DH123AT 1.5 Amp HO Scale Mobile Decoder for Athearn Standard Locos

Digitrax Real FX³

• Turn functions on and off. 
• Head lights and tail lights are automatically reversing unless you make them independent. 
• All function outputs have FX generators for prototypical lighting effects and have qualifiers for FX effects and qualifiers for standard on/off functions.
• All Digitrax Series 3 decoders have FX³ type functions.
• FX³ decoders offer full function mapping so you can choose which function (F0-F12) controls each function lead.
• FX³ decoders offer master light switch capability.
• FX³ decoders offer qualifiers for FX function operation qualified by one of the following:  the loco's direction of travel, whether F0 is on or off, loco direction and F0, or whether the loco is moving or not. These qualifiers are also available on function outputs that are used as standard on/off functions.

Motor Isolation Note:  FX³ decoders have motor isolation protection. 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 functions but the motor will not work.

Here is an explantion of how the CVs that control FX³ effects work.  Most modern Digitrax systems do not use hexadecimal format but it is provided here in case you need it for older systems.

CV 49-52, CV113-116, CV62 & 63: Digitrax Real FX³ Special Light Effects

Decoders with FX³ features have 8 user configurable, independent special effects generators.  These are set up by programming CV values as described below.  If your decoder is not a “series 3” decoder, please check the spec sheet to determine which type of functions it supports.

FX³ functions incorporate FX generators with additional dynamic and static qualifiers.  FX³ functions are fully remappable so they can be controlled by any function key on your system.  A master light switch can be set up to turn off all lights on a locomotive. Functions associated with advanced consists can be controlled, too.

Setting Up FX³ Effects On Function Outputs 

1. Each function output has an FX³ control CV associated with it. Using TABLE IVa below, determine which CV you need to program to set up an FX³ feature for the function output you are working with. For example, if you want to set up an FX feature on your forward headlight, you will use CV49 to control the FX³ feature for the lamp attached to F0F. Some decoders do not have function output wires attached. See the specific decoder instructions to determine which "pad" on the decoder controls each function. Use thin wire or wire saved during previous decoder installations to solder function output wires to the pads associated with the function you want to use.

 TABLE IVa:  FX³ Generator CVs  

 NOTE:  Decoders with FX function generators use different CVs to control function outputs.  Click here to go to FX page.  CV53 & CV54 are not used for FX³ control.     

2. Each FX³ effect has a CV value that generates the effect you want and controls how the effect works with respect to locomotive direction and the head light (F0) function.

The FX³ CV value is made up of 2 digits. The second digit determines which FX³ effect will be generated. The first digit determines how the effect will work with respect to the locomotive direction, the head light and other functions. Use TABLE IVb to determine the second digit and Table IVc to determine the first digit of the FX³ CV value to program into the CV selected in step 1.

  TABLE IVb:  The Second digit of the FX/FX³ CV value determines which FX³ effect will be generated.

TABLE IVc  The first hex digit of the FX³ CV value determines how the effect generated will behave. For example, two strobe lights can be set up to flash alternately by setting one to phase A and the other to phase B. The strobes can also be set up to be on when the loco is moving forward and off when moving backward.

TABLE IVc:  How FX³ effects generated will work 

3. Program the FX³ CV value from step 2 to the FX³ CV identified in step 1. If you are using the PR1, an FX set up section is available where you can just "point and click" to set up the effects you want to use. The software lets you select which function output and which FX feature you want from a menu so you don' have to use the tables above to determine which CV or CV value to use. 

4.  For FX³ decoders, you can set up as many as 8 function outputs. All FX³ outputs can be set up with FX³ effects. 

5.   If you want any function output to remain a simple on/off output, leave it programmed to the factory default of CV value 00.      

Customizing FX³ Effects-Rate and Keep Alive: CV62 

CV62 lets you control the rate and keep-alive brightness for each FX³ effect you set up. The CV value for CV62 is made up of 2 digits, the first digit and the second digit.

The first digit controls the keep alive/baseline off voltage for incandescent lamps. This value should be between 0 and F. A value of 0 gives no keep alive and a value of F gives maximum keep alive. Values between the high and low allow you to vary whether the lamp actually goes off between light pulses or whether it stays on very dimly or more brightly. (If you are using LEDs, the first digit for CV62 should be 0.)

The second digit controls the rate of the FX³ effects programmed. This value should be between 0 and F. A value of 0 gives a fast rate and a value of F gives a slow rate of operation. We recommend you start with a 4 and adjust it up or down until you get the effect you are looking for.

Ditch Light Hold Over Time CV63

If you are using the ditch light effect in conjunction with F2, CV63 lets you set up a hold over time to control how long the ditch lights continue to blink after F2 turned off by releasing the key on the throttle. Remember that F2 is a momentary key on most Digitrax throttles that will keep function 2 on as long as you hold the key down and then turn function 2 off when you release the key. This allows the ditch lights to be on steady during regular operation and to begin alternate flashing when F2 (usually the horn) is activated and to continue flashing alternately for a predetermined length of time after F2 is released; just like the prototype. A value of 00 yields no hold over time, a value of 40 yields a realistic time of about 5 seconds. A value of 255/xFF yields about 20 seconds hold over time.

FX³ Examples

Any function output on the decoder can be set up for any FX³ effect by programming its associated FX³ CV to the appropriate FX³ CV value. For example, if CV52, the FX³ CV for F2, is programmed with an FX³ CV value of 002/x02, the violet F2 function output will be a Mars light when F2 is turned on for this decoder address and the decoder's direction is forward.

TABLE IVd:  FX³ CV EXAMPLES

CVs that affect all FX³ function outputs 

 CVs that affect specific FX³ outputs:

To set up two alternating double pulse strobes on the green and violet function outputs controlled by turning on both F1and F2, program CV51 to a CV value of 037/x25 and program CV52 to a CV value of 053/x35. This is an example of using the alternate effects phases A & B.

For FX³ decoders you have 8 FX³ generators available to use with your function outputs.

Setting Up Static (Non-FX³) Functions with FX³

When an FX³ decoder output is set up for static on/off operation (no FX³ effect), you can use static qualifiers to customize the operation of the on/off function of that output.

In this case, the second digit of the FX³ control CV will always be 0 to set the decoder for static (no FX³)function operation. The first digit is determined by the following table according to how you want it to work.

Troubleshooting FX³ effects

Common problems with FX³ set up are:

Trying to program a decoder for FX³ when the decoder does not support FX³. Be sure the decoder you are programming has FX³ features. Digitrax introduced FX³ in 2002 in the “series 3” decoders. Digitrax introduced FX in the summer of 1995 in all of its premium decoders so if your decoder was made before then it does not have FX capability. FX & FX³ decoders use different CVs for controlling the function outputs of the decoder.

FX³ effects don't work as expected. Review the qualifiers you set up for the effect. For example, if the effect is set up to come on only when F1 and F0 are active and the loco is headed in the forward direction, be sure you have met those conditions.

Setting Up A Master Light Switch with FX³ Decoders

For FX³ decoders F0 can be used as a master light switch to turn off all lights in the locomotive when F0 if OFF.  To do this set up all functions qualified to be on when F0 is on and off when F0 is off.  See Table IVc above and use 4, 5 ,6, 7 ,E, or F as the first digit of the FX/FX³ control CV to enable the master light switch on F0.

Digitrax Decoder Series Numbers

Over the years as technology advanced, Digitrax has added more and more features to our mobile decoders.  Also, over time, the industry standards and uses of come CVs have changed.  Each of our decoder web pages includes a link to a specification sheet for that particular decoder so that you will know which CVs are used for which features in that particular model.

Digitrax uses series numbers to let customers know which feature set is part of a particular decoder.

The fifth character of each mobile + function decoder part number is the Digitrax series designator.  For sound + motor + function decoders we typically use the sixth character as the series designator.  There are variations in a few part numbers.

 Series 6

Compatible with Digitrax PX series Power Xtenders to keep locos and sound running in the presence of dirty/poor track work.
FX³ outputs optimized for both LED and bulb applications.
FX³ outputs have configurable pulse available on all outputs.

SoundFX Series 6 Features

Sound decoders available with either 8 bit standard or 16 bit premium sound.
Sound decoders configured for 8 Ohm speakers.
Allows for longer sound fragments.
Available in either standard 3 or premium 4 voice versions.
Auto CV configuration by sound projects
Scaleable Speed Stabilization (BEMF) optimized for sound operation.

Series 5

Sound Bug Compatible:  Series 5 Digitrax Decoders add the ability to add sound to regular mobile decoders with Sound Bug.  Some Series 5 decoders have sockets for simply plugging in the Sound Bug while others require soldering to wire the Sound Bug to the decoder.

Series 4

First generation SoundFX decoders

Most are mobile, sound and function decoders, some are sound and function only decoders.

Series 3

Series 3 decoders with 6 functions have FX³ function outputs

Torque compensation

SuperSonic motor drive for quiet operation (silent operation)

Support for all DCC programming methods as of the time of release

Operations mode read back capability for CV read back on the main line

Scaleable Speed Stabilization (Adjustable Back EMF)

One Step decoder Factory CV reset (CV08=8 or CV8=9 to preserve loadable speed tables)

Motor Isolation Protection

Transponding

White or Golden Yellow LEDs on decoders that come equipped with LEDs

Series 3 decoders with less than 6 functions have a modified set of features

Series 3 Economy

Digitrax Decoders have all Series 3 features EXCEPT Scaleable Speed Stabilization (BEMF)

Series 2

FX function outputs

Scaleable Speed Stabilization (Back EMF)

Transponding

Series 1

Digitrax decoders have standard or configurable strobe function outputs.