Tamper Protection of Libraries
When releasing a library, PLCnext Engineer calculates checksums over the contained components. These checksums are used as signature. By means of this signature, the library can be identified uniquely. The signature is verified when including a library into a project and each time the project with included library is loaded. This way, any modifications (new version?) or data corruptions are recognized.
Non-IEC firmware libraries may contain a signature too which is also verified when including the library or opening the project where the library is already included.
| Note
The signature checksum is different from the library ID PLCnext Engineer writes when releasing the library. This means that the checksum is always recalculated each time a library is released - independently of the setting for the checkbox 'Create new library ID'. |
If an included library has been modified externally and, as a result, the signature of the library is no longer valid in the current project, a corresponding error icon appears at the 'Libraries' folder 
as well as at the library symbol 
.
By default, the library content is not loaded and the contained elements cannot be used in the project.
You can accept the modified library in PLCnext Engineer in order to keep on using it in the current project: Right-click the respective library node and select 'Accept Library' from the context menu.