Mitsubishi Electric MEsoftstart/I01 Users, Installation & Instruction Manual page 99

At present the following Modbus function codes (FCs) are supported:
4 = Read Input Register. (Read Only Registers)
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- 3 = Read Holding Registers. (Read/Write Registers)
6 = Write Single Holding Register.
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16 = Write Multiple Holding Registers.
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The soft starter RTU address can be configured from 1 to 247.
Any write action either to Configuration registers, or the Control Command register, that receives a positive response back from
the soft starter, may be interpreted by the Modbus Master as confirmation that the configuration data is correct and will be
saved in the soft starter, or that the command will be put into effect. An error response must be interpreted as the opposite.
Updates to individual configuration parameters should be done by sending the full complement of configuration parameters.
99 MEsoftstart PC Interface Application