A PC/PPI cable is for S7-200 only.
Most PC/MPI cables are capable of communicating with both S7-200 and S7-300/400.
Siemens has introduced a misunderstanding to the market by calling all these PLCs S7-something, but there a two very different families involved: S7-200 is in fact a TI PLC, while S7-300/400 are "real" Siemens PLCs. You need two separate software packages and the interfaces, although both are RS-485, use completely different protocols (PPI vs. MPI).
Kind regards,