Basic Understanding
Change from Analogue to Digital
First learn how the command station, address, decoder and track signal work together and which parts of an analogue layout can remain in use.
Understand Digital Model Railways →
Understand command stations, decoders, protocols and networks
Digital Model Railways: The Basics Explained
How does a driving command travel from the handheld controller to the locomotive? What is the difference between locomotive decoders, function decoders, feedback modules and boosters? This overview guides you step by step through the most important digital model railway terms.
Control several trains independently on the same track
How Does a Digital Model Railway Work?
On a digital model railway, the track carries a coded control signal. The digital command station generates this signal from inputs made using a handheld controller, touchscreen, smartphone or computer. Every digital locomotive contains a decoder with its own address and responds only to commands intended for it.
Several locomotives can therefore operate independently on the same electrically powered track. Speed, direction, lighting, sound, couplers and other functions are controlled using digital commands. Traction power and control information are transmitted together through the track.
The command station alone does not create a fully automated layout. Accessory decoders operate turnouts and signals. Feedback modules detect occupied tracks or triggered contacts. Boosters supply additional power districts. Digital buses connect controllers, feedback modules and other system devices.
Digital protocols determine how commands are encoded. DCC, mfx and Motorola are particularly widespread. Selectrix remains in use on existing and specialist layouts. RailCom adds a feedback channel from the decoder to compatible DCC control equipment.
Wi-Fi and LAN, by contrast, concern the connection between the digital command station, handheld controller, smartphone, tablet or computer. They do not replace the track protocol. A Wi-Fi command station can be operated through an app while still transmitting DCC to the track.
Choose a suitable starting point for your knowledge level
Four Learning Paths through Digital Model Railways
Components
Distinguish Decoders and Layout Modules
This path explains locomotive decoders, function decoders, accessory decoders, feedback, boosters and digital buses using practical examples.
Discover the Components →Protocols
Compare DCC, mfx, Motorola and Selectrix
Learn why the decoder and command station must support at least one common digital protocol.
Compare Protocols →Mobile Operation
Understand Wi-Fi, LAN, Smartphones and Tablets
Learn the difference between the network connection, user interface, app, router and track signal.
Understand Mobile Control →
Sixteen coordinated basic topics
All Digital Model Railway Topics
Begin with the general operating principle or open the explanation of the component or digital protocol you are looking for directly.
Complete System
Digital Model Railways Explained Simply
Addresses, driving commands, decoders, multiple-train operation and the difference between analogue and digital operation.
Recommended Starting Point
Open the Basics →Control
How Does a Digital Command Station Work?
Generating the track signal, managing locomotives, programming tracks, accessory control and connections to controllers and modules.
The Heart of the Layout
Understand the Command Station →Vehicle Control
What Is a Locomotive Decoder?
Installation position, motor control, locomotive address, lighting functions, interfaces and selection by motor current and vehicle size.
Motor and Locomotive Functions
Explain Locomotive Decoders →Coach Functions
What Is a Function Decoder?
Digital interior lighting, tail lights, couplers and special functions in driving trailers, passenger coaches and functional models.
No Regulated Motor Output
Explain Function Decoders →Layout Accessories
What Is an Accessory Decoder?
Control turnouts, signals, uncouplers, servos and lighting using digital accessory addresses.
Check the Output Type
Explain Accessory Decoders →Layout States
What Is a Feedback Module?
Detect track occupancy, contacts and sensors and report them to the command station or model railway software.
The Foundation for Automation
Explain Feedback →Track Power
What Is a Booster?
Provide additional power and divide the layout into separate power and short-circuit districts.
No Additional Addresses
Explain Boosters →System Connections
What Is a Digital Bus?
LocoNet, XpressNet, s88N, R-Bus, CAN and ECoSlink connect controllers, feedback modules, boosters and other devices.
The Connector Alone Is Not Enough
Explain Digital Buses →Compatibility
Digital Protocols Compared
Compare DCC, mfx, Motorola and Selectrix by addresses, registration, feedback and typical system environments.
Match the Command Station and Decoder
Open the Protocol Comparison →Two-Rail and International
DCC Explained Simply
Addresses, speed steps, CV programming, accessory commands, multiple-unit operation and cross-manufacturer use.
Widely Used Standard
Understand DCC →Automatic Registration
mfx Explained Simply
Locomotive registration, function symbols, mfx+, the Märklin system and differences from DCC and Motorola.
Focus on Märklin
Understand mfx →Historic Märklin Format
Motorola Explained Simply
Addressing, older Märklin decoders, solenoid accessories and use with modern multiprotocol command stations.
Important for Existing Layouts
Understand Motorola →Compact Digital System
Selectrix Explained Simply
Selectrix vehicles, the system bus, address space and the protocol’s importance for older N and multiprotocol layouts.
Particularly Relevant to Existing Systems
Understand Selectrix →Feedback through the Track
RailCom Explained Simply
Return decoder information, detect locomotive addresses and understand the RailCom cutout and suitable detectors.
An Extension for DCC
Understand RailCom →Networking
Wi-Fi and LAN for Digital Command Stations
Distinguish between routers, access points, network cables, IP addresses, range and stable connections to the command station.
Do Not Confuse It with a Digital Bus
Open the Network Basics →Mobile Control
Control a Model Railway with a Smartphone or Tablet
Combine apps, virtual throttles, track diagrams, Wi-Fi handheld controllers and computer programs effectively.
The App and Command Station Must Match
Open Mobile Control →
Distinguish the purpose, installation location and direction of data
Digital Components Compared Directly
| Component | Typical Installation Location | Main Purpose | Most Important Selection Criterion | Read More |
|---|---|---|---|---|
| Digital Command Station | Operating position or technical area | Generate commands and manage the system | Protocols, output, buses and operation | Command Station |
| Locomotive Decoder | Locomotive or railcar | Control the motor and vehicle functions | Interface, dimensions and motor current | Locomotive Decoder |
| Function Decoder | Coach or functional model | Switch lighting and auxiliary functions | Outputs, voltage and interface | Function Decoder |
| Accessory Decoder | Under or beside the layout | Operate turnouts, signals and accessories | Pulse, continuous current, servo or relay | Accessory Decoder |
| Feedback Module | At track sections and contacts | Report states back to the control system | Detection method and feedback bus | Feedback |
| Booster | Between the command station and track district | Amplify the digital track signal | Booster bus, voltage and output current | Booster |
| Digital Bus | Between system devices | Transmit commands and feedback | Protocol and electrical pin assignment | Digital Bus |
Remember: A locomotive decoder controls a vehicle,
an accessory decoder controls stationary accessories, a feedback
module sends information back and a booster supplies additional
power. The digital bus connects these system devices.
Go directly to the appropriate basic guide
Which Question Would You Like to Answer First?
From a finger on the throttle to an occupied block section
How Commands and Feedback Flow through the Layout
1. Operating Device
A handheld controller, touchscreen, smartphone or computer generates the required driving or switching command.
2. Digital Command Station
The command station converts the input into a digital protocol supported by the decoder.
3. Booster
The power stage provides voltage and current for the respective track district.
4. Decoder
The locomotive or accessory decoder recognises its address and executes the received command.
5. Feedback Module
A current detector, contact or sensor recognises a state on the model railway layout.
6. Digital Bus
The report travels through the appropriate bus to the command station or control software.
Consider size, voltage and current together
Digital Technology for Z, N, TT, H0, 0, 1 and G
Gauges Z, N and TT
Small vehicles require particularly compact decoders. Installation space, component height, motor current and a low track voltage are more important than the highest possible booster output.
Common Interfaces
Next18, NEM 651, PluX12 and PluX16.
H0, H0e and H0m
H0 offers the widest selection of locomotive, sound and function decoders. Centre-stud and two-rail systems affect the vehicle version and feedback technology.
Common Interfaces
PluX22, 21MTC, NEM 652, Next18 and specialist circuit boards.
Gauges 0, 1, G and IIm
Powerful motors, sound, lighting and smoke generators require high-capacity decoders, heavier wiring and clearly separated power districts.
Common Connections
Wires, screw terminals, large-scale interfaces and system circuit boards.
Compatibility before the number of functions
Select Digital Components in Six Steps
Step 1
Identify the Track System
Record whether the layout uses two-rail or centre-stud track and note the gauge.
Step 2
Record the Protocols
Note DCC, mfx, Motorola and Selectrix in the existing vehicle fleet.
Step 3
Check the Interfaces
Never choose a decoder solely by the number of pins or a product photograph.
Step 4
Calculate the Current Requirement
Consider the motor, sound, lighting, smoke and accessories realistically.
Step 5
Plan the Bus and Network
Select feedback modules, controllers and interfaces that suit the command station.
Step 6
Test Each Component Individually
Test a locomotive, turnout and detection section before completing the full expansion.
Avoid misunderstandings and unsuitable purchases
Common Mistakes When Getting Started with Digital Technology
Assuming All Digital Products Are Compatible
The decoder and command station must support at least one common protocol.
Using a Function Decoder as a Locomotive Decoder
Without a regulated motor output, it cannot control a powered locomotive.
Choosing an Accessory Decoder Only by Its Output Count
Solenoid mechanisms, motors, servos and lighting require different outputs.
Failing to Match the Feedback Module to the Track System
Current detectors and common-ground contacts require different wiring.
Electrically Bridging Booster Districts
Incorrect connections cause short circuits and equalising currents.
Assuming Every RJ45 Connector Is Ethernet
s88N, LocoNet and other buses are not ordinary LAN connections.
Decoders, switching modules, feedback modules and boosters
Suitable Products for Digital Model Railway Basics
This selection contains 26 products for different gauges and tasks. The interface, voltage, current capacity, protocol and system bus must be checked before purchasing.
Gauges Z, N and TT: Compact Vehicle Decoders
Small designs for restricted installation spaces, low motor currents and compact interfaces.
Miniature Locomotive Decoder
ZIMO MN150N
Compact driving decoder for very small installation spaces.
View Product →
Multiprotocol Decoder
ESU 59814 LokPilot 5 micro
Compact locomotive decoder for suitable N and TT vehicles.
View Product →
TT Driving Decoder
Tillig 66035 PluX12
Suitable locomotive decoder for compatible TT vehicles.
View Product →
TT Function Decoder
Tillig 66031
Digital auxiliary functions in suitable TT vehicles.
View Product →
Next18 Function Decoder
PIKO 56518 PSD XP 5.1 F
Compact function decoder for suitable coach circuit boards.
View Product →H0, H0e and H0m: Locomotive and Function Decoders
Decoders for common H0 interfaces, vehicle functions and higher current requirements.
PluX22 Locomotive Decoder
PIKO 56500 PSD XP 5.1
Multiprotocol decoder with modern motor control.
View Product →
21MTC Multiprotocol
ESU 59619 LokPilot 5
Motor control and numerous vehicle functions.
View Product →
Function Decoder
ESU 59210 LokPilot 5 Fx
For driving trailers, lighting and models without a motor.
View Product →
Six Function Outputs
Uhlenbrock 76800
Switches, dims and flashes lighting functions.
View Product →
High-Power Locomotive Decoder
Uhlenbrock 77200 ID2
For vehicles with increased motor and function output requirements.
View Product →Gauges 0, 1, G and IIm: Robust Large-Scale Technology
Powerful vehicle and layout modules for large motors, lighting, accessories and outdoor railways.
Large-Scale Functions
Massoth 8152620 4FXW
Digital lighting and auxiliary functions in large-scale vehicles.
View Product →
Large-Scale Switching Decoder
Massoth 8156110 4K III
Four channels for turnouts, signals and lighting.
View Product →
Large-Scale Feedback
Massoth 8170010 FB Module
Detects contacts for train reporting and automation.
View Product →
Energy Storage
Massoth 8151321 Powercap 2300
Bridges short interruptions in current collection in large-scale vehicles.
View Product →All Gauges: Accessory Decoders, Feedback Modules and Boosters
Stationary modules for turnouts, signals, occupancy detection, feedback and additional power districts.
Solenoid Accessory Decoder
PIKO 55032 SD 2000
Controls turnouts, signals and suitable lighting.
View Product →
Eight-Output Accessory Decoder
ESU 51831 SwitchPilot 3 Plus
Configurable outputs and local OLED operation.
View Product →
Märklin Switching Module
Märklin 60832 m83
Controls up to four turnouts or other solenoid accessories.
View Product →
Six-Output Accessory Decoder
Lenz 11150 LS150
Controls turnouts, signals and other accessories.
View Product →
Z21 Feedback
Roco 10819 Detector X16
Detects multiple track sections and contacts.
View Product →
Multiple-Bus Feedback
YaMoRC YD6016LN-CS
Sixteen current-sensing inputs for two-rail layouts.
View Product →
LocoNet Feedback
Uhlenbrock 63320
Monitors eight two-rail track sections.
View Product →
Contact Feedback
Viessmann 5217
Feedback module for contacts and automated sequences.
View Product →
Z21 Power Expansion
Roco 10805 Z21 Booster
Additional power district with RailCom support.
View Product →
SmartControl Booster
PIKO 55827 SmartBooster
Expands a compatible SmartControl WLAN system.
View Product →
Universal Booster
YaMoRC YD7403
Galvanically isolated power expansion for digital layouts.
View Product →
ECoS Power District
ESU 50012 ECoSBoost
Powerful booster for the ESU system.
View Product →
Apply the basics and classify products
Related Categories and Further Guides
Answers for getting started digitally
Frequently Asked Questions about the Basics
What do I need for a digital model railway?
A digital command station, a suitable power supply and locomotives with compatible digital decoders are required. Accessory decoders and feedback can be added later.
Can an analogue locomotive run on a digital layout?
This depends on the system and is not generally recommended. Fitting a locomotive decoder that is compatible with the command station is the safer solution.
What is the difference between a locomotive decoder and a function decoder?
A locomotive decoder has regulated motor control. A function decoder switches lighting or auxiliary functions but does not control a traction motor.
Can one accessory decoder control every turnout?
No. Twin-coil mechanisms, motor-driven mechanisms and servos require different output signals and switching times.
When is a feedback module required?
Feedback is important for staging yards, block operation, train tracking, automatic routes and computer control.
When do I need a booster?
A booster is required when the command station does not provide enough power or the layout should be divided into several separate short-circuit districts.
Does a booster increase the number of locomotive addresses?
No. A booster only increases the electrical power available for the digital signal.
Are all digital buses compatible with one another?
No. LocoNet, XpressNet, s88N, R-Bus, CAN and ECoSlink use different protocols and electrical pin assignments.
What is the difference between DCC and mfx?
DCC is a widely used digital protocol supported by many manufacturers. mfx is particularly closely associated with Märklin command stations and automatic locomotive registration.
What does RailCom provide?
RailCom allows compatible DCC decoders to return data through the track. Suitable detectors are required for location-specific identification.
Are Wi-Fi and LAN digital protocols?
No. Wi-Fi and LAN connect operating devices or computers to the command station. DCC, mfx or Motorola is then transmitted to the track.
Can I control the model railway using only a smartphone?
An app can replace a handheld controller but not the digital command station and its track output. The command station, app and network must be compatible.
Organised by Technical Function
The overview separates vehicle decoders, layout modules, digital protocols, system buses and network connections according to their actual purpose.
Update Date
Content status: 17 July 2026. Consult the current instructions, voltage specifications and compatibility information before installation and connection.
From Digital Basics to a Complete Model Railway Project
The main guide connects digital technology with gauges, layout planning, track, scenery, vehicles, repairs, maintenance and garden railways.