As it's possible in e.g. C++ to have default function arguments, I'm now wondering if this is also possible in CoDeSys ?

C++ example

int Increase(int nValue, int nStep=1){return nValue+nStep;};

Following function calls are both valid ...

int nTest = 0;
Increase(nTest);      //nTest is incremented with 1
Increase(nTest,5);    //nTest is incremented with 5

In the CoDeSys help I found info about VAR_INPUT CONSTANT, but if I try this I get compile errors when calling the method with not all inputs filled in.

METHOD mnIncrease : INT
VAR_INPUT
  nValue : INT;
END_VAR
VAR_INPUT CONSTANT
  nStep: INT := 1;
END_VAR
VAR
END_VAR
----------------------------
mnIncrease:=nValue+nStep;
----------------------------
mnIncrease(nTest,5); //nTest is incremented with 5
mnIncrease(nTest);   //generates compile error

Does anyone have an idea if my idea is possible ?

it is possible with a FB by using an initial value to the input variable definition like Input :Byte := 4;, But not possible with a FUN that I am aware of, CoDeSys will not compile if the input to a function is not connected to a variable. Why do you need to do this?

The default argument causes default method operation. All method calls that require default operation then need to pass the default argument. A lot simpler and safer if you can omit it as in C++, no ? Thx !

I do not have the problem

Please add a Function_Block to your project

FUNCTION_BLOCK My_FB

VAR_INPUT

nValue : INT;

END_VAR

VAR_INPUT CONSTANT

nStep: INT := 1;

END_VAR

VAR

END_VAR

Code is only a ;

Declare a instance in the PLC_PRG

VAR

mfb : My_FB;

END_VAR

And use it with mfb();

Set a BP to mfb()

And step into with F8

There you’ll see nStep is 1

I'm using CoDeSys v3.3

It indeed works for Function Blocks ... Thanks ! However, I need to explicitely pass the input name in the FB call ...```

mfb(nValue:=99);

```

Tried the same now with a method but then I get a compile error that tells me the method requires exactly 2 inputs

Any idea on that ?