Initialize a Function Block using __NEW that has explicitly defined the FB_init method

Question

Suppose I have a function block (A) that has defined the FB_init method, for example:

{attribute 'enable_dynamic_creation'}
FUNCTION_BLOCK A
  METHOD FB_init : BOOL
    VAR_INPUT
      bInitRetains : BOOL;
      bInCopyCode : BOOL;
      parameter: BOOL;
    END_VAR
  END_METHOD
END_FUNCTION_BLOCK

And I have another function block (B) from which I want to initialize this (A) FB dynamically:

FUNCTION_BLOCK B
  VAR
    a := POINTER TO A;
  END_VAR
  METHOD FB_init : BOOL
    VAR_INPUT
      bInitRetains : BOOL;
      bInCopyCode : BOOL;
      parameter: BOOL;
      somethingElse: INT;
    END_VAR
    a := __NEW(A); // No matching FB_init method found for instantiation of A
    a := __NEW(A(TRUE)); // Build returns errors
    a := __NEW(A(parameter := TRUE)); // Build returns errors
  END_METHOD
END_FUNCTION_BLOCK

I am unable to dynamically create an instance of the A function block. Is this even possible, or am I doing something wrong?

PS. I am using Schneider SoMachine V4.3

Answer 1

You have error in function block B. I tried with TwinCAT 3 and it works.

Change

a := POINTER TO A;

to

a : POINTER TO A;

After that the following works:

A:

{attribute 'enable_dynamic_creation'}
FUNCTION_BLOCK A
VAR_INPUT
END_VAR
VAR_OUTPUT
END_VAR
VAR
END_VAR

METHOD FB_init : BOOL
VAR_INPUT
    bInitRetains : BOOL; // if TRUE, the retain variables are initialized (warm start / cold start)
    bInCopyCode : BOOL;  // if TRUE, the instance afterwards gets moved into the copy code (online change)
    parameter: BOOL;
END_VAR

B:

FUNCTION_BLOCK B
VAR_INPUT
END_VAR
VAR_OUTPUT
END_VAR
VAR
    a : POINTER TO A;
END_VAR

METHOD FB_init : BOOL
VAR_INPUT
    bInitRetains : BOOL; // if TRUE, the retain variables are initialized (warm start / cold start)
    bInCopyCode : BOOL;  // if TRUE, the instance afterwards gets moved into the copy code (online change)
    parameter: BOOL;
    somethingElse: INT;
END_VAR

a := __NEW(A(parameter := TRUE));