Layout Command Control

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See the Video.

Summary: An NMRA standard for a Layout Command Control bus. This provides a communications protocol which adds additional capability to your layout. Doing for accessories what DCC does for the track. LCC does not replace DCC, but enhances it.


Layout Command Control (LCC) is a peer-to-peer (computing device to any other computing device on the network) system for controlling all of the functions on your layout unrelated to how fast the locomotive is moving -- things like signals, turnout control, or layout lighting. Layout Command Control is the NMRA approved portions of the OpenLCB protocols.

The purpose of LCC standard is to not only take the load off the DCC bus with respect to signaling, turnout routing, and other aspects of operations not related to control of locomotives, but to provide bi-directional access to the system. With a few minor exceptions, the DCC system is not suitable as a two way network. When the DCC Protocols were designed in the early 1990s, no one foresaw applications like sound, multiple engine consists, stationary decoders controlling signals, signal systems and detection using the track or proprietary throttle buses. This has led to congestion on the network, delaying commands getting to their recipient.

What is the Purpose of Layout Command Control?

LCC is designed as a separate, generic control bus which is positioned to take the load off your throttle bus. It is a bi-directional data bus that can send and receive data.

Since it is an NMRA Standard, you are not confined to one manufacturer's products. Any manufacturer can make LCC compatible devices.

What Is Layout Command Control?

Layout Command Control is a Common Language

Layout Command Control is a common language for various layout elements to communicate with each other

Layout Command Control is a layout control bus standard

  • Endorsed by the NMRA
  • Open, and available royalty free to all manufacturers
  • Based on modern technology that is robust, fast, and easy to use
  • LCC over the CAN Bus is an order of magnitude faster than DCC
  • Robust, with noise immunity, which only requires simple wiring

Why is Layout Command Control Better?

Layout Command Control is not dependent on Digital Command Control. For example, it can operate with analog or Märklin (Alternating Current) layouts, nor is it locked to your brand of DCC system.

Plug and Play!
  • No Addresses to configure
  • No accidental duplication of messages
  • Easy to understand interface

Layout Command Control is Future Proof

A future proof protocol protects your current investment.


Present: CAN Bus


  • WiFi
  • LCC scales from two boards to thousands of modules. LCC can be routed to other networks
  • LCC Gateways can connect Lenz, NCE Digitrax and other throttles to a common network.

Layout Command Control Wiring


  • Noise immunity, error correcting
  • Power for small Nodes
  • Up to 40 nodes per segment
  • Cable runs up to 300m (1000 ft) using CAT5 cables

Gateways and Repeaters

  • Allows multiple bus segments to be networked together
  • Interface to legacy systems
  • Optional: Backbone network via Ethernet or WiFi.
Future Possibilities

Many things are possible with Layout Command Control. The following would require manufacturers or third party developers to create them and offer them on the market to LCC users:

  • Legacy Bus: Connections to LCC from your existing throttle bus network
  • Make your legacy boards appear on the LCC Bus
  • Additional applications for tablets or smartphones
    • Panels
    • Accessory Control
    • Throttles


As an NMRA Standard, all LCC products meeting the standard should be interoperable, so you can deploy different manufacturers’ products in one LCC setup.

Will Layout Command Control work with Digital Command Control?

Absolutely! Layout Command Control and Digital Command Control are totally compatible. You do not need to replace your DCC system.

Digital Command Control on the Track, Layout Command Control beside the Track!

Layout Command Control can enhance Digital Command Control. Layout Command Control is takes some of the workload from your Digital Command Control setup, meaning it can run smarter and faster. Whatever Digital Command Control system you use, Layout Command Control will work with it.

There is no need to abandon a perfectly good DCC system, it can co-exist alongside with any Layout Command Control system, independently or interconnected.

Layout Command Control will work alongside AC, Analog DC, DCS, TMCC, etc.

Will Layout Command Control work with an Analog Direct Current layout?

Yes. Layout Command Control will work with an analog layout.

In fact, it supports not only Digital Command Control, but also Analog (Direct Current), PWM, Marklin and other systems.

What are some of the Layout Command Control Compatible Systems

LCC is bridgeable to CBus, ATbus, Loconet, XpressNet, NCE, C/MRI, etc.

What Other Features Does Layout Command Control Offer?

  • Transport Agnostic: it works on Ethernet, Wifi, RF, CAN, RS-422/485, etc.;
  • Sympathetic to the unique challenges of modular and large layouts;
  • Simple for the novice: plug and play, no setting of IDs or addresses, push-button programming;
  • Discoverable: A user can find out what devices are connected, and how they’re configured;
  • Expandable and extensible: new functionality to be added easily.

To do this, LCC has:

  • No central control: a computer may optionally be attached to aid in configuration, debugging or operations, but is not required for the system to work;
  • Preassigned IDs: world-wide unique – so no address conflicts;
  • Large IDs: large enough to accommodate legacy addresses and future systems;
  • Events, Datagrams, and Streams: to handle small, medium and and continuous messages;
  • System Messages dealing with system-level processes such as node announcement, description, and status.
  • Internet-based routing and filtering.
  • Self-description and self-documentation: stored on the node;
  • Orthogonal protocols: new ones can be added easily.

What can I do with Layout Command Control?

Anything. LCC is designed to be used for almost any task you can dream of.

LCC is compatible with DCC, and even Analog layouts can implement LCC for their purposes. It doesn't replace DCC, it enhances it. Signalling systems, structure lighting, and even room lighting can be controlled using LCC devices, present and future. LCC was designed with a capacity ten to a hundred times greater than the typical throttle bus, making things possible without sacrificing performance.

What is Required to Get Started with Layout Command Control?

LCC-compatible devices. Designed for LCC, based on the LCC Standard. Devices are now becoming available, see below, and should cost about the same as other system's devices. Also, it should be easy to implement on your layout.

What will you use LCC for?

The LCC Channel #2 The Minimum LCC System

This is a recording of an online Zoom meeting I did on Sept 3, 2020 to the Sunrise Division NMRA club in Aurora, CO. The presentation is a basic introduction to LCC: the background, pieces, and implementation. LCC, Layout Command Control, is a control system for model railroad layout accessories and controls.

Controlling Turnouts with LCC

LCC - Best Way to Move Points

Availability of Layout Command Control Devices

Main article: Layout Command Control/Devices

As of Jan 2016 LCC compatible devices are becoming available. The best way to encourage more LCC devices is to ask the manufacturers what they plan to do, and if they plan to make the devices you want.

Layout Command Control Compatible Devices

LCC is extremely flexible and easily adapted to a wide variety of products. Virtually anything you imagine could be implemented with LCC.

  • signal systems,
  • intercoms,
  • structure lighting,
  • room lighting

Why was Layout Command Control not Integrated into Digital Command Control?

The DCC command bus was designed to carry repetitive mobile decoder commands and occasional accessory commands in one direction only. The LCC bus is designed to carry individual commands, at high speeds, in both directions. This allows it to accommodate many more commands. When DCC was created a low volume unidirectional bus was considered adequate, and most systems were not even very demanding of that bus. The LCC bus was designed for a lot more capacity, in both directions, giving it ten to a 1000 times more throughput and flexibility.

Programming and Layout Command Control

Yes, some configuration is usually required, but the developers learned some valuable lessons from DCC programming frustrations.

Instead of cryptic CV numbers and bit values, the LCC is designed to be configured using plain language option names with understandable values in the data fields, either directly entered by you, or selected using drop-down menu options.

Further Reading

If you want to know more, read the LCC FAQ posted by the NMRA. The LCC standard was and is being developed in public by the OpenLCB group. Further protocols are being actively developed, and may be adopted by the NMRA as part of LCC in the future. Because OpenLCB is designed as a family of protocols which are independent, the addition of new protocols should be straight-forward, and maintain backwards compatibility. Please refer to the OpenLCB website for the latest developments. A discussion group is maintained at OpenLCB chat.

The NMRA Standards and Technical notes are available as a Zip file.

The NMRA also has video on LCC on their website. (Introduction to Layout Command Control (LCC) Presented by Balazs Racz, David Harris and Stuart Baker, 2016 National Convention - Indianapolis, IA)

Available Layout Command Control Devices


RR-CirKits has announced several LCC products which are available for sale now.

LCC Buffer-USB

It will allow you to directly connect a CAN bus to your computer.


  • NMRA CAN bus LCC to USB interface.
  • 2,500 Volt Digital isolation between CAN bus LCC and USB port.
  • Simplify your LCC configuration and/or use a PC based CTC. Compatible with JMRI and other software.
  • Type B USB connector for computer connection.
  • Dual RJ45 connectors for LCC loop through connections.

Read the flyer here.

Signal LCC

The Signal LCC is a specialized signal driver board with these features:

  • 16 lamp drivers. Selectable CA or CC polarity LEDs.
  • 8 general purpose input/output lines. Each line can either be programmed to be an output, or as an input.
  • 32 logic cells. These can be programmed to calculate signal aspects, perform specialized processing, and/or control the lines on this or other products.
  • 8 Mast control circuits, each of which can convert 8 signal rules into the required aspects for your rail road. Each aspect can use up to 4 of the available output drivers.
  • 8 Coded Track Circuits which allow pairs of Tower-LCCs and/or Signal LCCs to easily link together and coordinate their functions.

Read the manual here.

Tower LCC

The Tower LCC allows you to control accessories on your layout, and has the following features:

  • 16 general purpose input/output lines. Each line can either be programmed to be an output, with settable characteristics, such as flashing, or as an input to connect to a push-button, switch or touch control.
  • 32 logic cells. These can be programmed to perform specialized processing, and can control the lines on this or other products.
  • 8 Coded Track Circuits which allow pairs of Tower-LCCs and/or Signal LCCs to easily link together and coordinate their functions.

Read the flyer here.

LCC Power Point

Supplies regulated power to the LCC bus. Read the flyer here.

LCC CAN bus Terminator

Each LCC bus must have a terminator at each end. The RR-CirKits terminator includes indicators showing bus power and bus activity. Read the flyer here.

LCC - LocoNet Gateway

This device allows you to connect your LocoNet to an LCC network.

  • Two LocoNet ports
  • Two LCC ports (RJ45)
  • One USB port (for LCC network only)

Powered by an external DC power supply or an external CAN Bus repeater.

Read the manual for more details.


  • 2016.02.20 LCC Standards Documents fully accepted at the winter NMRA Board meeting. Firmware Upgrade and an enhanced CAN Physical standards have been accepted for public comment. The physical layer adds a low level DCC signal.
  • 2015.02.26 NMRAnet has be renamed to LCC. The first set of documentation has been presented to the NMRA Board, and is now open for comment. See NMRA Standards at
  • 2012.08.27: NMRAnet is a new standard for a Layout Control Bus (LCB) that is used to control MRR accessories. It is being developed by modellers for modellers in public at It is agnostic towards transport and motive power. It will use different transports, including CAN and Ethernet, and interface to DC, PWM, and DCC. The National Model Railroad Association will adopt a version of it in the future as S-9.7 NMRAnet. Progress can be monitored at
  • The NMRA Board of Directors adopted the first set of standards documents which standardize the physical specifications of the NMRAnet as implimemented on CAN.

See NMRAnet Physical Layer

2011.11: UPDATE: NMRAnet is to be based on the work of the OpenLCB group and labeled as S-9.7. The last two NMRA magazines had brief notices:

NMRANET standard adopted

The board heard updated presentations for two versions of the definition of the physical layer of the layout control bus called NMRANET. In a change from its position at the winter BOD meeting, the Board selected S-9.6.1, but the final approval must await Board review of the final wording of the new Standard.
The Board thanked the developers of both versions, which were led by Don Voss and Bob Jacobsen. They and their teams contributed countless hours of development work toward NMRANET, and Digital Command Control users as well as the model railroad industry as a whole will greatly benefit from their efforts. Several manufacturers have been waiting for this new Standard so they can adopt it for their product lines.


Stephen Priest writes in Observation Car:

Train Hibernation Time

Changing gears a little, I want to thank the members of the NMRANet team that I am privileged to be working with. The BOD had enough faith in me to make me co-chair with Karl Kobel of the NMRANet working group. We are tasked with taking the working groups drafts, concerns and progress to the board. For those wondering what in the world I am talking about, NMRANet is a communications protocol (system) that can be used to control most non-train devices on your model railroad. The idea is to split off turnout control, signal operations, and the like onto a separrate bus to free up train control and onboard sound. Currently identified as Standard 9.7, this is an ongoing open effort to pool resources, minds, and ideas. The working group creates documents that are then approved by the BOD as Standards and Recommended Practices. This cooperation is occuring between NMRA and the OpenLCB group. The effort is being driven by people who have been involved academically and professionally in designing networks that are intended to scale and intended to be flexible enough to serve for many years to come.

Additional Information

  1. More about the CAN Bus: Control Area Network
  2. Concepts and Terms: LCC Concepts
  3. OpenMRN: Software implementation of LCC