I've created a function for linear interpolation and depending on how I call it either works or doesn't. Using the shorter method of function call doesn't work. I'm using Codesys 3.5 SP8 Patch 4.

interp_in := 7;

// function call - linear interpolation
lin_interp( x0:= 0, x1:= 100, y0:= 0, y1:= 50, in:= interp_in, out=> interp_out0 );

// function call - linear interpolation (same as above, different format)
interp_out1 := lin_interp( 0, 100, 0, 100, interp_in ); //this format is not working correctly, I don't know why

Are you sure it is a function?

It seems to be a function block, which is different.

Try this:

lin_interp( 0, 100, 0, 100, interp_in );
interp_out1 := lin_interp.out;

This should work if it is a function block.

This doesn't work: interp_out1 := lin_interp.out;

It doesn't like the .out

It says 'out' is no input of 'lin_interp'

The function in the tree menu shows, lin_interp (FUN). This would be a function or not necessarily?

Originally created by: scott_cunningham

If you only have one output for the function, don't define it as a var out.

Don't:

FUNCTION MyFunction
VAR_INPUT
   VarIn : BOOL;
   Var2 : INT;
END_VAR
VAR_OUTPUT
   Out1 : BOOL;
END_VAR
Out1 := VarIn;

Do:

FUNCTION MyFunction : BOOL
VAR_INPUT
   VarIn : BOOL;
   Var2 : INT;
END_VAR
MyFunction := VarIn

Now you can call it in the way you want:

Answer := MyFunction(TRUE, 27);

If you define one or more VAR_OUTPUTs, then you have to use the full notation so the compiler knows which output you want.

This worked thanks!

I changed the function by removing the out var, and setting the function name := (equation).

And then updated the code to:

// function call - linear interpolation
interp_out0 := lin_interp( x0:= 0, x1:= 100, y0:= 0, y1:= 50, in:= interp_in);

// function call - linear interpolation (same as above, different format)
interp_out1 := lin_interp( 0, 100, 0, 100, interp_in );

I believe I found the old method in the help file too, not so helpful!