Page 18 Non-Sound Decoder MX618 - MX634 and Sound Decoder MX640 - MX648
CV
Designation
Range
Default Description
#10
Compensation cut-off
This CV is seldom required
0 - 252
0
Assigns an internal speed step where back EMF inten-
sity is reduced to the level defined in CV #113. CV #10,
#58 and #113 together define a back-EMF curve.
= 0: default curve is valid (as in CV #58).
#113
Compensation cut-off
This CV is seldom required
0 - 255
0
The BEMF intensity is reduced to this value at the
speed step defined in CV #10.
CV #113
together with CV’s #58 and 10 form a 3-point
BEMF curve.
= 0: actual cutoff at speed step in CV #10. Usually
CV #10 is also set to 0.
#145
#147
#148
#149
#150
Experimental CV’s for
test purposes,
to find out whether
certain automatic
settings have a negative
effect on motor
regulation.
Using these
experimental CV’s will
deactivate the automatic
settings.
CV’s #147 – 149 will
likely be removed again
from the decoder SW at
some time.
CV #145 = 10,11,12,13
for C-Sinus motors
See chapter 6 (Installa-
tion)
0
0
0
0
--- CV #145 = 1: Special setting for Fleischmann round
motor.
--- CV #147 Sampling time ---
Useful initial value: 20;
Too small a value leads to jerky behavior.
Too large a value leads to poor low speed control.
0= automatic control (CV #147 has no effect)
--- CV #148 D-Value ---
Useful initial value: 20;
Too small a value leads to poor regulation (regulates
too little, too slow, engine jerks (rather slowly).
Too large a value leads to over compensation, the en-
gine runs rough/vibrates.
0 = automatic control (CV #148 has no effect)
--- CV #149 P-Value ---
0 = automatic control (CV #149 has no effect)
1 = P-Value is fixed as per CV #56 (tens digit)
--- CV #150 Load compensation at top speed ---
Load compensation at top speed is normally always 0.
This can be changed with CV #150.
Example: CV #58 = 200, CV #10 = 100, CV #113 = 80
und CV #150 = 40 --> Result: Regulation at speed
step 1 is 200 (of 255, almost 100%), at speed step 100
it is 80 (@1/3
rd
of 255), at speed step 252 (full speed) it
is 200 (of 255, almost fully regulated).
We kindly ask for your cooperation. Please send us
your test results!
The Motor Brake
This brake is useful for vehicles without worm gears to prevent them from rolling away on inclines, picking up speed
on declines as well as to prevent a heavy train from pushing a standing engine downhill.
CV
Designation
Range
Default
Description
#151
Motor brake
0 - 9
0
= 0: brake not active
= 1 … 9: The motor brake is gradually actuated (over a
period of
1, 2 … 8 seconds, up to full braking power by
shorting both motor end stages) if target speed is not
reached (not slowing down) after cutting power to the
motor (Zero PWM to the motor).
The higher the value, the faster and harder the brake
is being applied.
3.7 Acceleration and Deceleration:
The basic acceleration and deceleration times (momentum) are set with
CV’s #3 and #4
according to the relevant NMRA standard, which demands a linear progression (the time between
speed step changes remains constant over the whole speed range).
For simple smooth drivability use values 3 or higher but for really slow starts and stops start with a
value of 5. Values over 30 are usually impractical!
The sound proj
ect in sound decoders always comes with different values in CV’s #3 and #4 (as well as
many other CV’s) than what is listed in the CV charts. Often the sound can only be played back correct-
ly in conjunction with the acceleration times provided by the sound project (or certain minimum values),
so
the sound project’s default values should therefore not be changed too much.
Acceleration and deceleration behavior, especially starting and stopping, can be further improved by
the “exponential” and “adaptive” acceleration/deceleration features (CV’s #121, 122 and 123).
To eliminate a start-up jolt after changing the direction, caused by gear backlash in gearboxes, use
CV #146:
Some free play between gears of a drivetrain is essential to prevent them from binding. This creates
backlash and may be more severe on some engines than on others, especially when fitted with a
worm gear or an excessively worn gearbox.
Excessive backlash leads to a peculiar behavior especially after changing the direction: When the
motor starts turning
in the opposite direction it doesn’t move the engine right away because it has to
eliminate the backlash first. And to make matters worse, the motor starts to accelerate already during
this phase. When the engine finally start
s moving, the motor’s speed has exceeded the normal start-
up rpm, which results in an unpleasant jolt. This can be avoided with the help of CV #146.
CV
Designation
Range
Default Description
#3
Acceleration rate
0 - 255
(2)
The value multiplied by 0.9 equa
ls’ acceleration time in
seconds from stop to full speed.
The effective default value for sound decoders is usual-
