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Foward/Reverse?

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  • Member since
    March, 2002
  • 224 posts
Foward/Reverse?
Posted by mike33469 on Saturday, September 02, 2017 8:22 PM

I have an engine that runs backwards in foward and foward in reverse.  I put it back on the program track 3 times and changed CV 29 to 0, to 1 and back to 0 but it never changes to the correct direction. What am I doing wrong?

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Posted by maxman on Saturday, September 02, 2017 8:46 PM

http://www.2mm.org.uk/articles/cv29%20calculator.htm

Link to CV29 calculator.  I think you probably want some other value in CV29 other than 0 or 1.  Those two values by themselves are supposed to change the normal direction of operation, but you need some additional values if you want to use 28/128 speed steps and loco long address.  If only 0 or 1 you end up programming decoder to run at 14 speed steps which it probably won't do.

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Posted by BigDaddy on Saturday, September 02, 2017 9:39 PM

Or you could change the engine wires on the decoder.  Probably not something you wanted to hear.  

 

Henry

COB Potomac & Northern

By the Chesapeake Bay

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  • 224 posts
Posted by mike33469 on Saturday, September 02, 2017 9:47 PM

No, not really. Anyone know what values I could try other than 0 and 1?

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Posted by maxman on Saturday, September 02, 2017 9:56 PM

mike33469

No, not really. Anyone know what values I could try other than 0 and 1?

Look at the calculator link.  All you have to do is check the boxes of what you want and leave blank what you don't want.  The calculator does the work for you.

Oh, you don't happen to have a loco that runs long hood forward normally, do you?

  • Member since
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  • From: Reading, PA
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Posted by rrinker on Sunday, September 03, 2017 11:30 AM

 Direction of travel is the one that is the easiest. But it's not making CV29 1 or 0, it's changing the first BIT to a 1 or 0.

 This one is easy because most systems set the other bits of CV39 for you when you program an address. So to get back to where it was, you need to set the address again and let the system apply a valid value to CV29.

 Then if the loco runs the wrong way, read the current value of CV29 and ADD 1. Not make it one, ADD 1 to the current value. If you click the boxes on the calculator you can see how it affects the actual value shown at the bottom, which is what you put in CV29.

 If this is a wired install, the RIGHT way to fix it is to swap the motor wires. Even if that means connecting an orange wire to the gray, and the gray to an orange. All 4 of my P2k Geeps is that way, there were factory wired to run short hood forward which is wrong for almost every single roadname they released them in. They had the crew figures facing the short hood, but they DID properly put the little F decal on the long hood end - so they KNEW that was supposed to be the front.

                                --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by jjdamnit on Sunday, September 03, 2017 12:18 PM

Hello all,

Before you break out the Weller...

When you turn the locomotive "around" or backward to the direction you are seeking does it then respond correctly?

I hate to sound like IT tech services but...have you tried to reset the decoder?
(For most decoders set CV 8 to a value of 8 then cycle the power. To be sure check your mfg website or documentation.)

What kind of loco is it?

As has been posted, some companies hard-wire the motor to run either cab forward or cab back despite the prototype or where the "F" forward marking is.

In some of my decoder installations it wasn't clear which was the "+" or "-" side of the motor. I soldered the Orange and Gray wires and set the direction of travel through CVs.

I use Bachmann, TCS and Digitrax decoders; all non-sound.

Good luck and hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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  • From: Dearborn Station
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Posted by richhotrain on Monday, September 04, 2017 5:33 AM

mike33469

I have an engine that runs backwards in foward and foward in reverse.  I put it back on the program track 3 times and changed CV 29 to 0, to 1 and back to 0 but it never changes to the correct direction. What am I doing wrong?

 

That should work although as others have pointed out, CV29 is a multi-function CV.  Here are some common values.

CV29=0 Fwd/14 speed steps

CV29=1 Rev/14 speed steps

CV29=2 Fwd/28,128 speed steps

CV29=3 Rev/28,128 speed steps

CV29=34 Fwd/28,128 speed steps/Long address

CV29=35 Rev/28,128 speed steps/long address

CV29=38 Fwd/28,128 speed steps/Long address/DC operation

CV29=39 Rev/28,128 speed steps/long address/DC operation

I would suggest that most of us use a value of 34 or 35 in CV29.

Hope this helps.

Rich

Alton Junction

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