RailCom FAQ - Spring 2004

RailCom® - Advanced DCC Model Railroad Control

Lenz GmbH first presented the concept for RailCom at the Spring 2000 meeting of the NMRA DCC Working Group. Recognizing that the NMRA DCC Working Group has been working for several years to find a suitable solution for two-way communication in the DCC environment, Lenz GmbH has developed a new technology which the NMRA is using as the basis of a new NMRA set of Recommended Practices, that integrate two-way communication into the NMRA DCC environment. Release of Digital plus products that incorporate RailCom will wait to provide some more time for the NMRA to fully test and specify it's full two way communication protocols. 

What Can RailCom do?

What components do I need to implement RailCom?

There are three components needed to achieve the benefits of RailCom

1) Bit Cutout Device - RailCom transmits during a very brief period when no power is on the layout.  To generate this transmission window you will need a device that removes (or cut outs) either 2 or four preamble bits.  You need one of these devices per power district. The most cost effective way of doing this is inside the power station (booster).  Our LZV100 and LV102 units already have the cutout device incorporated and all you need to do is activate it.  For older units you will need a to add a cutout device between the power station and the track.

2) Decoders that transmit - Our Gold decoders will be our first decoders that transmit RailCom information.  Other manufacturers such as Zimo have also announced decoders that transmit the same information.  NMRA DCC RPs define the interchange standards so any manufacturer can choose to implement the same features.

3) RailCom detector -  This device reads the information that the decoders transmit.  You can achieve a lot of benefits with only one detector per power station or chose to place detectors around your layout.

What will RailCom cost?

Cost is a key design criteria for RailCom.  Additional decoder cost is pennies and the detectors are being designed to be very affordable and a breeze to install and use.  Best of all, unlike other approaches, you do not need a vast number of detectors and a complicated network to reap the vast benefits of RailCom.

Doesn’t RailCom rely on patented technology?

Absolutely!  We have been granted a US patent for much of the RailCom technology and have patent applications in for the remainder.  We have donated this technology to the NMRA DCC WG for use in advancing DCC technology.  We did this because we believe very strongly in advancing DCC and feel that open technology is the only way to preserve your hobby investment. All NMRA DCC manufacturers will be able to use this technology in their NMRA DCC products free of any licenses.

Why is Lenz releasing this technology to the NMRA DCC Working Group?

Three reasons.

1) The future of multi-manufacturer DCC depends on all manufacturers working closely with the NMRA DCC Working Group to enhance DCC in an orderly fashion. To fully realize the full potential of RailCom will require multiple manufacturers to implement the protocols.

2) To gain the full potential we will need some additional packets and we feel that these should be created in a joint fashion.

3) NMRA DCC is not a static control system, but one which can grow for many years to come.  To gain the benefits we have all enjoyed for the future means that we must plan for the growth now. 

But don't you loose your competitive advantage by releasing your intellectual property to the NMRA DCC Working Group?

We have no problems competing in an open market. We believe that standards help the overall market grow and as the market grows we also grow.  While it is true that we have invested a lot of time and resources into the development of RailCom, we believe our investment can best be realized by worldwide adoption of this technology.

What if the NMRA DCC Working Group changes the technology?

No problem. Over the years we have worked closely with the committee and the result is a much better approach. When the NMRA improves on the technology, then of course we will adopt it.

How does it work?

RailCom works on the concept that a decoder is sent a packet requesting information and the decoder then responds by encoding 3 bytes of information that is transmitted during the first part of the preamble.  This allows transmission of much more than just a simple yes/no answer.  For example, we can send a speed packet and receive back the actual voltage level being sent to the motor by a back-emf decoder. This allows the command station to understand the load that the train is pulling and allows it to adjust the operation accordingly. For the first time the locomotive engineer will be able to feel the load that the train provides.  

Is RailCom the same as Transponding?

Transponding is a technology where a device constantly sends out its identity and a receiver can determine the identity of the transmitter, if it passes near the receiver. This technique is used today in full scale railroads. Several model  manufacturers have developed  transponding technology which can be used with any model railroad control system. (DC, AC, or DCC).  Currently another DCC manufacturer is using this same commonly used term to refer to what the NMRA DCC refers to Operations Mode Acknowledgement.  RailCom also performs this same function but it is much more as it also provides the ability for the decoder to send a lot of data..

Will RailCom work with all DCC systems and all existing product?

RailCom has evolved over the years and there is a lot of the negative marketing information others have put out refers to earlier designs.  As we have evolved the approach it has improved greatly.  RailCom is not fully compatible with all decoders and systems that actually implement the NMRA DCC specifications.  RailCom now has two modes. A simple mode with 2 bit cutout for older systems and a full 4 bit cutout mode for systems built to generate the additional preambles as specified in RP-9.3.1.

Can I still use my existing Decoders?

Any decoder that actually follows S-9.1 and S-9.2 will have no problems on a RailCom equipped layout.  This includes all motor drives including high frequency motor drives. One reason we promote NMRA conformance so highly is that we want to ensure that our products will never have problems with any future NMRA DCC evolution.  However, not all product in the market have NMRA warrants and some product in the market does not actually follow the existing DCC standards.  In 2002 we worked with the NMRA DCC WG to identify products that had problems.  Most fixed the problems and will offer upgrade options for effected products.  One manufacturer has not fixed the bug in their products and we are currently working on approach to handle this problem.

Will RailCom increase the cost of decoders?

The first decoder with RailCom (ZIMO's in market now) actually costs the same as the replacement without RailCom.  RailCom costs about 0.03 cents in additional parts for the decoder and more software.  The micro-processor used in the decoder has to have enough power for the additional functions.  Fortunately these new micros are now available at no increase in cost.

What about operation with a non decoder equipped locomotive?

RP-9.3.1 requires that all loads connected to the DCC track be protected by a rectifier.  All NMRA DCC decoders have this component as part of their normal design but a locomotive without a decoder does not.  Placing a locomotive without a decoder on a DCC track causes the motor to whine and heat up which is not all that friendly to the motor.  To correct both problems and to also eliminate any RFI noise that a DC motor can generate, we developed a very small and simple circuit that is inserted in one of the motor leads.  This circuit will be required if you desire to operate a non decoder equipped locomotive and receive information back from the decoder at the same time.  We are sharing this circuit with the locomotive manufacturers as it is less costly to incorporate than the existing capacitors and inductors they use for RFI suppression.

Does this mean I will have to add rectifiers to my existing lighted passenger cars?

It depends.  With RailCom you have a budget.  Each unprotected load consumes a part of this budget. Block occupancy detectors and resistor wheel sets also consume part of this budget.  On a typical layout that does not use resistor wheel sets and older bock occupancy detectors you likely will not need to do anything with your lighted passenger cars. However if you are near the edge of the budget, adding a few diodes will improve the lighting and allow the budget to be used elsewhere.

Will all new products incorporate RailCom?

Eventually all our advanced products will. However, we expect  there will still be a large market for low end products that do not incorporate these features.  Like all features the end modeler gets to choose which futures they desire.

What about my existing Power Stations?

RailCom detectors can either be integrated into power stations or left as an external device. Testing done by the NMRA to date has not found a problem with any existing DCC power station on the market. 

To get the full advantages of RailCom won't I need a new Command Station?

It depends.  Many of the RailCom features will be available through add on devices which work with all existing DCC Command Stations on the market.  But to get the full advantages of the capabilities of RailCom you will need new command station software.  We first released our popular line of command stations in 1993.  Since then it has always been our policy to keep our systems up to date by releasing low cost software and hardware upgrades.  We do this to protect your hobby dollar investment.  We will continue this tradition with the release of RailCom.

Does RailCom infringe on any other Patents or Intellectual Property?

None that we are aware of.  Patents currently exist for a variety of detection schemes which are not used by RailCom detectors.  One of the reasons we submitted patents for this technology was to ensure that we did not infringe on any existing technology.

Why the delay, why was RailCom not developed till now?

For years we have been working with the NMRA DCC working group to achieve such a concept.  In the past the technology was not possible.   New micro controller technology together with a much better understanding of how information can be transmitted has made RailCom a possibility.

When will it be available for sale?

 While RailCom is very powerful, there are limits to the technology and therefore the community must choose carefully which information we desire to transmit back.   It is important that this information be standardized so that one decoder manufacturer does not decide to transmit one type of information, which another's interprets differently.   The technology was tested on a number of large layouts and worked flawlessly. The results of the tests now provide us a green light for product release. Currently the LRC1020 Local Detector is in market, to be used with our GOLD decoders, that support RailCom.

Whats Next?

RailCom has now exceeded all our design requirements, the NMRA has approved initial RPs and we have worked with the NMRA on a set of significant enhancement which are now being considered and should have no problems being approved as they eliminate the system incompatibility problems the previous approaches had.    We will continue to work with the WG and the entire DCC community to refine the protocols to ensure that your hobby dollar investment is protected.  The future continues to be bright for the evolution of DCC and we are proud to be a part of it.  

 Copyright Lenz Agency and Lenz GmbH 2008