The 6ES7902-2AG00-0AA0 is a 50-meter TTY (20 mA current loop) point-to-point connection cable with 9-pin D-Sub connectors—plug at one end, socket at the other. It links a SIMATIC S7/M7 CP 340 or CP 341 serial communication processor to a TTY partner device—a programming device, a serial printer, or an intelligent instrument—across the longest standard reach in the 6ES7902-2 series.

Why TTY instead of RS232 or RS422?

TTY uses a 20-milliampere current loop rather than voltage-level signaling. The practical advantage is noise immunity over long cable runs—current-loop signaling tolerates industrial electromagnetic interference better than RS232, and the 50-meter reach of this cable takes full advantage of that. Historically, TTY was the standard physical layer for programming devices and operator panels on early SIMATIC S5 and S7 systems. Today, RS232 and RS422 have largely superseded TTY for new designs—which is why Siemens has announced a phase-out for this product.

Important lifecycle note

Siemens has announced a product phase-out date of October 1, 2024 for the 6ES7902-2AG00-0AA0. If your design calls for a 50-meter TTY cable and has a production horizon extending past that date, verify successor availability on the Siemens Industry Mall. The 10-meter TTY variant (6ES7902-2AC00-0AA0) shares the same electrical interface and may have a different lifecycle timeline—check both before finalizing the BOM.