PARAMETERIZABLE Special Module (PSM), Function - GF54.21-D-0002P

Model 906 with code ED5 (Parameterisable special module) with code XM0 (Facelift) Description of control unit 

Courtesy of MERCEDES-BENZ USA

Connection, shown on model 906 with code (ED5) Parameterizable special module (PSM) 

The PSM control unit forms the interface between the vehicle and the body manufacturer electronics.

Thanks to the body manufacturer electronics, vehicle information can be read in and vehicle functions controlled (e.g. the central locking (CL)) by means of the PSM control unit via the interior CAN (CAN-B). For this purpose, there are digital and analog inputs and outputs (10 discrete inputs and 20 discrete outputs; the latter can also be used as inputs). The body manufacturer CAN (CAN-ABH) is available as an additional interface for complex bodies that require more inputs or outputs. A multitude of vehicle signals are transmitted on this. In addition there are some "free messages" which can be freely assigned with arbitrary contents.

The PSM control unit can thus forward information, which it receives via the CAN bus messages, to discrete outputs or the CAN-ABH. In exactly the same way, the PSM control unit can pass on discrete inputs or information from the body manufacturer CAN to CAN B.

Over and above the interfaces internal functional units are available in the PSM control unit, e.g.:

• Access to motor functions (working speed control, engine start/stop)
• Programmable logic controller (PLC) functionality (logic operations AND, OR etc. of signals)
• Undervoltage detection

The type and direction of information and interfaces are parameterized with the aid of the diagnostic unit. Only through this parameterization is the usability of the PSM control unit established and adapted to the corresponding body. For SA codes available from the plant, parameterization of the PSM control unit can be performed at the touch of a button via the menu item "Standard coding" (offline) or via the menu item "SCN coding" (online). Parameterization via the expert coding is required for all other adjustments.

The SA codes available from the plant are:

• Retarder with code (BR9) preinstallation for Telma retarder
• Working speed control:
  • With code (MT4) Variable electronic rpm governor
  • With code (MT4) Variable electronic rpm governor and with code (N05) Countershaft power take-off (2c) without flange
  • With code (MT4) Variable electronic rpm governor and with code (N07) Countershaft power take-off (2b) with flange
  • With code (M53) Constant rpm control
  • With code (M53) Constant rpm control and with code (N05) Countershaft power take-off (2c) without flange
  • With code (M53) Constant rpm control and with code (N07) Countershaft power take-off (2b) with flange
  • With code (JV5) Preinstallation for crash data recorder