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4
MODBUS STANDARD FUNCTIONS
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(2) Response message format (Slave → Master)
(When completed normally)
The slave returns the request message received from the master as it is.
(When completed with an error)
Function code
Function code
Exception code*
(95
)
H
: When completed with an error, the exception code and error code are stored
into the buffer memory.
Refer to Section 11.3 for the storage location, confirmation method and more
details.
POINT
Even if the slave (QJ71MT91) receives this function with the programmable
controller CPU file register (ZR) set as read only (for example, the storage location
of the file register [ZR] is a Flash card), the slave responds normally.
In this case, however, the Write file record is not performed.
When performing the Write file record, previously confirm whether the
programmable controller CPU file register (ZR) is writable.
Data
MELSEC-Q
4 - 18
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