Abstract:
Methods for connected tractor and trailer identifications and the order of hook-up of multiple trailers to a tractor enable the tractor and trailer identification and the order of trailer hook-up to be remotely broadcast from the tractor or trailers. In one aspect, the detection of vehicle identification and the order of trailer hook-up are determined by PLC tags mounted in the trailers or by a PLC Gateway mounted in the tractor or one of the trailers utilizing the PLC system on the tractor/trailers. In another aspect, the vehicle identifications are extracted from electronic modules existing on the tractor and trailers and sent to the PLC Gateway for broadcast from tractor/trailer.op

Description:
CROSS REFERENCE TO CO-PENDING APPLICATIONS 
       [0001]    This application claims priority benefit to the filing date of co-pending U.S. Provisional Patent Application Ser. No. 61/568,837 filed on Dec. 9, 2011 in the name of Raymond A. Suda, and entitled “Method to Identify Trailers and The Order in Which They Are Hooked Up”, and co-pending U.S. Provisional Patent Application Ser. No. 61/672,432 filed on Jul. 17, 2012 in the name of Raymond A. Suda, and entitled “Method to Identify Trailers and The Order In Which They Are Hooked Up,” the contents of both of which are incorporated herein in their entirety. 
     
    
     BACKGROUND 
       [0002]    The present description relates, in general, to tractor-trailer communication system. 
         [0003]    The freight industry employs tractors which move one or more tandem or serially connected trailers between various locations. A standard seven conductor umbilical cord is coupled between the tractor and the first trailer, and between each pair of trailers to provide electrical power from controls in the tractor to the trailer brake lights, turn signals etc. However, the increased use of electronic modules on the trailer requires additional data communication conductors to avoid the expense of a separate umbilical cord to control such electronic modules, such as an ABS controller, an air tire pressure controller, or a refer temperature controller on the trailers. Power line carrier systems have been devised which provide data signals over one of the umbilical cord conductors to communicate information bidirectionally between the tractor and each trailer via power line carrier readers or gateways. 
         [0004]    Today&#39;s freight companies transport goods over wide geographic locations. This widespread geographic area coupled with the trend for adjusting time deliveries as well as overnight deliveries, has necessitated a need for a freight company to know where each tractor and trailer is at any given time so as to coordinate delivery schedules, change routing etc. 
         [0005]    Tractor communication systems have been devised along with GPS systems on the tractor and/or trailers, to provide remote communications which enables a central office of a freight company to immediately identify the geographic location of a specific tractor or trailer. 
         [0006]    However, while such systems allow a freight company to determine the identification entity location of any trailer or tractor in its system at any given time, it has not yet been possible to determine the specific order that multiple trailers are connected in tandem to a particular tractor. This is important for scheduling and deliveries in a time efficient manner. 
         [0007]    The electronic identification of particular tractor or trailer identification has required the use of specific power line carrier modules which can be programmed with a particular tractor or trailer identification number on which they are mounted. This is added cost to the power line carrier system. 
         [0008]    PLC identifier tags, such as a PLC identifier tag manufactured by Hegemon Electronics, Inc., Sterling Heights, Mich., have been available since at least as early as 2005. Such PLC identifier tags, when installed on a tractor or trailer, send out a unique programmable identification number at regular intervals onto the vehicle PLC power line. This periodic vehicle identification transmission is detected by a PLC Gateway mounted in the tractor or trailer and used to detect the connection and disconnection of a trailer to and from a tractor. The detection of a connection or disconnection event is then transmitted by the PLC Gateway to a remotely located processor. 
         [0009]    It would be desirable to provide improvements in tractor-trailer communication and identification systems using a power line carrier system. 
       SUMMARY 
       [0010]    A method to identify a plurality of trailers, each having unique trailer identification, and the order of hook up of the trailers sequentially coupled to a tractor. Each of the plurality of trailers and the tractor are in data communication via a power line carrier system, the method identifies the trailer identification in the order of coupling of each trailer to the tractor using, in part, the power line carrier system. 
         [0011]    A power line carrier system including at least one power conductor is coupled between a tractor and each of the plurality of trailers for communicating data signals between the tractor and each of the plurality of trailers. 
         [0012]    Identifying the trailer identification providing unique power line carrier identification in each of the tractors and the plurality of trailers. 
         [0013]    The step of providing the PLC identification includes providing an identification tag on each trailer configured to broadcast unique trailer identification from each trailer to the power line carrier system. 
         [0014]    The method further includes providing a wireless transmitter on each of the tractor and the plurality of trailers, each transmitter transmitting a message containing a unique wireless identification and an indication whether the vehicle is a tractor or one of the plurality of trailers, providing a wireless transmitter on each of the plurality of trailers coupled to the power line carrier system through the identification tag, the wireless receiver communicating the identification from the tractor and the plurality of trailers to the power line carrier system via the identification tag. 
         [0015]    A method to identify the order of a plurality of trailers serially coupled to a tractor coupling includes a power line carrier system including at least one power conductor coupled between a tractor and each of the plurality of trailers for communicating data signals over the at least one power conductor between the tractor and each of the plurality of trailers, coupling a power line carrier gateway in one of the tractor and one of the plurality of trailers to the power line carrier system, mounting a wireless transmitter in the tractor, mounting a wireless receiver and a wireless transmitter in each of the plurality of trailers, providing a unique trailer identification on the trailer and on each of the plurality of trailers, transmitting by the power line carrier gateway a message on the power line carrier system containing information identifying the tractor and including the tractor identification, receiving by the wireless receiver on each of the plurality of trailers the message from the power line carrier gateway, transmitting by the wireless transmitter on each of the plurality of trailers the trailer identification to all of the trailers and the tractor within a signal range of each respective transmitter, determining a match by the PLC gateway between the tractor identification and the tractor identification received by only one of the plurality of trailers to identify the first trailer coupled to the tractor, transmitting by the first identified trailer a message on the power line carrier system that it is the first trailer coupled to the tractor, and receiving by each of the remaining plurality of trailers the message from the first trailer, and comparing the identification of the first trailer with the identification received by the wireless receiver on each trailer and determining a match, the match identifying the second trailer immediately coupled to the first trailer. 
         [0016]    In one aspect, each tractor and trailer identification is stored in a readable power line carrier tag mounted respectively on each tractor and trailer and coupled to the power line carrier system. 
         [0017]    In one aspect, the method includes the step of wirelessly transmitting by the trailers each identification on the power line carrier system, receiving the trailer identification by the power line carrier data terminal, receiving by each wireless receiver on each trailer all of the wireless identifications broadcast by the transmitters on all other of the plurality of trailers, transmitting by each trailer all of the trailer identifications onto the power line carrier system, receiving by the power line carrier gateway all of the trailer identifications and determining a match with the identifications received from the initial trailer identification broadcast, the power line carrier gateway comparing the trailer identification data to determine the trailer identification that reported the tractor identification, and for each remaining one of the plurality of trailers, the PLC gateway determining a match between the power line carrier tag on trailer which read the trailer identification from the proceeding trailer. 
         [0018]    A method to identify the tractor and one or more trailers serially coupled to the tractor includes a power line carrier system coupled to at least one power conductor coupled between a tractor and each of the plurality of trailers for communicating data signals over the at least one power conductor between the tractor and each of the plurality of trailers, a power line carrier gateway mounted in one of the tractor and one of the plurality of trailers and coupled to the power line carrier system, a readable vehicle identification is stored in an electronic module in each of the tractor and the trailers. The power line carrier gateway extracts the vehicle identification from each of the tractor and the trailer electronic modules. 
         [0019]    According to one aspect, the power line carrier gateway is mounted in one of the plurality of trailers and extracts the vehicle identification from the tractor via the power line carrier system to identify the particular tractor coupled to the trailer carrying the power line carrier gateway. 
         [0020]    In the method each transmitter on each of the trailers has an effective transmission range to reach only a distance to a front portion of the next adjacent serially connected trailer to receive a message transmitted from the transmitter. 
         [0021]    According to the method the electronic module mounted on each trailer and each of the plurality of tractors includes one of an ABS controller, a tire air pressure apparatus and a trailer temperature controller. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0022]    The various features, advantages and other uses of the present apparatus and method will become more apparent by referring to the following detailed description and drawing in which: 
           [0023]      FIG. 1  is a block diagram of one aspect of the tractor-trailer identification and order of hook-up apparatus; 
           [0024]      FIG. 2  is a detailed block diagram of the PLC tag and wireless RX shown in  FIG. 1 ; 
           [0025]      FIG. 3  is a block diagram of another aspect of the tractor-trailer identification and order hook-up apparatus and method; 
           [0026]      FIG. 4  is a block diagram of another aspect of the tractor-trailer identification and order hook-up apparatus and method; 
           [0027]      FIG. 5  is a block diagram of a tractor-trailer identification apparatus; 
           [0028]      FIG. 6  is a block diagram showing a modification to the apparatus and method depicted in  FIG. 4 ; 
           [0029]      FIG. 7  is a block diagram showing a modification to the apparatus and method depicted in  FIG. 5 . 
           [0030]      FIG. 8  is a flow diagram depicting the sequence of operation of the aspect of the tractor-trailer identification apparatus and order of hook-up shown in  FIG. 1 ; 
           [0031]      FIG. 9  is a flow diagram depicting another aspect of the sequence of operation of the tractor-trailer identification and order of hook-up apparatus and method shown in  FIG. 1 ; 
           [0032]      FIG. 10  is a flow diagram depicting the sequence of operation of the aspect of the tractor-trailer identification apparatus and order of hook-up shown in  FIG. 4 ; and 
           [0033]      FIG. 11  is a flow diagram depicting the sequence of operation of the aspect of the tractor-trailer identification apparatus shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Referring now to the drawing and to  FIGS. 1 ,  2  and  8  in particular, there is depicted one aspect of the tractor-trailer data communication apparatus  20  and method for determining the identification entity of and the order of hook-up of a tractor and the plurality of serially or tandem connected trailers. For example, as shown in  FIG. 1 , a tractor  22  has a plurality with three trailers  24 ,  26  and  28  shown by way of example only, connected serially or in tandem to the tractor  22 . It will be understood that the trailer  24  is usually directly connected to the tractor  22 ; while trailers  26  and  28  ride on dollies connected to the rear end of the proceeding trailer  24  or  26 . 
         [0035]    In the trucking industry, the tractor  22  is electrically connected to the trailer  24  and the trailers  24 ,  26  and  28  are connected to each other by seven conductor umbilical cords connecting the electrical systems of tractor  22  to the electrical systems of the trailers  24 ,  26  and  28  to control trailer lighting, brake lights, braking, etc. 
         [0036]    Due to the introduction of additional electronic systems in trailers, such as ABS brake controllers, tire air pressure monitor systems and refer temperature controls, a power line carrier (PLC) system is used to bi-directionally transmit signals along one of the conductors of the PLC system between the tractor  22  and the trailers  24 ,  26 , and  28 . As shown in  FIGS. 1 and 3 , the PLC system  34  is shown extending in signal communication from the tractor  22  through each of the trailers  24 ,  26  and  28 . 
         [0037]    In the first aspect shown in  FIGS. 1 and 2 , the apparatus  20  includes the following hardware on the tractor  22  and each trailer  24 ,  26  and  28 . The PLC system  34  includes a PLC Gateway or reader  40  in the form of a data communication terminal, as well as a PLC bus  34  which includes at least one of the conductors in the umbilical cords connecting the tractor  22  to the trailer  24  and the trailers  24 ,  26  and  28  to each other. 
         [0038]    The tractor  22  carries a wireless transmitter  50  which is capable of transmitting via radio frequency communications typically at a designated frequency, over a short range sufficient to reach the forward or front end of the next adjacent trailer  24  in the tandem series of trailers  24 ,  26  and  28 . The wireless transmitter  50  may have a range of approximately 10 feet so that the signal transmitted by the transmitter  50  is receivable by an appropriately tuned receiver only within the 10-foot distance. 
         [0039]    A PLC Gateway  40  also referred to as a PLC Gateway reader  40 , is illustrated in the first aspect as being mounted in the tractor  22 . It will be understood that the PLC Gateway  40  may be mounted in either the tractor  22  or any of the trailers  24 ,  26  and  28 , as described in subsequent aspects. 
         [0040]    The PLC gateway  40  can also be a PLC CAN gateway sold by Hegemon Electronics, Inc. The gateway  40  provides a gateway for CAN, RS232, J1708 or J1939 equipped devices to get access to the PLC messages that reside on the tractor and trailer power lines  34 . The PLC gateway  40  thus acts as an interface between the telemetrics unit  44  and the PLC tag  30  to bidirectionally relay messages from the PLC tag  30  to the telemetrics unit  44  and vice versa. 
         [0041]    A telemetrics unit  44  is also mounted in the tractor  22  and provides communication between the tractor  22  and a remotely located central processing unit  13 , which can be mounted at the headquarters of the trucking company. 
         [0042]    The PLC gateway  40  typically communicates by hardwire conductors  42  to the telemetrics unit  44  using any OBC device using J1708, J1939, J1587, RS232, CanBus USB etc. As shown in  FIG. 1 , the telemetrics unit  44  communicates through an antenna  46  to a satellite, not shown, or to a cell tower  17  through the Internet and/or hardwired conductors to communicate the data from the PLC Gateway  40  to an external host computer remotely located processor  13 . The telemetric unit  44  can also communicate with the external satellite and computer based host system through cellular, satellite, Wi-Fi, 802 etc., communications. The telemetrics unit  44  can also have tracking options such as GPS, RFID, RTLS, etc. 
         [0043]    Telemetric units  44  are available from a number of companies, including, for example, Qualcomm, GE, International Telemetrics, RTL, Xata, Peoplenet, Skybitz, StarTrak, Partech, Cadec, FleetMind, Turnpike, Navman, etc. 
         [0044]    Each trailer  24 ,  26  and  28  includes a wireless receiver  52  tuned to the frequency of the transmitters  50 ,  54 . The receiver  52  is mounted on the forward end of the front nose of each trailer. 
         [0045]    A wireless transmitter  54  is also mounted on each trailer  24 ,  26  and  28 , generally adjacent the rear end of each trailer  24 ,  26  and  28  and coupled to an antenna  55 . 
         [0046]    A PLC tag  30  is also mounted on each trailer  24  in data communication with the PLC bus  34 . The PLC tag  30  may be a PLC identifier tag manufactured by Hegemon Electronics, Inc., Sterling Heights, Mich. The PLC tag  30  functions as a reader to read data from the memory  72  of the PLC tag  30  and transforms the data into a format capable of communication over the existing tractor-trailer PLC bus  34 . The PLC tag  30  includes a processor  70  which accesses data and a control program stored in one or more memories  72 . The PLC tag  30  includes input and output ports namely, UART, I 2 C, or SPI. 
         [0047]    The PLC tag processor  70  communicates through a PLC transceiver  74  and a power line interface  76  to bidirectionally receive and transmit data from the PLC tag  30  over the existing PLC bus lines  34  to the PLC gateway or reader  40  mounted in the tractor  10 . 
         [0048]    During the installation of the communication system  20  on the tractor  22  and the trailers  24 ,  26  and  28 , the tractor  22  and each trailer  24 ,  26  and  28  will be provided with at least one unique identification number or identification. Each identification is unique to each trailer or a tractor and can include a particular identification identifying it as a tractor or a trailer. For example, the identification may include an alphanumeric segment identifying a particular tractor and trailer. A prefix, suffix, or a segment of the message may also include a binary code identifying the particular identification as uniquely belonging to a tractor or a trailer. 
         [0049]    Alternately, the identifications assigned to tractors may be of a particular class to readily identify identification as belonging to a tractor or a trailer and to differentiate such tractor identifications from the trailer identifications, which are part of a different alphanumeric class. 
         [0050]    A wireless identification is stored in the tractor transmitter  50  and each wireless transmitter  54  on the trailers  24 ,  26  and  28 . Similarly, a PLC identification is stored in the PLC tag  30 , such as in a memory  72 . Both the wireless identification and the PLC identification may be the same for a tractor or trailer. 
         [0051]    The wireless receiver identification and the PLC identification may be manually programmed into the memory of the wireless receiver  50  or  54  and into the memory  72  of the PLC tag  30  during the installation of the software into the processor in each wireless receiver  50 ,  54  or PLC tag  30 . 
         [0052]    Alternately, the wireless identification and the PLC identification may be installed in each tractor  22  and each trailer  24 ,  26  and  28  via data communication from the remote central processor  13  through the telemetrics unit  44 . The remote control station  13  can initiate the programming by issuing an ID programming command. The command will contain the address of the component to be programmed and the new ID. The remote station  13  sends the command out to the network  17  and then onto the vehicle  22 . The telemetrics device  44  in vehicle  22  picks up the command and passes it onto the PLC gateway  40 . The PLC Gateway  40  then puts the information on the PLC Bus  34  and all PLC Tags  30  pick up the information. Only the addressed PLC Tag  30  accepts the information. All the rest of the PLC tags  30  reject the information. For example, PLC Tag  30  in trailer  24  is addressed and accepts the information. PLC Tag  30  in trailer  24  looks at the information. If the ID is for trailer  24 , the PLC tag  30  then erases its old ID and then saves the new ID in non-violate memory. If the new ID is intended for the wireless TX  54  on trailer  24 , the TX  54  is coupled to the PLC tag  30  then the PLC tag  30  passes the new ID onto the wireless TX  54  along with a new ID command. This will also work if the PLC gateway is installed in a trailer, such as in  FIG. 3 . 
         [0053]    The operation of one aspect of the communication system will now be described in conjunction with  FIGS. 1 and 2  and the flowchart shown in  FIG. 8 . 
         [0054]    At power up (ignition on or continuously), step  200 , the PLC Gateway  40  will transmit in step  202  a PLC message on the PLC bus  34 , which will contain information identifying it as a tractor and the PLC identification. Each PLC Tag  30  in the trailers  24 ,  26  and  28  will receive this information over the PLC Bus in step  204  but, at this time the PLC tags  30  do not know which trailer  24 ,  26 ,  28  is connected to the tractor  22  or the order of the trailer hook-up. 
         [0055]    Also at power up, each transmitter  50 ,  54  will transmit in step  205  a wireless message containing the wireless identification and the vehicle type either, tractor or trailer. Each wireless RX  52  will read the wireless message in step  206  from the transmitter  50 ,  54  in front of it. This wireless message will contain what vehicle the message was received from (tractor or trailer) and its wireless identification. It should be noted here that each wireless RX  52  may read more than one identification due to other vehicles being in close proximity and powered. After reception, the wireless RX  52  will relay all identifications it has read to the PLC Tag  30  on the same trailer  24 ,  26 ,  28  in step  207 . 
         [0056]    At this point all PLC Tags  30  know all the devices that are attached to the PLC bus  34 , where they came from (tractor or a trailer), the PLC identification, and all wireless identifications read by its wireless RX  52 . Each PLC Tag  30  will now, in step  208  sort through all the wireless identifications it has received and throw out the wireless identifications that do not have a corresponding PLC identification. This will eliminate all trailers that are not attached to the tractor  22 . 
         [0057]    Next each PLC Tag  30  in step  210  will look at the remaining wireless identifications and for a match in step  212  between the tractor PLC identification and the wireless tractor identification. Only one Tag will have a match because the wireless transmitters  50  is not powerful enough to reach the second, third, trailers  26 ,  28 . The PLC Tag  30  that has received the wireless tractor identification is connected right behind the tractor  22  and therefore is trailer #1 in the lineup. 
         [0058]    At this time trailer  24  knows it is hooked up right behind the tractor  22  so it now broadcasts a PLC message in step  214  stating that it is the #1 trailer in the tandem trailer sequence. This message will contain its PLC identification, its wireless identification, and its position, in this case trailer #1. The PLC tags  30  in trailers  26  and  28  pick up this message. The tractor  22  ignores this message. Trailer  26  and trailer  28  now compare in step  216  this wireless identification with the wireless identification they received from their wireless receiver. A match in step  218  will mean the next trailer #2 in the hook-up sequence is trailer  26 . 
         [0059]    The process is now repeated. Trailer  26  transmits a PLC message, in step  220  containing its PLC identification, its wireless identification, and its hook-up position (#2). The tractor  22  and trailer  24  ignore this message. Trailer  28  uses this information to figure out it is trailer #3. This process is repeated until all trailers have established their placement in step  222 . 
         [0060]    An alternate method for determining the tractor  22  and trailers  24 ,  26 ,  28  identification and the order of hook-up of the trailers  24 ,  26  and  28  to the tractor  22  is shown in  FIG. 9 . 
         [0061]    This method has the same hardware configuration shown in  FIG. 1 . The difference between the first method and this method is that all decision making with respect to determining the hook-up order of the trailers  24 ,  26  and  28  to the tractor  22  is done in the PLC gateway  40 . 
         [0062]    On power up, step  300 , all transmitters  50  and  54  transmit the wireless identification and vehicle type information to broadcast all of the respective wireless identification vehicle type. All wireless receivers  52  read all wireless identifications that are within range including the wireless TX  50 ,  54  in front of it in step  304 . Such wirelesses RXs  52  send all wireless of the identifications it has read to its PLC tag  30  in step  304 . The PLC tags  30  broadcast this information onto the PLC bus  34  in step  306 . The tractor PLC Gateway  40  picks up all of these PLC broadcasts with wireless information and now knows who is connected to the tractor but does not know the order. 
         [0063]    Also power up step  300 , all PLC Tags  30  broadcast their PLC identification onto the PLC bus  34  in step  306 . 
         [0064]    The PLC Gateway  40  then sorts in step  309  through all the wireless identifications it has received in and throws out all the wireless identifications that do not have a corresponding PLC identification that was received in steps  304  and  306 . This removes all unconnected vehicles from the database. 
         [0065]    The PLC Gateway  40  now knows the wireless and PLC identification for each trailer. PLC Gateway  40  in step  309  now sorts through the data in step  309  and looks for the PLC tag  30  that reported that it saw the tractor  22  wireless identification in step  310 . The Gateway  40  now knows that trailer  24  is trailer #1. 
         [0066]    The PLC Gateway  40  now repeats step  309  and sorts through the data and finds the PLC Tag  30  who read the wireless identification from the trailer #1. It now knows which the second trailer  26  is. 
         [0067]    Step  309  is repeated by the PLC Gateway  40  until all trailers have been ordered per step  314 . 
         [0068]    The PLC Tag  30  and the wireless receiver  52  on each trailer  24 ,  26  and  28  can be combined into one module  53  for cost reductions. 
         [0069]    The wireless transmitters  50 ,  54  and the wireless receivers  52  utilize ultrasonic, low frequency radio waves, or medium frequency radio waves or Bluetooth. 
         [0070]    Referring now to  FIGS. 4 and 10 , another aspect of the communication apparatus and method will be described. This method is a low cost solution to accomplish the above described methods by using existing electronic modules  56  on the tractor  22  and the trailers  24 ,  26  and  28 . This apparatus includes the same hardware as shown in  FIGS. 1-3 , except that the PLC portion of each PLC tag  30  is incorporated into one wireless receiver as module  53  as shown in  FIG. 2 . 
         [0071]    A unique vehicle identification, such as the vehicle&#39;s VIN (Vehicle Identification Number) or other number uniquely identifying the vehicle, is read directly from factory installed electronic modules  56  on each trailer  24 ,  26  and  28 , as well as on the tractor  22 . Examples of existing electronic modules which can communicate through the PLC bus  34  to the PLC Gateway  40  include, but are not limited to the trailer or tractor ABS controller, the trailer or tractor tire air pressure system, and the trailer refer temperature controller. In the following description of the control sequence used in this method, as shown in  FIG. 10 , the vehicle electronics will be referred to as the ABS controllers  56 , for example. 
         [0072]    Upon power up, all wireless transmitters  50  and  54  transmit a wireless identification and vehicle type. All wireless receivers  53  read in step  402  all wireless identifications that are within range including the wireless TX  50  or  54  in front of it. The wireless RXs  53  broadcast all wireless identifications read and the VIN number onto the PLC Bus  34  in step  408 . The tractor PLC Gateway  40  picks up all of these PLC broadcasts and wireless information. 
         [0073]    At install, the wireless RX/PLC module  53  is programmed with vehicle&#39;s VIN number. This can be done in a variety of ways ranging from automatic to human programming. This can be a one-time event. 
         [0074]    Also on power up (ignition on or continuously), step  400 ,  FIG. 10 , the PLC tags  53  interrogates their respective vehicle electronic modules  56  for the vehicle VIN number in step  402 . 
         [0075]    Upon power up in step  400 , all wireless receivers  53  read in step  402  all wireless identifications that are within range including the wireless TX  50  or  54  in front of it. The wireless RXs  53  broadcast all wireless IDs read and the VIN onto the PLC bus  34  in step  408 . The tractor PLC Gateway  40  picks up all of these PLC broadcasts and wireless information. 
         [0076]    The PLC Gateway  40  then repeats steps  309 - 314  of the method shown in  FIG. 9  as follows. The PLC Gateway  40  then sorts through all the wireless identifications it received in step  309  and throws out all the wireless identifications that do not have a corresponding PLC identification that was received in step  402 . This removes all unconnected vehicles from the database. 
         [0077]    The PLC Gateway  40  now knows the wireless identification and VIN number for each trailer  24 ,  26 , and  28 . It now sorts through the data and looks for the RX/PLC module  53  that reported that it saw the tractor  22  wireless identification. The PLC Gateway  40  now knows which is the first trailer in the hook-up order to the tractor  22 . 
         [0078]    The PLC Gateway  40  now sorts through the data and finds the RX/PLC tag  53  who read the wireless identification from the first trailer  24 . It knows which is the second trailer  26  in the hook-up order. 
         [0079]    Step  309  is repeated until all trailers have been ordered in step  314 . 
         [0080]    Referring now to  FIGS. 5 and 11 , there is depicted another aspect of a communication apparatus and method which can also be used as a very low cost vehicle tractor-trailer identification system. To be a low cost vehicle identification system, the wireless devices  50 ,  52  and  54  installed on the trailers  22 ,  24 , and  26  are not required. 
         [0081]    To identify all trailers and the tractor by their unique identification, the only new module required is the PLC Gateway  40  which is mounted on one of the trailers  24 ,  26  or  28 . Upon power up step  500 ,  FIG. 11  the PLC Gateway  40  will extract the VIN numbers, or other identification, out of each trailer&#39;s and tractor&#39;s existing vehicle electronic box in step  502 ,  504 . The only new component required for purchase by the customer is the PLC Gateway  40 . 
         [0082]    It should be noted that although  FIG. 5  shows the PLC Gateway  40  as being located on the trailer  24 , the PLC Gateway  40  can alternately be mounted on the tractor  22  on any of the trailers  24 ,  26  and  28 . Regardless of the mounting location, the PLC Gateway  40  is uniquely capable of extracting and reading the VIN numbers or other tractor or trailer identifications from any of the serially connected tractor  22  and trailers  24 ,  26  and  28 . 
         [0083]    Generally, the PLC Gateway  40  is located close to and usually in the same vehicle as the GPS tracking system used to track the particular vehicle, whether it is the tractor  22  or the trailers  24 ,  26  and  28 . 
         [0084]    Referring now to  FIG. 6 , there is depicted a modification to the apparatus shown in  FIG. 4 . A J1708 and/or a J1939 port can be added to the PLC gateway  40 . The J1708 and/or J1939 port enables all information that is not available through the PLC port to the telemetrics  44 , but is obtainable through the J1708 and/or J1939 port, to be supplied to the telemetrics device  44  for off-trailer transmission to the remote processor  13 . For example, such information may include trailer mileage, tractor mileage, etc. 
         [0085]      FIG. 7  depicts the same addition of a J1709 and/or a J1939 port to the PLC Gateway  40  in the apparatus shown in  FIG. 7  where the PLC Gateway  40  is programmed to extract the trailer or tractor identifications from the respective vehicle electronics  53 . 
         [0086]    It should be also noted that all of the information that is available on the PLC bus  34  is supplied to the PLC Gateway  40  and can be transmitted off-trailer to the remotely located processor  13 . Such information can include the trailer and tractor mileages, the ABS status, the tire pressure, door status, either opened or closed, and trailer temperature can also be provided for any or all of the tractor and the trailers.