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4Control Engineering Objects

Objects in 4Control can be considered as elements of a 4Control project to which properties and entries have been assigned. They include e.g. variable lists, POUs, instances and libraries. In the various views of the Navigator and in the object list, objects are identified by corresponding icons.

Resources are displayed and managed in the Class view of the Navigator and in the object list

The resource can be opened in the 4C text editor

A constant has a fixed identifier (name), a fixed data type and a fixed value which matches the data type. Constants are defined using constant lists which are valid for the entire project. Thus, you can use them in all objects of the project instead of literals.

Constant lists are displayed and managed in the Class view of the Navigator and in the object list.

The constant list can be opened in the 4C text editor

Global variable lists (GVL) are ASCII text files used to define global variables. The variable declarations of the GVLs are enclosed by the VAR_GLOBAL and END_VAR keywords and separated by semicolons. In addition, the CONSTANT and RETAIN attributes can be specified directly after the VAR_GLOBAL keyword. They refer to all variable declarations specified before END_VAR.

Global variable lists are displayed and managed in the Class view of the Navigator and in the object list.

The global variable list can be opened in the 4C text editor.

Different data types can be grouped in a new, structured data type which is called a structure.

Structures are displayed and managed in the Class view of the Navigator and in the object list

The structured data type is opened in the 4C text editor.

The POU classes of the Program type are displayed and managed in the  Programs folder of the Class view of the Navigator and in the object list.

In 4CONTROL, programs are not directly called by tasks, but after a program instance has been created within the task.

Program instances are not stored in separate files, but they are declared by instantiation in the calling task (in the source code of the resource).

Function blocks are displayed and managed in the Function Blocks folder of the Class view of the Navigator and in the object list.

Since function block instances are declared by instantiation within the calling POU, they are not saved in separate files. In the Instance view of the Navigator, they are indicated by the  icon and displayed below the POU in which the function block was instantiated.

Functions are parameterizable POUs which have no internal memory. Function calls with identical input values produce identical output values.

Functions are displayed and managed in the  Functions folder of the Class view of the Navigator and in the object list.

Each resource can include one or more tasks which, in turn, call one or more POUs of the Program type. Tasks are displayed and managed in the Class or Instance view of the Navigator and in the object list.

Libraries are collections of the following 4C objects: 

• Constant lists 
• Structures 
• Function blocks 
• Functions 

Libraries are stored as separate files so that they can be made available and used in any 4C project. There are two different types of libraries: 

• Standard libraries: These libraries are supplied on the 4CONTROL Installation CD or can be purchased separately. Not only blocks which implement basic functionalities, such as the library 4C_IEC1131_3 which provides the blocks defined in the IEC61131_3 standard, but also libraries that fulfill special tasks are available. The latter include, for example, the library 4C_FileAccess which contains blocks for file access. You will find more detailed information on the supplied standard libraries in the Libraries directory of this Online Help. Standard libraries cannot be changed by the user. 
  
  
• User-defined libraries: User-defined libraries are created by the user in the process of compiling a project to build a library. Like standard libraries, user-defined libraries can be shared by several projects and are integrated into a project in the same way as standard libraries.

The libraries belonging to a project are displayed and managed in the  Libraries folder of the Class view of the Navigator and in the object list