Category Common

The category Common contains general information and meta information of the project file. TwinCAT uses this information to create keys in the Properties tab. For example, if the Company text field contains the name "Company_A", the Properties tab contains the Company key with the value "Company_A".

Project information

For a library project, a company, title and version must be entered in order to be able to install the library.
Company	Name of the company, which created this project (application or library). In addition to the library category, it is used for sorting in the library repository
Title	Project title
Version	Project version, e.g. "0.0.0.1"
Released	: Protection against modification enabled. Consequence: When you now edit the project, a prompt will appear asking you if you really want to change the project. If you answer this query once with Yes, the prompt will no longer appear when the project is edited again.
Library Categories	Categories of the library project by which you can sort in the Library Repository dialog. If no category is specified, the library is assigned the category "Other". To assign it to another category, the category must be defined. Library categories are defined in one or several external description files in XML format. To assign the library, you can either call such a file or another library file that has already picked up information about the categories from a description file. Requirement: The project is a library project.
	The Library Categories dialog opens, in which you can add library categories.
Default namespace	The default setting for the namespace of a library is the library title. Alternatively, a different namespace can be defined explicitly, either generally for the library in the project information during library generation, or in the Properties dialog of the library reference for local use of the library in a project. The namespace of the library must be used as prefix of the identifier, in order to enable unambiguous access to a module that exists more than once in the project, or if the use of this prefix is enforced by the library property LanguageModelAttribute "qualified-access-only" ("Unambiguous access to library modules or variables"). If you do not define a standard namespace here, the name of the library file is automatically used as the namespace.
Placeholder	At this point, a default name for the placeholder can be specified, which represents or references this library. If a placeholder is not specified explicitly at this point, the default setting for the placeholder name of a library corresponds to the library title.
Author	Project author
Description	Brief description of the project (e.g. content, functionalities, general information such as "for internal use only", etc.)

Library features

Creating a global version structure	Creates a global variable list in the PLC project, which contains the version information.
Automatically generate library information POU	Add button: POU objects of type "Function" are automatically created in the project tree, which can be used to access project properties in the application program. In this case, special functions are generated for the properties Company, Title and Version (F_GetCompany, F_GetTitle, F_GetVersion). If these functions have been added to the project by clicking Add, they can be removed from the project by clicking Remove.
Documentation format	Options: Up to TC3.1 Build 4024: reStructuredText: From TC3.1 Build 4026: TcDocGen During library creation, comments that correspond to a specific format are restructured and displayed in the Documentation tab of the Library Manager in this customized view. This opens up additional options for library documentation.
Allow implicit checks for compiled libraries	Available from TC3.1 Build 4026 : TwinCAT executes implicit checks also for function blocks from protected libraries (.compiled-libraries). Requirement: The compiler definition "checks_in_libs" is entered in the PLC project properties* in the field Compiler definitions (category Compile). See also: Using function blocks for implicit checks
Force Qualified_only for library access	Available from TC3.1 Build 4026 : Objects from this library may only be used with the specification of the namespace of the library. See also: Attribute 'qualified_only'
Allow referencing as library	Available from TC3.1 Build 4026 : You can reference the PLC project in another PLC project as a library. See also: Use PLC project as referenced library

General

Minimize ID changes in TwinCAT files

Category Common 7: : The GUIDs of the PLC objects (e.g. POUs) are linked to those of the PLC project (using XOR). This avoids changes to the GUIDs of the PLC objects if they are used several times in different projects.

Library Categories dialog

List of categories	List of categories assigned to the library project. They can come from several sources. When you have entered all the desired categories, confirm the dialog with OK.
Add	The commands From Description File... and From Other Library... appear.
Remove	TwinCAT removes the selected category.
From description file...	The Select Description File dialog appears, in which you can select a description file with the extension .libcat.xml. The file contains command categories. When you exit the dialog with Open*, TwinCAT applies these categories.
From another library....	The Select Library dialog appears, in which you can select a library (.library) whose command categories are to be adopted. When you exit the dialog with Open*, TwinCAT applies these categories.
OK	TwinCAT provides the categories as project information and displays them in the Library Categories field.
Cancel	Closes the dialog. The process is aborted.

See also:

PLC documentation: Configuring a PLC project
PLC documentation: Using libraries