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This review was taken from the December 2000/ January 2001 issue of Model Railroading Magazine and is reproduced with permission of Highlands Station, Inc., Aurora, CO.

ATLAS MASTER DCC AND NEW SOUNDTRAXX DECODERS
(Please refer to the article for table information)

Review by Larry Puckett

Atlas Master DCC

In my last DCC Update I introduced you to the New Atlas Master DCC system, based on the small amount of information that had been released at the NMRA convention. Now that I’ve had a couple weeks to work with one I figured I’d bring you up to date on its features and functions, and give you my impressions.

My first impression as I took the Commander from the box was how small and light it is -- you could almost use it as a walk-around throttle! And setup is made very easy with the screw-clamp connectors for attaching wires to the Commander and the spring clips used on the Generator -- I was running trains in less than five minutes. It’s a real plus that Atlas released a properly sized transformer (the Generator) at the same time as the Commander. This will make it a lot easier for beginners and new users to get started. In the past one of the challenges was to find the correct transformer and then put together a power supply before you could even get up and running or else limp along on an under-rated power pack. To sweeten the pot, Atlas offers both the Commander and Generator as a package deal at a discounted price.

You can tell right away that the unit is a Lenz product: after all, it says “Made in Germany” right on it, and the green connectors on the rear are identical to other Lenz systems right down to the alpha designations for each. The connectors include (Photo 1) power input, track output, programming track output, booster signal output, and the 6-pin telco jack for the XpressNET bus. The XpressNET bus is used for connection up to five command stations and/or handheld controllers. As a test of how easily the XpressNET connection worked I plugged in the handheld throttle from my Lenz Set02 and selected a loco address in no time (Photo 2).  Atlas hopes to have its own handheld throttle available in the near future.

The layout of the buttons and display seem well thought out. The buttons to select addresses are right under the red LED display, and the direction buttons are just to the left of the speed control knob. Buttons to control functions F0-F2 are above the pot and a panic button is to its upper right. There are only a small number of situations where buttons are used for multiple purposes. For example, to enter the menu system you have to push the forward and the reverse direction buttons at the same time. This type of basic simplicity contributes to the Commander’s ease of use.

Overall I consider this the best all-around system for a beginner or even a more advanced modeler who only needs to operate a few locomotives on a small to modest sized layout. This is particularly true for those who do not intend to expand their needs in the future. Even this maybe a moot point if Atlas does eventually introduce more components and an advanced system that beginners can move up to. And if you want to move up to a more advanced Lenz system, the Commander can be used in slave mode as a stationary throttle with a Lenz Set01 or Set02. In spite of a couple oversights, the instruction manual that comes with the Commander is very clear and straightforward with step-by-step examples. Add to that the simplicity of setup, program-ming and operation and Atlas has a real winner on their hands. Let’s take a closer look at the system and go over a few details as there were a few things not explained in the manual that I thought would be useful to a new user.

As I mentioned above, up to three functions (F0, F1, F2) can be controlled. This should be more than adequate for turning headlights on and off but don’t expect to be able to access some extended functions on advanced decoders – including headlight dimming on the Atlas Dual-mode decoder. Typically F0 turns headlights on and off and a combination of F0, F1 and F4 are used for controlling individual headlights and dimming. As I’ll explain in more detail below, with the Atlas decoder, dimming of directional headlights uses F1, but if the headlights are set for independent manual control, dimming is done with F4. Also since you have to be able to change the settings of CV51 in order to use anything other than the standard directional headlights, it’s a moot pint anyway. I‘m not saying that this is any kind of problem with the Commander just that there are certain limitations that you need to be aware of – some advanced decoders have up to eight functions, and you won’t be able to control most of them with the Commander.

Expansion is supported through compatibility with all XpressNET components and Atlas has expressed a desire to release a whole series of expansion components. For example, up to five additional Commanders or throttles can be used along with three additional boosters. There are outlets on the Commander for a separate programming track, and power to the main track is lost during programming. However, if you add another Commander as a slave it can be used for programming while the main track remains active. Slave Commanders can be used with or without a power supply, but must have one to be used for programming. A transformer such as the Generator capable of providing 14-16VAC or 14-18 VDC at 3 amps is required for maximum operation. If you use a larger amperage transformer make sure to use a 3-amp fuse between it and the Commander to prevent damage in case of shorts. When a short occurs, the power to the track is shut off, and the display flashes “OFF”. Unfortunately the manual doesn’t tell you what to do when this occurs in order to get power back on. After fiddling with the buttons I found that after clearing the short, pressing the “Stop” button and waiting a few seconds would get the power back on. If the transformer ever overheats it will restart as soon as it cools down.

To acquire a locomotive address all you have to do is scroll through the 100 possible addresses until you find the one you want then turn the pot. The instructions also explain that the Commander has an 8-address stack memory (after you select a ninth locomotive the first one in the stack drops out). To get to the stack just press the arrow button for the direction the loco is traveling then scroll through the stack to the desired loco address.

Programming is fairly straightforward and is accessed through the menu system by pressing both direction buttons at the same time. Contrary to some of their literature, only register-mode programming appears to be supported. I’ve listed the registers that can be programmed in Table 1 along with the range of values and corresponding configuration variables (CVs). Note that only five of the registers can be changed, with R5 (the equivalent of CV 29) being the most important. I’ll go over the various values for R5 (CV 29) in a moment. Another inaccuracy I ran across in the instructions was the statement that you can program addresses 0-255 into R1. Actually, because address 0 is reserved for operating analog locos (those without a decoder) and because only locos (those without a decoder) and because only addresses to 127 can be stored in R1 the actual range is 1-127. Addresses 128-9999 are stored in CV 17 and 18. This is all kind of superfluous though since the Commander can only operate locos addresses 0-99.

Because it supports 2-digit addresses it can control 99 different mobile or accessory decoders and one locomotive without a decoder. Consisting is not available although you can easily assign the same address to all the locos in a consist -- this is called basic or address consisting. Speed control is through a single large knob. All three speed-step modes (14, 28, 128) are supported. Also be aware that the Commander defaults to speed step 28 so if you want to use a 14 or 128 speed-step decoder make sure you go into the speed-step menu and select the correct one for the selected address. In addition to programming and speed-steep selection there are two other selections in the menu system -- one for controlling accessory decoders and the other to review the system settings. Accessory decoders with addresses up to 99 can be activated in much the same fashion as loco addresses are selected. The only system setting that can be changed is master vs. slave mode. Now let’s move on to the third component of the Atlas Master DCC system, the dual-mode decoder.

Atlas Dual-Mode Decoder

The Atlas dual-mode decoder is essentially a Lenz LE103XF decoder, even down to the “precisions glider motor control.”  The GP38 I tested ran very smooth and quite. The dual-mode plug on the decoder allows you to bypass the DCC circuit and operate without the delays that can occur when running a decoder-equipped loco on a DC layout. The plug can be easily accessed through a removable hatch on the long hood of the GP38 (Photo 3).

This is an advanced decoder that supports 4-digit addresses; 14, 28 and 128 speed-step modes; user-loadable speed tables; and Rule 17 dimmable headlights. Configuring the decoder for these functions is done using CV 29 (Register 5) and CVs 51 and 52. Since many folks new to decoder programming have problems understanding these CVs I put together a couple of tables that hopefully will make it easier -- let’s look at CV 29 first. In Table 2 I’ve provided the values of CV 29 for various combinations of loco direction, speed steps, whether or not the decoder will operate on DC power, use of user-defined speed curves and 2- vs. 4-digit addresses. For example, if you want the decoder set for normal direction, 28/128 speed steps, DC operation, factory speed curves and 4-digit address then you’d enter a value of 38 in CV 29. One useful tip is to remember that simply adding a 1 to an even value in CV 29 will reverse the direction setting of the decoder. This is useful for correcting the setting when the loco is going forward, but the throttle says it is going reverse, for example when your prototype railroad designated the long hood as the front, but the decoder is installed with the assumption that the short hood is front. However, it cannot correct a situation where the locomotive direction and headlights are out of sync, this is due to the motor being wired in reverse and can only be fixed by swapping the motor connections.

Now let’s move on to configuring the headlights using CV 51. The decoder comes with a value of “0” in CV 51, which as you can see from Table 3 results in headlights that change automatically when the direction of the locomotive changes. Entering a value of 2 gives you the same directional headlights, which will dim when you press F1. If you’d rather turn the front and rear headlights off independently just enter a value of 1 and then F0 will turn the front headlight on and F1 will turn on the rear headlight. Other values allow you to dim the headlights using F4. Finally, CV 52 controls the amount of dimming, and can be set anywhere from 0-255 with 0 being no light and 255 full brightness.

Last time I speculated that the decoder will be available separately and would fit older Atlas locos. I picked up a couple from a fellow who took them out of his new GP38s figuring I could put them in my Atlas RS3s. However you know what they say about the best laid plans of mice and men -- the dual-mode plug sticks up just far enough to prevent the shell from fitting all the way down. Atlas has told me that the aftermarket decoder will have a lower profile and will fit in the RS2. I was able to install one in an Atlas GP7 (Photo 4) but had to cut out the molded-in pins that hold the light tubes in place and shorten the light tubes. I also tried to install one in a Kato and a Stewart locomotive, but the screw mounts on these locos are a little farther apart than the slots provided in the board. Most decoders designed for installation in both Atlas and Kato/

Stewart locos have small semi-circular cutouts for these screws but not the Atlas dual-mode decoder, and components on the board prevented me from cutting my own.

This is a smooth, quite decoder with some advanced features that will be very useful for modelers who don’t need ditchlights or flashing beacons and Mars lights. There will be a lot of very reasonably priced decoders available from folks who remove them from their new Atlas locos to install the more advanced decoders that offer these features. Email me at ljpuckett@starpower.net if you want to unload a decoder or two. For more information on Atlas’s new Master DCC system check out their web page at www.atlasrr.com or ask your local dealer for a demonstration.