Mutiple Unit Consisting/Consist Configuration Variables

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When using a Consist Address (Decoder Assisted Consisting, CV19), these CVs allow tailoring the operation of the locomotives by determining which locomotive in the consist will act on function commands, headlight operation, and make adjustments to the acceleration/brake rates to simulate a load on the consist.

A Decoder Assisted Consist is also known as an Advanced Consist.

Optional Configuration Variables

As these configuration variables are optional, they may not be available on a specific multifunction decoder. Verify with the manufacturer's instructions that they are present.

They become active if the Consist Address in CV19 is set to a value other than 0 or 128, making the multifunction decoder part of an Advanced Consist.

Function Control

Default for these CVs is Zero.

Consist Address Active for F1-F8

CV 21

Defines for functions F1-F8 whether the function is controlled by the consist address. For each Bit a value of "1" indicates that the function will respond to instructions addressed to the consist address. A value of "0" indicates that the function will only respond to instructions addressed to the locomotive address. F1 is indicated by bit 0, F8 by bit 7.

Consist Function Group 1
Bit 7 6 5 4 3 2 1 Bit 0
F8 F7 F6 F5 F4 F3 F2 F1

By setting this register, the lead locomotive will respond to function commands while all others in the consist will ignore these commands.

For example, setting this CV to a value of 1 (20) allows the F1 command to activate a response from this decoder. A setting of 4 (22) activates and F3. By adding 1 and 4, then writing the sum (5) to the CV activates both F1 and F3.

Consist Address Active for FL and F9-F12

CV 22

Defines for function FL whether the function is controlled by the consist address. For each Bit a value of "1" indicates that the function will respond to instructions addressed to the consist address. A value of "0" indicates that the function will only respond to instructions addressed to the locomotive address. FL in the forward direction is indicated by bit 0, FL in the reverse direction is controlled by bit 1. Bit 2 corresponds to F9, while Bit 5 corresponds to F12. There is no specified default value in the NMRA standard, so consult the manual for the decoder. A typical default is "0" (zero).

Consist Function Group 2
Bit 7 Bit 0
X X F12 F11 F10 F9 F0 (R) F0 (F)

Bits 6 and 7 are reserved.

This register allows differentiation of the headlights (Forward and Reverse). By setting this register in the lead engine while leaving all others at the default of zero, the lead engine's headlight will be on when the consist is moving forward, all others will be off. It can also be used to control the activation of the headlight in the trailing unit.

There may exist some inconsistencies between various manufacturers in the implementation of these CVs. When part of a consist, some decoders may respond to both the decoder and consist address, others may only respond to the consist address.

Multifunction decoders may use additional CVs to control functions greater than F12.

Acceleration

Default for these CVs is Zero.

Acceleration Rates: CV23 & 24
Bit 7 Bit 0
Sign D6 D5 D4 D3 D2 D1 D0

Summary: A CV value between 0 and 127 will increase the base acceleration or braking rate. Values between 128 and 255 will decrease the decoder’s base acceleration or braking rate. Values of 128 or greater are considered to be negative numbers in binary arithmetic in this case, as bit 7 functions as the sign.

Acceleration Adjustment

CV 23

This Configuration Variable contains additional acceleration rate information that is to be added to or subtracted from the base value contained in CV3 using the formula

CV23 × 0.896 ÷ number of speed steps in use.

This is a 7-bit value (bits 0-6) with bit 7 being reserved for a sign bit (0-add, 1-subtract). In case of overflow the maximum acceleration rate shall be used. In case of underflow no acceleration shall be used. The expected use is for changing momentum to simulate differing train lengths/loads, most often when operating in a consist.

The value is –127 to +127, providing a corresponding offset to the acceleration rate when in a consist. If the sum of CV3 and CV23 is a negative value, the acceleration rate will be set to Zero. If the sum exceeds 255, the maximum acceleration rate of 255 will be applied.

When the Consist Address is set to Zero, this CV will have no effect.

Deceleration Adjustment

CV 24

This Configuration Variable contains additional braking rate information that is to be added to or subtracted from the base value contained in CV4 using the formula

CV24 × 0.896 ÷ number of speed steps in use.

This is a 7-bit value (bits 0-6) with bit 7 being reserved for a sign bit (0-add, 1-subtract). In case of overflow the maximum deceleration rate shall be used. In case of underflow no deceleration shall be used. The expected use is for changing momentum to simulate differing train lengths/loads, most often when operating in a consist.

The value is –127 to +127, providing a corresponding offset to the braking rate when in a consist. If the sum of CV3 and CV24 is a negative value, the braking rate will be set to Zero. If the sum exceeds 255, the maximum braking rate of 255 will be applied.

When the Consist Address is set to Zero, this CV will have no effect.