In order to be able to use POUs, which are provided in a library POU, in the application, the library has to be integrated in the ⮫ Library Manager in the project. The requirement for this is the installation of the library in the library repository.

The Library Manager displays all integrated libraries according to their library type and the respective properties. In the Library Manager, you can add more libraries from the library repository, remove libraries, and edit library properties.

The Library Manager can be inserted into the “POUs” view or the “Devices” view. As a result, a project can have a Library Manager for each application, as well as a Library Manager in the “POUs” view for use across all applications. The library POUs of the integrated libraries in the “POUs” view can be called regardless of the application. The library POUs of the integrated libraries in the “Devices” view can be called in the respective application code only. Furthermore, placeholder libraries behave differently when downloading depending on their positions.

Libraries that are integrated to a specific version in the project also have a placeholder for that version (placeholder library). You can define special placeholder resolutions. You can also use the placeholder resolution that is defined for a device in the device description or that is stored in the library repository for a library. The Library Manager notifies you about the actual placeholder resolution and shows the version that will be loaded when an application is downloaded (effective version).

When a Library Manager in the “POUs” view is integrated across all applications, you can access its contents globally. If placeholder libraries are integrated, then only the placeholder resolutions in the device description or library repository are checked.

A Library Manager is usually integrated in the “Devices” view. Then only the application code below it calls library POUs from it. Moreover, the special placeholder resolutions are checked first for placeholder libraries. Only after that are the placeholder resolutions checked that are in the device description or that originate from the library repository.