As in case of Masterdrives we Simolink Communication(Simolink Card) for fibre optic communication,so please let me know the alternate option in Sinamics family with authentic documentation and justification.
What you can use for sinamics is what is called Sinamics Link. This is effected through use of the CBE20 card in the CU.
Also available for the sinamics DC master is the parallel interface which is RS485 communication between drives.
I guess you are thinking AC drive, so I suggest you look up Sinamics link in the S120 function manual. for more detail