I have read the post that I found in the search for the answer but I don't understand completely, I need help. I want use this example to help you understand what I am after: In DC you place a loco on the track and it goes the way that YOUR normal forward is regardless of the way the loco is facing. In DCC it is the opposite of that. What I am wanting to do is to make all the DCC locos run that same way. I need to understand step by step how to program it that way with my Zephyr. I don't quite understand all the CV's and such as yet as I am new to this side of DCC. The only thing I have done in the past is pick up my friends throttle and ran the train. If that is not possible to do then how to change the CV for the direction. I need it step by step so I can do it and understand. That way I can go into the system and change it as I need to do so. For ease of the help I have Digitrax Zephyr. Thanks for the help.
The easiest way to do this is pick up a Digitrax MS100, download JMRI and set up your CV's fast and easily that way. It's all point and click without having to worry about what CV's you have to change or how to setup your Zephyr for programming etc. It's all I ever use and honestly wouldn't want to try it any other way. But the Zephyr and decoder manual will tell you all you need...
Your DCC locos will run in the direction of travel selected by the direction control lever on your Zephyr regardless of rail polarity. If you have any locos that run contrary to the direction selected, or if you have any locos that you want to run in the direction opposite of what is selected (say, when you want to run one F7 unit forward and the other in reverse for back-to-back running), CV29 can be programmed to determine direction of travel. With most decoders an even number is programmed for normal forward running and an odd number for reverse running. Read CV29 on the programming track for any loco that you want to change. If the reading is an even number, program CV29 to the next highest odd number. If the reading is an odd number, program CV29 to the next lowest even number. Writing down the reading and the new value that you program for each loco is helpful. Let us know how you fare doing this. Ben
Ok thanks, I understand this now all I have to do is try it. I will be sure to take notes as I go. Still crawling at this stage of learning the system.
You can change the CV as noted in the above post but it you are telling the loco to move forward and it moves backwards the motor is in upside-down or your leads on your hardwired loco going to the motor are reversed. You can change the CV but your lights may not work correctly and you will have to reprogram the CV's for that also.
ok what is the procedure for the CV re-adjustment for the lights? Would it be the same as for the direction CV?
Are you having issues that when the engine is running long hood the short hood light is on and then when running short hood the long hood like is on?
For some decoders you can control the headlight/rearlight with CV's 33 & 34. For headlight CV33 Normal 1, Off 0. For rearlight CV34 Normal 2, Off 0. This is not true of all decoders including the Lenz decoders in Atlas DCC locos. It would be helpful if you would post what decoders you are using. Ben
I use decoders from Digitrax and will be getting a few from Soundtraxx later on in the months to come.
For the Digitrax decoders CV's 33 & 34 are used as stated above. I'm not familiar with the Soundtraxx decoders. Soundtraxx does publish some if not all its manuals online. Ben
A re-cap and some answers... For DC operation, you are facing “forward” if the positive rail is on your right. If you are standing behind a loco with the positive rail on the right, it will move away from you. Pick the loco up and turn it around, and it will STILL move away from you, even though it’ is going “backward” in relation to the cab end. Reverse the polarity on the rails such that positive is on the left rail, and the loco will move toward you in both cases. With DCC, “forward” is always toward the front of the loco. Pick up a DCC loco moving away from you, turn it and set it back down, and it will now be moving toward you. Flip the “polarity” of the rails (actually, phase, as DCC is a form of AC), and the loco will continue as before. Polarity/phase makes no difference with DCC. To change loco direction, a DCC command to change from “forward” to “reverse” is addressed to a loco, is received by the decoder and acted upon to change the DC polarity fed from the decoder to the motor, thus changing direction of travel. Now as to CVs…. CV 29 is a basic configuration variable for all DCC decoders. It is actually a memory location in the decoder that is comprised of 8 bits, each one of which, alone or in combination, controls a certain aspect of the locomotive’s operation. Bit 0 (the least significant bit) of CV29 sets the normal direction of travel (NDoT) for the loco. All this does is to determine the polarity of the voltage sent from the decoder to the motor (orange and gray leads) when the decoder is told to move the loco “forward”. Normally this is used for locos that are typically run with the cab to the rear, such as the trailing A unit on an ABA diesel consist, so that when a consist is commanded to move “forward” the lead unit moves cab first, and the trailing unit moves cab last. Although not its primary purpose, the NDoT setting can bail you out of some of those “I couldda sworn I did it right” mistakes we all make. Typical would be where the orange and grey leads to the motor somehow got wired backwards. A “forward” commanded loco moving backwards would result. Changing the NDoT setting of CV29 by reprogramming it from even to odd (i.e., from x06/006 to x07/007 for example) is thus a quick fix. Now for the lights… There are two basic light functions F0F (the forward headlight) and F0R (the reverse headlight). These are activated first by turning on F0 (duh), and next, by the direction of travel as commanded to the loco. If for some reason the motor were wired backwards as described above, then the forward direction (with the front headlight on) would have the loco moving backwards. You can change NDoT as above, but that would also reverse the headlight commands as well, and the lights would still be opposite from the direction of movement. The way to get things back in sync (without rewiring the motor or the lights) would be to “re-map” the F0F and F0R functions so that they would be reversed from normal. For Digitrax decoders, the various bits of CV33 determine which physical decoder output connection is controlled by F0F, and the bits of CV34 determine which output is controlled by F0R. Normally CV33 is set to x01/001 (forward light) and CV34 is set to x02/002 (rear light). By swapping these values (i.e. CV33=x02/002 and CV34=x01/001), the lights are brought into sync with the miswired motor. (In this case, I suppose you could say two wrongs do indeed make a right). All of this is covered in the Digitrax Mobile decoder Manual. It can be a bit of a tough read, but it’s all there.
