New to DCC Gremlins Continue: Loco Suddenly Running Backwards?

[tehachapifan]

in addition to my odd effects lighting issues that are occurring with two of the same decoders for the MP15DC, now one of the locos has decided to run backwards (lights come on in the direction it is moving as well). Was not doing this earlier tonight. Have not (knowingly) done anything to CV29. How can a loco suddenly decide FWD is REV and vice versa. The board is in the correct way (can only go one way).

[NSGeorge]

You brought back a memory.  I have 3 Atlas MP15DCs all of which have Digitrax DN163A3 decoders in them.  To my surprise, two of them ran opposite the directional indicator on the throttle when I installed the decoder.  I reset CV29 to 039 and all behaves as I want.  The third locomotive behaved "normally".  I've never researched beyond that.  I haven't gone back on the Atlas Web site to determine dates of manufacture to see differences in motors, etc.

[lyled1117]

Just to build on NSGeorge's advice, unless you want or need to run on DC as well as DCC program CV29 to be 34 or 35 as needed for long address or 2 or 3 for short address. These values turn OFF DC capability of the decoder. It doesn't happen often, but a decoder with the DC option ON can sometimes go into a full speed runaway. On power up, if a decoder does not see commands in a certain time it decides it must be on DC track, turns on the motor outputs and stops listening for commands. If you don't need DC capability, it's a wise idea to turn it off.

Lyle

[tehachapifan]

Thanks, guys! I've seen a lot of cautions about messing with CV29 in my various booklets, but I guess I'll need to give some adjustments a try.

[peteski]

Thanks, guys! I've seen a lot of cautions about messing with CV29 in my various booklets, but I guess I'll need to give some adjustments a try.

Warnings?  CV29 is one of the basic places where the decoder is configured.    It has to be messed around with. 

Here is a handy calculator to take the guessing (and complication) out of CV29 (there are also many other similar calculators available - just Google for cv29 calculator).
http://www.digitrax.com/support/cv/calculators/

[tehachapifan]

Thanks, Peteski! I've actually been staring at that calculator for the past couple days.....in complete bewilderment. Learning curve is still completely vertical.

[peteski]

Thanks, Peteski! I've actually been staring at that calculator for the past couple days.....in complete bewilderment. Learning curve is still completely vertical.

What is confusing you?  You just select the options you want and the calculator tells you  what value to program into CV29.  Are the options themselves confusing?  The Digitrax calculator explains what each selection does.

[tehachapifan]

Being brand new to it, everything is confusing. Keep in mind, I'm now at the age where my kids need to operate the TV remote.

[tehachapifan]

Played around with some CV29 and some other settings and the loco stopped running completely (still had [goofy] lights). Did the CV08/08 reset thing twice and still nothing. Walked away for awhile, posted a response of dejectedness (since edited), then when out for one last try and the loco ran(????). Back to running backwards, but running. I guess I need to live with it the way it is, which bites because I already went through the trouble of installing LED's and resistors inside the loco shell which I guess I can't fully utilize.

[peteski]

While DCC offers lots of added and useful functionality, it is not as easy to work with as it should be.

If I remember correctly, your DCC system can only write CV (cannot read them)?  If that is the case then you don't have a way to verify whether what you thought was written to the CV inside the decoder might not have gotten there. 

A default setting for CV29 is 6.  As the Digitrax calculator shows, that will configure CV29 for:
Advanced 28/128 speed step control - Use with decoders that will be run on most modern command stations
2 Digit Addressing - Use CV01 to set the address. On Digitrax throttles the display shows this as AD2
Analog mode on - for when you want to run your decoder on non-DCC layouts and on DCC
Default direction Forward - Use to run decoder in the normal direction of travel defined by the loco wiring
Speed Table Disabled - Use CVs 02, 05, & 06 to set up simple 3 step speed table if desired

If you successfully reset your decoder using the CV8 reset procedure then CV29 would have  been set to 6 (enabling the options mentioned above).  It would also have a short address of 03. Is that what happened?  If not  then the reset didn't work.

Try resetting it again. and see if you can control it on short address 03.  We'll take it from there. 

EDIT: I red your edited message and looks like it now runs (backwards) and you have lights control too.
If you didn't play around with CV 29 then it is set still to 6.

Go ahead and program a 7 into CV29.  That should keep all the other parameters but change the direction.

One more question:  Since you installed a decoder in this particular loco, has it even worked correctly (as far as forward/reverse direction goes)?

[tehachapifan]

I BELIEVE that it was going the correct direction at first, but then changed somewhere along the line. This was all with the shell off, so I suppose I could've not noticed initially. So, one MP15DC runs the right way, and the other one runs backwards. I have successfully reset the loco back to factory defaults and address 3 on several occasions now. I have also successfully changed the loco direction using CV29=039 (I seem to kill the loco entirely when I change CV29 to 7).

Now I'm back to my original problem, which is no effects lighting in either MP15DC when the locos are set to FWD, either via the board-mounted LED or any of the pads. However, all effects work via rear LED and pads when the locos are in REV. I would love to know if anyone can get the stock LED to produce a lighting effect on their MP15DC as I'm starting to think it's a problem with the board itself.

Also, my system does allow me to read CV's on the programming track.

[peteski]

I was trying to go back to basics, but you are way ahead of me and doing more advanced settings.

CV29=39 means
Advanced 28/128 speed step control - Use with decoders that will be run on most modern command stations
4 Digit Addressing - Use CV17 & CV18 to set address. On Digitrax throttles the display shows AD4 and the process is automated
Analog mode on - for when you want to run your decoder on non-DCC layouts and on DCC
Default direction Reverse - Use to run decoder in opposite direction of travel defined by the loco wiring
Speed Table Disabled - Use CVs 02, 05, & 06 to set up simple 3 step speed table if desired

This setting means you are using 4-digit addressing.  That confuses things as on many DCC systems loco address 1-127 can be either assigned as 2 or 4 digit address (and they can coexist).  Assuming that you are still using address 03, you can lose control of the loco if the decoder is set for a 2-digit address 03 and you select 4-digit adddress 03 on your throttle.  If your loco works on with CV29=39 but not with CV29=7 that is because you change the address scheme from 2 digit to 4 digit.  Fun, isn't it?    Like I said, CV29  seting can change many different functionality of the decoder. BUt once you understand it, things become easy.

CV29=38 has the same functionality as CV29=39 except for the travel direction.

Sounds like you got the loco running by now. So what exactly is your current problem?  Just the lights?  Do you have an additional light(s) besides forward and reverse lights wired up?  If yes, forget the effects for now. Lets start with the basic on/off functionality of those additional functions.  Remind me what brand/model decoder is in that loco.

[tehachapifan]

Thanks, Peteski. Yes, the loco is now running the correct direction but lights are now the issue. Tech Support wrote back and said, to get a MARS effect out of F1, you need to set CV51 to 34. This worked but everything I found up to then led me to believe that CV51 would need to be set to 02 for F1 MARS. They included a link to something that has a table I haven't seen before and I'm only just now learning that something I thought was a CV entry is actually a value that need to be added to something else entirely. Learning is taking place....I think!

[peteski]

Could you answer these:

What decoder is it?

Do you have an LED and a resistor hooked up to function 1 (in addition to F0F and F0R headlights)?

Have you tried to control F1 as a simple on/off function (no effects)?

Does that work (by pressing F1 on your throttle)?

[jagged ben]

Now I'm back to my original problem, which is no effects lighting in either MP15DC when the locos are set to FWD, either via the board-mounted LED or any of the pads. However, all effects work via rear LED and pads when the locos are in REV. I would love to know if anyone can get the stock LED to produce a lighting effect on their MP15DC as I'm starting to think it's a problem with the board itself.

Digitrax has some stupid limitations on lights with respect to forward and reverse direction, but in my experience the problems are always the opposite, i.e. getting them to work when the loco is in reverse.   

Questions:
Which lighting effect(s) are you trying to set up?  (e.g. gyralight, dimming, etc.)
The locomotive direction setting is now normal (i.e. factory), right?