# How do I change CV29 bit O to 1



## nrscroller (Dec 3, 2018)

I realized now I have the decoder wired backwards so my lights don't go on right. It says I can change cv29 bit 0 to 1 to invert direction. How do you change that with programming???
I don't know how to do the bit thing.
Thanks
nrscroller


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## CTValleyRR (Jul 26, 2014)

In binary, bit 0 is the ones place. Add 1 to whatever value is currently programmed in CV 29. You'll need a system or a tester that can read back CV values to do that.


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## GNfan (Jun 3, 2016)

There are 10 kinds of people in the world - those who understand binary numbers; and those who don't.


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## wvgca (Jan 21, 2013)

just add 1 to the value already in there for cv29 ....
if you can't read CV29, then a calculator for CV29 will come in handy ...
you don't actually change 1 bit in binary, you change the full value of CV29 in ascii


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## mesenteria (Oct 29, 2015)

http://www.digitrax.com/support/cv/calculators/

Here is a CV calculator. See the section on CV29. There is a table associated with it where you look up all the behaviours you need to be active in CV29 and then find the appropriate numeral that will be your programmed number for that CV.


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## DonR (Oct 18, 2012)

It seems to me that Nscroller is asking how you
actually change the CV. 

Your DCC manual should tell you how to do this.
Tell us the DCC system that you have and a user
of that system can give you step by step how to's.

Don


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## mesenteria (Oct 29, 2015)

If you are correct, Don, I agree. He must acquire a manual, even if going to the DCC site for his model and downloading the PDF file. But, once he knows how to effect the change to CV's, the calculator will tell him which value he needs. When he gets the value, he gets the right bits and doesn't need to know what they are. He just needs to enter programming mode, and he must choose the right one to change CV29 on the main, acquire CV29 on his display, dial in the correct value, press enter, exit programming mode, and he's off to the races.


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