The Siemens 6ES7901-3BF21-0XA0 is a PC/PPI cable for connecting an S7-200 CPU to a PC's serial port. It comes with a 90-degree connector and an RTS switch, and the cable length is 5 m.
Key specs and fit
The 5 m length covers typical distances from a desk to a panel-mounted S7-200. The 90-degree connector keeps the cable profile low on the CPU port — useful when the connector sits near other wiring or a panel door. The RTS switch handles flow control for older PC serial ports that need hardware handshaking.