well... I would really appreciate if you would show me the Version 6.3 of WinCC. I only know the Version 6.2 with SP... but V 6.3 would be much to new.

About your question I would recommend to use the Version of SIMATIC NET that has been released with your WinCC Version, see With what is SIMATIC WinCC V 6.x compatible?. If you have done this you may use the OPC Server for S5 compatible Communication and FDL to send and receive the Data from the S5 CP 5431 DP/FMS. This has to work. The only thing I do not know is how the Data looks like you receive and send with COROS OLB. This has to be managed by you.

Best regards