6DD1688-1AA0
The SS1 thick-film interface IC is used in the SIMADYN D system for configuring a physical interface for a processor module. 

The interface connector configured with SS1 is a 20 mA interface. This is also referred to as a TTY or current loop interface.

User Manual for Serial interface SS1 has 3 editions:
  • Serial interface SS1 - 03.1991
  • Serial interface SS1 - 05.1995
  • Serial interface SS1 - 04.1997
Siemens
Siemens Teleperm XP (T2000)