# Digitrax CV5 - Vmax Help



## xrunner (Jul 29, 2011)

Well, I just installed a brand new Digitrax DN163K1C in my Kato Sd70 and it works great!. But, I am trying to use Cv5 Vmax and it has no effect, neither does CV6. Cv2 works OK. 

I have set CV5 to very low values such as 20 and it doesn't move the top speed down. I have read the manual and several web sites and it should just work by entering values, no other CVs seem to have to be set. So, what's wrong?


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## oldSmokey (Jul 31, 2011)

*Digitrax CV5*

Hi xrunner,

This may help you a bit, there are many movies on Youtube about setting CV's
I just came across this one and while it is on speed matching he does show you
Cv2, 3, 4, 5, 6 so it may help.

http://www.youtube.com/watch?v=mAux4KGPhlA


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## xrunner (Jul 29, 2011)

oldSmokey said:


> This may help you a bit, there are many movies on Youtube about setting CV's
> I just came across this one and while it is on speed matching he does show you
> Cv2, 3, 4, 5, 6 so it may help.


Thanks and I watched it but it doesn't change a thing on this end. CV 5 has no effect at all here. It doesn't affect the Max speed of the loco. I have a brand new Digitrax decoder which specifically states these things should occur - but they do not. I can change the address and CV2 and CV 29 etc., but CV5 isn't slowing down the Loco at all. Is it really that difficult ... or is there something left unsaid by Digitrax in the documentation? I suspect the latter.


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## gc53dfgc (Apr 13, 2010)

try setting it to one and see if that makes any difference at all, then set it to like 50-100 and see if that makes a difference. That is the only advice I can give on it, none of my engines have needed CV 5 changed so far.


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## xrunner (Jul 29, 2011)

gc53dfgc said:


> try setting it to one and see if that makes any difference at all, then set it to like 50-100 and see if that makes a difference. That is the only advice I can give on it, none of my engines have needed CV 5 changed so far.


OK I'll try it tomorrow, but I've set it as low as 20 (255 is Max) and it doesn't reduce the Max speed of the Loco. Right now the Loco will run like a slot car if the speed on the controller is set to 99, and that is too fast. I want to make the Max speed waaaaaay slower than that, and that's what CV5 is supposed to do. The decoder accepts a change to CV5 and I can read out the new value I set, but it has Zero effect on the Max speed of the Loco. This is contrary to Digitrax documentation. I'm lost on why this is.


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## oldSmokey (Jul 31, 2011)

Hi xrunner,

What I would do is a reset on the decoder just in case any other cv's have changed like speed steps etc.
Then go to this digitrax page:
http://kb.digitrax.com/index.php?a=87

Go down to CV05 V-Max (Maximum Voltage) and read that section.


If V-Max is accidentally set below V-mid, the decoder will use the 
V-mid setting as V-max.

Note: Some Digitrax decoders are not able to set V-max in 128 
speed step mode. If you encounter this problem, status edit the 
decoder to run in 28 speed step mode and you will be able to set 
up v-max.


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## xrunner (Jul 29, 2011)

oldSmokey,

Ya, I've been there done that. I've read up on this and experimented for several hours this afternoon, before posting this question. I don't want to waste people's time so I make sure I've done all I could before posting questions.

CV5 doesn't affect my Loco's top speed as it should. There is nothing else wrong with the decoder as as far as I can tell. I've reset it and tried everything I can thing of. Somebody here must know more about it than I do, because I am a newbie still, but learning very fast.


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## cabledawg (Nov 30, 2010)

What is CV29 set to on your decoder?


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## BMK (Sep 13, 2011)

The Digitrax DN163K1C literature states the decoder has “Torque Compensation.

http://www.digitrax.com/ftp/dn163k1c.pdf

The CV02, CV06, CV05 - Three Step Speed Table states:
“NOT recommended for locos using torque compensation or scaleable speed stabilization. Turn off these features if you want to use the 3 step speed table.”

http://kb.digitrax.com/index.php?a=87

Not sure how to turn off these features. Good luck……
If you fined out please post.


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## xrunner (Jul 29, 2011)

BMK said:


> The Digitrax DN163K1C literature states the decoder has “Torque Compensation.
> 
> http://www.digitrax.com/ftp/dn163k1c.pdf
> 
> ...


Aha - OK I'll try it tomorrow after I get home from my part time job. I'm in bed now with my laptop searching for answers. I'll report back tomorrow. Thanks.


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## NIMT (Jan 6, 2011)

Set CV 29 to 6 if you want to use CV2, CV5, & CV6
Set CV 29 to 22 if you want to use CV67 -CV94 for the speed table!
I can give you all the #'s for each CV if you want a set a good speed curve, That's how all of mine are set up! It works better that Vstart, Vmid and Vmax!


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## xrunner (Jul 29, 2011)

NIMT said:


> Set CV 29 to 6 if you want to use CV2, CV5, & CV6


My CV29 is 38 because I'm also using 4 digit addressing. Nevertheless, I can't limit the top speed with CV5 at any setting. Why?



> Set CV 29 to 22 if you want to use CV67 -CV94 for the speed table!
> I can give you all the #'s for each CV if you want a set a good speed curve, That's how all of mine are set up! It works better that Vstart, Vmid and Vmax!


Thanks and I appreciate that, but first I want to understand what is going on here. Why doesn't CV5 / VMax limit the speed like the manual says it should? I'm going to try what BMK suggested later; can you explain why CV5 isn't working here?


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## BMK (Sep 13, 2011)

Ok
I did a little more research and experimentation and found out CV 54 “Torque Compensation” needs to be turned OFF (CV54 = 16).

http://kb.digitrax.com/index.php?a=90

To get my Digitrax DN163K0a decoder to work I set:
CV02 = 50
CV06 = 100
CV05 = 150
CV54 = 16

I also made sure:
CV03 = 0
CV04 = 0 

With this programming I did not have any runaway engine operation.


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## Massey (Apr 16, 2011)

2 reasons why CV5 may not be working. First is your decoder may be using speed tables instead of the Vstart Vmid Vmax, in which case the decoder ignores anything put into those settings. 
Second some torque compensating decoders also ignore the Vstart, Mid, Max settings as well, since they use a variable speed table that changes as the demands on the engine change. 

Massey


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## BMK (Sep 13, 2011)

Try to reset the decoder to the factor default state and then rebuild the CV's as needed.


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## xrunner (Jul 29, 2011)

BMK said:


> The Digitrax DN163K1C literature states the decoder has “Torque Compensation.
> 
> http://www.digitrax.com/ftp/dn163k1c.pdf
> 
> ...


OK that was it. I also found this -



> When CV57=0, CV2, 5 and 6 respond as in the manual.
> 
> When CV57>0, the rules change. When CV6=0, CV5 does nada. When CV6=0.5CV5,
> then CV5 starts to work. I ended up having to set CV6 to about 80% of CV5 to
> ...


If I set CV57 to Zero CV5 works. Seems like this should be specifically mentioned in the section which talks about the 3 step table you can make with CV2,5, and 6. It isn't clearly documented at all in the 2 manuals I got with the system, nor the documentation I got with the decoder. Painful.


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## NIMT (Jan 6, 2011)

xrunner, Welcome to DCC!
Now get a PR3 and you SEE what the decoder is doing!
I don't even know the CV's anymore because when you use a PR3 and JMRI it gets more in depth than simple CV setting.
And excellent research BMK!:thumbsup:


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## xrunner (Jul 29, 2011)

NIMT said:


> xrunner, Welcome to DCC!
> Now get a PR3 and you SEE what the decoder is doing!
> I don't even know the CV's anymore because when you use a PR3 and JMRI it gets more in depth than simple CV setting.


Funny you should mention a PR3. I just ordered one from Tony's Trains. 

The little handheld controller is OK as far as it goes, but really, a system like this just cries out for much more information on display to the user, and in a much more user friendly way. For example, instead of labeling a variable as "CV2" how about labeling it "Start Voltage"? I know, a crazy idea but that's just me.


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## Massey (Apr 16, 2011)

Try checking out what DCC was like 15 years ago... Not fun if you did not understand binary or hex. Today you can use decimal which makes life easy. Not all decoders use the same function for each CV that is why they are not labled. the NMRA standards do not cover what CVs control what other than the address, after that each manufacturer can do as they wish. The CV list that the NMRA has is a recomended practice, which means this is a good idea but not required.

Massey


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## NIMT (Jan 6, 2011)

Massey,
Thanks for bringing back the scary days!!!:knock_teeth_out::dunno::sly::retard: 
xrunner,
This is what you'll see!


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## cabledawg (Nov 30, 2010)

Hey Sean, how do you add a pic of the loco to the roster tab? It has the provision for a pic, but I cant seem to add one


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## xrunner (Jul 29, 2011)

Massey said:


> Try checking out what DCC was like 15 years ago... Not fun if you did not understand binary or hex. Today you can use decimal which makes life easy.


That reminds me of ham radio (I have a General class license) years ago when you had to learn morse code to get any license. People would say, why do I have to learn morse code? I just want to have fun talking to people with SSB! 

"Well, 'cause ya just gotta son, that's why!"

They finally eliminated that requirement.



NIMT said:


> Massey,
> Thanks for bringing back the scary days!!!:knock_teeth_out::dunno::sly::retard:
> xrunner,
> This is what you'll see!


Oh, I can't take something like that - it's way to easy to use. Make it harder! :retard:


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## NIMT (Jan 6, 2011)

Cabledawg,
Just open the JMRI roster and edit the one you want go to roster media, open the file and drag the picture file to the blue frame and walla done!


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## cabledawg (Nov 30, 2010)

Pfft, that was easy..................



Thanks Sean :thumbsup:


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## NIMT (Jan 6, 2011)

Yea but is a odd way of doing it, Cut/Copy and Paste would be a better way of doing it! Oh and if you right click on the square you can remove a picture!


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## cabledawg (Nov 30, 2010)

You're the man with the answers today!


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## xrunner (Jul 29, 2011)

xrunner said:


> Funny you should mention a PR3. I just ordered one from Tony's Trains.


Digitrax PR3 backordered from Digitrax. 

I was also concerned this morning whether or not it would install on Win 7 / 64 bit, because the instructions say only up to Vista, but I found enough references from people to know it will work. However I'm concerned that Digitrax hasn't updated it's requirements to let people know this. It only says it will install on 2000, XP, and Vista. Win 7 has been out for what now - 2 years?


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## Massey (Apr 16, 2011)

If you cant get a PR3 and still want computer interface then check out the Locobuffer from this site.

http://www.rr-cirkits.com/

It will not let you upload sounds to a programable sound decoder but it will interface a Digitrax system with your computer using JMRI. I have one of these and it works great.

OH and it works with all windows OS's from XP and up.

Massey


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