create Library in step7 with protection

Function blocks (FBs) belong to the blocks that you program yourself. A function block is a block
"with memory." It is assigned a data block as its memory (instance data block). The parameters
that are transferred to the FB and the static variables are saved in the instance DB. Temporary
variables are saved in the local data stack.
Data saved in the instance DB are not lost when execution of the FB is complete. Data saved in the
local data stack are, however, lost when execution of the FB is completed.
Note
To avoid errors when working with FBs, read Permitted Data Types when Transferring Parameters
in the Appendix.
Application
An FB contains a program that is always executed when the FB is called by a different logic block.
Function blocks make it much easier to program frequently occurring, complex functions.