computer/model railroad interface (c/mri) 101- the basicspotomac-nmra.org/clinics/mer2018/mer...

Bruce Chubb’s

Computer/Model Railroad

Interface (C/MRI)

101- The Basics

By Jay Beckham

http://jaysoscalelayout.blogspot.com/

[email protected]

Visit the layout Sunday Afternoon1


mailto:[email protected]

My presentation is based in part on Bruce

Chubb’s presentations used with his

permission. I am grateful that he not only

agreed to my use of his presentations but

furnished me the presentations which I

have modified and adapted.

First I would like to briefly present some

electronic/electrical fundamentals that

confused me when I first got into building

and using the C/MRI system.

Then I will cover the basic parts that

makeup the signaling system and CTC.2

Basic Electronics101

In C/MRI grounding a circuit turns it on and no ground turns it off. This is just the opposite of what

we would normally think. This method is called Current-Sinking and it the default method used by

C/MRI devices. In house wiring we put the wall switch on the hot side of the circuit.

In C/MRI we would ground an LED to make it light or ground the terminal on the switch machine circuit

(SMC12) to make it throw the turnout to the diverging route. And the occupancy detector grounds the pin on an Input board to tell the computer that a electrical block is occupied.

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Example C/MRI application areas:• Optimized occupancy detection (OD and DCCOD)

• Signaling systems (very simple, ABS, APB and CTC)

• Interface with Command Control including DCC

• Staging track control (manual to fully automated)

• Grade crossing warning systems (PGCC)

• Turnout control (including software diode matrix)

• Junction and terminal interlocking

• Fast time clocks and layout-room lighting

• Driving real-time engine/dispatcher simulators

•Automated operations

• Reducing layout wiring

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A very extensive series

of articles about C/MRI

can be found in Railroad

Model Craftsman starting

with the December 2015

issue.

This series consists of

14 parts concluding with

the April 2017 issue.

Signaling in general and

C/MRI is covered in

great detail in this series.

Well worth the time it will

take to read all the parts.

Signaling Basics covered

in a 4-part series:

“Signaling Made Easier”

January through April 2004

Model Railroader Magazine

❑ This series is an excellent

source for getting started in

Signaling and the C/MRI

❑ Copies are available

directly from Kalmbach

and from NMRA’s Kalmbach

Memorial Library

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32 pages in the

March 2007 issue of

Scale Rails covering:

❑ State-of-the-Art

Electronics to

Enhance Operations

❑ Sunset Valley

Oregon System

❑ My Life with Bruce

and the Sunset Valleyby Janet Chubb

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An updated V3.1 User’s Manual now available

If you have V3.0 then you do not need V3.1

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During this presentation we will cover:

• Interfacing made easier

• Block occupancy detection

• Signaling and turnout control

• Centralized Traffic Control Systems

•System assembly and simplified wiring

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Interfacing your railroad to a computer is as

easy as connecting a single “super mini-node”

card (SMINI) to your computer’s serial port

❑ 48 outputs for driving signals, switch motors and panel LEDs

❑ 24 inputs for reading block occupancy detectors, switch position

and pushbuttons

❑Can use USB port with USB to RS232 converter cable

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SMINI CARD

Simply connect

each signal,

switch motor,

detector, etc.

to the SMINI

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Distributed serial:

• Up to 128 nodes

• Devices connect to

nearest node

• Use maxi-node for

• concentrated I/O

• Everything connects

w/single 4-wire cable

• 72 I/O per SMINI

• 2048 I/O capacity per

MAXI-node

• 262,144 total I/O

capacity

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Each card adds 32 inputs or outputs

up maximum of 64 cards per node (2480 I/O lines)

Need more I/O, simply plug in another I/O card

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Each input card provides 32 added inputs

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Handling C/MRI inputs is straightforward

❑ Input open circuited is hardware logic 1 (+5Vdc)

❑ Input grounded is a hardware logic 0 (0 volts)

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Example C/MRI input connections:

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Each output card provides 32 added outputs

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Every C/MRI output can be considered

to be a simple SPST toggle switch

❑ Software simple turns the toggle switch on or off

❑ When the toggle is on it is grounded

❑ Each SMINI provides 48 output lines (switches)

❑ Each DOUT32 provides 32 output lines (switches)

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Drive almost any devices directly

from C/MRI output line

Within .3A , 40volt limit

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Each output can drive multiple devices

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Programming the C/MRI is straightforward:

- like using the English language:

An extremely active User’s Group is available to

help you in every step:

http://groups.yahoo.com/group/CMRI_Users

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All C/MRI programs follow the

same logic flow diagram

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•

• Block occupancy detection

•

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For best possible performance:

❑use the DCCOD for DCC railroads

❑use the OD for DC railroads

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Advantages provided by DCCOD are numerous:

❑Transformer isolated

❑High 150K ohm pot adjustable sensitivity

❑Turn-on turn-off delay

❑Monitor LED for setting sensitivity

❑Open collector output (.3A, 40Vdc)

❑Track current up to 20A

❑Small modular unit for easy plug-in and system debug

❑Priced very reasonable - $9 for medium size layout

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Everything is out in the open with the C/MRI

Including full schematics, parts lists and assembly instructions

as well as extensive application information

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A Mother Board (ODMB) is available to

further simplify wiring and system debugging

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•

• Signaling and turnout control

•

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Signaling can add so much interest, beauty

and operational realism to a model railroad…

…and it is so easily and cost effectively

accomplished using the C/MRI

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Five great reasons for using a

computer to signal your railroad:

1. Simplicity

2. Flexibility

3. Prototypical fidelity

4. Easy expandability

5. Low cost

(See www.jlcenterprises.net or separate handout

provided for details expanding upon each benefit)

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http://www.jlcenterprises.net/

Using the C/MRI makes prototype signaling easy

to accomplish:

• Straightforward application

• Well proven technology

• Available as boards only, complete kits or

fully assembled and tested

• Everything out in the open - full schematics,

parts lists and abundant software

• Total flexibility to accomplish every need

• Very cost effective solutions

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Light Emitting Diodes (LEDs) are basic elements

to designing most signal systems

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Preferred (most common) method of wiring color light signals

❑ Uses outputs configured for standard current sinking

❑ Applies when signals are wired with common anode

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Driving a searchlight signal using a

3-lead bi-color LED

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Two color signaling a small railroad

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Three color signals with 2-headed signals

leading into passing sidings

In each example, C/MRI documentation leads you

step-by-step through the complete interfacing project

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Connecting switch motors directly to C/MRI outputs

Requires 2 outputs per switch motor

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Alternatively, only a single output is required

when incorporating an SMC12 card

Also, interface cards are available for

connecting to twin-coil switch machines 47

Easiest to implement local panel for

emulating the operation of a dual-

control power switch motor

Additional options provided in Handbook include

adding padlock function and using separate toggles

for the Selector Lever and Hand-Throw Levers

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• Centralized Traffic Control Systems

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CTC machines can be great

additions to any size railroad

Dirk Start using a GRS style machine modeling

the C&O operating on the former PM between

Holland and Grand Rapids Michigan

A small size CTC

machine covering

the east end of

UP’s Albina Yard

in Portland OR on

the SVOS

Wiring switch and signal levers and

code button is easy with the C/MRI

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Wiring the switch and signal indication

lamps is just as easy

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CSX Clinchfield Dispatching Center is quite

applicable to a C/MRI based club size system

Some C/MRI users are already interfacing to five

monitors within computerized dispatching centers

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Monitoring operational status is readily

available by studying the graphics display

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Modern dispatching with C/MRI

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•

• Additional applications

•

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Automated room and scenic lighting control tied

to fast clock simulating 24-hour day-night

operation easily accomplished using the C/MRI

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Night operation can be dramatic and including

sunrise and sunset effects can be spectacular

New Prototypical Grade Crossing Control (PGCC)

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Drives gates, flashers (w/fade-in and fade-out), real grade bell

digitally recorded sound and 4-prototypical bell control options

and all exactly like the prototype

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Automate scenic lift-up to totally

eliminate duckunders

Two new

Railroader’s Applications Handbooksare availiable

Together these totally replace single Volume V2.270


• System assembly and simplified wiring

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You can easily take

advantage of the

C/MRISeveral options available:

❑ bare board from JLC Enterprises

❑ complete kits fully assembled

and tested from Don Wood.

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The C/MRI documentation is

extremely thorough and follows

a step by step everything

explained process:

❑ User’s Manual V3.1

❑ Application Handbook Volume 1

❑ Application Handbook Volume 2

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My CTC board. It is based on US&S type

board. Each panel is 30 inches wide so the

CTC is 120 inches wide. My board also

includes a screen display. The screen also

provides a number of trouble shooting routines.

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To add in wiring and reduce the number of printed

circuit boards required, I have developed two small

boards that are helpful. These boards are available

from me. They are bare boards but I provide a list of

parts and where they can be obtained. Currently the

cost is $2 for either board plus postage.

The boards use the standard network CAT5/6 cable (8

wires) to help with wiring. It has an RJ45 connecter for

that cable on one end and either a Molex connector or a

screw terminal block on the other end. The Molex fits

all the standard C/MRI boards. The Molex option and

the screw terminal option.

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The second board I call my Signal Control Circuit or SCC for

short. It also has the CAT5/6 connector at the right and 15 screw

terminals across the bottom. Also 2 screw terminals for 5+ Volts

and Common connections. It allows 4 pair of wires to control a

total of 12 LEDs in signals. Previously you saw a diagram of a

standard OS section which had one double head three color

signals and two single head three color signals. That is a total of

12 LEDs to light. Rather than use 12 outputs from a SMINI board

we only need 8 outputs thus saving on boards, wire, and effort.

The 12 resistors can be matched to the particular LEDs you use.

Currently these boards are also $2 each plus shipping.

In summary – You have seen that a

computer will add a new dimension

and even more enjoyment to your

model railroading hobby

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•The C/MRI is easy to apply

• It is an educational project

• It is a fun project

• Include the C/MRI on your railroad

• I know that you will love it!

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I would like to thanks a number of people who have

been helpful with my understanding of C/MRI, with

the building of the 100+ printed circuit boards, wiring

my CTC panel, creating over 5,000 lines of Visual

Basic 6.0 code, running several thousand feet of

wire, and building almost 100 temporary signals that

we are using till I have time to build detailed

PB&JRY and PRR signals.

They are: Bill Carr, Gail Carr, Bruce Chubb, Jim

Withrow, Don Wood, and the members of the C/MRI

Users Yahoo Group.

A question and answer session will conclude my

presentation.

THANK YOU

For Attending

C/MRI 101- The Basics

By Jay Beckham


[email protected]

Visit our layout:

Sunday Noon to 6:00

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mailto:[email protected]

computer/model railroad interface (c/mri) 101- the basicspotomac-nmra.org/clinics/mer2018/mer...

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