SUSI

== SUSI - Serial User Standard Interface ==
Interface definition between decoders and external extension modules (SUSI-modules). Developed by Dietz the SUSI interface allows a multifunction decoder to pass the information on to additional devices – up to three (3) SUSI modules. Function keys on the throttle control the module(s). 
SUSI is an NMRA Standard TI-9.2.3. (Also known as the SUSI 1.3 Specification). More details can be found in the standard.
=== SUSI Applications ===
At present, there are two core applicatons for SUSI-modules.
;Sound Modules
:Modules to generate sound based on the messages from the decoder. For example, this allows the sound to change based on speed changes, as the decoder is requested to reduce speed the SUSI sound module could play a brake squeal sound.
;Additional functions
:Modules to increase the number of outputs available. These are defined as Auxiliary outputs. The specifications allow for Aux. outputs A-P to be defined. These can then be mapped (as with on-decoder functions) to DCC functions e.g., F5 triggers AUX Output D.
Some SUSI modules can control external devices such as a smoke generator. By using the SUSI interface, the smoke unit can respond to outputs from the decoder for more realistic effects.
SUSI can also be used as an interface to a LISSY module, a communications technique similar to RailCom except it uses Infrared Light.
With the arrival of multifunction decoders with integrated sound, the need for SUSI declined. SUSI devices are still available, often used with large-scale decoders. While originally developed for DCC, some Selectrix decoders also have SUSI interfaces.
=== Development ===
SUSI and the SUSI-LOGO were developed by
DIETZ MODELLBAHNTECHNIK
Hindenburgstraße 31
D-75339 Höfen
Germany
e-mail: info@d-i-e-t-z.de
http://www.d-i-e-t-z.de
===Connections===
The hardware connection to the SUSI module is a PTPPoint to Point connection with 2 signals plus 2 supply lines. The data line must be pulled up to 5V. The clock and data lines must have a 470R resistor in series on both sides, µC and Module. Since the connection between the decoder and module is short, no error correction is used.
The clock signal must not have a period greater than 500µs; the high and the low times of that period must be greater than 10µs. Data must be stable at the clock's falling edge. Two or three bytes are transmitted with LSB (Bit 0) first.
==== SUSI Interface ====
The connections between the decoder and the SUSI module uses 4 wires:
Pin Number	Signal 	Wire Colour
1 	Ground 	Black
2 	Data 	Grey
3 	Clock (CLK)	Blue
4 	Power 	Red
Colours are those recommended by the NMRA.
==== Technical Details from the NMRA Standard ====
The connection is made by means of a 4-pole socket (JST SM04B-SRSS-TB (side entry) or JST BM04B-SRSS-TB (top entry) on both decoder and SUSI- module. Connection is established by cable with plug (JST 04SR-3S or SHR-04V-S-B) on both sides and pin 1 connected to pin 1, etc. It is allowed to have the wires on the SUSI-module side directly soldered to the PCB.
==== 2024 Draft Standard ====
The following appear in the draft for the updated SUSI standard. For more detail see the draft standard on the NMRA website (linked below).
===== Mechanical =====
Three plugs have been defined for the SUSI interface:
# Classic SUSI
# Micro SUSI
# Power SUSI
Classic SUSI has been known since 2003 and is mainly found in H0 scale.
Micro SUSI is a small design introduced in 2017, e.g. for N scale. 
Power SUSI was added in 2018 for larger scales and modules with higher power requirements. This interface uses a 5 – Pin connector, instead of the 4 – pin JST connectors normally used. The pinout is also different.
It is also possible to connect a SUSI module to a decoder interface as described in S-9.1.2.3, S-9.1.2.4, and S-9.1.2.5.
===== Logic Level Interface =====
Voltages can be 5V or 3.3V. Master units which operate at 3.3V only shall be marked SUSI3. Masters with Micro SUSI connectors are not required to have this marking.
Slave units can operate at either voltage. Those that accept 3.3V may be marked as SUSI3 
==== Other Interfaces ====
PLuX connectors also support SUSI.
=== CVs ===
A specific set of CVs has been assigned to SUSI modules to store their settings: 897-1024
As you can connect up to 3 SUSI modules to a host decoder the CVs are split into 3 ranges to prevent conflicts between SUSI modules. These are selected by setting CV 897
Name 	CV Range 	CV 897
SUSI-I 	900 to 939 	1 (or Zero)
SUSI-II 	940 to 979 	2
SUSI-III	980 to 1019	3
Full details of the CVs can be found in the NMRA SUSI 1.3 Specification
===Decoders with SUSI Support===
A number of European DCC manufacturers offer compatible decoders and SUSI devices.
==== Multifunction Decoders ====
* Lenz
** LE1835
** Gold decoders
* Uhlenbrock Elektronik
** 76500 Decoders
** 2011 Catalog
* Zimo
** MX620, MX63, MX64, MX69 and MX690 decoder series
* Tams
** Tams LD-G-33, LD-G-34, LD-W-33 locdecoder series and functionsdecoder FD-M, FD-XL
* Kühn Digital
** N-45 Lokdecoder
==== SUSI Modules ====
* Dietz
** (English translation)
* Uhlenbrock Elektronik
** IntelliSound
* Tams
** Micro-XS
== Further Reading ==
* DCC Decoders
* 
* Serial User Standard Interface NMRA S-9.4.1 (June 2024 DRAFT) 
* urc - SUSI.wiki
* Rail Community Norm: RCN-600 (German)
* RailCom
* LISSY
Category:Hardware
Category:Multifunction Decoder Features