Siemens S7 300 400 PC/MPI PCMPI USB MPI+ 6ES7 972-0CB20-0XA0 Cable PLC Cable 6ES7 972-0CB20-0XA0 (6ES79720CB200XA0) USB MPI+ Optical Isolated USB-MPI+ OCB20 is with better quality than the fourth generation USB-MPI+(S7 200/300/400)