SoundTraxx LC Series Owners Manual - Manual (Page 22)

LC SERIES DIGITAL SOUND DECODER OWNER’S MANUAL 22
Using different values for the forward and reverse trim will yield different forward and reverse
speeds.
Adjust the Motor Drive Frequency
Virtually all DCC decoders, including the DSD-LC, drive the locomotive motor using a technique
called Pulse-Width-Modulation or PWM. PWM works by alternately switching the motor from full
off to full on. If the motor is switched fast enough, the speed can be controlled by varying the
ratio between the time the motor is on and the time the motor is off. One drawback to PWM is
that it can cause the locomotive to buzz, sometimes quite loudly, at low speeds.
To mitigate some of this noise, the DSD-LC provides CV 9, Motor PWM Period to control the
frequency at which the motor is switched on and off. By adjusting this CV, one can usually find a
drive frequency that is quieter than others.
CV 9 can be programmed with any value between 0 and 230. A CV value between 170 and 190
works well for most locomotives.
Step 4: Configuring for Consist Operation
The DSD-LC supports advanced consist operations which use three related CVs:
CV 19, Consist Address
CV 21, Consist Function Enable
CV 22, Consist F0 Function Enable
Consists Explained
A consist is a group of locomotives that are setup to respond to throttle commands as a single
unit. Consists make it easy for one operator to run a double headed steam train or a multi-unit
diesel lash-up for example. The consist CVs allow the DSD-LC to recognize a new address
assigned to the consist without changing its primary or extended addresses. Additionally,
they allow each locomotive in the consist to be run as a single unit but with different function
properties allowing for example, only the horn to blow on the lead engine.
Consist Address
Each locomotive in the consist is assigned the same consist address by programming CV 19
with the consist address between 1 and 127. If a locomotive is facing backwards in the consist, it
should be programmed with the same consist address plus 128. If the forward facing locomotives
are set to consist address 60 for example, the backwards engine must be set to 60+128 = 188.
Failure to do this will turn the consist into an angry pushme-pullyou as all locomotives will try to
move forward from the perspective of their own cab and a few pulled couplers might result!
To deactivate the consist address and restore normal operation, CV 19 must be reprogrammed
to 0.
Note that when the consist address is set, the DSD-LC will continue to respond to instructions
sent to its primary or extended address except for speed and direction data.
The DSD-LC will not to respond to operations mode programming commands sent to its consist
address. These commands must always be used with the primary or extended address.
Consist Function Enable
CV 21 and 22 allow you to define how each engine individually responds to function commands
sent to the consist address. When the consist is enabled, CV 21 controls which of functions 1-8
are active and CV 22 controls the F0 function for forward (F0 (f)) and reverse (F0 (r)).
CV 21 and 22 take effect only when the consist address is set. When function commands
are used with the DSD-LC’s primary or extended address, all functions will continue to work
regardless of the settings of CV 21 and 22.