# CV values and their meanings



## hokie1525 (Jan 13, 2015)

So I've found plenty of lists of the CV values (except for my Bachmann which I'm still looking for). What I really need is a layman's explanation of them. Some of them are fairly obvious, but with others I don't know what effect they will have on the operation. 

For instance:
- What are analog functions? Does that mean DC?
- How does VStart (CV2) affect operations? Does a higher value mean when I turn on the controller the motor doesn't start until I turn the dial a bit?
- What is a BEMF?
- Packet timeout?
- How do I know what sounds are available on my decoder to program in to F0-12?
- How do I program F13-28?
etc


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## Brakeman Jake (Mar 8, 2009)

1-Indeed,analog functions are the features available when a loco is run on DC.Most (if not all) newer decoders allow DC operation (if configured to do so) while older generation decoders may not.

2-VStart is the way the decoder controls the voltage sent to the motor when dialing throttle step 1.By nature,some locos will have a "rabbit start" on throttle 1 while others just won't move at all.VStart allows tuning this to your liking.

BEMF is a neat feature that controls engine speed under different situations.Itadds voltage to the motor during climbs and reduces it while going down a grade,so that the train speed remains pretty constant without changing the throttle setting.

3-Packet timeout?I'll let someone else explain this one,it's still is a bit of a mystery to me.

4-To know wich sounds are available,you'll have to check the specific decoder manufacturer's documentation.Even then,most sounds & lights features are limited as to wich function knob they can be re-mapped to.

5-Assuming both the decoder and your DCC set have the full 28 functions available,they're not more complicated to configure within some re-mapping limits however.


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## mopac (Feb 24, 2011)

Try this site for your Bachmann trains. http://www.soundtraxx.com/factory/OEM pages/bachmann/bachmann.php

cv2 I think is for voltage for the motor. I adjust that cv so that when speed setting
is on 1, the engine starts to creep, I do this on all my engines. I have had engines out 
of the box not move till speed setting is turned to 5. It should start moving on 1.

I like to adjust cv3&4.


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## hokie1525 (Jan 13, 2015)

mopac said:


> Try this site for your Bachmann trains. http://www.soundtraxx.com/factory/OEM pages/bachmann/bachmann.php
> 
> cv2 I think is for voltage for the motor. I adjust that cv so that when speed setting
> is on 1, the engine starts to creep, I do this on all my engines. I have had engines out
> ...


That's actually a big help!


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## mopac (Feb 24, 2011)

How do I program F13-28?

Its not hard, I don't remember though. What brand is your DCC system? It probably
is different for different brands. Somebody should be able to help you after you let
us know what brand DCC you are using. My stuff is boxed at the moment, that's why
I don't remember.


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## hokie1525 (Jan 13, 2015)

mopac said:


> How do I program F13-28?
> 
> Its not hard, I don't remember though. What brand is your DCC system? It probably
> is different for different brands. Somebody should be able to help you after you let
> ...


I have the digitrax Zephyr.

The instructions say how to control F0-F12, but nothing more. And even that is limited to only certain sounds for certain function buttons.


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## mopac (Feb 24, 2011)

I have digitrax also. Mine is the "super chief" but they probably work the same way.
I dug out the manual for mine. Here is what it says. For functions F13-F19, 
hold
function key down, hold the 1 key down, release both at the same time. Then press
last number of function you want. Example- you want function 15 so hold function key
and the 1 key down and release at same time. then press the 5 key. For functions
20-28 press and hold function key and the 2 key and then press last number of 
function you want. Example- you want function 23 so hold function key down, then
press and hold the 2key, release at the same time and then press the 3 key.
Hope that works for you.


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## hokie1525 (Jan 13, 2015)

mopac said:


> I have digitrax also. Mine is the "super chief" but they probably work the same way.
> I dug out the manual for mine. Here is what it says. For functions F13-F19,
> holdhold
> function key down, hold the 1 key down, release both at the same time. Then press
> ...


I don't think I explained it. I know how to activate those function calls (there's a 10+ and 20+ button), but I don't know how to program them. The manual only tells you that CVs 33-46 program F0-12, but how do I program the rest?

Hope I explained better...


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## mopac (Feb 24, 2011)

I might be wrong and maybe misunderstood you again. But I think any cv would
program the same way as any other cv. No matter what number cv it is.


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## fcwilt (Sep 27, 2013)

Every manufacture of decoders I have used has documentation online for each model of decoder.

Some of the manuals for sound decoders are quite large - you just need to work through them.


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## hokie1525 (Jan 13, 2015)

mopac said:


> I might be wrong and maybe misunderstood you again. But I think any cv would
> program the same way as any other cv. No matter what number cv it is.


What I'm trying to figure out is if there is a CV that controls what sounds or lights are controlled by F13-F28. If it's even possible to have that control. Not that I really need it at this point, I'm just curious.


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## mopac (Feb 24, 2011)

That. I have no idea.


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## fcwilt (Sep 27, 2013)

hokie1525 said:


> What I'm trying to figure out is if there is a CV that controls what sounds or lights are controlled by F13-F28. If it's even possible to have that control. Not that I really need it at this point, I'm just curious.


Each brand and model of decoder will have CVs that determine what F13-F28 do - assuming the decoder supports F13-F28.

What brand and model are you working with?


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## mopac (Feb 24, 2011)

Right, You have to have the cv chart and function chart for your decoder. I think if you program a
cv, it will program no matter which function it is associated with.


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## hokie1525 (Jan 13, 2015)

fcwilt said:


> Each brand and model of decoder will have CVs that determine what F13-F28 do - assuming the decoder supports F13-F28.
> 
> What brand and model are you working with?


That's what I was missing. I have a Paragon, and it is defined in the Broadway Limited instructions. Thanks!


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## Cycleops (Dec 6, 2014)

It is confusing. Just because you have 28 functions it doesn't mean to say they are all supported on various decoders. As fcwilt says you need to sit down and go through the makers manual. You don't say which decoders you have but Tsunamis are particularly involved with a large range of functions and options available.

Btw I wouldn't program any decoder for dual DC/DCC use as this can often cause problems.


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