4.2.4 Assigning the Global Variables
Before any program code can be created, it is necessary to specify and assign all pre-allocated
physical PLC inputs and outputs including any shared variables that are to be used in the pro
-
ject.
Double Click the mouse pointer on
Global_Vars
to open the Editor for the Global Variables. This
is called the Global Variable List - GVL.
Global Variables are the link to the physical PLC devices.
As discussed previously, if IEC conventions are to be applied, then symbolic identifiers (names)
must be used instead of discreet addresses in our program. These addresses must therefore be
declared in the Global Variable List (GVL). The identifier must be filled in, using its’ PLC address
(either using Mitsubishi or IEC notation) and its’ type, for example; whether it is a ‘bit’ or ‘word’
device. Once completed, this list can be used by all of the POU’s that will be created.
Building a Project Application Program
Training Manual GX IEC Developer 4 - 9
To Next Page
Loading...
