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DCC Function keys while running a consist

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  • Member since
    August 2007
  • From: New Bedford, MA
  • 253 posts
Posted by Jake1210 on Thursday, October 11, 2007 2:30 PM
 Don Z wrote:

 dadret wrote:
Thanks for the information.  I understand the arithmetic but where did the table for the numeric values of the different bits come from?  I just spent a lot of time with the QSI manual and I can't find anything that resembles this.  Pages 44 and 45 of the manual show recommended values for CV21 and C22 but there are just binary numbers.  Is there another reference source I should be looking at?

The 8 bits have a predetermined value....they are:

 bit7   bit6  bit5  bit4  bit3  bit2  bit1  bit0
  F8     F7   F6    F5    F4   F3    F2    F1
 128 + 64 + 32 + 16 +  8 +  4 +  2 +  1 = 255

When you are adjusting the CV, you are simply 'turning on or off' the specific bit within the CV that you want to alter. That is represented by the example on page 44 of the manual. You add the numeric value for each bit that is turned on and that numeric value is what you enter into the CV value.

Does this help?

Don Z.

 

So if I'm getting what you are saying, each bit has a value double of the on preceding it, and half of the one after it? In other words, progressive doubling?

  • Member since
    April 2003
  • 305,205 posts
Posted by Anonymous on Thursday, October 11, 2007 3:22 PM
 Jake1210 wrote:
 Don Z wrote:

 dadret wrote:
Thanks for the information.  I understand the arithmetic but where did the table for the numeric values of the different bits come from?  I just spent a lot of time with the QSI manual and I can't find anything that resembles this.  Pages 44 and 45 of the manual show recommended values for CV21 and C22 but there are just binary numbers.  Is there another reference source I should be looking at?

The 8 bits have a predetermined value....they are:

 bit7   bit6  bit5  bit4  bit3  bit2  bit1  bit0
  F8     F7   F6    F5    F4   F3    F2    F1
 128 + 64 + 32 + 16 +  8 +  4 +  2 +  1 = 255

When you are adjusting the CV, you are simply 'turning on or off' the specific bit within the CV that you want to alter. That is represented by the example on page 44 of the manual. You add the numeric value for each bit that is turned on and that numeric value is what you enter into the CV value.

Does this help?

Don Z.

 

So if I'm getting what you are saying, each bit has a value double of the on preceding it, and half of the one after it? In other words, progressive doubling?

No.

 11111111 = 255

 11111110 = 254

 11111101 = 253

and so on.

What number do you think this one is?

 11000001

Take out your desktop calculator on your computer.

Open it up.

Set view to scientific.

Enter your number.. like 253

Change your value from Dec to BIN for BInary and it should come up properly. And vice versa.

Hex is for Hexdecimal and it is possible to jump among all three groups.

  • Member since
    January 2002
  • From: Portland, OR
  • 3,119 posts
Posted by jfugate on Friday, October 12, 2007 3:16 AM
 Falls Valley RR wrote:

I suffer Math Anxiety. The kind that disables and reduces a stout heart to a blubbering pile of wet fur mewing for mercy. I rather run Donner on ice than do math.

anyhow. Some of the links in this particular thread led me off to more CV's and more lists of Decoders and more, more and even more.

Has anyone thought to say for one second.. ENOUGH!?

Enough CVs already. We use what? 255 of them?

For the first time last night I pushed away from these decoder CV lists feeling as if there was one bottle of schnapps too many and have to take one more to straighten things out.

Even though I am a trained software developer who can do binary and hexadecimal in my sleep, I recommend people get a computer interface capable DCC system and use the free DecoderPro software available from the JMRI group.

With DecoderPro, you can program even complex sound decoders by pointing and clicking on sliders and radio buttons, just the way you'd like to do! No need to memorize CVs or do binary math. If you do want to see what's going on at the CV level you can, but you don't have to.

I find using DecoderPro lets me program a fleet of locos in a few minutes, even if the decoders are from various manufacturers. DecoderPro has a decoder discover feature that's pretty slick, but you need to put the loco on the programming track to use it. After that you can program on the main to your heart's content.

Once you use DecoderPro, you'll never go back to programming decoders using decoder manuals, juggling CVs, or making yourself cross-eyes with bit-fiddling binary math. Smile,Wink, & Grin [swg]

Joe Fugate Modeling the 1980s SP Siskiyou Line in southern Oregon

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,134 posts
Posted by CSX Robert on Monday, October 15, 2007 11:00 AM
 Don Z wrote:

...

I use an NCE system and when I create a consist, I don't have to change any CV values. The system takes care of modifying whatever CV's need to be changed so only the lead unit blows the whistle and has a headlight on, etc. Your system might require you to adjust each unit individually.

Don Z.

NCE does not automatically change CV21 and CV22. What NCE does is allow the user to designate a locomotive as the lead locomotive and it sends the function commands to the lead locomotive. In most situations, this is probably good enough, but there are many situations were the user will want more control over how the functions respond. If you have a consist of sound locomotives, you would want the headlight, horn and bell to only work on the lead unit, but you may want other sounds, such as the dynamic brakes and doppler effect, to work on all of the units. Using the lead locomotive feature of NCE, the other sound effects would not work on the other units. 

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