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Exception code = 01
A function code that does not exist has been specified.
Confirm the function code.
Exception code = 02
An address that cannot be used has been specified.
- Confirm the start address or the start a (the number of coils, statuses or registers).
(Function code 1 to 6, 15 and 16)
Exception code = 03
Specified data is out of range.
- Confirm that the number of coils, statuses or registers are within readable range.
(Function code 1 to 4)
- Confirm that the output value is 0x0000 or 0xFF00.
(Function code 5)
- Confirm that the output value is from 0x0000 to 0xFFFF,
or that they are not specified within start address 54.
(Function code 6)
- Confirm that the number of coils or registers are within the range.
(Function code 15 and 16)
- Confirm that the number of bytes can be obtained from the number of coils or registers.
(Function code 15 and 16)
- Confirm that every byte of the transmitted format is correct.
(Function code 1 to 6, 8, 15 and 16)
The slave device ignores requests from the master device and will not respond in
the following cases.
- When the specified slave address No. and the actual address do not match.
- When the error-check code does not match.
- When communication errors such as parity errors are detected.
- When the spacing of the frame configuration data 1.5 characters or more.
- When the slave address No. is set as 0.
Key points
