Dc Brake Sections, "Märklin Brake Mode; Constant Stopping Distance - ZIMO MX638 Series Instruction Manual

Page 24 Non-Sound Decoder MX618 - MX638 and Sound Decoder MX640 - MX659
CV Denomination Range
Asymmetrical
1 - 14,
threshold
101 - 114,
for
stopping with 201 - 214
#134
asymmetrical DCC signal
(Lenz ABC method).
=
0,1 - 1,4 V
High-speed correction
for the ABC
#142 0 - 255
asymmetrical stop
method
3.11 DC Brake Sections, "Märklin brake mode"
These are the "classic" methods of automated speed influence or stopping at a "red" signal. The re-
quired settings for ZIMO decoders are spread over several CV's.
CV Denomination Range
Single Bits in each of
these CV's are
#29,
responsible for the
#124, -
correct reaction to the
#112
DC and Märklin brake
sections.
Default Description
Hundreds digit: Sensitivity adjustment, improves the
asymmetric-recognition by changing the speed with
which the asymmetry is being recognized.
= 0: fast recognition (but higher risk of errors,
may lead to unreliable stopping).
= 1: normal recognition (@ 0.5 sec.), fairly
reliable (default).
= 2: slow recognition (@ 1 sec.), very reliable.
106
Tens and ones digit: Asymmetrical threshold in tenths
of a volt. The voltage difference between the two half
waves of the DCC signal defines the minimum required
to be recognized as asymmetrical that starts the in-
tended effect (usually braking and stopping of a train).
= 106 (Default) therefore means normal recognition at
0.6 V asymmetry. This value has proven itself to be ap-
propriate under normal conditions; by using 4 diodes to
generate the asymmetry.
A delayed recognition (see CV #134), but also unrelia-
ble electrical contact between rails and wheels, have a
larger effect on a stop point at higher speeds than at
12
lower speeds. This effect is corrected with CV #142.
= 12: Default. This setting usually works fine with the
default setting in CV #134.
Default Description
When using track polarity dependent DC brake
sections set
CV #29, Bit 2 = "0" and CV 124, Bit 5 = "1"!
-
For polarity independent DC braking (Märklin brake
sections) set
CV #29, Bit 2 = "0" and CV 124, Bit 5 = "1" and
additionally CV #112, Bit 6 = "1"!
3.12 Distance controlled stopping –
After the type "constant stopping method" has been selected with
the stopping distance will be kept as close as possible to the one defined in
independent of the current speed at the start of the braking sequence.
This method is especially suitable in connection with automated stops in front of a red signal with the
help of the signal controlled speed influence (ZIMO-HLU) or the asymmetrical DCC-signal (Lenz-
ABC). CV #140 is set to 1 or 11 for this purpose.
Although of lesser practical value, distance controlled stopping for manual driving can also be acti-
vated (by programming CV #140 with appropriate values of 2, 3, 12, or 13), which is executed when-
ever the speed is set to 0 (by the cab, throttle, computer...).
Distance controlled
stopping
(constant stopping
#140
distance)
0 - 255
Select a braking method
and braking process
Distance controlled
stopping
(constant stopping
#141 0 - 255
distance)
Distance calculation
Distance controlled
#143 stopping, compensation 0 - 255
using the HLU method
The distance controlled stopping can take place in two possible ways; see diagram below: The first is
the recommended method (CV #140 = 1, 2 ,3), where a train entering at less than full speed contin-
ues at the same speed for some time before it starts braking at a "normal" deceleration rate (same
rate as would be applied at full speed).
In the second method (CV #140 = 11, 12, 13), the train immediately starts braking when entering the
stop section, even when entering at a lower speed, which may lead to an un-prototypical behavior. It

Constant stopping distance

CV #140 (= 1, 2, 3, 11, 12, 13)
CV #141,
Activates distance controlled stopping as per CV #141
instead of time-constant braking according to CV #4.
= 1: automatic stops with ZIMO HLU (signal controlled
speed influence) or ABC (asymmetrical DCC signal).
= 2: manual stops using the cab.
= 3: automatic and manual stops.
0
The start of braking is delayed in all cases above (= 1, 2
or 3) when the train travels at less than full speed, to
prevent unnecessary long "creeping" (recommended).
On the other hand:
= 11, 12, 13 same meaning as above, but braking
always starts immediately after entering the brake sec-
tion.
This CV defines the "constant stopping distance". The
right value for the existing braking sections has to be
determined by trial & error.
Use these figures as a starting point:
0
CV #141 = 255 is about 500m (547 yards) for a
real train or 6m (20 ft) in HO.
CV #141=50 about 100 m (109 yards) for a
real train or 1.2m in H0 (4 ft.).
The HLU method is more reliable than the ABC method;
0 no recognition delay is usually required in CV #143; this
CV can remain at default value 0.