Although I enjoy altering CV values to obtain my own preferences in performance and sound with DCC and Sound equipped locos, nevertheless the owners handbooks provided with these locos, and all too often the information on the manufacturers’ web sites, gives only basic detail. There are then dire warnings from some manufacturers concerning certain CVs.
To take one example at random, the instructions for the Trix Mikado give details and the variation of CV values available for CVs 1 to 6, 17 and 18, and 61 to 63. It also gives information on CVs 29 and 49 which I’ll come back to in a moment. However, it also contains a dire warning that the following CVs must not be changed under any circumstances 7, 9, 11, 13, 14, 23, 24, 33 to 48, 56 to 58, 60, 66, 95, 113, 114, 115 and 121. For CV 29, it contains the following: “Caution! Very complex! Total value must be calculated. Total value = value of bit 0 + value of bit 1 + value of bit 2 + value of bit 4 + value of bit 5”. There is a similar note regarding CV 49. Now while I think I understand what is required, there must be an idiot’s guide somewhere that lifts the veil of mystery from all this. I am aware of the basic stuff on the NMRA site but this really does not give the answers.
Mindful of the fact that we have many DCC experts reading these posts, I wonder if anyone could suggest a good book or other source explaining the function of all CVs regularly appearing in decoders - and the effect when different values are programmed into them. A few, of course, are self explanatory and I’ve also had some very pleasant surprises in discovering different sounds and effects not even mentioned in the handbooks when playing around with different values. I must confess, however, to being in the dark about the majority and I anticipate that I’m not alone. Even though I keep a careful note of changes I make, all too often I find myself restoring the default settings and starting again, having created a conflict or some
I, too, am perplexed and dismayed with the instructions for the Loksound ESU decoder in my Trix Mikado. Also, I don’t believe all manufacturers necessarily walk in step with respect to which CV’s do what in a given decoder. For example, hard reset in a Loksound is in CV8, but in QSI it is in three CV’s.
Keep in mind though, that “the effect when different values are programmed into them” may vary from decoder to decoder and from manufacturer to manufacturer due to differences in the way they’re implemented.
Also, as you go through the list at the provided link and look at the “Additional Comments”, you’ll see that quite a few CV’s are “Reserved for manufacturer use”. In other words, each manufacturer can use those CV’s however they want.
For those two reasons, the manufacturer’s data sheets are probably still the best source for CV info.
I went with JMRI Decoder Pro (it is FREE) and let it do the translations for me. All I do is slide bar and it wites the value for sounds, volume, speed etc.
Im sure the NMRA standards are for some CVs like addresses and motor control so any decoder can run on any system. But lighting and especialy sound controling CVs are under no set standard. Those are determined by the decoder manufacture. Loksound and Soundtrax have there own way of doing things. I wish there was some magical book or chart of suporting CVs with values but there is not. The best way to configure CVs is to try them and make notes of the changes. It would be horrable to have to do a hard reset because of one sound change just when you have the lites do what you want them to. Most DCC manufactures have Yahoo forum sites to go to. They are a great help. Remember that its a hobby and not a job.
Mostly replying to bump this post so the people who enjoy this sort of question will see and reply to it. Edit: Well I see in the hour it took me to compose this several others did see and reply.
I agree some manufactures do not give enough basic information (MRC/Athearn come to mind) , but I think one cannot expect the manufacturers’ to publish elementary binary math classes. There is a base set of knowledge 1111b = Fx = 16d that one can be expected to understand if they are going to start poking at the bits on a digital circuit.
There is the first problem I think most poeple have with DCC. They make it to be harder than it is. There is no mystery. This is all basic binary (eg. digital) stuff. All the CVs do is hold switch settings (on or off) or numbers (0-255) that tell the decoder how to function. The “hard part” comes when there are eight “switches” grouped into a single CV (eg. CV29) and they have to be masked in order to be accessed individually or a number larger than 256 is needed. Since people don’t like talking in binary -11010001 01000111 11010110 - so the sequences get translated to hex or decimal. Base translation has been taught in elementary level math classes in the US long before anyone ever thought computers would be in people’s homes let alone their model trains.
But failing that, there are computer programs that hook up to the programming track do this translation. One can program without knowing or caring about CVs. The program says, “Select 2 or 4 digit address”, "enter c
While SoundTraxx, especially for the Tsunami, and QSI have very comprehensive manuals online, adding DecoderPro has many advantages:
It presents a GUI interface: sliders, text, etc., relating to what the CVs actually do.
While different decoders have different “stuff” (like the simplest motor & lights decoders vs. the Tsunami’s 200+ CVs), what you see on the screen is very consistent.
Things like the 2- and 3-part QSI CVs are vastly simplified: just click on what you want, DecoderPro figures out how to make it happen.
As you program decoders, you can easily build a complete roster of all your equipment, including all the settings for each. (For locos already programmed, you can just read their current settings and save the results.) This is especially handy if you have to do a decoder reset, or manage to mess one up – it’s then easy to have DecoderPro re-set everything.
It works with most any command station that can be connected to a computer (Windoze, Mac, or Linux).
In fact, even if your system cannot hook up to a computer, you can use DecoderPro to set CV values - indirectly. After you make all the changes using the easy check boxes and drop downs, there is a final page that will show on screen all the CV values that will get written if you actually could press the WRITE button. It also conveniently changes the color of any CV that needs to be changed, so you can see at a glance what would be changed.
CV29 is a special animal, and it’s one of the NMRA specified ones, so you can’t blame the manufacturers. The purpose is to switch on and off various options, so each bit in the value represents a different switch. Converting binary to decimal is a real pain - even I have to think about it for a while. But binary goes to hexidecimal very easily - just put them in groups of 4. This applies to any CV that uses different bits to mean things - many of the lighting effect CVs are like this: bit 0 = normal light, bit 1 = Mars light, bit 3 = rotary beacon, etc. (not actualy values that I know of, just an example). Remember that Bit 7 if the left-most bit and bit 0 is the right-most. So if by reading the documentation you find that to get what you want it says to set CV999 bits 2, 5, and 6, you write it out as 0110 0100. That’s bits 2, 5, and 6 set to 1. Every 4 bits is a hex number. There is NO grouping of binary bits that equals one decimal digit. This is why I say hex is MUCH easier. So convert each group to a hex number: 0110 = 6 hex and 0100 = 4 hex. How did I get that? Remember place value from elementary school? In the decimal system we have 1s, 10s, hundreds, thousands, etc. In binary, it’s 1s, 2s, 4s, 8s. So for 0110: 0 8s, 1 4s, 1 2s, and 0 1s (ok that’s hard to read maybe). Add them up - 0 + 4 + 2 + 0 = 6. You can see that it would be possibl to make a number where the sum adds up to 10 or more. That’s why in Hex there are the letters A through F = 10 through 15. Example #2: Binary 1011 = 1 8s, 0 4s, 1 2s, and 1 1s = 8 + 0 +