Abstract:
The model train controller interface device provides a user with the capability of operating model train engine, switch and accessories of one manufacturer with the handheld wireless device of a second manufacturer. Inserted between the command base units and controller devices of different model train manufacturers, the interface device allows the wireless remote of one train system to operate components of the other train system without loss of functionality by either model train system.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to control systems for model trains, and particularly to devices that interface between control systems of different model train manufacturers, allowing one vendor&#39;s control unit to operate components of a competing manufacturer.  
         [0003]     2. Description of the Related Art  
         [0004]     Model train control systems have, as basic building blocks, a set of interconnected sections of train track, electric switches between different sections of the train track, a variety of electrically controlled devices, and finally, at least one electric train engine.  
         [0005]     Standard O-gauge electrical train operation is characterized by an AC track signal, wherein the AC signal is switchably offset by a DC signal used to enable various train accessories such as the horn/whistle function. The AC track signal energizes the electric motor of the train engine, with the DC offset enabling a train engine relay unit to activate the appropriate bell or whistle feature. In addition, certain standard O-gauge type transformers include fixed AC voltage supply terminals for operating lights and additional accessories.  
         [0006]     In order to ensure compatibility of their products and accessories with those already in use, current manufacturers have adhered to the basic electrical standard, namely the AC track signal voltage and DC control offset popularized by the standard O-gauge transformer. The standardization of this power arrangement ensures the continued compatibility of vintage train engines with new engines and other model train technologies.  
         [0007]     The vintage train engines utilize a transformer with a variable output voltage controls the speed of the engine by directly controlling the voltage applied to the track; the greater the voltage, the greater the speed.  
         [0008]     In newer engines digital control systems are employed in which a set voltage is applied to the track and the train responds to command signals from a command unit that transmits signals to the train. There are several manufacturers of both the vintage and command signal model train methodologies, and within the command system category of model trains, different manufacturers employ different command signals for the control of their engines.  
         [0009]     One example of the legacy control system includes U.S. Pat. No. 6,624,537, issued to Richard Westlake in September 2003. The &#39;537 patent discloses a plural output control station having a data processor for monitoring and controlling the signals generated at a plurality of transformer-driven power output terminals. The variable-voltage outputs are controlled by a data processor, which responds to respective operator-controlled throttles for varying the AC output voltage and therefore the rate of movement and direction of electric train engines.  
         [0010]     Digital model-railway control systems have been state-of-the-art for several years. In such control systems the full driving voltage, e.g. 16 volts AC, is continually applied to the track. The rails serve simultaneously to transmit digital data, forming a so-called data bus. For this purpose, appropriate digital control commands are superimposed on the driving voltage and include commands specifying direction, velocity and ancillary functions, such as activation of lights or automatic coupling. These digital control commands are encoded by a control system in a digital transmission format, e.g. NMRA/DCC, with address information designating a particular engine. Each engine has a decoder for picking out its commands. Such decoders can also be used in other functional articles such as cranes, switches or the like, for the remote triggering of control commands. Model train systems incorporating digital control systems include TrainMaster Command Control (TMCC) from Lionel Trains, Inc. and the DCS from Mike&#39;s Train House (MTH).  
         [0011]     The Lionel TMCC, for instance, utilizes a wireless control unit (CAB), which transmits a signal to the TMCC base, which in turn, modulates a 455 KHz carrier signal. The FM modulated signal is then capacitor coupled to the common of the track system. An FM receiver in the engine detects the modulated signal and performs the required function. The TMCC also controls the operation of track switches and other devices by means of Accessory Switch Controllers (ACS). The TMCC transmits a digital signal to the ASC containing command information along with an address field. Each ASC has an unique address which responds to the address transmitted by the TMCC. Upon command from the Lionel wireless control unit (CAB), an ASC can operate eight accessories or four switches and ten train routes. In addition to receiving commands from the wireless digital controller, the TMCC has a port for receiving digital signals from a user provided digital device such as a computer.  
         [0012]     An alternative control system for model trains is provided by Mike&#39;s Train House Inc. (MTH) DCS, which is based upon U.S. Pat. Nos. 6,457,681 and 6,655,640, issued to Wolf et al. in October 2002 and December 2003 respectively. The &#39;681 patent discloses a handheld remote control unit through which various commands may be entered to control not only the train engine, but also track switches and ancillary electric devices. A Track Interface Unit (TIU), in RF communication with the handheld controller, converts the commands to a modulated signal and transmits control signals to the engine over the power rail of the track system. The control signal is not a wireless FM signal and requires electrical connectively between the train and the track. The train picks up the modulated signal, retrieves the entered command, and executes it through use of a processor and associated circuitry onboard the engine.  
         [0013]     As with the TMCC, the MTH DCS permits remote control of track switches and accessories by the use of a TIU connected Accessory Interface Unit (AIU), which has a set of output relays that are coupled to various portions of the track layout through standard hard wiring.  
         [0014]     The AIU is electrically connected to the TIU by a variety of electrical means and operates the various accessories in response to user commands initiated by the handheld unit. Because of their popularity most of the O-gauge world runs TMCC and DCS and many model train enthusiasts have both systems and may want to control their TMCC trains using their MTH handheld remote  
         [0015]     Both the Lionel TMCC and the MTH TIU have serial data ports that once connected allow for limited interoperability between the two competing systems. In order to do this, a serial data cable must be connected between the MTH TIU and the Lionel TMCC, and the MTH TIU must then be programmed to transmit Lionel train commands over the serial interface to the TMCC. However, as noted, the interface is limited. DCS can control TMCC but TMCC cannot control DCS. Furthermore, the TMCC command base port to which the TMCC-TIU cable is connected is the same port used to connect to the TMCC ASCs. Therefore, the use of the TMCC-TIU cable precludes the use of the TMCC ASC devices, and for all intents and purposes, renders the CAB-1 hand held remote ineffective to control TMCC accessories through TMCC ASC devices.  
         [0016]     MTH DCS and TMCC are not the only model train control systems that have been developed. Other systems have been disclosed in U.S. Pat. No. 6,065,406, issued to M. Katzer in May 2000, and U.S. Pat. No. 6,441,570, issued to Grubba et al. in August 2002.  
         [0017]     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, a model train controller interface capable of interfacing disparate model train systems is desired.  
       SUMMARY OF THE INVENTION  
       [0018]     The model train interface device provides a user with the capability of operating model train engines, switches and accessories of one manufacturer with the handheld wireless device of a second manufacturer. Inserted between the Track Interface Unit (TIU) supplied by Mike&#39;s Train House (MTH) and the TrainMaster Command Control (TMCC) command base station manufactured by Lionel, Inc., the interface allows the MTH hand held remote to control TMCC devices without limiting the functionality of the TMCC wireless controller. The interface converts the signals from the TIU to the TMCC protocol and transmits them to the TMCC base station. The TMCC base station then transmits engine commands to the locomotives or echoes switch and accessory commands to Accessory Switch Controllers through the interface.  
         [0019]     Unlike simple serial cable interfaces which permits a DCS handheld control device to operate TMCC equipped trains at the price of rendering useless TMCC switch and accessory control components, embodiments of the present invention do not limit functionality of the TMCC components.  
         [0020]     The model train interface device comprises three embodiments. The first embodiment comprises a housing, which includes a printed circuit board, a plurality of connectors in electrical communication with a first train controller device, a second train controller device, and at least one train accessory controller device. The device receives AC power from a transformer or the train track and produces an operative voltage to the electronic circuitry contained within the housing.  
         [0021]     The printed circuit board contains electronic circuitry that controls the flow of data between the interconnected devices. The circuitry includes a microcontroller with memory, interface logic and program instruction code stored within the memory. The microcontroller controls the flow of commands from the MTH TIU to the TMCC command base. Furthermore, the microcontroller accepts commands received from any other source of TMCC commands, such as the action Recorder Controller (ARC) and multiplexes these commands over the data link to the TMCC command base.  
         [0022]     The second embodiment is an interface cable having two connectors disposed on either cable end, and includes a pigtail having at least two leads extends from one of the cable connectors and is adapted for attachment to terminal leads disposed on the switch and accessory device controllers. Designed to operate in combination with the commercially available TIU/TMCC serial cable, the present invention allows MTH DCS wireless controls to command TMCC equipped engines, while retaining the ability of the TMCC remote handheld to command TMCC equipped switch and accessory controller devices.  
         [0023]     A third embodiment, similar to the interface cable of the second embodiment, connects directly to the TIU and is designed to eliminate the need of the prior art TIU/TMCC serial cable.  
         [0024]     These and other features of the present invention will be apparent upon consideration of the following specification and drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]      FIG. 1  is a block diagram illustrating a model train controller interface device according to the present invention interconnecting a MTH TIU with a TMCC command base.  
         [0026]      FIG. 2A  is a block diagram of the prior art illustrating a track layout incorporating MTH DCS and TMCC equipped but non-communicating model train components.  
         [0027]      FIG. 2B  is a block diagram of the prior art illustrating a model train layout having the MTH TIU and the TMCC command base connected by a TIU/TMCC serial cable.  
         [0028]      FIG. 3  is a representative schematic of the model train controller interface device according to the present invention.  
         [0029]      FIG. 4  is a perspective view of a second embodiment of the present invention comprising a cable having male and female connectors and pigtail leads.  
         [0030]      FIG. 5  is a block diagram illustrating the second embodiment according to  FIG. 4  integrated in a model train track layout.  
         [0031]      FIG. 6  is a perspective view of a third embodiment of the present invention comprising a cable having two male connectors and pigtail leads.  
         [0032]      FIG. 7  is a block diagram illustrating the cable interface of the third embodiment according to  FIG. 6  connected directly between the TIU and the TMCC command base. 
     
    
       [0033]     Similar reference characters denote corresponding features consistent throughout the attached drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0034]     The present invention is a model train controller interface device, designated generally as  100  in the drawings, that allows communication between components of Mikes Train House (MTH) DCS model train system and model train systems incorporating TrainMaster Command Control (TMCC) developed by Lionel, Inc.  
         [0035]      FIG. 1  represents a block diagram of a first embodiment of the present invention  100  incorporated in a model train layout having both TMCC and Mike&#39;s Train House (MTH) model train components.  FIG. 2A  represents prior art and illustrates a train layout in which the MTH model train components provide no commands to TMCC equipped components. In other words, the MTH handheld wireless device  102  can control only MTH engines and devices connected to the Accessory Interface unit (AIU)  112 . Likewise, the CAB- 1  remote  110  can control only TMCC engines and TMCC controllers, such as Accessory Switch Controllers (ASC)  116 - 120  and the Action Recorder Controller (ARC)  114 .  
         [0036]     Still illustrating the prior art,  FIG. 2B  represents an alternate track layout in which the MTH TIU  104  and the TMCC command base  108  are interconnected by a TIU/TMCC serial cable  206  having female and male 9-pin connectors  202 ,  204  connected between TIU  104  port  130  and TMCC base command unit  108  port  132  respectively. Implementing the TIU/TMCC cable  206  allows a DCS handheld wireless device  102  to command TMCC equipped engines and precludes the use of the TMCC controller devices  114 - 120  which must be connected to the same port, that is TMCC base command unit  108  port  132 .  
         [0037]     Referring back to  FIG. 2A , a model train layout utilizing the TMCC system requires, at a minimum, a CAB-1 remote control  110 , which is used by the operator to control all model train functions, and a TMCC command base  108 . The command base  108  receives signals from the CAB-1  110  and relays them to TMCC controllers  114 - 120 . The command base  108  relays signals to the layout in two ways. The first way uses radio waves, so that signals to engines are carried along the outside rail  122  of the layout. This requires a single wire connecting the command base  108  to an outside rail  122  of the track  128  or a transformer&#39;s common or U terminal. Engines, placed on the track, pick up the signals independent of their location on the track  128 . The second means by which the TMCC command base  108  communicates is via an asynchronous data link that uses 2 wires connected to a serial port  132  integrated in the command base. Port  132  of the command base  108  echoes on its transmit lead all commands received from the CAB-1  110 . In addition to echoing signals received from the CAB-1  110 , the transmit lead on port  132  echoes back all commands received on the receive lead of port  132  after being processed by the command base  108 . The wires carrying the command signals can be daisy-chained from one TMCC device to another, so a layout that uses multiple TMCC equipped controllers only needs to have one pair of wires connected to the command base  108 . One such controller for controlling up to 4 switches or up to 8 accessories is the Accessory Switch Controller (ASC)  116 - 120 . An Action Recorder Controller (ARC)  114  is also available, which records whatever commands are generated by the CAB-1 remote  110 , storing them for future playback.  
         [0038]     The data link between port  132  and the TMCC controllers  114 - 120  transmits and receives signals utilizing a 9600-baud, one stop bit, and no parity protocol. The data is transmitted in a three-byte format, the first eight-bit byte being hexadecimal “FE”. The remaining two bytes, as shown in Table 1, consists of address and data bits, whereby the CAB-1 handheld remote  110  can transmit switch commands, route commands, engine commands, train commands, accessory commands and group commands.  
         [0039]     Table 2 represents the command set the command base  108  uses to communicate with the ASCs for controlling routes. Table 3 represents the command set that the TMCC  108  sends to the ASCs  116 - 120  for controlling track switches, and Table 4 represents the commands sent by the command base  108  to the ASCs for controlling accessories.  
                                                                                                                                                                     TABLE 1                           TMCC Command Base General Command Format                Bit Order                MSB                                                           LSB           15   14   13   12   11   10   9   8   7   6   5   4   3   2   1   0                        Switch   0   1   A   A   A   A   A   A   A   C   C   D   D   D   D   D       Commands       Route   1   1   0   1   A   A   A   A   A   C   C   D   D   D   D   D       commands       Engine   0   0   A   A   A   A   A   A   A   C   C   D   D   D   D   D       Commands       Train   1   1   0   0   1   A   A   A   A   C   C   D   D   D   D   D       Commands       Group   1   1   0   0   0   A   A   A   A   C   C   D   D   D   D   D       Commands       Accessory   1   0   A   A   A   A   A   A   A   C   C   D   D   D   D   D       Commands                 Definitions            A—Address field            D—Date Field            C—Command Field:            00 - action            01 - Extended            10 - Relative speed            11 - Absolute speed             
 
         [0040]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                   
               
               
                 TMCC Route Commands 
               
             
          
           
               
                 Route Commands 
                 Command field 
                 Data Field 
               
               
                   
               
             
          
           
               
                 Route throw 
                 0 
                 0 
                 1 
                 1 
                 1 
                 1 
                 1 
               
               
                 Route clear 
                 0 
                 1 
                 0 
                 1 
                 1 
                 0 
                 0 
               
               
                   
               
             
          
         
       
     
         [0041]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                   
               
               
                 TMCC Switch Commands 
               
             
          
           
               
                 Switch Commands 
                 Command field 
                 Data Field 
               
               
                   
               
             
          
           
               
                 Throw THROUGH 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Throw OUT 
                 0 
                 0 
                 1 
                 1 
                 1 
                 1 
                 1 
               
               
                 Set address 
                 0 
                 1 
                 0 
                 1 
                 0 
                 1 
                 1 
               
               
                 Assign to route 
                 1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 THROUGH 
               
               
                 Assign to route 
                 1 
                 1 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 OUT 
               
               
                   
               
             
          
         
       
     
         [0042]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                   
               
               
                 TMCC Accessory Action Commands 
               
             
          
           
               
                 Accessory action 
                   
                   
               
               
                 commands 
                 Command field 
                 Data Field 
               
               
                   
               
             
          
           
               
                 AUX1 off 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
               
               
                 AUX1 option 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 1 
               
               
                 AUX1 option 2 
                 0 
                 0 
                 0 
                 1 
                 0 
                 1 
                 0 
               
               
                 AUX1 on 
                 0 
                 0 
                 0 
                 1 
                 0 
                 1 
                 1 
               
               
                 AUX2 off 
                 0 
                 0 
                 0 
                 1 
                 1 
                 0 
                 0 
               
               
                 AUX2 option 1 
                 0 
                 0 
                 0 
                 1 
                 1 
                 0 
                 1 
               
               
                 AUX2 option 2 
                 0 
                 0 
                 0 
                 1 
                 1 
                 1 
                 0 
               
               
                 AUX2 on 
                 0 
                 0 
                 0 
                 1 
                 0 
                 1 
                 1 
               
               
                 Numeric command 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 0 
               
               
                   
               
             
          
         
       
     
         [0043]     Still referring to the prior art of  FIG. 2A , the MTH DCS features two required components, the DCS Remote Control  102  and the Track Interface Unit (TIU)  104 . An additional component, the Accessory Interface Unit (AIU)  112 , can be added to provide control over the accessories and switches. The DCS operates by transmitting an electrical “digital” signal superimposed upon the power from the transformer  106  into the center rail  126  of the railroads track  128 .  
         [0044]     The MTH DCS controls switches and accessories by means of one or more AIUs  112 . The AIU  112  receives its commands from the TIU  104  and supplies relay contact closure outputs to accessories and switches. One interface protocol between the TIU  104  and the AIU  112  is defined in U.S. Pat. No. 6,457,681, issued to Wolf et al. in October 2002 and incorporated herein by reference in its entirety. The disclosed interface consists of a three-wire serial interface port  134 , wherein one wire is a data line that is set to the value of the most significant bit of the data byte being sent. A clock line is then pulsed high then low to clock in the signal into an 8-bit shift register in the AIU. After 8 bits have been clocked in, the entire byte is clocked out by pulsing the third line, which is a latch. The data in the byte is therefore essentially 7 bits of address to select the particular relay in the AIU that the user wishes to open or close and 1 bit to either open or close the relay.  
         [0045]     As previously discussed, MTH DCS has the capability, by means of the TIU/TMCC serial cable  206 , to permit a MTH DCS wireless remote to command TMCC equipped engines.  
         [0046]     Now referring to  FIG. 1 , the first embodiment of the Model Train Controller Interface  100  acts as a bridge between MTH and TMCC components. As shown in  FIG. 1 , the interface  100  includes a plurality of digital ports connected to circuitry  136 . Port J 1 , is connected to port  130  on the TIU  104  by means of a standard 9-pin serial null model cable and receives therefrom a first digital data stream  141  formatted in the TMCC protocol. A second port J 2  connects to port  134  on the TIU  104  and receives therefrom a second digital signal  142  in a second protocol that would normally be received by an AIU. A third port J 3  may be connected to command generating devices such as the ARC  114  from which the interface  100  receives a third digital signal  143 . A fourth port J 4  connects to port  132  on the TMCC command base  108  by means of a standard 9-pin male-to-male null modem cable. Port J 4  is bidirectional, transmitting a fourth digital signal  144  in TMCC protocol on pin  2  to the TMCC command base  108  and receiving back a fifth digital signal  145  from the command base  108  on pin  3 . This fifth signal  145  is transmitted as signal  146  on port J 3 , to device controllers  114 - 120 . Power is supplied to the device by means of a pair of wires  148  wired to the transformer  106 . Signal ground  150  is received from the TMCC command base  108  on pin  5  of J 4  and is passed along on lead  152  to device controllers  114 - 120 .  
         [0047]      FIG. 3  is a representative schematic of the circuit  136  mounted within the housing of the interface  100 . The electronic circuit controls the flow of digital data between the TIU  104 , the TMCC command base  108 , and TMCC devices  114 - 120 . The circuitry includes a microcontroller U 1  with built in memory, discrete electronic devices, and program instruction code stored within the memory. The firmware stored in the memory controls the multiplexing of the various data streams and is of a level of complexity known to those skilled in the art of programming.  
         [0048]     In operation, the interface  100  transmits commands received on ports J 1 -J 3  to the TMCC command base  108 . For instance, engine commands in data stream  141 , originating from the MTH DCS handheld remote  102 , are received by the TIU  104  and are transmitted on port  130  through a standard commercially available serial cable to port J 1 . Switch and accessory commands generated from the MTH DCS handheld remote  102 , are relayed through port  134  on the TIU  104 , and are received in data stream  142  on port J 2 . The signal is read by shift register U 2  and after 8 bits have been clocked in, the entire byte is clocked into U 1 . Finally, pin  3  on port J 3  receives digital data stream  143 , a third source of command data from any ARC  114  or other automated device that generates TMCC commands intended for TMCC controlled components.  
         [0049]     Still referring to  FIG. 3 , engine and accessory commands received in data streams  141 - 143  on ports J 1 -J 3  respectively are processed by circuitry shown in  FIG. 3  and are read by microcontroller U 1 . The microcontroller U 1  reads the data stream presented by the three digital input streams, converting the data received to the TMCC protocol disclosed in Tables 1-4 as necessary. The microcontroller multiplexes the data and outputs a data stream which is processed by R 5 , R 6  and Q 2  into a digital data stream  144  on pin  2  of port J 4  to port  132  of the TMCC command base  108 . Upon receipt of the data stream transmitted from port J 4  pin  2 , the TMCC command base  108  transmits engine commands to a model train engine (not shown) via Frequency Modulation (FM).  
         [0050]     Without the present invention  100 , switch and accessory commands from the TMCC command base  108 , would normally, as shown in  FIG. 2A , be contained in transmit signal  145  wired directly to controllers  114 - 120  through port  132 . Use of the present invention  100 , however, requires that port  132  be wired to J 4  of the interface  100 . Therefore, since the TMCC command base  108  has only one port  132 , the transmit lead of the command base  108  must route the data stream  145  back to J 4  pin  3  of interface  100 . Data stream  145  is then transmitted on pin  2  of J 3  to the receive port of the daisy-chained device controllers  114 - 120  via data stream  146  as shown in  FIG. 1 .  
         [0051]     A rectifier circuit  140 , known to those skilled in the art converts the AC signal from the transformer  106  to the DC voltage required by the present invention  100 .  
         [0052]     The microcontroller U 1  is a commonly available commercial device, such as the PIC17C42A or the newer PIC18F4220, and is typically found with an oscillator circuit formed by C 1 , C 2  and crystal Y 1 . Similarly, a power on reset function is provided by R 1 , C 3  and D 1 .  
         [0053]     Table 5 provides representative values for components disclosed in  FIG. 3  and is based upon known interfaces for the various model train components and the design preferences of those skilled in the art of electronic design.  
                                 TABLE 5                           Representative Component Values                Reference                   Number   Component   Value                       U1   Microcontroller   PIC17C42A           U2   Shift Register   74HCT164           Y2   Crystal Oscillator   32 Mhz.           C1   Capacitor   33 uF           C2   Capacitor   33 uF           C3   Capacitor   0.1 uF           Q1   Transistor   2N3904           Q2   Transistor   2N3906           Q3   Transistor   2N3904           D1   Diode   1N914           D2   Diode   1N914           D3   Diode   1N914           R1   Resistor   100K           R2   Resistor   100K           R3   Resistor   100K           R4   Resistor   100K           R5   Resistor   100K           R6   Resistor   100K           R7   Resistor   100K           R8   Resistor   100K           R9   Resistor   100K                      
 
         [0054]      FIG. 4  illustrates a second embodiment of the present invention in which a specially designed interface cable  400  retains the ability of the CAB-1  110  remote to command TMCC equipped switch and accessory device controllers  116 - 120  while permitting the MTH DCS remote  102  to command TMCC equipped engines.  
         [0055]     Interface cable  400  comprises a cable  402  having at least two electrical conductors connected between two commercially available 9-pin “D” shell connectors  404 ,  406 , one connector  406  is a 9-pin male connector and the other a 9-pin female connector  404 . The interface cable  400  is similar to a commercially available “null modem” cable in that pin  2  of one connector is wired to pin  3  of the connector at the other end. Signal ground is transmitted though pin  5  on both connectors. Although the TMCC does not presently send commands to the TIU and therefore would not require a transmit lead from the TMCC to the TIU, this lead is made available for future use.  
         [0056]      FIG. 5  illustrates the interconnection of interface cable  400  within the model train layout. Male connector  406  is adapted for mounting to port  132  of the TMCC command base  108 , and female connector  404  is connected to the male connector  204  of the MTH/TIU serial cable  206 . Unlike standard “null modem” cables, the cable converter  400  includes a pigtail  414  comprising three conductors  408 - 412  extending from a connector, the three conductors  408 - 412  being in electrical contact with pins  2 , 3 , and  5  of connector  406  respectively. Although the pigtail  414  may extend from connector  404 , in the present design, pigtail  414  extends from connector  406  and conductors  408 - 120  are soldered or crimped to pins  2 , 3  and  5  of connector  406  respectively. The end of wire  408  is connected by a tightening screw connector to the receive terminal of the first device controller  114  and is the means by which commands are transmitted from the TMCC command base  108  to device controllers  114 - 120 . The end of wire  410  is screwed on to the transmit terminal of any transmitting device controller  114  and transmits commands back to the TMCC command base  108 . Wire  412  carries signal ground from the command base  108  to device controllers  114 - 120 .  
         [0057]     A third embodiment  600 , similar to the cable converter disclosed in  FIGS. 4-5 , is illustrated in  FIG. 6 . Similar to the embodiment  400 , interface cable  600  is designed to replace the need of the MTH TIU/TMCC serial cable  206  shown in  FIG. 5 . As best illustrated in  FIG. 7 , connector  604  engages port  130  of the TIU  104 , and connector  606  engages port  132  of TMCC command base  108 . The interface cable  600  differs from embodiment  400  shown in  FIG. 4 , in that interface cable  600  has male connectors  404 ,  406  on both ends of cable  602  and pin  3  of connector  406  is wired to pin  9  of connector  404 , for unlike standard practice, the TIU transmits on pin  9  instead of pin  2 .  
         [0058]     Still referring to  FIGS. 6-7 , interface cable  600  is similar to the cable interface disclosed as embodiment  400 , in that pigtail  414  and conductors  408 - 412  extend from pins  2 , 3  and of connector  606  and are connected to device controllers  114 - 120 .  
         [0059]     It is to be understood that the present invention is not limited to the embodiment described above, but encompasses any and all embodiments within the scope of the following claims.