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Refer the attached COM_MOD_MAST picture.
FCT, ADDR, NB and DATA
1.FCT is a function code. 3 for read the data from slave.16 for write.
2.ADDR is starting address. For example , In ABB VFD reading actuals starts from 40100. so in ADDR we will provide 100.
3 .NB means number of byte. If you want to read a 40101 register, NB is 2 ADDR is 40100.
4.In DATA block you will map that starting address to %MW 0.x