Page 12 Function-Decoders MX681, MX685, MX686, MX687, MX688
#432
Swiss Mapping Group 1
“A1” forward
Bits 0 - 3:
1 - 12
14 (FO0f)
15 (FO0r)
Bits 5 - 7:
0 - 7
0
Bits 0 - 3:
Function output to be switched ON in forward direction
provided that both the
“F” and “M” keys are ON (if Bit 7
for the “M” key of this group is 1, otherwise “F” key ON
is sufficient).
Bits 7, 6, 5 (7 possible values or zero):
Number of the applicable dimming CV. For example:
Bit 5 = 1 means dimming according to CV #508 etc.
#433
Swiss Mapping Group 1
“A2” forward
Bits 0 - 3:
1 - 12
14 (FO0f)
15 (FO0r)
Bits 5 - 7:
0 - 7
0
Bits 0 - 3:
Additional function output to be switched ON in for-
ward direction provided that both the
“F” and “M” keys
are ON (if Bit 7 for the “M” key of this group is 1, oth-
er
wise “F” key ON is sufficient).
Bits 7, 6, 5 (7 possible values or zero):
Number of the applicable dimming CV. For example:
Bit 5 = 1 means dimming according to CV #508 etc.
#434
Swiss Mapping Group 1
“A1” reverse
As above
0
As above but for reverse direction
#435
Swiss Mapping Group 1
“A2” reverse
As above
0
As above but for reverse direction
#436 -
441
. . .
Group 2
.
. . .
0
All 6 CVs of Group 2 are defined the same way as the
6 CVs in group 1.
#442 -
447
. . .
Group 3
.
. . .
0
All 6 CVs of the following groups are defined the same
way as the 6 CVs in group 1.
#448 -
477
. . .
Group 4 to 8
.
. . .
0
. . .
#508
#509
#510
#511
#512
Dimming values for
“Swiss Mapping”
(0- 31)*8
(only Bits
7 - 3 are
used)
0
Each group CV (i.e. #432, 433, 434, 435) can be
linked to one of these five dimming CVs. The value to
enter is the dimming value (0
– 31) times the function
output number. (i.e. dimming value = 16 for function
output 6: 16 x 6 = 96 is the value to enter).
This will dim the relevant function outputs accordingly.
Only with function outputs FO0 to FO8.
3.11 Dimming, Low beam and Direction Bits
Some elements connected to function outputs often are not designed to operate with full track power,
as is the case with 18V bulbs at 24V track voltage (quite common on large scale model railroads).
Other times the brightness needs to be reduced simply because the light is too bright.
The best solution in such cases is to connect the positive pole of such devices to the low voltage sup-
ply of the decoder (see chapter “Technical Information”). Such low-voltage outputs are fully stabilized
and the voltage will not fluctuate with changes in track voltage.
Alternatively or in addition to this (the dimming effect is not limited to devices connected to full track
power but also works with low voltage), the PWM (pulse width modulation) voltage reduction is also
available with
CV #60,
which defines the PWM duty cycle. Of course, this kind of voltage reduction is also interesting be-
cause it is easy to change at any time.
NOTE: Bulbs with voltage ratings as low as 12V can be dimmed with this PWM dimming function with-
out damage even if track voltages are considerably higher; but
not
bulbs rated below that such as 5V or
1.2V bulbs. These must be connected to one of the decoder’s low voltage supply pins instead of a nor-
mal positive pin (see chap
ter “Installation and Wiring”).
LEDs, on the other hand, require a series resistor; if however, the resistor is designed to operate at
5V, the PWM dimming is also sufficient at a track voltage of 25V (in this case the setting would be
CV #60 = 50, so a reduction by one fifth).
CV #60 generally affects all function outputs. The dimming function can be restricted to specific func-
tion outputs using the following dim mask CVs.
CV
Denomination
Range
Default
Description
#60
Reduced function output
voltage
(Dimming).
Affects all
function outputs.
0 - 255
0
Reduction of function output voltage with PWM (pulse-
width modulation). Useful for example for headlight
dimming.
Example values:
CV #60 = 0 or 255: full voltage
CV #60 = 170: 2/3 of full voltage.
CV #60 = 204: 80% of full voltage.
#114
Dim Mask 1
=
Excludes certain
function outputs from
dimming per CV #60.
For higher function
outputs go to
CV #152.
Bits
0 - 7
0
Enter function outputs that are
not
to be
dimmed
as
per CV #60. These outputs will use the full voltage
available from th
e decoder’s positive pin.
Bit 0 - front headlight,
Bit 1 - rear headlight,
Bit 2 - function output FO1, Bit 3 - FO2,
Bit 4 - function output FO3, Bit 5 - FO4
Bit 6 - function output FO5, Bit 7 - FO6
Bit value = 0: Output will be dimmed to the value
defined in CV #60.
Bit value = 1: Output will not be dimmed.
#152
Dim Mask 2
Continuation of
CV #114
Bits
0 - 5
… Continuation of CV #114.
Bit 0 - function output FO7,
Bit 1 - function output FO8,
Bit 2 - function output FO9,
