I’m a recent newcomer to dcc attempting to use a NCE procab on a short 4ft shunting layout so need to set my CVs to achieve slow running but am getting in a right pickle choosing suitable numbers. Could anyone suggest suitable figures for CVs 2,3,4,5,and 6
CV 2 sets the starting speed. Usually a fairly low number will work, depending on how free running your loco is. Start with 1 and increase it until the loco starts to move reliably on throttle speed step #1.
CV 5 sets the maximum speed. Try starting with 128 for a small layout which is half of full speed and adjust to suit.
CV 6 sets the mid-range speed. For a linear response set it to 1/2 of the value in CV 5. This can be varied depending on how you like your loco to respond to throttle changes.
CVs 3 and 4 control momentum, 3 for acceleration and 4 for deceleration. I would set both to 5 until you gain some experience running on your layout. This low value will smooth the transition between throttle changes without making it difficult to control the loco. Some decoders allow you to use active braking which works well with higher momentum setting if you get into that.
Mark Vinski
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My advice is to re-do the speed table so its range reflects the scale speeds you’ll actually use, not the theoretical range the locomotive drive or motor is capable of producing. That should get you around some of the usual concerns with locomotives that have an artificially high starting voltage (e.g. have older sound capability) but should not be allowed to receive higher effective voltage than reasonable (perhaps what would correspond to 30smph for a switching/shunting layout).
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Appreciated thanks
If you still experience difficulties after changing your CVs as per Mark’s recommendations, let us know what type of engines you are running and what issues you might still have.
Simon
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Many thanks, will do
As you are getting started, you might find it easier to use Decoder Pro software, which is subset of JMRI (Java Model Railroad interface). You need a piece of hardware to interface between your computer and a programming track (a CV programmer). Your computer tells the CV programmer what CVs to program, and the CV programmer sends the program information to the locomotive in the DCC language for programming CVs. The software is free, but the hardware will cost $75-100 depending on what you get. I like using a DCC-EX unit because it can do more than just program a loco and is very well supported. In my opinion, the digitrax and other programmers offered have very little manufacturer support, and their drivers are difficult to install correctly on some computers.
The cool thing about Decoder Pro is you don’t need to know much about individual CVs. Decoder pro will read the decoder in your loco, identify make and model of the decoder, and will know what CVs do what. Decoders you can buy these days are quite complex, and most will use indexed CVs for many functions, which if you are using your NCE unit, will require to program values in 2 or 3 CVs in specific sequence to set the parameter you want to program. That can be a big head-scratcher, unless you are very savvy with how it all works. Decoder Pro will know all of that for your decoder. Decoder Pro will provide a list of the things you can program, which is different list for different decoders, and identify them by what the decoder can do rather than just a CV number. With your NCE cab, you need to look up the CV in the decoder manufacturer’s documentation, and program that CV with a number you think will give the performance you want. There is usually some trial and error with that. With Decoder Pro, instead of looking up a motor, sound, or light configuration and programming the individual CVs, you select what you want to do from the Decoder Pro menu for your decoder, tell it to program that, and Decoder Pro does the complex part.
There are several CVs, like those discussed here, that are pretty much standard for all decoders, but for things like sound selection and volumes, it seems like every decoder manufacturer does it differently. Decoder Pro bypasses all of that confusion for you.
You may not be interested in more than what you asked about now, but later, you almost certainly will want to do some customization. Yes, doing it with Decoder Pro will add some complexity to get set up, but after that, decoder programming becomes MUCH easier. So right now, use your NCE Pro Cab because you want to get your loco going. But consider that this will make it easier and more fun later because there can be far less hassle and frustration.
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Sincere thanks, lots there that I’d never known or thought about. What happened to the simple just two wires that promoted the early systems
Still ‘two wires to the track’ when you go to run trains. All this discussion is about how to configure them so they run as expected responding to the signals going through those two wires…
I generally leave CV2 at zero unless an engine is very sluggish getting started compared to another engine I’m trying to speed match it with.
If you have a sound equipped diesel, the engine “rumble” motor sound should ramp up before the engine starts to move, so having enough momentum in CV3 for that to happen can add to the realism.
Decoders default setting is a straight line “speed curve”, so you don’t really need to change CV6, just leave it at zero. The decoder will automagically adjust each speed step based on CV2 and CV5.
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Appreciated thanks
Hello All,
Welcome Eastdorset!
Yes, you can run JMRI DecoderPro without connecting it to a pike or programming track to calculate CVs.
Digitrax offers a CV calculator as well.
Hope this helps.
I have a 50 foot long point to point layout and all I have is two wires going to the track, period. That’s all, end of thought. I despise wiring and soldering almost as much as I despise building benchwork. I don’t own a computer so I will not experience JMRI. My layout works just fine with two wires only and I get along perfectly well without the complications of JMRI. I’ve never liked computers since they came in and destroyed my employability years ago, and now that I’m retired, I don’t need to fool with them at all, ever again.
But I don’t find CVs that complicated after working with them a while, starting about 17 or 18 years ago now.
I have Soundtraxx tsunami2-2’s and Blunamis in most of my engines, which are all steam. I have never had to set CV2 above 0, which gives the best low speed performance and combination with other CVs. I know that some people that don’t like momentum in their engines. I’ll never understand that when CV 3 and 4 can give you the most realistic performance you could possibly imagine. I like to set CV3 at 50 and CV4 at 35, which to me provides extremely realistic acceleration and acceleration. If you’re in the Train operation and what it is realistic as possible, CV3and CV4 are indispensable.
Tsunami 2–2 and Blunami have motor control CVs that can help you really smooth your engine’s performance out. CV209 has a default value of 48 and CV210 has a default value of 16. I’ve never found those numbers to be optimum, CV 209 in my experience has to be a good bit higher than default, and 210 somewhat higher. These vary between locomotives and can be best determined by trial and error. CV 211 has a default value of 180, but I found that dropping it down to 120 gives a little better slow speed performance. CV 215 default value is 150, but I found the dropping it down below 100 or lower will slow the engine down.
You can try all these CVs and see how they affect your engines, but you should get better performance after you learn how to work them some. It will take some time, but you really should make the effort to educate yourself about these. Don’t be afraid of them. You can always reset them to default if you’re unhappy with something.
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Many thanks. Plenty to think about there
I was thinking that, even though my layout is a lot longer than yours, it is still basically a switching layout with everything running at extremely slow speeds most of the time.
I’ve never found any need to use speed tables or change the default settings of CV5 and 6. Or digging into the train brake and independent brake settings. I run at 128 steps and barely ever have to get the engines above 15 or 20 steps on the throttle. Things are just so slow, none of those advanced controls have much effect on anything I do. If I was doing a lot of mainline extended running, I might get into that.
Are you interested in discussing CV’s for sound?
That right there is a sign you should remap the table so the 128 steps control the range you use the ‘15 to 20’ to access. That would probably give you better starting and crawling behavior, and let you use momentum for switching and the like more enjoyably.
Of course, there is only so much ‘magic’ DCC PWM can produce with some model locomotive motors, but it’s surely worth the experiment.
The video I just posted shows pretty darn good slow speed control. But I’ll work on it and see. Probably on some engine I haven’t shopped yet.
Thanks again for your advice. No need to discuss sound, it’s a complication best avoided in my case.