Please note that the following text describes the decoders and
controlling devices of the pre-mfx era, i. e. the märklin motorola system
components. They are now superseded by the märklin mfx system.
Introduction - Digital Model Railway Control
Undoubtedly Märklin has played a leading role in the introduction and establishment of digital control in the model railway business. Its proprietary Märklin/Motorola system has successfully survived the competition of various systems. The dominant alternative is the DCC/NMRA system introduced by Lenz, which has been adopted by model railway manufacturers like Arnold, Roco, and recently, Fleischmann. Other proprietary systems seem to be dying out gradually, like Fleischmann's FMZ, ZIMO's system, and SelecTrix.
There is one principal problem with proprietary systems. They are the idea of one company which tries to hide any technical details to prevent competitors to copy their intellectual property. Märklin is no exception. The märklin digital system is also known as the märklin/motorola system, because the data protocol used for information transmission is based on ICs by Motorola which were designed for remote control applications. In fact, these Motorola ICs are still used in decoders for turnouts, for example.
In general, any digital control system consists of transmitter devices, which the user is operating; and receiver devices, which process the received commands into actions. The information is carried over the rails by encoding the information into a signal, i. e. an appropriately shaped voltage. This mapping of information into a signal (the protocol) makes the difference between the various systems.
The transmitter devices, in the case of märklin, comprise a transformer as power supply, a central unit, which generates the electrical signal for the rails, and a control 80, where loco commands can be entered. Central unit and control 80 were two separate devices but are nowadays combined as one device, called control unit. Furthermore there is a keyboard, where turnout commands can be entered, an interface, to allow connection to a computer, and other devices. If the power output of the control unit is not sufficient for the whole layout, it has to be partitioned into several sections. A transformer and a booster is required for each new section. Here in the case of the märklin system, the user's control panels only produce a märklin/motorola signal. Other control panels may produce other system signals, like the Intellibox (märklin/motorola, DCC, Selectrix), the TWINCENTER (FMZ, DCC, Selectrix), or the software-based DDL (märklin/motorola, DCC).
The receiver devices are called "decoders". There are loco decoders inside the locos on the rails, and stationary decoders with momentary outputs for turnouts and permanent switching outputs to switch lights, for example. Some decoders understand several protocols, and most loco decoders also support the "analog" mode. "Analog" means you turn up the trafo, and all locos on the track go faster, they directly follow the analog voltage on the track. In the digital mode, the loco decoders listen to the digital signal on the rails, and interprete those commands addressed to them and act accordingly. Such action can be driving the motor, switching front lights, or activating additional functions, like smoke units, additional illumination, or sound effects. Of the multi-protocol decoders some automatically decide to which protocol to listen, others need to be configured to fix their current mode.
Thanks to many curious and smart people, the Märklin digital system
is no secret any more but piece by piece uncovered and explained.
By now the data protocol of the Märklin/Motorola is documented,
the circuit diagrams of Märklin's Delta and digital decoders are
reverse engineered, the schematics of turnout and permanent device
decoders are found, do-it-yourself instructions are available to
build your own devices cheaper than the originals. Other companies
offer equivalent devices and kits.
Since märklin digital has been brought to the market, märklin have developed various types of decoders. The following two pages focus on the decoders.
Usually, the model railway hobbyist thinks of märklin decoders by their
name (e. g. DELTA) or number (e. g. 60901). However, here I
specify the chips used in loco decoders. As some computer software, for example, requires a certain processor
(e. g. must be a 386 or higher), certain features of loco decoders require
certain chips on the decoders. However,
the presence of a chip is no guarantee that the decoder indeed offers the features.
The other decoder hardware might be inappropriate, and you have to do some soldering to
exploit all features.
list of märklin's most frequently used decoders, including different c80, c90, old and new DELTA decoders, and k83 und k84 accessory decoders.
With control unit I mean the "console" you use to control your trains, and maybe other accessories. Note that any märklin control unit can be combined with any märklin decoder, e.g. a 6021 central control can control a DELTA loco, a 6604 delta control can control a 37xxx high performance digital loco.
Central Unit, generates the old Motorola protocol. For loco control, control 80 units
can be plugged to the right. For turnout and accessories control, keyboards can be
plugged to the left. For computer interface, an interface can be plugged to the right.
Control Unit, with built in control 80f device. Generates the new Motorola protocol. For loco control, control 80 (6035) and control 80f (6036) unit can be plugged to the right. For turnout and accessories control, keyboards (6040) can be plugged to the left. For computer interface, an interface (6050, 6051) can be plugged to the right.
Control Unit, which addressed four locos (#10, #20, #30, #40)
and four turnouts (#253, #254, #255, #0). Equivalent to a 6020, generates the old Motorola protocol.
Control 80 units, keyboards, and interface can be plugged in.
Central Control, a 6020 with built in interface. Generates the old Motorola protocol. Control 80 units and keyboards can be plugged in.
Control Unit. With address selector switch. Addresses 4 Delta locos. Emits the old Motorola protocol. The external 6605 handheld (wired) control addresses a 5th loco. No control over loco function possible, function is always off. No control over turnouts possible. No computer interface possible. Max. output current approx. 2 A, rated power supply: 16 V AC, min 32 VA. The control unit can directly be used as a (low power) digital booster. The control unit can be modified to address a total of 16 locos, and control the function of the locos.
To use a 6604 as booster, you have to
These links illustrate how to control the function. Simply connect momentary push button switches to pins 25 and 26 of the main chip as shown. They differ in which pin is the on and off input. In my case the first version applies. Just try.
These links illustrate how to control up to 16 locos.
Control Unit. Successor of the 6604. Available in starter sets since mid of 2002. Similar to a 6604 delta control, but extended by a speed control knob. Thanks to the included speed knob with accompanying electronics, the 66045 controls the loco speed over the full range with less load dependence. With address selector switch. Addresses 4 Delta locos. Compared to the 6604, this one has an additional button to control the function (headlights) of digital (not delta) locos. The external 6605 handheld (wired) control addresses a 5th loco. No control over turnouts possible. No computer interface possible. The control unit can alternatively be used as a (low power) digital booster. Power rating is equal to a 6604. The control unit can be modified to address a total of 16 locos.
To use a 66045 as booster, you have to
Control Unit. With connectors for up to 4 handheld controllers. The hand controller addresses 4 Delta locos. Emits the old Motorola protocol. No control over loco function possible, function is always on. No control over turnouts possible. No computer interface possible. The only control unit for outdoor use. Max. output current approx. 2.5 A, recommended power supply: 16 V AC, 52 VA or higher. The control unit can be modified to control the function of the locos.
For infos on control 80 (6035), control 80f (6036), keyboard (6040), interface (6050, 6051), and booster (6015, 6017) check the following links:
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last update: 2004-02-21; webmasterbogobit.de