manual controllers to be independently set
while displaying the current locomotive
address of each controller!
The only thing you have to do is to build
two to eight copies of the deluxe address pro-
grammer board.
The selector switch can now be discarded,
with each input instead being connected
directly to one pin of connector K2 on the
master controller board. In addition, all of the
address programming boards are intercon-
nected via the K2 connectors on the individ-
ual programming boards, using a 10-way flat
cable and suitable headers (you can use a
1.4-m length of 10-strand flat cable with a
total of eight headers attached every 20 cm).
This cable supplies power to all of the pro-
gramming boards and provides a sort of inter-
nal bus for the addresses to be set.
Naturally, only one address programming
board (the master) can be fully populated and
connected to the S88 bus. On all of the other
address programming boards (the slaves),
IC2 is not fitted, R21 must be omitted and
connectors K3 and K4 may be omitted.
Many different combinations are possible,
such as using only four address programming
boards for four manual controllers (in which
case it is recommended to ‘hard code’ the
addresses of controllers 5 through 8 to 0, to
avoid selecting an address that is already
used by one of these controllers), or even a
combination of one address programming
board with a 4-position switch for four man-
ual controllers (5–8, for example) and four
address programming boards for direct
address programming of manual controllers
(for example 1–4).
The double-sided printed circuit board
(
Figure 4
) is designed to have K2, K3 and K4
fitted on the back side (solder side), so the
board with the rotary switch and display can
be fitted directly behind a front panel (see
Figure 5
).
EEDTS Pro keypad
Take four red pushbutton switches and four
green pushbutton switches and connect
them to an EEDTS train detector module (
Fig-
ure 6
) that is connected to the EEDTS Pro S88
bus.
Voilà
– you now have a genuine keypad!
This approach is primarily interesting for
modellers who build ‘real’ control panels with
physical pushbuttons, since in this concept
the switches are not located on the printed
circuit board, but instead are connected using
wires. With the arrangement shown in Fig-
ure 6, up to 248 pushbuttons (31
×
8) could be
built into such a panel for controlling loads.
The entire control panel can be connected to
the master controller using only five wires!
For people who regret the fact
that Märklin no longer makes a
switchboard, this represents a very
attractive alternative.
As noted in the discussion of the
address setting, the first module is
reserved for setting addresses and
must be present in all cases. After it,
you can put together a chain of key-
pad modules.
Märklin S88 modules may also be
used for the keypad modules (see
Figure 7
).
The first module following the
address programming module has a
fixed address of ‘1’, the second ‘2’
and so on, up to ‘31’.
This approach has been chosen
for the sake of simplicity. Note that
Märklin S88 modules occupy two
GENERAL
INTEREST
40
Elektor Electronics
11/2002
Figure 5. Detail of the connectors fitted to the solder side of the board.
0
G4
R4
G3
R3
S88
1
2
3
G2
R2
G1
R1
4
5
6
7
EEDTS
train detection module
PCB 87291 - 8
020125-14
Figure 6. An EEDTS Pro keypad can be built using eight pushbutton switches and a
train detector module.
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