Address - Decoder

A number assigned by the user to a particular mobile or stationary decoder. The DCC system uses the decoder address to send commands to the appropriate loco or accessory.

Address - Range

Various DCC systems have a certain number of addresses that it can handle. Lower end DCC systems can be as low as 6 addresses. Average systems usually handle between 99 & over 9000 addresses, while advanced systems almost always go to 9000 or more addresses.


A combination of lights or positions on a railroad signal which has a predefined meaning.



The booster is sometimes referred to as a the "Power Station" and is responsible for combining the intelligence from the command station with the power of the power supply. Typically, a booster is combined with your first command station. More boosters can been added to layout as demand for power increases.



A cab is the controller, fixed or handheld. Each cab can control multiple locos - either by switching between locos using pre-assigned buttons or by calling-up the loco in the normal way.

Command station

The command station is the real intelligence of the DCC system. Typically, the command station is combined with the booster into a single device; however you can buy additional booster-only units for larger layouts that need more power (more trains). The command station contains a microcontroller and is responsible for all communication between the throttles and the decoders. The command station communicates with decoders by transmitting packets of data to them through the rails. Each digital packet tells a train how to run: fast, slow, forwards, backwards, or to turn lights, sound, and other effects on and off.


Consisting is when you use more than one locomotive at a time on a train.



CV/ Configuration Variable


Configuration variables or CVs are the means for controlling the performance of a DCC decoder. Decoders must be programmed by the user to reach their full potential. While they come with basic "default" programs, most users will want to customize the decoder address, motor control, lights, sound, and other functions to meet their specific needs.




Decoders are the "brains" of the locomotive. They monitor the DCC data and listen for commands with their address. Wired between the track and the motor, lights, and sound, these tiny special purpose computers rectify the current to DC and vary the voltage and polarity to provide the motor control, as well as creating any lighting or sound effects they may be capable of performing.




The software that has been 'burned' into a chip, such as the software on a decoder, or the software the controls the command station. Firmware upgrades are sometimes available by vendors. Sometimes the new chip will need to be replaced by manufacturer or authorized dealer. In some cases, the fireware can be upgraded/replaced by the end user.

Functions (Decoder)

Functions are relays, or small switches on decoders that can control can control anything you can think of - lights, sounds, smoke, animation, uncoupling devices, etc. There are currently 13 functions, F0-F12, however there is a proposal to extend this to 19 functions F0-F18.



Digitrax developed LocoNet to handle the communications between throttles, some stationary decoders, and other devices that need to talk to the command station. This network allows faster communication between devices not related to running the actual train itself. The command station decides what signals to route to the train tracks, or what needs to stay in the LocoNet only.



Magic Smoke

This is a whimsical way to describe how a DCC decoder, or any electronic device, really works. The theory is that electronic devices work only because they are filled with a "Magic Smoke". If you let the "Magic Smoke" out of the device, it fails to work. Of course, there is no Magic Smoke. However, electronic devices tend to fail dramatically, often due to a short circuit or overload. When they do, the result is often a singed, acrid burning smell that is unique to electronic devices. Sometimes a puff of smoke may be noticed at the same time. This is the "Magic Smoke" of legend.

MU/Multiple Units

See Consist.


Power supply

The power supply is just a transformer which supplies low-voltage AC or DC to the Command Station and Booster. Depending on the scale you are operating, you'll need a power supply with various voltages (covered later). For now, just think of the power supply as a transformer that brings down your house power to a level that can be handled by the booster.



Speed steps

Speed Steps are literally the number of steps between stop and fullspeed, there are 3 modes of speed steps 14, 28, and 128.