Configuration Variables (CVs ) for Atlas #345 DCC Decoders as Used in Decoder-Equipped Atlas HO-Scale H-15/16-44 Diesel Locomotives

CV

Register

Description

Range

Default Value1

1

1

Locomotive Address
This is the (2 decimal digit) address used to
select the locomotive that you wish to run

1-99

3

2

2

Start Voltage:
This is the voltage applied to the motor in speed step 1.
Set this value so that the locomotive just starts moving in speed step 1

0-31

8

3

3

Acceleration Momentum
Determines the rate of change of speed upon acceleration.
A higher value leads to a slower acceleration.

1-255

1

4

4

Brake Momentum
Determines the rate of change of speed upon braking.
A higher value leads to longer brake distance.

1-255

1

-

5

Contains CV29 (see CV29 below)

0-255

6

-

6

Page Register
Normally this CV is not modified directly by a user.
For correct operation, this CV should be set to have a value of "1" after any use.

0-127

1

-

7

Version Number
This location stores the version number of the decoder.
This location is read-only.

-

46

-

8

Manufacturer's Identification/Factory Reset
This value is the manufacturer ID of the decoder.
(Atlas=127) Writing a value of decimal "33" to this Register resets all CVs to their factory defaults.

-

127

17

-

Extended Address High Byte

192-231

0

18

-

Extended address Low Byte
The two byte (4 decimal digit) address, if used, is contained in CV17 & CV18.

0-255

0

19

-

Consist Address

1-99

0

The advanced consist address, if used, is stored in CV19.

29

Decoder Configuration, Byte 1
Several decoder properties are set with this byte. Changes are easiest if done in binary mode, but can also be done by adding the decimal values (in parenthesis) for all the desired features together and writing the total into CV29.

0-255

6

Bit 0

Locomotive direction:
Locomotive's normal direction; this bit sets the direction the locomotive will move when told to move forward in digital mode.
0 = Locomotive's direction is normal.
1 = Locomotive's direction is inverted.

0,1

0 (1)

Bit 1

Headlight mode:
0 = Operation with 14 or 27 speed step systems. This setting is selected when the locomotive decoder is used with any DCC system that does not support 28 speed step mode. If the headlights turn on and off as the speed is increased, the command station is configured for 28 speed steps, and the decoder is in 14 speed step mode.
1 = Operation with 28, 55, or 128 speed steps. If you use this setting, the command station must also be configured to use 28 speed step mode or 128 speed step mode for the decoder's address; otherwise, the headlights cannot be controlled.

0,1

1 (2)

Bit 2

Usage on conventional DC layouts
0 = Locomotive operates in digital mode only
1 = Locomotive can operate on either conventional DC or on DCC

0,1

1 (4)

Bit 3

Always 0

0

0

Bit 4

Speed Curve Selection
0 = Factory pre-set speed curve is used.
1 = User-defined speed curve is used.
Please enter the appropriate values into CVs 67 to 94 before setting this bit.

0,1

0 (16)

Bit 5

Extended Addressing:
0 = Normal (single byte) addressing
1 = Two byte extended addressing

0,1

0 (32)

Bit 6

Always 0

0

0

Bit 7

Always 0

0

0

50

Decoder Configuration, Byte 2:
CV50 is similar to CV29, but is used to set other properties.

0-255

1

Bit 0

Not used

0

Bit 1

Not used

0

Bit 2

Brake momentum on DC operation
Used to achieve prototypical braking at red signal indications
If conventional DC control is disabled (CV29.2 =0)2,
0 = Locomotive proceeds with track voltage dependent speed inside the conventional DC section.
1 = Locomotive brakes in the conventional section with pre-set brake momentum.

0,1

0 (4)

Bit 3

Motor Drive Selection
0 = Silent Drive off
1 = Silent Drive on

0,1

0 (8)

Bits 4-7

Not used

0

51

Light effects for output A (front headlight)

0,1

6

Bit 0

0 = The headlights are directional per Rule 17.
1 = The headlights are independent with F0 controlling front headlight and F1 controlling rear headlight.

0,1

0 (1)

Bit 1

If CV51.2=1, the value in CV52 is used for front headlight dimming with dimming controlled as follows:
0 = Front headlight always dimmed
1 = Front headlight dimmed by F1when CV51.0=0 and dimmed by F4 when CV51.0=1

0,1

1 (2)

Bit 2

0= Front headlight cannot be dimmed
1= Front headlight can be dimmed

0,1

1 (4)

Bit 3

Not used

0

Bit 4

1 = Front headlight functions as Gyro light

0,1

0 (16)

Bit 5

1 = Front headlight functions as Mars light

0,1

0 (32)

Bit 6

1 =Front headlight functions as single pulse Strobe light

0,1

0 (64)

Bit 7

1 = Front headlight functions as double pulse Strobe light
Note: bits 4-7 effective only if bit 1 is set. If several of bits 4-7 are set, only the highest bit is effective.

0,1

0 (128)

52

Dimming CV - contains the value used for dimming output A 0 is dark; 255 is maximum brightness.

0-255

64

54

Function Mapping for Outputs C and D (front & rear marker lights)

0-255

2

Bit 0

1 = Marker lights controlled by F1

0,1

0 (1)

Bit 1

1 = Marker lights controlled by F2

0,1

1 (2)

Bit 2

1 = Marker lights controlled by F3

0,1

0 (4)

Bit 3

1 = Marker lights controlled by F4

0,1

0 (8)

Bit 4

1 = Marker lights controlled by F5

0,1

0 (16)

Bit 5

1 = Marker lights controlled by F6

0,1

0 (32)

Bit 6

1 = Marker lights controlled by F7

0,1

0 (64)

Bit 7

1 = Marker lights controlled by F8

0,1

0 (128)

57

Light effects for output B (rear headlight)

0-255

6

Bit 0

Not used

Bit 1

If CV57.2=1, the value in CV58 is used for rear headlight dimming with dimming controlled as follows:
0 = Rear headlight always dimmed
1 = Rear headlight dimmed by F1when CV51.0=0 and dimmed by F4 when CV51.0=1

0,1

0 (2)

Bit 2

0= Rear headlight cannot be dimmed
1= Rear headlight can be dimmed

0,1

1 (4)

Bit 3

Not used

0

Bit 4

1 = Rear headlight functions as Gyro light

0,1

0 (16)

Bit 5

1 = Rear headlight functions as Mars light

0,1

0 (32)

Bit 6

1 = Rear headlight functions as single pulse Strobe light

0,1

0 (64)

Bit 7

1 = Rear headlight functions as double pulse Strobe light
Note: bits 4-7 effective only if bit 1 is set. If several of bits 4-7 are set, only the highest bit is effective.

0,1

0 (128)

58

Dimming CV - contains the value used for dimming output B0 is dark; 255 is maximum brightness

0-255

64

67 to 94

Values for user-defined speed curve
These registers are used for a user-defined speed curve.
The factory setting for these registers is shown in Figure X. The value that is stored in each CV determines the Velocity of the locomotive for each assigned speed step. For the 14 speed step mode, only the odd CVs are used. It you are using the 128 speed step mode and you have activated the user-defined speed table, the intermediate speed steps are calculated by the decoder.

0-255

For the default Velocity values at each Speed Step, please refer to the table entitled Default Speed Curve in Figure X.

128

Decoder Software Version - read only
1. Each number shown in parenthesis in the "Default Value" column is the decimal value that must be written into a CV to yield a binary "1" in the particular bit position that is being defined in that row of this table. In order to write binary '1's" into multiple bit positions of a particular CV, simply add up the decimal values shown in parenthesis in this table for all of the bit positions of the CV for which a binary "1" value is desired and then write this total decimal sum into the CV.
2. The notation Cx.y = z means that Bit y of CVx has a value of z. For example, CV29.2 = 0 means that Bit 2 of CV29 has been set to the value 0.

1