Attribute qualified_only

Overview

When the pragma {attribute 'qualified_only'} is assigned on top of a global variable list, the variables of this list can only be accessed by using the global variable name, for example gvl.g_var. This works even for variables of enumeration type. It can be useful to avoid name mismatch with local variables.

Syntax

{attribute 'qualified_only'}

Example

Assume the following global variable list (GVL) is provided with attribute 'qualified_only':

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

Within POU PLC_PRG, the global variable has to be called with the prefix GVL, as shown in this example:

GVL.iVar:=5;

The following incomplete call of the variable will be detected as an error:

iVar:=5;