Guide to Digitrax Decoder Features

Feature explainations follow the end of the table.
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Link to Digitrax Decoder Manual

Feature Name DCC Features

Basic

2 & 4 digit addressing

3 Step Speed Tables

Paged & Register Mode Programming

Advanced Consisting

Standard Function Outputs

Basic-FX

2 & 4 digit addressing

3 Step Speed Tables

Advanced Speed Tables

Paged & Register Mode Programming

Advanced Consisting

FX or Configurable Strobe Function Outputs

Economy

2 & 4 digit addressing

3 Step Speed Tables

Advanced Speed Tables

Support for all DCC programming methods

Advanced Consisting

Transponder ID

Motor isolation protection

Supersonic™ motor drive for silent motor operation.

One-step decoder factory CV reset

FX3 Function Outputs

Premium

2 & 4 digit addressing

Scaleable Speed Stabilization (Back EMF)

3 Step Speed Tables

Advanced Speed Tables

Paged, Register, Direct & Ops Mode Programming

Advanced Consisting

Transponding

Motor Fault Detection at initial power on

FX or Configurable Strobe Function Outputs

Economy Series 3

2 & 4 digit addressing

3 Step Speed Tables

Advanced Speed Tables

Support for all DCC programming methods

Advanced Consisting

Transponder ID to work with surround sound systems

Motor isolation protection

Supersonic motor drive for silent motor operation.

One-step decoder factory CV reset

2 FX3 Function Outputs

Decoder Lock

Series 3

2 & 4 digit addressing

Simplified Scaleable Speed Stabilization (Back EMF)

3 Step Speed Tables

Advanced Speed Tables

Support for all DCC programming methods

Operations mode read back capability

Advanced Consisting

Transponding

Motor isolation protection

Supersonic motor drive for silent motor operation.

One-step decoder factory CV reset

White LEDs on decoders that come with LEDs

6 FX3 Function Outputs

Decoder Lock

DCC Feature Explanations:

Analog Mode Conversion: When a Digitrax decoder does not “see” DCC packets on the layout it automatically changes to DC operation. This means that if you take your Digitrax decoder equipped locomotive to a friends layout that uses a DC control system, your decoder will automatically convert to analog (DC) operation. In this case, your decoder equipped loco won’t begin moving until about 5 volts is applied because of the decoder circuitry in the loco. Not all DCC decoders have this capability and in some non-Digitrax decoders you will have to re-program them to address 00 to have them run on an analog layout. Some non-Digitrax decoders have a shorting plug that lets you change from DCC to DC operation by opening the loco and moving the shorting plug. Analog mode conversion is NOT part of the DCC “standards.”  Analog mode conversion can be disabled by programming an appropriate CV value into CV29 (see your Digitrax Decoder Manual for complete instructions for programming CV29).

Locomotive Consisting Options: the action of linking more than one power unit together to be controlled by commands sent by the throttle and command station to a single address. Also called Multiple Unit Operation, MU'ing, Multiple Unit Lash Ups, etc. Three methods of consisting are available with your Digitrax system: Basic consisting, Universal consisting & Advanced consisting.

Basic Consisting Method: Program all the locomotives in a consist to the same address and run them off one throttle. In this case all the locos must be running in the same direction.  This method is available in all DCC systems available today. This is the least flexible method of consisting.

Universal Consisting method is the Digitrax preferred method of consisting.  Consisting handled by the command station and allows you to consist locos with any DCC decoder as well as an analog loco. The locos can be added to and deleted from the consist in any orientation head to head or tail to tail.  This is the most flexible method of consisting. It does not require special decoders or difficult programming steps. Consist maintenance is easy.

Advanced Consisting Method:  Consist information is stored in each Advanced Consist Capable decoder. The locos can be added to and deleted from the consist in any orientation. This method requires that all locomotives in the consist be equipped with decoders that support Advanced Consisting. This means that you can not add locos that are not equipped with advanced consist decoders to your consists, this includes locos with no decoder. This method allows you to set up a consist that will be "transportable" from one DCC layout to another but you must be sure to always put the locos back on the track in the same order and orientation you programmed them for or you can get some unexpected results.

One step decoder factory CV reset is a handy feature when you want to “start over” with your decoder programming. By programming CV08 to a value of 008, you can reset the CV values for decoders that have this feature to their original factory settings. If you want to start over with everything except your 28 step speed tables, just program CV08 to a value of 009.

DCC programming methods: Decoder programming is the action of entering CV values into CVs in DCC decoders to make them run on the address you choose and with the characteristics you choose. Check your Digitrax Decoder Manual for complete descriptions of the decoder characteristics controlled by the many CVs available and what effect different CV values you can program into them will have on the way they make your loco operate. Most DCC systems support all methods of programming. Some DCC decoders do not support all methods because of limited resources.

There are two modes of decoder programming: Service Mode and Operations Mode.

Service Mode Programming occurs on a programming track which is an electrically isolated track section used for decoder programming. An isolated programming track is needed because with service mode programming, the programmer sends a broadcast message to all decoders on the track. By using a programming track, you can send programming commands to the specific decoder you want to program.

There are three methods of service mode programming:  paged mode, direct mode and physical register mode

Paged mode is the most commonly used programming mode and is the Digitrax preferred method.

Direct mode is another mode allowed by the DCC “recommended practices.”

Physical register mode is an older method of programming that is not used in current production decoders.

Operations Mode Programming occurs anywhere on the layout. With Ops mode programming, the programmer directs programming commands only to the decoder address you select. For ops mode programming to work, the decoder you are using must be capable of this feature.

Operations Mode Read Back Capability is the ability of Digitrax systems to read back CV Values from locos with ops mode readback capable decoders that are on track equipped with transponder detectors.

Motor Fault Detection is included in decoders with FX function outputs. After the decoder in installed for the first time and power is applied, these decoders will indicate the presence of a short circuit by flashing the loco’s lights.  If you see this blinking, remove the loco from the track immediately and correct the short circuit before proceeding.  This is only an indication of a short circuit and does not protect the decoder from damage, if you do not remove the loco from the track immediately, it is possible to damage the decoder.

Motor Isolation Protection is included in decoders with FX3 function outputs.  If the decoder senses that the motor is not isolated, it will not run the motor.  In this case, you will be able to control the loco’s function outputs but the motor will not work.

SuperSonic motor drive for silent motor operation. Included with all Series 3 decoders. The Supersonic feature is pre-set at the factory for optimal operation. The Digitrax SuperSonic feature is compatible with Digitrax Transponding.

128 speed step control comes with all Digitrax decoders. 128 step operation delivers smooth as silk operation. With control this smooth, it’s easy to use your throttle to simulate prototypical acceleration and deceleration without setting up these variables in each decoder. Decoders can also be set for lower resolution speed control (12 or 28 step) for systems that are do not support 128 step operation.

Smooth deceleration to stop before changing direction when locomotive is reversed. No sudden, non-prototypical stops! It’s OK to press the reverse key while the loco is moving, in fact many customers do this during low speed switching operations for a realistic effect. If your Digitrax decoder equipped loco is moving and you press the reverse key, the loco will slow down at the programmed deceleration rate and speed up again at the programmed acceleration rate.

Torque compensation for the smoothest silent operation ever. When DCC decoders run in SuperSonic mode, torque compensation smoothes out operation. Torque compensation improves loco performance by internally adjusting for the loss of torque caused by SuperSonic operation.  This feature is turned on at the factory.

Momentum with acceleration and deceleration settings. In the real world locos don’t start moving immediately when throttle is applied and they don’t stop immediately when you put on the brakes. Now your models can simulate the movements of the prototype. Use acceleration settings to make your loco ramp up speed like the real thing. Use deceleration to make your loco ramp down speed like the real thing. These settings are “remembered” by the decoder until you change them.

Set normal direction of travel for your loco. Some prototype diesel locomotives run long hood forward and others run short hood forward. In some cases the same loco model was run differently by different railroads.  With this feature, you decide which way is forward for each individual loco.

Switching speed feature for quick access to slower switching speeds. This feature effectively reduces the throttle’s target speed by about 50% and reduces the effects of  accel and decel programmed into the decoder by ¼ when the switching speed feature is activated by turning on F6.

Speed Tables-Customizing Throttle Response. As you increase or decrease your throttle to command the decoder to move the loco forward or reverse at any speed you will notice that the loco responds to the change in throttle settings according to the relationship between motor voltage applied and the throttle setting. The factory settings for this throttle response curve results in a steady progression from 0 to full speed. In the real world, locomotives don’t respond to increases and decreases in throttle settings in a straight line. You can set up a more realistic throttle response curve by using one of the two types of speed tables available: Simple 3 Step Tables and 28 Step Tables with 256 level resolution.

Simple 3 Step Speed Tables use CV values programmed for Start voltage, Mid-point voltage, and Max voltage to define a throttle response curve. This method is simple to do and gives a reasonably good curve.

28 Step Tables with 256 Level Resolution use CV values programmed for 28 values along a customized throttle response curve to define how the decoder will respond to throttle changes.  This method is more complicated and also more precise.

Scaleable speed stabilization (Back EMF) smoothes out low speed performance using “back emf” technology. Digitrax offers scaleable speed stabilization to work better with US prototypes in consists and helper situations. This means that you can set how much compensation you want the decoder to provide. This can be anything from no load compensation at all to full load compensation that will maintain the loco’s speed no matter how heavy the load or how steep the track grade. 

Decoder Lock allows you to use more than one decoder in a locomotive and be able to program their CVs separately.  For example, if you use a mobile decoder and a sound decoder together in your locomotive, you can use the same mobile decoder address during operation and when programming you can unlock only the one you want to program.  This prevents the inconvenience of needing to uninstall one of the decoders to program is separately from the other decoder you are using in the loco.