Operator: ADR

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

‎ADR‎ yields the 32-bit address (or the 64-bit address, if possible) of its argument. You can pass this address to the manufacturer functions or assign them to a pointer in the project.

Syntax

VAR
    <address name> : DWORD | LWORD | POINTER TO < basis data type> | __XWORD ;
END_VAR

<address name> := ADR( <variable name> );

Example

FUNCTION_BLOCK FB_Adress
VAR
        piAddress1: POINTER TO INT;
        iVar1 : INT := 5;

        lwAddress2 : LWORD;
        iVar2 : INT := 10;

        xwAddress3 : _XWORD;
        iVar3 : INT;
END_VAR
piAddress1 := ADR(iVar1); // piNumber is assigned to address of iVar1
lwAddress2 := ADR(iVar2); // works for 64 bit run time system
xwAddress3 := ADR(iVar3); // works for 32 bit and 64 bit systems

NOTICE

Different from CODESYS V2.3 Gateway Server, you can use the ‎ADR‎ operator with function names, program names, function block names, and method names. Therefore, ‎ADR‎ replaces the ‎INDEXOF‎ operator.

When using function pointers, note that you can pass a function pointer to external libraries, but it is not possible to call a function pointer from within CODESYS. To enable a system call (runtime system), you must set the respective object property (“Build” tab) for the function object.

CAUTION

When you use an online change, the contents of addresses can shift. As a result, ‎POINTER TO‎ variables could point to an invalid memory area. To avoid problems, you should make sure that the value of pointers is updated in every cycle.

CAUTION

Do not return ‎Pointer-TO‎ variables of functions and methods to the caller or assign them to global variables.

See also: ⮫ POINTER TO