MSS Standard
MSS Resources
MSS User Guide
MSS Home
MSS Home
copyright 2005-2017
Modular Signal System - MSS
2000: Gregg Fuhriman (Northern California Free-mo, aka NorCalF) installs commercial signal animator products on his Glen Frazer passing siding Free-mo module. Optical sensors are used to set the signals to Stop when a train arrives, and timer circuits sequence the signals to Approach and then Clear a short time after a train departs.

2001: Chris Palomarez and Michael Mosher (San Luis Obispo Free-mo, aka SLO-Mo) propose the concept of a train detector wired to signals facing outward at the ends of a signal block, for use in Free-mo modular layouts.

2001-2004: Gregg Fuhriman expands the concept into a complete, multi-indication signaling system by inventing the MSS core concepts of a modular Occupancy Bus Layer with Cascade and Crossover elements using Cat-5 network cables, a Detection Layer with complementary current and optical sensors, and a Signaling Layer. The system is incorporated into NorCalF and SLO-Mo modules for testing.

2004: Gregg Fuhriman produces the Occupancy Bus Utility Board (OBUB) to help simplify the installation of MSS into modules and layouts. The OBUB is the first product specific to the MSS.

2005: Rail Model Journal magazine publishes Gregg Fuhriman's article presenting the MSS to the model railroading world. Later, this article becomes the de facto "MSS V1.0" standard.

2005-2011: The MSS grows in popularity among Free-mo groups throughout the US and Canada. The 2011 National Train Show held in Sacramento, CA hosts a large multi-group Free-mo layout featuring a fully operational MSS extending through most of the layout.

2011-2014: Barry Draper (Southern California Free-mo) invents the Approach Diverging feature used at MSS junctions. Additional MSS-specific products begin to appear, many of which re-assign one or more MSS Occupancy Bus wires for other purposes. Potential incompatibilities arise, leading to the need for an MSS Standard.

2014-2015: An MSS Standards development group, consisting of product manufacturers, produces the MSS V2.0 Standard that specifies the MSS core requirements, resolves nascent incompatibilities, and formalizes the optional Approach Diverging feature.

2015: The MSS V2.0 Standard is published on this website.

2015-Present: MSS V2.0 compliant products appear. The MSS user base continues to grow, especially in the modular model railroad format.