ND Holmes : MRBus MRB-ABS ABS/APB Signal Node browse

MRB-ABS Introduction

The ABS/APB/Intermediate Signal Node is designed for those not wanting full CTC or for those needing intermediate signals between CTC control points. The node is capable of controlling two signal heads. While it's intended to control one head in each direction at a given point, there's no reason that it has to be used that way. The two heads have completely separate logic.

While eventually I'll be adding blinking yellows, three-light signals, etc., for now it's just a standard red-yellow-green arrangement on a three-wire, bi-color LED interface. There are provisions for such features as double yellow approaches and tumbledown logic.

As has been mentioned elsewhere, the MRBus system has been developed in C using Pavel Baranov's C2C compiler. It's not free, but it's quite reliable and very reasonably priced for what it does and there is a free trial version available. For those looking for a good quality PIC C compiler on an affordable budget, I recommend it. As a truly free, open-source PIC compiler becomes available and matures (come on, SDCC people, I'm counting on you...), I'll probably migrate over. For those without the compiler, I've included the compiled hex file for use with pretty much any standard PIC programmer.

Documentation and Source Code

Schematics

Version 1.0

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Firmware

Version 1.0
Finished MRB-ABS firmware, released 6-Apr-2003

[src] - [hex]

Photos

Installed MRB-ABS Module
Posted 20-Apr-2003 - A finished unit installed on the Wind River RR at the fictitious small town of Thompson Springs, UT (only loosely based on the real Thompson, UT).

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Intermediate Signals at Thompson Springs, UT on the WRRR
Posted 20-Apr-2003 - The signals that the unit in the previous photo controls - due to the narrow right of way at this point, the signals exist back-to-back. Eventually the area will get scenery and the signals will be permanently mounted - for now, they just help prevent collisions.

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