need to write a program to read or write data to PLc by rs232 using modbus protcol

how can i do it

Thanks in Advance

You may get more help in the C forum.

but i need this in C++ or VC++ :(

Anything you can do in C you can also do in c++ (its a superset for the most part). I just think people who claim to be "C experts" typically know more about serial IO than people who claim to be "C++ experts". Of course this is not a general rule, just what I've seen in my experience.

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