When you define a library block, the block can input, process, and output buses just as an ordinary subsystem can.
You need to provide the appropriate input bus signal if:
You have a bus routing block (Bus Creator, Bus Selector, or Bus Assignment) block that is in a library.
That block depends on signals that are input to the library.
To change that block in a library, perform these steps. For details about modifying library links, see Work with Library Links.
Copy the library block that uses that block to a model that connects an input bus.
Disable the link to the library block in this model.
Edit the bus routing block within the context of the outside model.
Resolve the link to the library.
In the Link Tool, in Push/Restore Mode,
Push to place the edited content
into the library.
Save the library.
Alternatively, to configure the library to supply an appropriate bus signal, use a bus object to lock in the data type at the interface of a library subsystem block .