Azbil F4Q, User Manual

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5-5
Chapter 5. Modbus Communication (RTU Mode)
Of the Modbus protocol exception codes, the following are supported.
Exception code (error termination code)
Error code Description Notes
01 ILLEGAL FUNCTION
•
Unsupported function code
No processing was performed.
03 ILLEGAL DATA VALUE
•
Start data address error (inaccessible area)
•
Error in the number of data records (illegal address included in the
specified data)
•
In a consecutive data access, an undefined data address followed or was
included.
•
The number of data records to access was outside the range.
•
Incorrect data size
•
The data to be written was outside the specifiable range.
•
A write command was received during zero point adjustment.
Handling Precautions
•
The success of writing when an error response is returned cannot be
guaranteed. If an error occurs during consecutive data writing, the data may
have been updated halfway. Be sure to write the data again with a correct
message.
„ Conditions under which no response message is returned (no-response conditions)
No response message is returned under the following conditions:
• The message was received during the device initialization period after power-on.
(Initialization takes about 10 seconds after power-on.)
• Mismatch of communication settings
• A CRC error occurred.
• Overflow of the received message (length over 256 bytes)
• Incorrect time interval between frames