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Since the beginning of DCC we have been able to send information out to locomotive decoders as they run on the layout, data flows out from the command station but, up until now, it has been difficult to receive data back from the locos.  DCC is known as a one way protocol.

RailCom allows information to be sent back from the locomotive decoders - for example the address may be read in a monitored section which allows you to positively identify which loco is on that track.  Because information can travel to and from the loco decoders, RailCom is known as Bi-directional communication.

All Lenz decoders are now supplied with RailCom as standard.  (RailCom is active as part of the factory setting - it may be turned off by setting bit 4 of CV29 to 0)  RailCom is now also used by Roco Z21, ESU Ecos and Uhlenbrock MARCo (RailCom Receivers specific to Uhlenbrock LocoNet system).

The following film shows the use of the LRC120 RailCom Display to monitor occupation of a track:

RailCom is the basis of the MARCo Automation system developed by Uhlenbrock.  MARCo can organise and control complex DCC automation without the aid of a computer.  MARCo is specifically designed to work with Uhlenbrock Digital systems.

RailCom is now being incorporated into the DCC Language - Technical details may be found under the NMRA Recommended Practices RP 9.3.2.  The RPs are the full technical documentation for the DCC Standard - They contain all the information a manufacturer needs to make DCC devices so can be a bit dry for the majority of us - Thankfully I do not need to understand it all to play my part.

RailCom is registered trademark of Lenz Elektronik GmbH

15105 LRC100 RailCom Transmitter Module 5 pack
LENZ1510515105 LRC100 RailCom Transmitter Module 5 pack

Lenz 15105 LRC100 RailCom Transmitter Module 5 pack

Manual in German, English and French

One transmitter module LRC100 is required for every locomotive whose address is to be read out, unless the decoder installed inside the locomotive is already fitted with one of these modules. Simply connect the transmitter module to the locomotive's track contacts. Thanks to its compact size, the transmitter module may be installed in almost any locomotive.

Address Information is transmitted via the normal track connections.  This address can be made visible on suitable displays (eg the LRC120).  The contents of CV's may also be displayed.

All new Lenz decoders are provided with RailCom as standard. The LRC100 allows you to upgrade older decoders to give them this function.  The LRC100 module on its own provides no motor or function control.

Requirements for RailCom

The necessary "blanking interval" (also known as RailCom cut-out) must be activated in order to run RailCom  (activation instructions are given in the booklet provided with the RailCom Transmitter modules and with all new Lenz decoders).  You will need an LZV200 command station or LV103 amplifier to run Railcom. The LZV100 and LV102 can generate Railcom.  An older LZ100 (version 3.5 or later) may be used in conjuction with an LV102 amplifier in order to run RailCom. - (Please note that amplifiers LV100, LV101, LV200 and compact are unable to provide the Blanking Interval necessary for RailCom).

15120 LRC120 Address display for loco addresses
LENZ1512015120 LRC120 Address display for loco addresses

Lenz 15120 LRC120 RailCom Address display 

This 4-digit display serves to depict the address of the locomotive located in a monitored track section. Installation is possible anywhere on the layout, for example inside a signal box.  The LRC120 can be used to monitor hidden sidings.  One useful feature is that it allows you to confirm that a locomotive decoder is correctly set up to broadcast the RailCom signal.  We have used the LRC120 with Lenz, Roco Z21 and with Uhlenbrock POWER4 generated RailCom.


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