Digitrax Decoder
Index
CV29: Configuration Register
Characteristics Controlled by CV29:
1. Speed step control: Advanced Mode (28/128 speed steps) or Standard Mode (14 speed steps).
2. Speed table On or Off
3. Analog mode conversion On or Off
4. Normal Direction of Travel (NDOT)
5. 2 digit addressing or 4 digit addressing
Speed Step Control. There are two modes for speed step control: Standard or 14 speed step mode and Advanced or 28/128 speed step control.
Because
of differences in the capabilities of DCC compatible command stations and
decoders, you may have to set CV29 in your decoders to different values to match
the mode of the command station you are using.
If you command station is sending standard 14 speed step mode commands,
your decoders must be programmed for standard mode in CV29. If your command station is sending advanced
28/128 speed step commands, your decoders must be programmed for advanced mode
in CV29. All Digitrax decoders are 128
speed step capable and we recommend that for best performance you run them in
128 speed step mode. If you are using
non-Digitrax decoders are not able to be programmed for advanced mode and you
want to run your command station in advanced mode, you can "status
edit" the standard decoders so that they can be run with your command
station. See your starter set manual
for the specifics of status editing.
Speed tables can be enabled or disabled with CV29. Speed tables are used to customize the throttle response curve of each decoder equipped locomotive. The speed table values can be stored in the decoder and then the table can be turned on or off with CV29. See the section on CVs 65-93 below for a complete description of how speed tables work.
Analog mode conversion is very convenient if you plan to run your Digitrax decoded locomotive on regular DC layouts. With analog mode conversion enabled, the decoder will automatically begin operating as a DC locomotive when no DCC signal is detected by the decoder. This means that if you place your Digitrax decoder equipped loco, with analog mode conversion enabled, on a regular DC layout, it will run on the DC layout. Disabling analog mode conversion can be useful too as the following example illustrates:
Brake Generator Example: If you disable the analog mode conversion feature in a decoder, when DC power is present the locomotive will stop. This gives you a very inexpensive way of generating a "brake section" for stopping DCC locomotives in front of red signals. By NOT allowing analog conversion in the decoder, a relay can supply DC voltage to a track section in front of a red signal to slow and stop a locomotive in the brake section. When the signal turns green, the relay can restore the DCC track signal, and the locomotive will restart. The decoder will slow to a stop and restart at its programmed deceleration and acceleration values. In addition, if you are using an FX decoder with CV13 programmed to keep functions running on DC, the loco's lights and functions will remain active when stopped on the DC brake section as long as DC power is supplied to the track while the loco is stopped!
Normal Direction of Travel, or NDOT for short, lets you set up your locos to run either long hood forward or short hood forward. Because with DCC the decoder determines which way the loco will move independent of track polarity, you can set up either direction as forward depending on the prototype. (Not all decoders have this feature so be sure to check the card that came with your decoder.)
2 Digit or 4 Digit Addressing all current production Digitrax decoders are capable of both 2 & 4 digit addressing. Some older decoders can only use 2 digit addressing.
Determining CV Value To Program Into CV29
The value you will program into CV29 will affect many important decoder characteristics. Each of these characteristics is controlled by a "software switch." This switch is either on or off depending on the CV value programmed. Following are two methods to determine the value to program into CV29.
Use Table 29 to select which features you want to activate and the related CV29 value to program into your decoder.
Look Up Table
Method
The
look up table below shows the effects of different CV values that
you
can program into CV29. CV values are
shown in both hex & decimal.
TABLE 29: 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.
The Addition Method
The table below shows each switch and its value if it is on or off. Notice that if the switch is off the value is zero. To determine the hexadecimal* value to program for your decoder just go down the list and add up the numbers for all the switches you want to set as ON. If you want to convert the hex value to decimal, a chart is provided at the end of this manual.
CV29 Examples of CV Values:
|
Switch # |
Characteristic if OFF |
Value if OFF |
Characteristic if ON |
Value If ON |
|
01 |
NDOT forward |
00 |
NDOT reverse |
01 |
|
02 |
14 speed steps |
00 |
28/128 speed steps |
02 |
|
03 |
Analog mode conversion off |
00 |
Analog mode conversion on |
04 |
|
04 |
Speed table off |
00 |
Speed table on |
10 |
|
05 |
2 digit addressing |
00 |
4 digit addressing |
20 |
All Digitrax decoders are shipped with a factory programmed value of 06 in CV29. This gives the decoders the characteristics highlighted.
|
Switch # |
Characteristic if
OFF |
Value if OFF |
Characteristic if
ON |
Value If ON |
|
01 |
NDOT forward |
00 |
NDOT reverse |
01 |
|
02 |
14 speed steps |
00 |
28/128 speed steps |
02 |
|
03 |
Analog mode conversion off |
00 |
Analog mode
conversion on |
04 |
|
04 |
Speed table off |
00 |
Speed table on |
10 |
|
05 |
2 digit addressing |
00 |
4 digit addressing |
20 |
|
Total
"ON" Value to Program in CV29 |
x06 hex |
|||
Note: 06 hex is the same as 06 decimal
A value of 27 programmed into CV29 will give you a decoder that has a normal direction of travel in reverse, operates in advanced 28/128 speed step mode, has analog mode conversion enabled, does not use a speed table and has 4 digit addressing.
|
Switch # |
Characteristic if
OFF |
Value if OFF |
Characteristic if
ON |
Value If ON |
|
01 |
NDOT forward |
00 |
NDOT reverse |
01 |
|
02 |
14 speed steps |
00 |
28/128 speed steps |
02 |
|
03 |
Analog mode conversion off |
00 |
Analog mode
conversion on |
04 |
|
04 |
Speed table off |
00 |
Speed table on |
10 |
|
05 |
2 digit addressing |
00 |
4 digit addressing |
20 |
|
Total "ON" Value to
Program in CV29 |
x27 hex |
|||
*The values shown on both tables are hexadecimal values. As you turn the throttle right hand knob to the right on a throttle that is using hexadecimal numbers, you will see 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 0A, 0b, 0c, 0d, 0E, 10, 11, 12 etc. Because the 6 & b look very similar on the display, be careful. If you use 0b, for example, as the value for CV29 you won't get the 06 effects you are expecting!
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This page, and all contents, are Copyright (C) 1998-2003 by Digitrax, Inc., Norcross, GA, USA.
Updated 01-15-03.