Zimo FS840D, Function/Sound Decoder - 21.5 x 15 x 3.6 mm - Audio 3 W (4–8 Ω) - 1.2 A - 8 Function Outputs

Function decoders are decoders designed for non-powered rolling stock; they lack a motor output stage but feature specific capabilities for use in cars that typically operate as part of a train consist alongside a powered unit (locomotive) (see next paragraph).ZIMO function sound decoders also feature a 16-bit sound output stage and can be used to provide sound effects in control cars and unpowered power cars.

A special feature of all ZIMO function decoders in the MX series (the FS series is to follow) is the programmable SECOND ADDRESS (CVs #64 to 68). This allows a wagon equipped with a function decoder to be addressed via an alternative address—typically set to match the address of the locomotive. If the other wagons in the train are equipped in the same way—meaning they can all be accessed via a single address (for instance, to switch on the lights throughout the train with the press of a single button)—this represents the simplest form of a (virtual) "TrainBus," a concept certain to play a key role in the future of train-level digital control.

Since function decoders are derived from "standard" locomotive decoders (sharing some circuit boards—albeit with slightly reduced component populations—and, in all cases, the same software), they offer the same features wherever applicable. Here is just a brief selection:

DCC addresses 1 ... 10239 (as primary and secondary addresses (MX only)), consist addresses 1 ... 127, MM addresses 1 ... 80

CV programming in "Service Mode" (on the programming track) and "Operational Mode"

Uninterrupted operation (without decoder reset or restart)

during power interruptions of up to 1 or 2 seconds (effective even without an external energy storage unit)

Updatable software: New software versions can be loaded without opening the locomotive using the ZIMO MXULF/A decoder update device, the MX32(FU) and MX31ZL control units, or—in the future—the MX10 base unit; ...via computer using the ZIMO Sound Tools (Sound Editor and Sound Creator), or directly via USB flash drive (using MX32(FU)/31ZL or the future MX10).

Overcurrent protection for all outputs, over-temperature protection; for details, see the information under "Continuous Current" and "Peak Current."

Voltage rating: 40 V (MX671), 50 V (MX685)

Wired versions are encased in fire-resistant, insulating, transparent heat-shrink tubing.

Full NMRA function mapping for F0–F12, plus ZIMO extensions (direction-dependent assignments, Swiss lighting system, etc.)

Dimming, flashing, American (Mars, Ditch, Strobe, etc.) and other lighting effects (soft start, brake light, flickering, automatic timed shut-off, etc.)

High-beam/low-beam switching via function key;timed coupler control for Krois and Roco, and "coupler waltz" (automatic pushing to relieve tension on the hook, followed by pulling away)

RailCom: CV reading "on-the-main" and confirmed programming,

many additional RailCom applications are planned for future software versions.