DCC Glossary

Acceleration and deceleration delay
Setting on a locomotive decoder. The delay determines how fast the loco reaches it set speed.

Accessory decoder
A decoder that is not intended to be installed in a locomotive, but remains in a fixed location and controls accessories such as signals or track switches/turnouts./p>

Address
The numeric identification code by which a decoder recognizes commands directed specifically to it. It is also the identifier that a transponder broadcasts. The address is usually unique for each decoder, but this is not a requirement.

Asymmetrical DCC
Asymmetrical DCC can be used to enforce speed control through important sections of your layout or to stop a train in a siding, in the station, or before an occupied rail crossing.  Using a few diodes, you can even protect a train from overrunning a turnout thrown in the wrong direction preventing unintended shorts, which could shut down a section of the railroad.

Back-EMF
Some locomotive decoders can sense the rotational speed of the motor and automatically adjust future digital pulses to the motor to maintain a desired speed. Also called load-compensating decoders. Back emf is the voltage developed by the spinning motor armature as it acts as a generator. EMF is short for electro-motive force. Back emf measurements are used for speed stabilization.

 

Braking sections
Track segments where the power supply is set up so that DCC trains stop automatically.

 

Bus
A set of wires that serves as a conduit for electrical signals and distributes them around the layout.

 

Command Station
The command station receives electrical signals (operator instructions) from the cab. The command station then creates NMRA DCC digital packets in accordance with NMRA specifications to achieve the desired results and transmits these packets to the power station.

 

Configuration variable (CV)
Memory location in the decoder that contains information that controls the decoder’s characteristics. A defined piece of information used by the decoder to adjust its operation. This information is permanently stored inside the decoder until the user wishes to change its value.

 

Consist
Operating and controlling several locomotives as if they were a single entity. There are three types of consisting: (1) Basic consisting is where all loco-motive decoders in the lash-up have the same address. (2) Advanced consisting is where the consist information is stored in CV19 in the decoder. (3) Universal consisting is where the consist information is stored in the command station.

 

Dither 

Is digital pulse power, it provides better and smoother low-speed performance and is especially helpful on locomotives that have high starting friction. Try experimenting with Dither to achieve better low-speed operation, the effect will narrow the window

between what point the locomotive starts to move and at what point it will stay running.

 

DCC
 Digital Command Control. The control information is provided in the form of a digital signal instead of a standard analog (DC or AC) power, overlaid with control information. NMRA DCC is a specific form of Digital Command Control specified by the NMRA as a non-proprietary international specification and is implemented by a significant number of manufacturers worldwide. On the most basic level, DCC encompasses systems and products that are interoperable with the basic NMRA DCC Standards.

 

Locomotive Decoder
Electronic device that receives the DCC signal from the command station through the track, decodes it and tells the locomotive it is controlling, what to do.

 

Function-only decoders

installed in equipment that moves, but function only decoders do not control movement. Rather, they control other functions like lights, sound, smoke or animation.

 

Occupancy detector
A device which senses and provides feedback for the presence of a train or specially equipped cars on a section of track.

 

Programming on Mainline (PoM)
Method where programming information is sent to a specific decoder on the layout instead of on the programming track. This method of programming decoders does not interfere with the operation or settings of other decoders on the same track. A programming track is not used, the information sent is directed to a specific address. Not all decoders accept PoM.

 

Power bus
Main wires that carry the power from the booster to provide power feeds to the power district.

 

Power station
Booster is the electronic device that combines and amplifies the DCC commands generated by the command station with power from the power supply. The booster sends the DCC commands as electronic signals along with the track power to the decoders to deliver both power and DCC signals to the DCC devices on the layout. A DCC system may have more than one booster. Boosters are also sometimes called power boosters or power stations.

 

Programming
The action of setting the internal parameters of decoders and other control equipment. During pro-gramming, values are set for CVs to determine the personality of locomo-tives, stationary decoders and other pro-grammable DCC devices.

 

Programming track
An isolated track section used for programming decoder equipped locomotives or transponder equipped rolling stock.

Speed Steps
Controllable voltage increments which are used to control motor speed. With some decoders, the output power can be set for each speed step. The range from zero to full power is divided equally into 14, 28 or 128 speed steps.

Stall Current
The maximum current draw in amps that a locomotive is capable of when stalled. When a motor is prevented from rotating and its maximum rated voltage is applied, the current draw of the motor is known as its stall current. Typically, it is safest to insure that the stall current rating of a locomotive decoder exceeds the stall current of the motor being controlled. In case of a derailment or gear bind and subsequent motor stoppage, the decoder will not be damaged.

Throttle Notches.

Determines whether a loco is controlled with 14, 27, 28 or 128 speed step mode.

USP Technology - Uninterruptible Signal Processing

Most decoders need a clean and constant connection to the track to pick up the DCC signal.  Even a small section of dirt can prevent the commands from getting to the locomotive.  Not so with USP Technology!  With USP, the decoder can read the signal on either rail or even if the locomotive is entirely on dirty track. 

 

XpressNet

High speed data communication network for connecting Digital plus input devices together.

 

XpressNet (XBUS) input devices

Devices that are used to control your layout.

i.e. hand helds, cab tower, interface, etc.