The 6ES7901-0BF00-0AA0 is a 5-meter MPI programming cable with 9-pin D-Sub plugs (male) at both ends. It connects a programming device—a PG, a PC with a CP 5512/5611/5711 adapter, or a USB-to-MPI converter—to the MPI port of a SIMATIC S7 PLC for program download, online monitoring, and diagnostics over the RS485-based MPI protocol at up to 187.5 kbps.

How is this different from the 6ES7902 PtP cables?

The 6ES7902 series cables (RS232, TTY, RS422) are permanent point-to-point communication links—you install them once between a CP 340/341 and a partner device, and they stay plugged in for the life of the machine. The 6ES7901-0BF00 is a programming tool—you carry it with the laptop, plug it in for commissioning or troubleshooting, and unplug it when you are done. Both ends are male D-Sub plugs because both the PG adapter and the PLC MPI port are female. The 6ES7902 cables are plug-to-socket (male-to-female) because they extend an existing port.

Five meters—long enough?

Five meters lets you set the laptop on a cart or a nearby workbench while the PLC cabinet is at standing height a couple of meters away. MPI at 187.5 kbps is reliable over much longer distances than five meters, so signal integrity is not a concern. If five meters is not enough—say, the PLC is in a cabinet on a mezzanine and you need to program from the floor below—use a longer third-party RS485 extension or a networked solution like Ethernet/Profinet with a CP 343-1 or CP 443-1, because Siemens does not offer a longer standard MPI programming cable.