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Decoder classes

The full functionality of the Qdecoder goes far beyond the usual, and is not required by all applications. Thus there are decoder versions with a reduced feature set compared to the 'all-in-one' decoder. So far there are the following classes of Qdecoder:

'All-in-one' - class +
These decoders support the full scope of the remarkable programming potential of the Qdecoder-world. They are prepared for (almost) every operation purpose and can be adjusted, for example via Qrail, but also with any controller via CV-programming.

Additionally to the standard-class decoders the 'all-in-one' decoder offers the following features:
  • Free programming (including re-configuration during operation) via CV-ranges (Qfunction-definitions).
  • Sequence control
  • Programmable complex signal aspects
  • Prepared CV-sets for the most common types of signals for download.
Standard-class (none)
These decoders offer the full feature set of functions that are adjustable with 'standard'-CV (and by this already exceed the 'usual'). Standard-decoder are able to:
Qdecoder of the standard-class can be upgraded to Qdecoder of the 'all-in-one'-class.
N These simple decoders offer basic functionality for solving frequently occurring standard tasks. { 
(e.g. switching of turnouts and signals)


To configure the 'all-in-ones' is a tasks for a skilled hobbyist.

For example, the Z1-8+ has over 470 configuration variables which all influence the behaviour of the decoder.

If you don't want to 'play' with the decoder and prefer 'playing' with the model railway, it is recommended to buy pre configured decoder (or a decoder of the standard or basic class)

If you like to experiment than the 'all-in-one' is the right for you.

Naming conventions of the Qdecoder

The decoder can be distingished by the type identifier, which consists of three or four parts. Examples are

F1-2, Z2-8N, Z1-16+, ...

The leading letter characterises the basic functionality of the decoder:

F Function decoder
are decoders with function outputs which are only connected to the tracks. These decoders feature a slimline design.
Function decoders do not have a locomotive engine connection. They are often 'riding' decoder, but can of course also be used stationary.
Z accessory decoder
are decoders for the stationary installation on the model railway. They can - depending on the class - control different electronic accessoires.
They often draw their energy from an accessory transformer in order to save 'expensive' digital energy, while receiving information from the tracks. However, they can also be supplied entirely from the tracks.
Accessories decoder do not have a locomotive engine connection and are bigger than function decoder.
L locomotive decoder
are decoders with function output and locomotive engine connection.

The first number defines the type of function outputs of the decoder:


The decoder has only 'normal' function output for lamps, LEDs, turnout switches and so on (The outputs can only be activated or deactivated.)

In addition to normal function outputs this decoder has bivalent function outputs. Servo motors or motor driven turnout drives can be switched between two of such function outputs. Another use case is an alternative red/green light signal per function output.

Another number after the hyphen defines the overall number of function outputs for function and accessories decoder. For locomotive decoder it describes the connector type:

Accessories decoder with 8 function outputs.
Locomotive decoder with 'normal' function output and 6-pin NMRA-connector
L1-8 Locomotive decoder with 'normal' function output and 8-pin NMRA-connector
Any final specifier describes the decoder class according to the table above.

Important decoder types are

  • Qdecoder Z1-8 - Decoder with eight function outputs, e.g. to control 4 turnouts
  • Qdecoder Z1-16 - a flexible decoder module with sixteen function outputs
  • Qdecoder Z2-8 - a decoder module with eight function outputs for the control of motors, motoric turnout drives and light signal that switch the LEDs between different function outputs (new Viessmann-series)
  • Qdecoder F1-2 - a simple decoder module with two function outputs.
  • Qdecoder F1-5 - a flexible decoder module with five function outputs.
  • Qdecoder L1-6 - a standard locomotive decoder with 6-pin NMRA-connector
  • Qdecoder L1-8 - a standard locomotive decoder with 8-pin NMRA-connector

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