KB557: CV29 - Configuration Register Look Up Table Method

This article was last updated on Aug. 15, 2011, 4:52 p.m. | Print Article | Leave Feedback

CV29 is called the configuration register. It controls the following decoder characteristics: 
1.  Whether the decoder uses 14 speed steps, 28/128 speed steps or loadable speed tables.  This affects how smoothly the loco will move and how it responds to throttle controls.
2.  Whether the decoder automatically converts to analog mode when no DCC signal is present.  This allows the decoder to operate on a DC layout even though it is DCC equipped.
3.  Defines the normal direction of travel for the locomotive. Normal Direction of Travel or NDOT can be changed when the motor connections of decoder have not been connected so that the locomotive runs in the "wrong" direction. Setting the NDOT to be long hood forward is also useful if you model Southern Railway from the 1960's on; Southern was famous for making the long nose of their road switchers the "front", contrary to virtually all other railroads' practice. By changing the NDOT, you can have your Southern diesels traveling in the "right" direction
4.  Whether the decoder will use a 2 digit or 4 digit address.

Look Up Table Method
The look up table below shows the effects of different CV values for CV29.

CV values are shown in both hex (for older Digitrax throttles) & decimal (for all current production throttles).

The table lists all usable values for CV29; the idea is to find the right combination of features and then match these up to the value that you program into CV29.

For example, programming a value of 032 for CV29 will make the locomotive operate in 14-step speed mode, with the ability to operate on an analog layout turned "off", it will operate in the normally forward direction and it will have a two digit address.

Another example is, programming CV29 with a value of 055 will make the locomotive operate in 28 or 128-step speed mode, the locomotive will be able to operate on a layout controlled by a traditional power pack, it will operate in the normally "reverse" direction and it will have a four digit address.

The factory default value for CV29 is 06. 

CV29 Values
:

CV Value

For CV29

Hex   Dec

Speed Steps/

Speed Table

Analog

Mode

Conversion

Normal

Direction

Of Travel

2 or 4

Digit

Address

x00

000

14

OFF

Forward

2

x01

001

14

OFF

Reverse

2

x02

002

28/128

OFF

Forward

2

x03

003

28/128

OFF

Reverse

2

x04

004

14

ON

Forward

2

x05

005

14

ON

Reverse

2

x06

006

28/128

ON

Forward

2

x07

007

28/128

ON

Reverse

2

x10

016

14 Speed Table

OFF

Forward

2

x11

017

14 Speed Table

OFF

Reverse

2

x12

018

28/128 Speed Tbl

OFF

Forward

2

x13

019

28/128 Speed Tbl

OFF

Reverse

2

x14

020

14 Speed Table

ON

Forward

2

x15

021

14 Speed Table

ON

Reverse

2

x16

022

28/128 Speed Tbl

ON

Forward

2

x17

023

28/128 Speed Tbl

ON

Reverse

2

x20

032

14

OFF

Forward

4

x21

033

14

OFF

Reverse

4

x22

034

28/128

OFF

Forward

4

x23

035

28/128

OFF

Reverse

4

x24

036

14

ON

Forward

4

x25

037

14

ON

Reverse

4

x26

038

28/128

ON

Forward

4

x27

039

28/128

ON

Reverse

4

x30

048

14 Speed Table

OFF

Forward

4

x31

049

14 Speed Table

OFF

Reverse

4

x32

050

28/128 Speed Tbl

OFF

Forward

4

x33

051

28/128 Speed Tbl

OFF

Reverse

4

x34

052

14 Speed Table

ON

Forward

4

x35

053

14 Speed Table

ON

Reverse

4

x36

054

28/128 Speed Tbl

ON

Forward

4

x37

055

28/128 Speed Tbl

ON

Reverse

4

The factory default value for CV29 is 06.

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