DCC QUESTION

[cumminspwr]

Well, I am new to the DCC scene and always wanted a DCC set-up for about 5 yrs. Now I finally broke down and I have purchased a Digitrax DCC Zephyr model.It states in their owners manual that it says you should physically have your loco's facing forward to run. My question is : I would like to run my loco's back to back to each other ,is it possible to just like switch the positive and negative wire's around to accomplish what I am looking for ? Any help would be appreciated...............John

[Jacktal]

OK....my answer may generate some correcting comments from experienced modelers......then great if it does.
From what I read about DCC so far,AC current is carried by the tracks...so interchanging the wires definitely will not help since proper polarity to the motor is achieved through diodes within the decoder.
And this being said,my theory is that you should be able to run two locos back to back,the first one being set in "forward" motion and the second one in "reverse",at least this is what I believe DCC should allow you(or anybody) to do.

I may be wrong but then if so....what is DCC for after all?

[cumminspwr]

Yeh, it should be possible to run back to back , I just need to do some homework.

[SteelMonsters]

http://www.digitrax.com/ftp/zephyr%20manual.pdf

In consisting it allows you to choose a direction. (reverse or forward) Follow the instructions for MU (pg. 29) and you'll be able to run any combonation of forward/reverse.

Hope that helps
-Marc

[cacole]

There's no need to change any wires -- one of the bits in CV29 can be changed to tell a locomotive to run backwards to its normal direction (what the Digitrax manual calls "Normal Direction of Travel" on page 27 of their Mobile Decoder User Manual). With DCC, the command station puts around 14 volts continuous DC on the track and superimposes the DCC high-frequency square-wave digital command signal onto that. This is not "AC" in the true sense -- it is high-frequency DC. The decoder in the locomotive runs the motor in whatever direction CV29 tells it to run. Look through your Digitrax documentation on decoder programming where the various CV29 options are explained. Page 29 of the manual cited above has a table of values for setting CV29. For example, if you are using a 4-digit locomotive address, 28/128 speed steps, DCC only, and want the engine to run backwards to its normal direction of travel, you would program CV29 with a value of 33 decimal.

[Anonymous]

When programming enginges in a consist, I physically place them on the same track, individually run them in the same direction, no matter which way either of them are facing, then add one to the other as a consist. The pair will automatically run the same direction with the TOP engine setting direction for both, regardless of the physical "Front" programmed in the decoders.

So, before you change the DOT (Direction Of Travel) in the decoder programming, try this, and let your engines naturally have the forward facing abilities that you want when they are running solo.