.
– Function code H10 (writing data to multiple holding registers)
When the number of registers is specified as one or more and there are one or more holding
registers to which data can be written.
In other words, when function code H03 or H10 is used and multiple holding registers are
accessed, an error response is not returned even if a nonexistent holding register or holding
register that cannot be read or written from/to is accessed.
쐃
Transaction
identifier
쐇
Protocol
identifier
쐋
Length field
쐏
Unit identifier
쐄
Function
쐂
Exception code
H
(8 Bits)
L
(8 Bits)
H
(8 Bits)
L
(8 Bits)
H
(8 Bits)
L
(8 Bits)
(8 Bits)
H80 + Function
(8 Bits)
(8 Bits)
Message Description
쐃
Transaction identifier
The master adds the data for the purpose of transaction control.
The same data is returned in the response from the slave.
쐇
Protocol identifier
Fixed to 0. (When the slave receives data other than 0, it does not send the response
message.)
0 is returned in the response from the slave.
쐋
Length field The data length from the unit identifier to the data is stored in byte.
쐏
Unit identifier Fixed to 255
쐄
Function The function code requested by the H80 is set.
쐂
Exception code The codes in the following table are set.
Tab. 6-131: Explanation of the Response message
Code Error item Error description
01 ILLEGAL FUNCTION
The query message from the master has a function code that cannot be han-
dled by the slave.
02
ILLEGAL DATA ADDRESS
햲
The query message from the master has a register address that cannot be han-
dled by the slave.
(No parameter, parameter cannot be read, parameter cannot be written)
03 ILLEGAL DATA VALUE
The query message from the master has data that cannot be handled by the
slave.
(Out of parameter write range, a mode is specified, other error)
06 SLAVE DEVICE BUSY
The request message cannot be processed because the slave is executing
another operation.
Tab. 6-132: Explanation of the error codes
NOTE
An error response is returned if none of the accessed holding registers exist. When an accessed
holding register does not exist, the read value is 0 and the written data is invalid.