Compiler Error C0201

Message: Type '<data type 1>' is not equal to type '<data type 2>' of VAR_IN_OUT 'Variable'

Possible error cause: The data type that is passed to the function as a VAR_IN_OUT parameter does not match the data type defined in it.

Error correction: Pass a variable with the correct data type.

PROGRAM PLC_PRG
VAR
    Inst: POU;
    b : BOOL;
END_VAR

inst(in_out := b);

FUNCTION_BLOCK POU
VAR_IN_OUT
    in_out : INT;
END_VAR