Does portability of IEC 61499 mean that once programmed control software runs everywhere?

Due to the defined requirements for software tools at the second part of the IEC 61499, it is possible to exchange once developed function blocks (abbr. FB) and created applications between different engineering environments. Thus, it is also possible to compile the once developed FBs for different runtime environments and to run even the same applications at several hardware platforms. But does this hardware vendor independence mean programming once and executing everywhere with the same execution results and machine behaviour, or may it be that exchanging only the used runtime environment lead to a totally different machine behaviour with violating specified safety constraints?Because the standard IEC 61499 does not specify exactly the execution of FBs and the scheduling of FBs executed in one resource, this contribution should show at a practical example of a real manufacturing plant the possibility to exchange the used runtime environment and how the impact to machine behaviour can be checked for several execution and scheduling possibilities by doing a formal verification.