Semantic Error (SEM1277): EN variables must be 'VAR_INPUT'.

In an included C# library, a POU contains an invalid declaration of an EN variable. Like each other POU input formal parameter, the EN input must be declared with the VAR_INPUT attribute.

Remedy

Double-click the error message to jump to the affected variable.

Contact the provider of the library.

If the library source code is available and can be edited:

Correct the variable declaration by specifying the correct attribute.
Release the library again.