What is C/MRI?

Train Detection

Installing the C/MRI detector cards is a great way to start building toward a more complete computer interface. You can use the detectors to indicate occupation status of hidden track and/or drive LEDs on your track diagram as trains progress, or to automatically control polarity in reverse blocks. With detectors installed, it's a natural step to use the C/MRI for signaling.

The OD is the original-design optimized detector and it can be used for all applications, including DCC. The DCCOD is the latest design in the optimized detector family specifically created for DCC equipped layouts. The DCCOD uses a pulse-type current-sensing transformer input. This provides complete separation of the track wiring from all the signal logic wiring enabling operation on any DCC system independent of how it is wired. The DCCOD is also the recommended first choice detector for use on Railcommand, CTC-80 and CTC-16 equipped railroads. The original design OD should be used for all straight DC railroads and the DCCOD for all railroads using pulse-type command control systems like DCC.

Signalling Systems

The C/MRI is by far the most popular method of hooking up truly functional signals on a model railroad. All prototypically based signaling systems, whether Automatic Block Signals (ABS), Absolute/Permissive Block (APB), or Centralized Traffic Control (CTC) are extremely logic intensive. This makes the available-for-free powers of the computer an ideal implementation choice. Also, you can’t beat the C/MRI approach for simplicity. There are no separate signal logic cards or signal driver cards, no relays and no multi-contact panel switches nor multi-contact requirements for your switch machines. Each signal, occupation detector and switchmotor simply plugs directly into the nearest C/MRI node. All the complex interlocking functions are handled for you by software where changes and updates are easily implemented.

Many modelers use the C/MRI interfaced to their lever type CTC machines. Others use extensive color graphics displayed on their computer’s monitor and with keyboard inputs emulate the most modern dispatcher centers. Others use the power of the internet tied into the C/MRI for remote dispatching from locations many miles from the railroad itself.

Reduced layout wiring.

One of the main advantages of the C/MRI’s distributed serial option is reduced layout wiring. A single 4-wire RS485 cable is the only connection required between the railroad and the computer. It’s the only connection required between the Dispatcher’s CTC panel and the railroad. Using multiple C/MRI nodes, all local wiring from every railroad device simply connects to the nearest node. The only wiring required between nodes is that single 4-wire cable.

A side benefit of the computerized approach is that diagnostic software can quickly help you locate any electrical problem. It’s also a great way to check out your complete system before that important operating session, convention open house or VIP visit.

Taking advantage of the C/MRI’s power to implement the Software Diode Matrix is a great way to simplify turnout control. This approach is extremely beneficial for staging yards, classification yards, terminal areas and major junctions.

Interface to Command Control (CC)

Many users have the C/MRI tied into their CC system. With most DCC systems, Railcommand, and CTC-80, you can employ a control panel card to assign, add and drop engine assignments from multiple points around your railroad rather than be confined to the computer keyboard or to one command station location. Also with DCC systems, the C/MRI allows you to use the lower cost "Utility", "Engineer" or "Buddy" type cabs for most of your operators.

The C/MRI cab to engine assignment panel is especially attractive for pre-computer modeling eras where you do not care to use the fancy throttles with their modern functioning LCD displays and their myriad of control buttons. With DCC, the C/MRI can handle the CC assignment functions as well as all other functions on your railroad such as CTC panel interface, turnout control, signaling, layout lighting, automated staging, and, if you desire, even automate the operation of some of your trains while you operate others.

Also, if you happen to have one of the earlier CC systems like CTC-16, 16e, Mann-Made, Onboard or Dynatrol, or even straight DC systems, you can use a standard C/MRI Digital-to-Analog Converter (DAC3) card to tie into your command station for automated train operation. By contrast, most modern DCC systems provide for a direct computer connection into their command station, thereby enabling for an easy tie in of the C/MRI with DCC.

Computer cab control (CCC)

Designed for use with DC systems, CCC can have the computer automatically connect blocks to your cab one step ahead of your train and disconnect blocks behind your train. Clear blocks can be automatically assigned to another train. This way you can operate multiple trains on your railroad without any regard to throwing manual block toggles or rotary switches and you do not need to install decoders, or receivers, in any of your locomotives.

For those desiring to combine multiple train DCC operation with multiple train DC operation you can do so by implementing the CCC option of the C/MRI and connecting one of the seven cab positions to DCC. This way you can operate six conventional DC trains simultaneously with any number of DCC trains. Clubs find this dual capability an especially attractive feature for using the C/MRI.

Computer block control (CBC)

CBC allows you to build on CCC by adding a separate Computer-Controlled Throttle (CCT) for each block on your layout - just like on the Sonoma club layout discussed in Chapter 2 of the User Manual. The computer reads the settings of each hand held controller and correspondingly sets the speed and direction for each block where each train is operating. Each of the standard CCT4 cards handle four blocks. With CBC you eliminate all block power switching and obtain great control flexibility. Walkaround controls can be a simple potentiometer and reverse switch. Software keeps track of which blocks are occupied by which trains and sets the speed and direction for each of the block throttles. Wherever you run a train on your railroad the train responds to your cab through the CBC software.

Using CBC is a neat way to achieve fully automated or display mode operation where the computer runs all the trains automatically or to augment regular manual operation by having the computer run some trains automatically while you and your crew run others. You can also use a CCT4 card to obtain automated operation on a CCC equipped railroad. With CCC and CBC no equipment modifications are required.

Staging track control.

With the C/MRI all you need to do is dial up a staging track, or some users have it set up so that you only need to dial up a train number, and the proper staging track is automatically aligned. For trains going into staging you can, if desired, simply have the computer automatically assign the next available track. You can have the C/MRI drive cab signals to guide engineers as they run into hidden staging. If you wish, you can have the trains automatically operate into and out of staging.

Computer interfaced fast time clocks and lighting.

Multiple variable-speed clocks, whether analog or digital, can be interfaced with the C/MRI. If you only need one clock it can be displayed on your computer's monitor. Once your fast-clock is in your computer it is a natural step to use the C/MRI for automatic control of your layout and room lighting to simulate day-night operations. Kirk Wishowski, a Sunset Valley Oregon System Operator and fellow electrical engineer, has designed a C/MRI compatible circuit for automatically controlling room lighting up to 15A at 120Vac. It’s great for simulating day-night operations. JLC Enterprises is providing the circuit board. If you need higher current capability, you simply add more circuits. Kirk has also come up with a circuit that enables the C/MRI to read analog-type fast clocks to keep the computerized lighting synchronized with your railroad's time.

Hump yard control

The C/MRI can automate your hump yard. For example, the operator can key in the last three digits of car numbers as they go over the hump and the computer automatically aligns turnouts for the car's destination and sets the retarders to the proper level based upon the car's rolling characteristics and the number of cars already in the designated track. By interfacing a bar-code scanner you can even eliminate the need to enter the car number.

Junction or terminal interlocking.

A complex, or ever simple junction, can require many checks before turnouts can be aligned and signals can be properly cleared - all easily handled functions with a C/MRI. For example, you can have a single button for each entrance and exit track. Reading the order of the button presses, the C/MRI checks for safe conditions and automatically sets up the best available requested route and clears the appropriate signals keeping all conflicting signals at stop.

Two such entrance-exit type interlocking plants are implemented via the C/MRI on the new SV Oregon System.

Driving real-time engine/dispatcher simulators.

Rather than unrealistically punching computer keys you can use the C/MRI to tie your simulator into actual controls like in a real cab or dispatcher panel. The system can be tied into your railroad layout or operated as a stand alone simulator used for crew training or for just plain fun.