Operator '__DELETE'

This operator is an extension of the IEC 61131-3 standard.

NOTICE

For compatibility, the compiler version must be >= 3.3.2.0.

The operator releases the memory of instances that the "__NEW" operator generated dynamically. The ‎__DELETE‎ operator does not have a return value and the operand is set to zero after this operation.

Requirement: In the properties dialog of the application, the “Use dynamic memory allocation” check box is selected in the “Application Build Options” tab.

‎__DELETE (<pointer>)‎

NOTICE

Two tasks should not call __DELETE simultaneously. Either you use a semaphore (SysSemEnter) or comparable method to prevent any concurrent calling of __DELETE , or you use __DELETE in one tasks only (recommended).

You can use a semaphore (SysSemEnter) to prevent two tasks from allocating memory at the same time. As a consequence, the extensive use of ‎__DELETE‎ causes higher jitter.

If ‎Pointer‎ references a function block, then CODESYS calls the associated ‎FB_EXIT‎ method before the pointer is set to zero.

Examples

FUNCTION_BLOCK FBDynamic 

VAR_INPUT 
  in1, in2 : INT; 
END_VAR 

VAR_OUTPUT 
  out : INT; 
END_VAR 

VAR 
  test1 : INT := 1234; 
  _inc : INT := 0; 
  _dut : POINTER TO DUT; 
  neu : BOOL; 
END_VAR 

out := in1 + in2; 


METHOD FB_Exit : BOOL 

VAR_INPUT 
  bInCopyCode : BOOL; 
END_VAR 

__Delete(_dut); 

  

METHOD FB_Init : BOOL 

VAR_INPUT 
	bInitRetains : BOOL; 
	bInCopyCode : BOOL; 
END_VAR 

_dut := __NEW(DUT); 


METHOD INC : INT 

VAR_INPUT 
END_VAR 

_inc := _inc + 1; 
INC := _inc; 


PLC_PRG(PRG) 

VAR 
	pFB : POINTER TO FBDynamic; 
	bInit: BOOL := TRUE; 
	bDelete: BOOL; 
	loc : INT; 
END_VAR 

IF (bInit) THEN 
	pFB := __NEW(FBDynamic);
	bInit := FALSE; 
END_IF

IF (pFB <> 0) THEN
	pFB^(in1 := 1, in2 := loc, out => loc); 
	pFB^.INC(); 
END_IF 

IF (bDelete) THEN 
	__DELETE(pFB); 
END_IF