2.5 m RS232 cable, still active production
The 6ED1057-1AA00-0BA0: Siemens notes the USB variant (6ED1057-1AA01-0BA0) can be used as an alternative if your PC lacks RS232, but this RS232 cable remains available as a spare part.
Sourcing reality
Current production; quoted to order. RS232 cable; USB variant (6ED1057-1AA01-0BA0) is an alternative.