This is an error response coming back from the modbus server saying you are setting a value that is not valid. I am not sure why the server would be responding with this response you might have to consult Fuji for details about how the registers are configured.
I recommend double checking the register type on the Fuji device matches the config set on the netbiters template.
Here the description of that error from Simplymodbus.ca
“A value contained in the query data field is not an allowable value for the slave. This indicates a fault in the structure of remainder of a complex request, such as that the implied length is incorrect. It specifically does NOT mean that a data item submitted for storage in a register has a value outside the expectation of the application program, since the MODBUS protocol is unaware of the significance of any particular value of any particular register.”