Can't write data in drive from plc at register on 40100 control word

I have also same problem i am not starting drive prom plc by modbus. I am facing problem in g120 drive cu230p-2hvac in modbus communication.  I can only read data by modbus on register 40340, 40341, 40342, 40343, 40344, 40345, 40346, 40347 and 40348,  i cant write data in drive from plc at register on 40100 control word, 40101 main set point.

i have many time try write data on 40101 but data is not write which main set point. what i will do.  main set point parameter is 2050(1)  drive mod is AUTO and application is pump. drive speed increase and decrease from plc by set point.

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