The Siemens 6ES7902-2AB00-0AA0 is a 5 m point-to-point cable for TTY serial connections between SIMATIC S7 or M7 devices, terminated with 9-pole D-sub connectors on both ends.
This cable links two TTY-capable devices — typically a programming device or operator panel to an S7-300/400 CPU or an M7 module — over a serial point-to-point link. The 5 m length covers typical cabinet-to-operator-station distances without needing a repeater.