PLC

Object DUT

Symbol:  icontextlistdut(DUT without text list support),  icondut(DUT of type enumeration with text list support)

A DUT (data unit type) describes a user-specific data type.

 

Creating an object DUT

1.
Select a folder in the Solution Explorer in the PLC project tree.
2.
In the context menu select the command Add > DUT...
The dialog Add DUT opens.
3.
Enter a name and select a data type.
4.
Click on Open.
The DUT is added to the PLC project tree and opens in the editor.
 
 

Dialog Add DUT

Name
Name of the DUT

Type

Structure
The DUT consists of a structure of different data types.
Extended: The structure extends an existing structure. The definitions of the extended DUT are therefore automatically valid in the new one.
(See also: Structure)
Enumeration
The DUT consists of a series of integer constants.
Textlist support  icon_activated: Textlist support enables localization of the enumeration components. In addition, the symbolic enumeration values (instead of the numerical values) are displayed in the text output of a visualization element. When a textlist-supported enumeration variable is entered in the Text variable property of a visualization element, the supplement <enumeration name> is added.
The buttons at the right edge of the editor can be used to switch between Textual view ( icontextualview) and Localization view (text list) ( icontabularview). The DUT object appears in the PLC project tree in the Solution Explorer with the following symbol:
 icondut
Example: The variable MAIN.eVar of type E_myEnum is used. E_myEnum is a text list-supported DUT. The entry in the properties editor then looks as follows: MAIN.eVar <E_myEnum>. If the enumeration name is changed in the PLC project, a prompt appears with the question whether TwinCAT should update the affected visualizations accordingly.
Textlist support can be added to or removed from an existing enumeration object at any time: The commands Add text list support or Remove text list support in the context menu of the object can be used for this purpose.
Textlist support  icon_deactivated: An enumeration without text list support is created. The DUT object appears in the PLC project tree in the Solution Explorer with the following symbol:
 icontextlistdut
(See also: Enumerations)
Alias
Definition of an alias for a pre-defined type.
You can enter the pre-defined type directly or select it via the input assistant or the array wizard.
Union
With this data type, all components take up the same memory space. The memory footprint of a union is determined by the memory footprint of its “largest” component.
(See also: UNION)
 
 

Declaring a DUT

Syntax:

TYPE <Bezeichner> : <DUT Komponentendeklaration>
END_TYPE

The component declaration depends on the selected type (e.g. structure or enumeration).

Example:

The following section shows two DUTs, which define the structures ST_Struct1 and ST_Struct2. The structure ST_Struct2 extends the structure ST_Struct1, which means that ST_Struct2.nVar1 can be used to access the variable anVar1.

TYPE ST_Struct1 :
STRUCT
    nVar1 : INT;
    bVar2 : BOOL;
END_STRUCT
END_TYPE

TYPE ST_Struct2 EXTENDS ST_Struct1 :
STRUCT
    nVar3 : DWORD;
    sVar4 : STRING;
END_STRUCT
END_TYPE