RMweb Gold Dagworth Posted October 8, 2009 RMweb Gold Share Posted October 8, 2009 This was originally posted on DEMU's forum, I'll post it here as it may be helpful to others. It is a hopefully simple explanation of how CV29 works and what effect different values will have on a decoder. CV 29 controls a bunch of switches that affect various aspects of the decoder setup. Each of these switches has a value. Switch one has a value of 1 and controls which way the loco thinks is forwards Switch two has a value of 2 and controls whether the loco works on 14 or 28/128* speed steps Switch three has a value of 4 and controls whether the decoder works on DC or not Switch four has a value of 8 and it's use varies between decoders Switch five has a value of 16 and controls whether the loco uses it's default speed curve or the user loaded speed table Switch six has a value of 32 and controls which address the loco uses, if the switch is off the loco will use the two digit address stored in CV1, if it is on then the loco will use the four digit address stored in CV17 and Cv18 Switch seven is not used. To select the value that is needed in CV29 select which options you require, then add together the values for each switch that needs to be ON, ignore any that need to be OFF. For example, if my loco needs to go backwards by default, work on 28 speed steps, work on DC, use a two digit address and the user speed table then I add together 1, 2, 4 and 16 and get a value of 23. Try different examples and you'll see that any value will give you a unique combination of which switches are on and off. I hope that helps and is not too complicated. *28/128 speed steps: The decoder will determine automatically which of these is sent out from the controller and behave accordingly, the setting for 28/128 is the same in the decoder. If the decoder is set to use 14 speed steps while the master station sends out 28 or 128 (or the other way round) then it will have a strange effect on the headlights and they will only come on at certain speeds! Andi Link to post Share on other sites More sharing options...
RMweb Gold beast66606 Posted October 8, 2009 RMweb Gold Share Posted October 8, 2009 Further to Andi's explanation - if anybody wants a Windows program to calculate CV29 for you then drop me a PM with your email address - it's free ! Link to post Share on other sites More sharing options...
Guest jim s-w Posted October 9, 2009 Share Posted October 9, 2009 Or you could just forget the math and look it up in a simple table like this one http://www.tonystrains.com/technews/cv29-lookup.htm Thats my idea of simple B) Cheers Jim Link to post Share on other sites More sharing options...
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