Attribute ‘qualified_only’¶

The effect of this pragma is that variables of a global variable list are only addressed by specifying the global variable name, for example gvl.g_var. This also applies to variables of the type Enumeration and can be helpful in avoiding being mistaken for local variables.

Syntax:

{attribute ‘qualified_only’}

Insertion position: line above VAR_GLOBAL in a GVL

Example

Global Variable List GVL:

{attribute 'qualified_only'}
VAR_GLOBAL
 iVar:INT;
END_VAR

Within a POU, for example PLC_PRG, the global variable iVar can only be addressed using the prefix GVL:

GVL.iVar:=5;

Conversely, the following incomplete call of the variable will create an error:

iVar:=5;