User Tools

Site Tools


Bi-Directional Communicatie



This is the Wiki Page for the Blueprint; the listed functionality here is only partly implemented.
Please modify this page if some information ist not correct.


RailCom is according to the RP 9.3.1 and RP 9.3.2 of the NMRA.

The RailCom technology seems to be unknown/ignored in the USA. Transponding seems to be the well known bi-directional communication technology in the USA.


Pro's & Con's

Technique Pro's Con's Retrofittable PoM CV-read Available since
Barcode reader Yes No -
LDT RFID Crosstalk problems by parallel tracks. Yes No -
Digitrax Transponding Standard LocoNet, 'Listening' by wire¹. Mounting of transponding receivers need some special attention. No¹¹ Yes, tested 1997
LISSY Standard LocoNet, easy to install, open protocol. Restricted² communication, only info on enter. Yes No 2004
RailCom NMRA RP 9.3.1 Need new DCC equipment, additional PC-interface³ for reporting,
restricted per section, sections should be twice as long as the longest locomotive³³.
No Yes late 2009

¹) Bundling detection sections is very flexible and 'unlimited'.
¹¹) None transponding decoders will cause unwanted events, so it is a DigiTrax only solution.
²) Data transfer is only possible at the "eye to eye" moment.
³) The RailComBus(ring) protocol is not published at the time of writing.
³³) Some Railcars pickup current on both ends and could be in the need for more than one meter at H0 scale… See for more information the RailComDisplay page from Paco

PoM CV-Read

PoM = Programming on the Main, also referred as OPS (Operations Mode Programming).

  • Very fast, no polling but direct answer.
  • If only interested in CV-Read, only one transponder receiver is needed for the whole layout. (Transponding)

Manual Mode

  • Show ident code, or loco ID if a match is found in the table, in the clients.
  • Set block as reserved in case it matches a loco.

Auto Mode

  • Check the ident code against the loco who reserved the block.
  • Set block as reserved in case it matches a loco and the block allows half auto mode.
  • Report as ghost train in all other cases.

Operator 'Game'

Can this be of any help or bring in some extra fun in case of the Operator 'Game'?


A Lissy transmitter is easy to install. This example is a H0 Roco NS2400 type:

sensor-bi-directional-nl.txt · Last modified: 2018/11/12 08:56 (external edit)