Patent Publication Number: US-6907445-B2

Title: Consistent application programming interface for communicating with disparate vehicle network classes

Description:
FIELD OF THE INVENTION 
   The present invention relates to vehicle communication networks and more particularly relates to providing an application programming interface which presents to programmers a common model covering a plurality of vehicle network classes. 
   DESCRIPTION OF THE PRIOR ART 
   Contemporary designs for the control and management of vehicle components increasingly rely on computer networking. Digital data is exchanged between component controllers over a common physical layer such as a twisted shielded pair of wires. Intelligible communication between two or more device controllers among a greater plurality of devices, all occurring over the common physical layer, depends upon the communicating devices being able to discriminate among messages they receive and respond to those messages directed to them. Such methods are well known in the art and are part of the standards which the Society of Automotive Engineers (SAE) has published and continues to publish as part of the SAE J1939 and the SAE J1587 protocols. 
   The J1939 protocol provides an open protocol and a definition of the performance requirements of the medium of the physical layer, but also allows for development of proprietary protocols. The SAE J1939 protocol is a specialized application of a controller area network (CAN) and may be readily implemented utilizing commercial integrated circuits such as the C167 Integrated Circuit manufactured by Siemens of Germany. 
   The CAN protocol is an ISO standard (ISO 11898) for serial data communication, particularly aimed at automotive applications. The CAN standard includes a physical layer (including the data bus) and a data-link layer, which define a few different message types, arbitration rules for bus access and methods for fault detection and fault confinement. The physical layer uses differential transmission on a twisted pair wire bus. A non-destructive bitwise arbitration is used to control access to the bus. Messages are small, at most eight bytes, and are protected by checksum error detection. Each message carries a numeric value which controls its priority on the bus, and may also serve as an identification of the contents of the message. CAN offers an error handling scheme that results in retransmitted messages when they are not properly received. CAN also provides means for removing faulty nodes from the bus. CAN further adds the capability of supporting what are termed “higher layer protocols” for standardizing startup procedures including bit rate setting, distributing addresses among participating nodes or kinds of messages, determining the layout of the messages and routines for error handling on the system level. 
   The SAE J1587 protocol relates to data exchange between microcomputers in heavy duty vehicle applications. The protocol defines formats for message and data, including field description, size, scale, internal data representation and position within a message. Guidelines for message transmission frequency and circumstances are provided. Message formats are to be published for information pertaining to vehicle operation and vehicle component performance, diagnostic and maintenance data, among other things. The protocol is used in conjunction with the SAE J1708, which defines requirements for hardware. 
   Digital data communications over serial data paths are an effective technique for reducing the number of dedicated communication paths between the numerous switches, sensors, devices and gauges installed on the vehicles. Multiplexing the signals to and from local controllers and switches promises greater physical simplicity through displacing much of the vehicle wiring harness, reducing manufacturing costs, facilitating vehicle electrical load management, and enhancing system reliability. 
   It is by no means clear that the two published standards will prove to be the universe of possible network protocols for vehicles. Indeed both standards provide for proprietary extensions to the protocols. The existence of more than one protocol complicates the work of programmers. Commonly, a separate programming interface for each class of vehicle network has been provided. Programmers have been required to know the details of the network protocol in order to program vehicle class networks. For example, a programmer has been required to know the details of network message formats and message structure. This forces programmers to spend time on nuances of network operation rather than applying a focused effort to programming related to vehicle operation. Generalized programming interfaces, for example, RP1210 and OPC have proved either too general or too poor in performance terms, and have lacked mechanisms for handling data in a consistent manner on all classes of networks. 
   Software development can be greatly aided by increasing the level of abstraction at which the programmer works. Increasing abstraction in a programming environment should be based on increasing independence from any one programming language or platform and allow sharing of fundamental components between programs. The flexibility and adaptability of such a system are enhanced by making the system extendible, which allows for evolution of the system and by providing a high level of robustness. 
   One system proposed meeting many of these criteria is the Microsoft Component Object Model (COM). COM provides a foundation for higher-level software services, which may be presented to a programmer at a high level of abstraction. COM provides mechanisms for communications between components, even across process and network boundaries, error and status reporting and for dynamic loading of components. Qualification of a software or data model or object as a COM component requires meeting certain interface design rules. 
   A programmer working in a COM environment is able to exploit a binary standard for function calling between components and to use common interfaces for strongly typed groups of functions. COM provides a base interface which allows components to dynamically discover the interfaces implemented by other components (through qualification) and which further provides reference counting to allow components to track their own lifetime and to delete themselves. See  The Component Object Model: A Technical Overview , Williams, Sara &amp; Kindel, Charles (1994). 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided a computer implemented translation system between a client and remote devices connected to a vehicle data network. The translation system presents programmers with a uniform abstraction of vehicle networks that permits programming and diagnostic procedures to be carried out without reference by the programmer to nuances of the particular network class used on the motor vehicle. As a result, a programmer works with any vehicle network through a common interface. Three major interfaces are defined to implement the invention. A network interface incorporates a plurality of functions representing a model of a physical network. A data link interface responsive to client requests for acquiring a network instance corresponding to a physical network from the network interface. The establishment of a network instance may involve reference to a database to obtain appropriate drivers for the underlying physical network represented by the network instance. A remote device interface incorporates a plurality of functions representing the physical devices callable through the network interface and handles messaging between the client and a physical device attached to the underlying physical network. 
   Additional effects, features and advantages will be apparent in the written description that follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is an illustration of a vehicle electrical system in a perspective, partial cutaway view of a truck; 
       FIG. 2  is a high level block diagram of a computer system used to implement the invention; and 
       FIG. 3  is an interface specification provided by the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Environment 
     FIG. 1  is a perspective view of a vehicle  11  and of an electrical control system  10  installed on the vehicle and vehicle chassis  13 . Vehicle electrical system  10  comprises a network which may, in one embodiment, comprise a twisted pair (either shielded or unshielded) cable operating as a serial data bus  18 . One node of bus  18  is a body controller  30 , which is a major component of a vehicle electronic control system. Body controller  30  manages a number of vocational controllers connected to bus  18  as nodes. Collectively, bus  18  and the various nodes attached thereto form a controller area network (CAN). Numerous opportunities exist for programming the various controllers. Alternative network classes may be employed. 
   Active vehicle components are typically controlled by one of a group of autonomous, vocational controllers, which include an instrument and switch bank  12 , a gauge cluster  14 , an engine controller  20 , a transmission controller  16 , and an antilock brake system (ABS) controller  22 , all of which are connected to body controller  30  over a serial data bus  18  and all of which are connected to bus  18  as nodes. The autonomous controllers include local data processing and programming and are typically supplied by the manufacturer of the controlled component. For each autonomous controller there is a defined set of variables used for communications between the autonomous controller and other data processing components on the network or attached to the network. Bus  18  is preferably a twisted pair cable constructed in accordance with SAE standard J1939 and is externally accessible via a diagnostic port  36 . Diagnostic port  36  is typically located under the steering column inside the cab of vehicle  13 , but may be located elsewhere. Although the autonomous controllers handle many functions locally and are functionally defined without reference to body controller  30 , they may report data to body controller  30  and may receive operational requests from body controller  30 . Gauge cluster  14 , transmission controller  16  and engine controller  20  all may communicate with body controller  30 , which also monitors inputs received from the auxiliary instrument and switch bank  12  over the serial communication link in harness  18 . For a CAN system a J1939 compliant cable  23  is connected from port  36  to a remote data link computer  44 . 
   External Hardware Implementation 
     FIG. 2  is a block diagram of a data processing system  43  incorporating a data link PC  44 . Data link PC  44  is a personal computer of substantially conventional architecture, adapted to communicate with a vehicle network meeting either of the SAE protocols. It is anticipated that any new protocols developed in the future will be as readily handled. Computer  44  is attached to the usual peripheral devices including a display  60 , a keyboard  62  and a pointing device  64 . Pointing device  64  and keyboard  62  are connected to the computer&#39;s serial bus  65  which transmits inputs from those devices to the motherboard in a conventional manner. Computer  44  further includes a PCI bus for the attachment of adapter cards, which include a network adapter  66  and a PCI to CAN adapter card  76 . The network adapter  66  allows connection via an external ethernet  68  to other data processing equipment such as an event logger  70 . Adapter card  76  allows two connections to a vehicle CAN bus  92  over which communication may be maintained to a remote device  94 . Alternatively, remote device  94  may be connected by an SAE J1587 bus  96  to a port adapter  90  allowing communication between the remote device  94  and computer  44  through the computer&#39;s serial bus  65 . Such communication would occur over a conventional personal computer serial port. Motherboard  72  includes a special data bus  78  for communication with a floppy drive  80  a CD Rom  82  and a hard drive  84  and controls the display  60  over a local video bus  86  and display interface  88 . Remote data link personal computer  44  executes data link software package  100  described below to allow programmer interaction with remote device  94  attached to a motor vehicle network. 
   Software Systems 
     FIG. 3  illustrates the component object model and interface design provided by a data link software package  100  of the invention. Software package  100  incorporates three COM interfaces through which a programmer may program or evaluate a vehicle network at an abstract level. Package  100  provides translation of a message moving between client and devices across a network boundary, relieving the programmer of concern for the details of specific network messaging. COM interfaces  38 ,  39  and  40  represent the highest level of abstraction of the system and, while believed by the present inventors to be a particularly convenient and logical way of presenting underlying systems, do not exhaust the possibilities for high level re-presentation. All COM interfaces must implement the interface for a root COM component+/Unknown. Every interface must have a unique interface identification (IID). An interface, once assigned an IID and published, becomes unmutable. Interface member functions should have a return type of HResult to allow reporting of remote procedure call (RPC) errors. String parameters in interface member functions should be in Unicode. Extensive descriptions of the Component Object Model are available from the Microsoft Online Library on the World Wide Web. 
   The IDataLink Interface 
   An IDataLink interface  38  provides the starting point for clients access to the functionality provided by the data link software package  100 . It provides a mechanism for acquiring network interface instances corresponding to a physical network. Interface  38  further provides for the enumeration of those networks that have already been acquired. IDataLink interface  38  includes two functions. One function is an “Acquire Network” function  270 . Function  270  returns an instance of an INetwork interface  39 . The INetwork interface  39  provides the gateway to a physical network in general, and particular devices connected to the physical network. The name and instance number of a physical network are concatenated to generate a unique name that is used to refer to the given network. Multiple calls to acquire network with the same name return an INetwork pointer that points to the same underlying physical network. An example of a network name/instance number concatenation where a CAN network is installed on a vehicle is:
 
Name= I+ME  PCI-IntelliCAN 1
 
The name is thereafter used to acquire additional network configuration data stored in the WIN32 registry. Entries within the WIN32 registry tell the software all the details of how to connect to the underlying physical network, e.g., which ports to listen on, which channel, etc. A cookie is implied by software returning a valid INetwork interface pointer to a COM object that represents an underlying network.
 
   The Acquire Network function  270  specifies three variables. The variables are denoted “Name”, “Instance” and “Network”. Name is the name of a hardware device that will represent a physical connection between the data link computer  44  and the SAE standard network installed on a vehicle. At present there are two SAE published standards, and the variable can assume one of two values: (1) “Dearborn protocol adapter” a value which implies the network shall be operating via physical connection to a Dearborn group DPA&#39;s II J1708 network interface (which is specific type of circuit board); and (2) “I+ME PCI-IntelliCAN” a value which implies that a network shall be operating via physical connection to a network utilizing the J1939 protocol (CAN). Should additional network protocols be defined, more allowed values may be added to software package  100 . The variable “Instance” refers to physical interfaces within a machine. An instance number is then used to pick up any additional configuration data needed to utilize a network interface. The variable “Network” is an INetwork object that is returned to a client. The client will then use this object to communicate with the network. 
   The function _Enumerate Networks_  258  is used by clients to enumerate all physical networks, typically vehicle networks, that are currently available. A network is defined as available if an instance for the physical network has been created using the Acquire Network function  270 . The client specifies a count of the number of INetwork pointers for which it is allocated storage. The data link software  100  then places as many enumerated networks into the network&#39;s array as possible. If there is insufficient storage, then the software returns only the count number of networks the client initially specified. Otherwise all networks that have been acquired are returned. When an acquired network is not called at all for an operating cycle, then count and networks return values are undefined and the HResult return code is set for fail. The return values for this function indicate success, a general failure that is a count or network&#39;s pointer, and a value for when no networks are successfully acquired. The variables include a count variable which is the number of networks that are in a set of networks returned to the client. Here the client specifies in a call the number of available network pointers in the network&#39;s variable. The client then receives the number of networks enumerated in this variable when the call returns. The second variable is the _networks_variable, which is a pointer to an array of INetwork object pointers that describe the networks of which the data link software package  100  is currently aware. 
   INetwork Interface 
   A second interface is the INetwork interface  39 . The INetwork interface  39  is a generalized software model of physical networks. Interface  39  provides data link interface clients with a way of communicating with a specific network. The data link software  100  performs the network&#39;s specific network connection per the network class that the user requests detection upon. This includes loading any proprietary network drivers and initializing them. If there are any start-up procedures that a device may need to perform to become an active member of the network (e.g., perform an address claim procedure on a J1939 network), then the Connect function  346  performs this operation. The Connect function  346  has no variables. 
   The Detect Device function  366  allows clients to detect devices on a physical network. Clients must perform a detection before they can communicate with a device in a network independent way. Detection on a given network occurs only once for a given platform. Additional data link clients can perform a device enumeration to get the proper references to available network devices. The variables for the Detect Device function  366  include “Notify Call Back”, which is a call back pointer that the software uses to notify a client that a given device has been detected. This value must contain a COM object that implements the IDetectNotify interface  438 . If the value does not return a COM object, then an error value is returned to the client. If a bad pointer value for the variable is passed, another error value is returned. A second variable for this function is a cookie which allows a client to effectively match a detection notification to an original detection request. 
   The “Disconnect” function  378  disconnects data link software  100  from the network. This step includes assuring failure of all future network requests as well as a disconnection of the network hardware and an unloading of any network drivers. No variables are required for this function. 
   An Enumerate Device function  426  is used to return the set of all devices that were detected the last time a detection occurred over the network. If there are no other remote devices on the network, then the set contains only the software&#39;s representation on the network. Variables for this operation include a Count variable which is the number of IRemoteDevice objects that are in the set of devices returned to the client. The client specifies on the call the number of available device pointers in the device less the number of variables. The client then receives the number of devices enumerated in this variable when the call returns. A device list variable is an array of IRemoteDevice objects that have been detected since the last network detection. 
   The “get_AdapterName” function  663  returns the adapter name of the underlying network. Its functional name is such that it can be used as a COM property or a function name. The only variable for this function is “adapter name” which is a storage place for the adapter name of the network represented by this object when returned to the client. 
   The “get_BaudRate” function  672  returns the operational baud rate of the underlying network. Its functional name is such that it can be used as a COM property or a function name. This whole variable for this function is “baud rate”, a storage place for the baud rate of a network represented by this object. 
   The _get_LastDeviceDetectionTime_function  681  returns the last time a device detection was performed on the underlying network. Its functional name is such that it can be used as a COM property or a function name. The sole variable for this function is the _last detection time_, a storage place for the last detection time of the network. 
   The “get_NetworkClass” function  690  returns the network class (e.g., J1939, J1587) of the underlying network. Again the function name can be used as a COM property or a function name. A variable for providing a storage place for the network class type of a network is provided. 
   The “get_NumberDetectedDevice” function  699  returns the number of devices detected the last time the DetectDevices function  366  was performed on the underlying network. Again the functional name is such that it can be used as a COM property or a function name. Variable “number of detected devices” is a storage place for the number of detected devices on the network. 
   The “RawMessageTrafficRegister” function  387  is used by clients to request all or a subset of message traffic that is transmitted on the network. The client specifies a filter if they want only certain data. Alternatively clients can also run in an unfiltered mode, receiving notifications when any message is transmitted on the network. A filter is not a filter mask, so if a given data link software client wishes to register for a set of messages within a range of values, they need to register each raw message separately. The same client can register for raw message multiple times with the same call back. In this case the client would be notified each time a message matched the client&#39;s filter criteria and if the client registered twice for the same message header then the client would be notified twice for each message received from the network. 
   Function  387  includes three variables. The “notify call back” variable is a call back pointer that the software uses to notify a client that a given message has been received that matches the client&#39;s filter criteria. This pointer must contain a COM object that implements the IRawMessageTrafficNotify interface  52 . If the pointer does not contain the COM object, an invalid argument result is returned to the client. If a bad pointer value for this variable is passed, a pointer error is returned. A filter variable specifies network header message comparisons within a particular range. The client specifies this as a mechanism for filtering out raw messages which are not of interest. A network cookie variable is returned to the client so the client can effectively match a detection notification to the original detect request. 
   A “RawMessageTrafficUnregister” function  402  is used to cancel a previous registration for raw message traffic using the RawMessageTrafficRegister function  387 . The client supplies a cookie given to it by the register call. The software then halts all future notifications for the registered filter criteria. If a client is receiving raw notifications for multiple registrations over the same call back mechanism then the other remaining raw message registrations remain in effect. Only the registration represented by the cookie is invalidated. Variable for this function is the cookie a client received from a previous registration with raw message traffic register. 
   The “TransmitRawMessage” function  411  is used by data link software clients to send out raw messages on the network. The client is wholly responsible for building the message header and message body, ensuring that it conforms to the protocol of the network and for checking for responses is appropriate. Time outs and message tries are wholly the responsibility of the client transmitting the raw message. Three variables provided for this function include, “header” which is a message header that is to be used when the message is transmitted on the network, “body size” which is the size in bytes of the message body and “body” which is the message itself. 
   A IRawMessageTrafficNotify interface  52  is one interface of a data traffic management facility  101  used by data link software  100  to notify data link clients that a raw message has been received from a network. This interface is reached through the INetwork  39  interface. Only one function is implemented with this interface, a message received function  285  which is implemented by a data link client and is used by the data link software  100  to call back to clients when raw message traffic that fit the client&#39;s criteria is received. Five variables are included within this function including “time stamp”, “header”, “body size”, “body” and “cookie” which is the cookie that was returned to the client when it performed a register for raw message traffic that subsequently triggered operation of this function. The character of each of the remaining variables tracks the names of the variables. 
   The INetwork interface  39  also communicates with an IDetectDeviceNotify interface  438 . Interface  438  is used by the data link software  100  and notify a data link client of the status of network detections. The interface includes two functions including a device detected function  440 , used by the data link software to notify the client that a previously commenced device detection has just detected another remote device on the network. This function has two variables, one a cookie, returned to the data link software client when it originally requests a detection commence, and a “remote device” variable which is a representation of the remote device that was detected on the network. The client can use this pointer for further network communications. 
   A “DetectionCompleted” function  452  is used by data link software  100  to notify a client that a previously commenced device detection has been completed. This gives the client the opportunity to wait until notification arrives before attempting additional network communications because not all devices might be detected as yet. The only variable return with this function is a cookie which is returned to the data link software  100  when it originally detected the detection commence. 
   IRemote Device Interface 
   An IRemoteDevice interface  40  is also accessible from the INetwork interface  39 . IRemoteDevice interface  40  includes a number of functions relating to receiving data from, and transmitting data to, actual physical devices. The structure of the interface reflects a generalization of a device and allows incorporation of a data base specifying operating parameters for physical devices. 
   IDataValueReceiveRegister function  480  is used by clients to request a particular data value from a remote device. The data link client specifies the data value that are of interest and a way of being notified by reference to a data base of values. The data link software  100  determines whether the message is broadcast by the remote device. If it is, then then the datalink software  100  notifies the client every time the message is received from the remote device. Otherwise the data link software  100  explicitly requests the data value from the remote device. If a device is unresponsive, then it is up to the data link client to determine this result. The data link software will not interpret the responsiveness of the device because the criteria for a responsive device may vary greatly from data link client to data link client. 
   DataValueReceiveRegister function  480  has three variables including a data value ID which is an abstract handle that represents the data value that is to be read from the remote device. Viable values for this handle can be found in the Tables. A notify call back variable is a call back pointer that the data link software  100  uses to notify a client that a given data link value has been received. This value must contain a COM object that implements the IDataValueReceiveNotify interface  53 . If it does not, then an invalid argument pointer is returned to the client. If a bad pointer value for the variable is passed in, another error value is returned. A cookie is returned to the client so that the client can effectively match a receipt notification to the original request and for unregistration procedures. 
   A “DataValueReceive” function  612  is used by clients to request a particular data value from a remote device. The data link client specifies the data value that it is interested in. This function call is different from data value receive register in that only one value is read, and it is a synchronous call. This means that the call will not return until the requested data value is received from the remote device, or a time out occurs. The time out value is controlled as a property of the network as defined in a WIN32 registry. The data link software determines whether the message is broadcast by the remote device. If it is, then the software waits for the next time the message is received from the remote device and then returns the data value to the client. Otherwise the data link software explicitly requests the data value from the remote device. When the answer arrives, then the data link software returns to the client with the data value. If the device is unresponsive, then it is up to the data link client to determine this. A device is classified as unresponsive if it displays a prolonged pattern of communication difficulties. Such communication difficulties may include continued time out of data value requests from a given remote device. The data link software will not interpret the responsiveness of the device because the criteria for a responsive device may vary greatly from data link client to data link client. A data link client might determine whether a device is responsive or not by periodically transmitting a message to it. If the periodically transmitted message continually times out for a period of five minutes, then the client may presume that the remote device is off line. 
   The data status variable reflects whether the data is actually valid or not. If it indicates an error, then the contents of data value are meaningless. Data status is distinctly different from an HResult return value because an HResult return value is used to indicate an operation error in the software whereas the data status variable indicates the status of remote device communications which may be operating correctly, but not returning the desired results. 
   Three variables are provided for this function including a “data value ID” which is an abstract handle that represents the data value that is to be read from the remote device. Allowable values for this handle may be found in an appendix to this application. The “data value” variable represents the data requested by the client. For example, if the client requested engine speed, then this variable is what contains the engine speed value. If there is a problem with the transmission as indicated by data status, then this value is undefined and should not be interpreted. Finally, a “data status” variable contains the status of network traffic that has generated this data value. If problems occur in obtaining the data value via the network then the data status variable reflects the problem. 
   A “DataValueReceiveUnregister” function  594  is used to cancel a previous registration for data value notification initiated using data value receive register function  480 . The client supplies a cookie given to it by the register call. The data link software then halts all future notifications for the registered filter criteria. If a client is receiving notifications from multiple registrations over the same call back mechanism, then the other remaining data value registrations remain in effect. Only the registration represented by the cookie is invalidated. The cookie is the only variable for this function and is the cookie that the client received from a previous registration with the data value receive register function  480 . 
   A “Change-of-Status(COS)DataValueReceiveRegister” function  492  is used by clients to request a change of state status for a particular data value on a remote device. The data link client specifies the data value that it is interested in and a way of being notified. The data link software  100  determines whether this message is broadcast by the remote device. If it is broadcast, then it notifies the client every time the message is received from the remote device. Otherwise the data link software  100  explicitly requests the data value from the remote device. 
   Data link software  100  can check data value as it is received from the remote device to ensure that the value does not fall outside of a tolerance range for the value. For example, if a data link client is monitoring a particular data value, it can specify notification if the value changes by 10%. In this case as soon as the data value changes more than 10% from the point of the original request, the client is notified. A number of variables are provided for this function. A data value ID variable is an abstract handle that represents the data value that is to be monitored on the remote device for a state change. A notify call back pointer is used by the data link software to notify a client that a given data link value has changed state. This value must contain a COM object that implements the ICOSDataValueReceiveNotifyinterface  57 . If it does not, then an error value is returned to the client. If a bad pointer is passed in another error is returned to the client. Yet another variable is the “state change type” variable. This variable describes the type of the state change that caused the notification. It is an enumeration that will either be state change which means the data is changed or a state constant which means that the data has remained constant, or has remained constant within a given value range. A tolerance variable is a tolerance value for change of data value as a percentage of the first value. Finally, a cookie is returned to the client so that the client can effectively match a change of state notification to an original request for unregistration purposes. 
   A “COSDataValueReceiveUnregister” function  585  is used to cancel a previous registration for change of state data value notification initiated using the change of state data value receive register function  492 . This function is used to cancel a previous registration for change of state data value notification. The client supplies a cookie given to it by the register call. The data link software then halts all future notifications for the registered filtered client criteria. 
   The DataValueTransmit function  627  is used by clients to send a particular data value to a remote device. The data link client specifies the data value that it is interested in and the data value it wants to send to the device. This call is different from the DataValuePeriodicTransmit-Registerfunction  642  in that only one value is sent, and it is a synchronous call. This means that the call will not return until the requested data value is sent to the remote device, or a time out occurs, The data status variable reflects whether the data transmission actually succeeded or not. The data link software  100  does not validate whether a value is in proper range. The caller is responsible for ensuring that any data value sent is in the proper value range. Variables for this function include data value ID, an abstract handle that represents the data value that is to be written to the remote device. A data value variable that the client requested to transmit to the remote device and a data status variable containing the status of network traffic that occurred with this data value transmit request. If there were any problems in obtaining the data value via the network the data status reflects this. 
   A DataValuePeriodicTransmitRegister function  642  is used by clients to send a particular data value to a remote device. The data link client specifies the data value in which it is interested and the data value it wants to send to the device. This call differs from data value transmit in that the value is periodically sent to the remote device based on a client&#39;s specify time value. This is an asynchronous procedure and means that the call will immediately return to the client. The client shall be notified at a later time of the result of transmissions to the remote device. The variables for this function include a data value ID which is an abstract handle that represents the data value that is to be written to the remote device. A data value variable that the client requested to transmit to the remote device. A timeout rate variable is a value representing the time value to wait in milliseconds for message transmission and an acknowledgment to complete. A transmit period variable indicates the periodic rate at which the software shall broadcast the data value to the remote device. 
   A DataValuePeriodicTransmitUnregister function  603  is used to cancel a previous registration to periodically transmit a data value using the data value periodic transmit register function. The client supplies a cookie given to it by the register call. The data link software then halts all future notifications for the registered filter criteria. If a client simultaneously receives notifications for multiple registrations over the same call back mechanism, then the other remaining registrations remain in effect. Only the registration represented by the cookie is invalidated. 
   The “get_DeviceAddress” function  522  returns the physical address or a remote device in the underlying network. Its function name is such that it can be used as a COM property or a function name. This property is read only enforceable because there is no corresponding published “put device address” function that would be used for setting the property externally via the interface. The variable included with this function is the “device address” variable, which is a storage place for the physical address of the remote device represented by this object. 
   A “get_IndustryGroup” function  549  returns the industry group for a remote device. Its functional name is such that it can be used as a COM property or a function name. The property is read only enforceable because there is no corresponding published put industry group that would be used for setting the property. The variable for this function is industry group which is a storage place for the industry group of the remote device. 
   A “get_VehicleSystemInstance” function  576  returns the vehicle system instance code of this remote device on the underlying network. Its functional name is such that it can be used as a COM property. This property is read only enforceable because there is no corresponding published put vehicle system instance function used for setting the property. The one variable defined for function  576  is a “vehicle system instance” variable which is the storage place for the vehicle system instance represented by the object. 
   A _get_VehicleSystem_ function  567  returns the vehicle system code of this remote device on the underlying network. Its functional name is such that it can be used as a COM property or a function name. The property is read only enforceable because there is no corresponding published put vehicle system that would be used for setting the property. One variable providing a storage place for the vehicle system represented by the object is defined for function  567 . 
   A “get_Function” function  540  returns the function code of this remote device. A functional name is such that can be used as a COM property or a function name. The property is read only enforceable. The sole variable for the function is entitled function which is again a storage place for the function code. 
   A “get_ECUInstance” function  531  returns a ECU instance for this remote device on the underlying network. The “ECU Instance” serves as part of the identification of the underlying device. Its functional name is such that it can be used as a COM property or a function name. The property is read only enforceable. ECU instance is the sole variable for this function which provides the storage place. 
   A “get_ManufacturerCode” function  558  returns a manufacturer code for a remote device on the underlying network. Its functional name is such that it can be used as a COM property or a function name. This property is read only enforceable because there is no corresponding published put manufacturer code that would be used for setting the property. Manufacturer codes are used for interrogating or querying a data base to obtain for a device values generated by a particular device, such as for an engine control module or anti-lock brake system. Manufacturer code is the only variable used with this function. 
   Finally a DataValueQuery function  660  provides a return route for placing requested values via variable names specified by the client. 
   Three interfaces are accessed through IRemoteDevice interface  40 . The first of these interfaces is an IDataValueReceiveNotify interface  53  used by the data link software  100  to relate information to data link clients about data values that they are registered for. Only one function, a receive function  306 , is provided for this interface and is used by data link software  100  to call back to clients when a data value that the client registered for is received over the network. Four variables are provided with this function including a time stamp, a data value, which may be specified by the manufacturer code, a status variable containing the status of network traffic that generated this data value and a cookie returned to the client when it performed a register for the data value that subsequently generated this function call back. An ICOSDataValueReceiveNotify interface  57  is used by the data link software  100  to relate information about the status of data values when they change state to data link clients that register for this notification. A data changed function  324  is used by the data link software to call back to clients when a data that the client registered for changes its state based on criteria specified by the client. Variables for this function include a time stamp, data value, data status, state status, which describes the type of state change causing the notification. This value is an enumeration that will either be state change which means the data changed or state constant which means the date is continually remaining constant within a tolerance range. A cookie variable is returned to the client when it performed a register for the data value that subsequently generated this function call back. 
   An IDataValueTransmitNotifyinterface  59  is used by data link software  100  to relate information about the status of data value transmissions to remote devices. A data transmitted function  461  is implemented through this interface to call back to clients when a data value that the client is transmitting has been sent to the network. The variables for this function include a time stamp. Another variable is transmit status which contains the status of network messages at the point of transmission to the network. Any problems in sending the data value are reflected in the field. 
   Database Support 
   A data link library or database provides definitions for the data link software  100  when applied to a heavy duty truck application. Clients use compiler mechanisms that need to be aware that they need to scope all data types defined within the data link library. The data link server exposes only one COM object that is externally creatable (i.e., creatable by third party software like data link clients). That COM object is entitled “DataLinks”. Data link clients are free to implement whatever COM object they deem suitable for handling their call back mechanism. The data link software requires only that for a given operation, the call back mechanism support a standard interface to call back on. For example, to provide a call back mechanism to the data link software  100  from notification on raw message receipt, the client needs only to provide an interface pointer that implements the IRawMessageTrafficNotify interface  52 . 
   Table 1 draws on a commercial database package, which specifies variable classes for devices used on motor vehicles, for examples of the kind of data the invention can be applied to. The specific product is the Dearborn Group&#39;s NASPAK3 product, available from Dearborn Group, 27007 Mills Tech Court, Farmington Hills, Mich. This product is occasionally updated and the values here are used only as an example. 
   
     
       
         
             
             
             
             
             
           
             
               TABLE 1 
             
             
                 
             
             
               Data Value ID 
               Variable Name 
               Units 
               Lower Limit 
               Upper Limit 
             
             
                 
             
           
          
             
                 
             
          
         
         
             
             
             
             
             
          
             
               REQUEST_SPEED_OR —   
               Request Speed 
               rpm 
               0 
               8031.875 
             
             
               SPEED_LIMIT 
               or Speed Limit 
             
             
               REQUEST_TORQUE_OR —   
               Request Torque 
               % 
               −125 
               125 
             
             
               TORQUE_LIMI 
               or Torque Limit 
             
             
               REQUESTED_PERCENT —   
               Requested 
               % gain 
               0 
               100 
             
             
               CLUTCH_SLIP 
               percent clutch 
             
             
                 
               slip 
             
             
               REQUESTED_GEAR 
               Requested gear 
               gear value 
               −125 
               125 
             
             
               SELECTED_GEAR 
               Selected gear 
               gear value 
               −125 
               125 
             
             
               ACTUAL_GEAR_RATIO 
               Actual gear ratio 
               no unit 
               0 
               64.255 
             
             
               CURRENT_GEAR 
               Current Gear 
               gear value 
               −125 
               125 
             
             
                 
                 
               (unit less) 
             
             
               NUMBER_OF —   
               Number of 
               unit less 
               0 
               125 
             
             
               SOFTWARE —   
               software 
             
             
               IDENTIFICATION_FIELDS 
               identification 
             
             
                 
               fields 
             
             
               WHEEL_BASED_VEHICLE —   
               Wheel-based 
               kph 
               0 
               251 
             
             
               SPEED 
               vehicle speed 
             
             
               CRUISE_CONTROL —   
               Cruise control 
               kph 
               0 
               250 
             
             
               SET_SPEED 
               set speed 
             
             
               ACTUAL_RETARDER —   
               Actual retarder- 
               % 
               −125 
               125 
             
             
               PERCENT_TORQUE 
               percent torque 
             
             
               BRAKE_PEDAL_POSITION 
               Brake pedal 
               % gain 
               0 
               100 
             
             
                 
               position 
             
             
               OUTPUT_SHAFT_SPEED 
               Output shaft 
               rpm 
               0 
               8031.875 
             
             
                 
               speed 
             
             
               PERCENT_CLUTCH_SLIP 
               Percent clutch 
               % 
               0 
               100 
             
             
                 
               slip 
             
             
               TOTAL_IDLE_FUEL_USED 
               Total idle fuel 
               L 
               0 
               2105540608 
             
             
                 
               used 
             
             
               TOTAL_IDLE_HOURS 
               Total idle hours 
               hrs 
               0 
               210554060.75 
             
             
               TURBO-OIL- 
               Turbo oil 
               kPa 
               0 
               1000 
             
             
               PRESSURE 
               pressure 
             
             
               TURBO-SPEED 
               Turbo speed 
               rpm 
               0 
               257020 
             
             
               AIR_START_PRESS 
               Air start 
               kPa 
               0 
               1000 
             
             
                 
               pressure 
             
             
               NOMINAL_FRICTION —   
               Nominal friction- 
               % 
               −125 
               125 
             
             
               PERCENT_TORQUE 
               percent torque 
             
             
               ENGINE_S_DESIRED —   
               Engine&#39;s desired 
               rpm 
               0 
               8031.875 
             
             
               OPERATING_SPEED 
               operating speed 
             
             
               ENGINE_S_OPERATING —   
               Engine&#39;s 
               engpw 
               0 
               250 
             
             
               SPEED_ASYMMETRY —   
               operating speed 
               r/ 
             
             
               ADJUSTMENT 
               asymmetry 
               engsp 
             
             
               TRIP_DISTANCE 
               Trip distance 
               km 
               0 
               526385151.9 
             
             
               TOTAL_VEHICLE- 
               Total vehicle 
               km 
               0 
               526385151.9 
             
             
               DISTANCE 
               distance 
             
             
               RETARDER_CONTROL —   
               Retarder control 
               step 
               0 
               250 
             
             
               METHOD 
               method 
             
             
               RETARDER_SPEED —   
               Retarder speed 
               rpm 
               0 
               8031.875 
             
             
               AT_IDLE-POINT-1 
               at idle, point 1 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_IDLE_POINT-1 
               at idle, point 1 
             
             
               MAXIMUM_RETARDER —   
               Maximum 
               rpm 
               0 
               8031.875 
             
             
               SPEED_POINT 
               retarder speed 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_MAXIMUM_SPEED —   
               at maximum 
             
             
               POINT_2 
               speed, point 2 
             
             
               RETARDER_SPEED —   
               Retarder speed 
               rpm 
               0 
               8031.875 
             
             
               AT_POINT_3 
               at point 3 
             
             
               PERCENT_TORQUE —   
               Retarder speed 
               % 
               −125 
               125 
             
             
               AT_POINT_3 
               at point 3 
             
             
               RETARDER_SPEED —   
               Retarder speed 
               rpm 
               0 
               8031.875 
             
             
               AT_POINT_4 
               at point 4 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_POINT_4 
               at point 4 
             
             
               RETARDER_SPEED —   
               Retarder speed 
               rpm 
               0 
               8031.875 
             
             
               AT_PEAK_TORQUE —   
               at peak torque, 
             
             
               POINT-5 
               point 5 
             
             
               REFERENCE_RETARDER —   
               Reference 
               Nm 
               0 
               64255 
             
             
               TORQUE 
               retarder torque 
             
             
               NUMBER_OF_REVERSE —   
               Number of 
               num 
               0 
               125 
             
             
               GEAR_RATIOS 
               reverse gear 
               gears 
             
             
                 
               ratios 
             
             
               NUMER_OF_FORWARD —   
               Number of 
               ratios 
               0 
               125 
             
             
               GEAR_RATIOS 
               forward gear 
             
             
                 
               ratios 
             
             
               HIGHEST_REVERSE —   
               Highest reverse 
               value 
               0 
               64.255 
             
             
               GEAR_RATIO 
               gear ratio 
             
             
               LOWEST_FORWARD —   
               Lowest forward 
               % 
               0 
               250 
             
             
               GEAR_RATIO 
               gear ratio 
             
             
               ACCELERATOR_PEDAL —   
               Accelerator 
               % 
               0 
               100 
             
             
               AP_POSITION 
               pedal (AP) 
             
             
                 
               position 
             
             
               PERCENT_LOAD_AT —   
               Percent load at 
               % 
               0 
               125 
             
             
               CURRENT_SPEED 
               current speed 
             
             
               DRIVERS_DEMAND —   
               Drivers demand 
               % 
               −125 
               125 
             
             
               ENGINE_PERCENT —   
               engine - percent 
               Torque 
             
             
               TORQUE 
               torque 
             
             
               ACTUAL_ENGINE —   
               Actual Engine - 
               % 
               −125 
               125 
             
             
               PERCENT_TORQUE 
               Percent Torque 
               Torque 
             
             
               ENGINE_SPEED 
               Engine Speed 
               rpm 
               0 
               8031.875 
             
             
               ENGINE_SPEED_AT —   
               Engine speed at 
               rpm 
               0 
               8031.875 
             
             
               IDLE_POINT_1_ENGINE —   
               idle, point 1 
             
             
               CONFIGURATION 
               (Engine) 
             
             
               PERCENT_TORQUE —   
               Percent Torque 
               % 
               −125 
               125 
             
             
               AT_IDLE_POINT_1 —   
               at Idle, Point 1 
             
             
               ENGINE_CONFIGURATION 
               (Engine 
             
             
                 
               Configuration) 
             
             
               ENGINE_SPEED_AT —   
               Engine speed at 
               rpm 
               0 
               8031.875 
             
             
               POINT_2_ENGINE —   
               point 2 (Engine 
             
             
               CONFIGURATION 
               configuration) 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_POINT_2_ENGINE —   
               at point 2 
             
             
               CONFIGURATION 
               (Engine 
             
             
                 
               configuration) 
             
             
               ENGINE_SPEED_AT —   
               Engine speed at 
               rpm 
               0 
               8031.875 
             
             
               POINT_3_ENGINE —   
               point 3 (Engine 
             
             
               CONFIGURATION 
               configuration) 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_POINT_3_ENGINE —   
               at point 3 
             
             
               CONFIGURATION 
               (Engine 
             
             
                 
               configuraton) 
             
             
               ENGINE_SPEED_AT —   
               Engine speed at 
               rpm 
               0 
               8031.875 
             
             
               POINT_4_ENGINE —   
               point 4 (Engine 
             
             
               CONFIGURATION 
               configuration) 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_POINT_4_ENGINE —   
               at point 4 
             
             
               CONFIGURATION 
               (Engine 
             
             
                 
               configuration) 
             
             
               ENGINE_SPEED_AT —   
               Engine speed at 
               rpm 
               0 
               8031.875 
             
             
               POINT_5_ENGINE —   
               point 5 (Engine 
             
             
               CONFIGURATION 
               configuration) 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_POINT_5_ENGINE —   
               at point 5 
             
             
               CONFIGURATION 
               (Engine 
             
             
                 
               configuration) 
             
             
               ENGINE_SPEED_AT —   
               Engine speed at 
               rpm 
               0 
               8031.875 
             
             
               HIGH_IDLE_POINT_6 —   
               high idle, point 6 
             
             
               ENGINE_CONFIGURATION 
               (Engine 
             
             
                 
               configuration) 
             
             
               GAIN_KP_OF —   
               Gain (KP) of 
               % 
               0 
               50.2 
             
             
               ENDSPEED_GOVERNOR 
               endspeed 
             
             
                 
               governor 
             
             
               REFERENCE_ENGINE —   
               Reference 
               Nm 
               0 
               64255 
             
             
               TORQUE_ENGINE —   
               Engine Torque 
             
             
               CONFIGURATION 
               (Engine 
             
             
                 
               configuration) 
             
             
               MAXIMUM_MOMENTARY —   
               Maximum 
               rpm 
               0 
               8031.875 
             
             
               ENGINE_OVERRIDE —   
               Momentary 
             
             
               SPEED_POINT_7 —   
               Engine Override 
             
             
               ENGINE_CONFIGURATION 
               Speed, Point 7 
             
             
                 
               (Engine 
             
             
                 
               configuration) 
             
             
               MAXIMUM_MOMENTARY —   
               Maximum 
               s 
               0 
               25 
             
             
               ENGINE_OVERRIDE —   
               momentary 
             
             
               TIME_LIMIT 
               engine override 
             
             
                 
               time linit 
             
             
               REQUESTED_SPEED —   
               Requested 
               rpm 
               0 
               2500 
             
             
               CONTROL_RANGE —   
               Speed Control 
             
             
               LOWER_LIMIT 
               Range Lower 
             
             
                 
               Limit 
             
             
               REQUESTED_SPEED —   
               Requested 
               rpm 
               0 
               2500 
             
             
               CONTROL_RANGE —   
               Speed Control 
             
             
               UPPER_LIMIT_ENGINE —   
               Range Upper 
             
             
               CONFIGURATION 
               Limit (Engine 
             
             
                 
               configuration) 
             
             
               REQUESTED_TORQUE —   
               Requested 
               % 
               −125 
               125 
             
             
               CONTROL_RANGE —   
               Torque Control 
             
             
               LOWER_LIMIT 
               Range Lower 
             
             
                 
               Limit 
             
             
               REQUESTED_TORQUE —   
               Requested 
               % 
               −125 
               125 
             
             
               CONTROL_RANGE —   
               Torque Control 
             
             
               UPPER_LIMIT 
               Range Upper 
             
             
                 
               Limit 
             
             
               TOTAL_ENGINE_HOURS 
               Total Engine 
               hrs 
               0 
               210554060.75 
             
             
                 
               Hours 
             
             
               TOTAL_ENGINE —   
               Total Engine 
               r 
               0 
               421108121500 
             
             
               REVOLUTIONS 
               Revolutions 
                 
                 
               0 
             
             
               SECONDS 
               Seconds 
               s 
               0 
               59.75 
             
             
               MINUTES 
               Minutes 
               minutes 
               0 
               59 
             
             
               TOTAL_VEHICLE —   
               Total Vehicle 
               hrs 
               0 
               210554060.75 
             
             
               HOURS 
               Hours 
             
             
               TOTAL_POWER_TAKE 
               Total Power 
               hrs 
               0 
               210554060.75 
             
             
               OFF_HOURS 
               Takeoff Hours 
             
             
               COMPASS_BEARIN 
               Compass 
               degree 
               0 
               502 
             
             
                 
               Bearing 
             
             
               NAVIGATION_BASED_ 
               Navigation- 
               kph 
               0 
               251 
             
             
               VEHICLE_SPEED_ 
               Based Vehicle 
             
             
                 
               speed 
             
             
               PITCH 
               Pitch 
               % 
               −200 
               302 
             
             
               ALTITUDE 
               Altitude 
               m 
               −2500 
               5531.875 
             
             
               TRIP_FUEL 
               Trip Fuel 
               L 
               0 
               2105540608 
             
             
               TOTAL_FUEL_USED 
               Total Fuel Used 
               L 
               0 
               2105540608 
             
             
               AXLE_LOCATION 
               Axle Location 
               val 
               0 
               250 
             
             
               AXLE_WEIGHT 
               Axle Weight 
               kg 
               0 
               32127.5 
             
             
               TRAILER_WEIGHT 
               Trailer Weight 
               kg 
               0 
               128510 
             
             
               CARGO_WEIGHT 
               Cargo Weight 
               kg 
               0 
               128510 
             
             
               MAXIMUM_VEHICLE —   
               Maximum 
               kph 
               0 
               250 
             
             
               SPEED_LIMIT 
               Vehicle Speed 
             
             
                 
               Limit 
             
             
               CRUISE_CONTROL —   
               Cruise Control 
               kph 
               0 
               250 
             
             
               HIGH_SET_LIMIT_SPEED 
               High Set Limit 
             
             
                 
               Speed 
             
             
               CRUISE_CONTROL —   
               Cruise Control 
               kph 
               0 
               250 
             
             
               LOW_SET_LIMIT-SPEED 
               Low Set Limit 
             
             
                 
               Speed 
             
             
               ENGINE_COOLANT —   
               Engine Coolant 
               Deg C. 
               −40 
               210 
             
             
               TEMPERATURE 
               Temperature 
             
             
               FUEL_TEMPERATURE 
               Fuel 
               Deg C. 
               −40 
               210 
             
             
                 
               Temperature 
             
             
               ENGINE_OIL_TEMPER- 
               Engine Oil 
               Deg C. 
               −273 
               1735 
             
             
               ATURE 
               Temperature 
             
             
               TURBO_OIL_TEMPER- 
               Turbo Oil 
               Deg C. 
               −273 
               1735 
             
             
               ATURE 
               Temperature 
             
             
               ENGINE_INTERCOOLER —   
               Engine 
               Deg C. 
               −40 
               210 
             
             
               TEMPERATURE 
               Intercooler 
             
             
               FUEL_DELIVERY- 
               Fuel Delivery 
               kPa 
               0 
               1000 
             
             
               PRESSURE 
               Pressure 
             
             
               ENGINE_OIL_LEVEL 
               Engine Oil Level 
               % 
               0 
               100 
             
             
               ENGINE_OIL_PRESSURE 
               Engine Oil 
               kPa 
               0 
               1000 
             
             
                 
               Pressure 
             
             
               CRANKCASE_PRESSURE 
               Crankcase 
               kPa 
               −250 
               251.99 
             
             
                 
               Pressure 
             
             
               COOLANT_PRESSURE 
               Coolant 
               kPa 
               0 
               500 
             
             
                 
               Pressure 
             
             
               COOLANT_LEVEL 
               Coolant Level 
               % 
               0 
               100 
             
             
               POWER_TAKEOFF —   
               Power Takeoff 
               Deg C. 
               −40 
               210 
             
             
               OIL_TEMPERATURE 
               Oil Temperature 
             
             
               POWER_TAKEOFF —   
               Power Takeoff 
               rpm 
               0 
               8031.875 
             
             
               SPEED 
               Speed 
             
             
               POWER_TAKEOFF —   
               Power Takeoff 
               rpm 
               0 
               8031.875 
             
             
               SET_SPEED 
               Set Speed 
             
             
               FUEL_RATE 
               Fuel Rate 
               L/h 
               0 
               3212.75 
             
             
               INSTANTANEOUS —   
               Instantaneous 
               km/L 
               0 
               125.5 
             
             
               FUEL_ECONOMY 
               Fuel Economy 
             
             
               AVERAGE_FUEL- 
               Average Fuel 
               km/L 
               0 
               125.5 
             
             
               ECONOMY 
               Economy 
             
             
               LATITUDE 
               Latitude 
               degree 
               −210 
               211.108122 
             
             
               LONGITUDE 
               Longitude 
               degree 
               −210 
               211.108121 
             
             
               LOCATION 
               Location 
               device 
               0 
               250 
             
             
               TIRE PRESSURE 
               Tire Pressure 
               kPa 
               0 
               1000 
             
             
               TIRE_TEMPERATURE 
               Tire 
               Deg C. 
               −273 
               1735 
             
             
                 
               Temperature 
             
             
               BAROMETRIC —   
               Barometric 
               kPa 
               0 
               125 
             
             
               PRESSURE 
               Presure 
             
             
               CAB_INTERIOR_TEMPER- 
               Cab Interior 
               Deg C. 
               −273 
               1735 
             
             
               ATURE 
               Temperature 
             
             
               AMBIENT_AIR_TEMPER- 
               Ambient Air 
               Deg C. 
               −273 
               1735 
             
             
               ATURE 
               Temperature 
             
             
               AIR_INLET_TEMPER- 
               Air Inlet 
               Deg C. 
               −40 
               210 
             
             
               ATURE 
               Temperature 
             
             
               ROAD_SURFACE_TEM- 
               Road Surface 
               Deg C. 
               −273 
               1735 
             
             
               PERATURE 
               Temperature 
             
             
               PARTICULATE_TRAP —   
               Particulate Trap 
               kPa 
               0 
               125 
             
             
               INLET_PRESSUR 
               Inlet Pressure 
             
             
               BOOST_PRESSURE 
               Boost Pressure 
               kPa 
               0 
               500 
             
             
               INTAKE_MANIFOLD —   
               Intake Manifold 
               Deg C. 
               −40 
               210 
             
             
               TEMPERATURE 
               Temperature 
             
             
               AIR_INLET_PRESSURE 
               Air Inlet 
               kPa 
               0 
               500 
             
             
                 
               Pressure 
             
             
               AIR_FILTER_DIFFER- 
               Air Filter 
               kPa 
               0 
               12.5 
             
             
               ENTIAL_PRESSURE 
               Differential 
             
             
                 
               Pressure 
             
             
               EXHAUST_GAS_TEM- 
               Exhaust Gas 
               Deg C. 
               −273 
               1735 
             
             
               PERATURE 
               Temperature 
             
             
               COOLANT_FILTER —   
               Coolant Filter 
               kPa 
               0 
               125 
             
             
               DIFFERENTIAL_PRESSURE 
               Differential 
             
             
                 
               Presure 
             
             
               NET- 
               Net Battery 
               A 
               −125 
               125 
             
             
               BATTERY_CURRENT 
               Current 
             
             
               ALTERNATOR_CURRENT 
               Alternator 
               A 
               0 
               250 
             
             
                 
               Current 
             
             
               ALTERNATOR —   
               Alternator 
               V 
               0 
               3212.75 
             
             
               POTENTIAL_VOLTAGE 
               Potential 
             
             
                 
               (Voltage) 
             
             
               ELECTRICAL —   
               Electrical 
               V 
               0 
               3212.75 
             
             
               POTENTIAL_VOLTAGE 
               Potential 
             
             
                 
               (voltage) 
             
             
               BATTERY_POTENTIAL —   
               Battery Potential 
               V 
               0 
               3212.75 
             
             
               VOLTAGE_SWITCHED 
               (Voltage), 
             
             
                 
               Switched 
             
             
               CLUTCH_PRESSUR 
               Clutch Pressure 
               kPa 
               0 
               4000 
             
             
               TRANSMISSION_OIL —   
               Transmission Oil 
               % 
               0 
               100 
             
             
               LEVEL 
               Level 
             
             
               TRANSMISSION_FILTER —   
               Transmission 
               kPa 
               0 
               500 
             
             
               DIFFERENTIAL —   
               Filter Differential 
             
             
               PRESSURE 
               Pressure 
             
             
               TRANSMISSION_OIL —   
               Transmission Oil 
               kPa 
               0 
               4000 
             
             
               PRESSURE 
               Pressure 
             
             
               TRANSMISSION_OIL —   
               Transmission Oil 
               Deg C. 
               −273 
               1735 
             
             
               TEMPERATURE 
               Temperature 
             
             
               STEERING_AXLE_TEM- 
               Steering Axle 
               Deg C. 
               −40 
               210 
             
             
               PERATURE 
               Temperature 
             
             
               DRIVE_AXLE_LOCATION 
               Drive Axle 
               location 
               0 
               250 
             
             
                 
               Location 
             
             
               DRIVE_AXLE_LIFT —   
               Drive Axle Lift 
               kPa 
               0 
               1000 
             
             
               AIR_PRESSURE 
               Air Pressure 
             
             
               DRIVE_AXLE_TEMPER- 
               Drive Axle 
               Deg C. 
               −40 
               210 
             
             
               ATURE 
               Temperature 
             
             
               BRAKE_APPLICATION —   
               Brake 
               kPa 
               0 
               1000 
             
             
               PRESSURE 
               Application 
             
             
                 
               Pressure 
             
             
               BRAKE_PRIMARY- 
               Brake Primary 
               kPa 
               0 
               1000 
             
             
               PRESSURE 
               Pressure 
             
             
               BRAKE_SECONDARY —   
               Brake 
               kPa 
               0 
               1000 
             
             
               PRESSURE 
               Secondary 
             
             
                 
               Pressure 
             
             
               HYDRAULIC_RETARDER —   
               Hydraulic 
               kPa 
               0 
               4000 
             
             
               PRESSURE 
               Retarder 
             
             
               HYDRAULIC_RETARDER —   
               Hydraulic 
               Deg C. 
               −40 
               210 
             
             
               OIL_TEMPERATURE 
               Retarder Oil 
             
             
                 
               Temperature 
             
             
               WASHER_FLUID_LEVEL 
               Washer Fluid 
               % 
               0 
               100 
             
             
                 
               Level 
             
             
               FUEL_LEVEL 
               Fuel Level 
               % 
               0 
               100 
             
             
               FUEL_FILTER_DIFFER- 
               Fuel Filter 
               kPa 
               0 
               500 
             
             
               ENTIAL_PRESSURE 
               Differential 
             
             
               ENGINE_OIL_FILTER —   
               Engine Oil Filter 
               kPa 
               0 
               125 
             
             
               DIFFERENTIAL_PRESSURE 
               Differential 
             
             
                 
               Pressure 
             
             
               INJECTION_CONTROL —   
               Injection Control 
               MPa 
               0 
               251 
             
             
               PRESSURE 
               Pressure 
             
             
               BLOWER_BYPASS —   
               Blower Bypass 
               % 
               0 
               100 
             
             
               VALVE_POSITION 
               Valve Position 
             
             
               GAS_SUPPLY_PRESSURE 
               Gas Supply 
               kPa 
               0 
               32127.5 
             
             
                 
               Pressure 
             
             
               AUXILIARY_PUMP —   
               Auxiliary Pump 
               % 
               0 
               4000 
             
             
               PRESSURE 
               Pressure 
             
             
               INJECTOR_METERING —   
               Injector Metering 
               MPa 
               0 
               251 
             
             
               RAIL_PRESSU 
               Rail Pressure 
             
             
               CARGO_AMBIENT —   
               Cargo Ambient 
               Deg C. 
               −273 
               1735 
             
             
               TEMPERATURE 
               Temperature 
             
             
               INPUT_SHAFT_SPEED 
               Input Shaft 
               rpm 
               0 
               8031.875 
             
             
                 
               Speed 
             
             
               TRANSMISSION —   
               Transmission 
               no unit 
               0 
               64250 
             
             
               REQUESTED_RANGE 
               Requested 
             
             
                 
               Range 
             
             
               TRANSMISSION —   
               Transmission 
               no unit 
               0 
               64250 
             
             
               CURRENT_RANGE 
               Current Range 
             
             
               PERCENT_TORQUE —   
               Percent torque 
               % 
               −125 
               125 
             
             
               AT_PEAK_TORQUE —   
               at peak torque, 
             
             
               POINT_5 
               point 5 
             
             
               HOURS 
               Hours 
               hrs 
               0 
               23 
             
             
               MONTH 
               Month 
               month 
               1 
               12 
             
             
               DAY 
               Day 
               day 
               0.25 
               31.75 
             
             
               YEAR 
               Year 
               year 
               1985 
               2235 
             
             
               ALTERNATOR_SPEED 
               Alternator speed 
               rpm 
               0 
               32127.5 
             
             
               SHIFT_FINGER —   
               Shift finger gear 
               % 
               0 
               100 
             
             
               GEAR_POSITION 
               position 
             
             
               SHIFT_FINGER_RAIL_ 
               Shift finger rail 
               % 
               0 
               100 
             
             
               POSITION 
               position 
             
             
               TRANSMISSION_SYN- 
               Transmission 
               % 
               0 
               100 
             
             
               CHRONIZER_CLUTCH —   
               synchronizer 
             
             
               VALUE 
               clutch value 
             
             
               TRANSMISSION_SYN- 
               Transmission 
               % 
               0 
               100 
             
             
               CHRONIZER_BRAKE —   
               synchronizer 
             
             
               VALUE 
               brake value 
             
             
               HIGH_RESOLUTION —   
               High resolution 
               m 
               0 
               21055406 
             
             
               TOTAL_VEHICLE —   
               total vehicle 
             
             
               DISTANCE 
               distance 
             
             
               HIGH_RESOLUTION —   
               High resolution 
               m 
               0 
               21055406 
             
             
               TRIP_DISTANCE 
               trip distance 
             
             
               SERVICE_COMPONENT —   
               Service 
               no unit 
               0 
               250 
             
             
               IDENTIFICATION 
               component 
             
             
                 
               identification 
             
             
               SERVICE_DISTANCE 
               Service distance 
               km 
               −160635 
               160640 
             
             
               SERVICE_DELAY_CAL- 
               Service 
               week(s) 
               −125 
               125 
             
             
               ENDAR_TIME_BASED 
               delay/calendar 
             
             
                 
               time based 
             
             
               SERVICE_DELAY_OPERA- 
               Service delay 
               hrs 
               −32127 
               32128 
             
             
               TIONAL_TIME_BASED 
               operational time 
             
             
                 
               based 
             
             
               FRONT_AXLE_SPEED 
               Front Axle 
               kph 
               0 
               251 
             
             
                 
               Speed 
             
             
               RELATIVE_SPEED —   
               Relative speed; 
               kph 
               −7.8125 
               7.8125 
             
             
               FRONT_AXLE_LEFT —   
               front axle, left 
             
             
               WHEEL 
               wheel 
             
             
               RELATIVE_SPEED —   
               Relative speed; 
               kph 
               −7.8125 
               7.8125 
             
             
               FRONT_AXLE_RIGHT —   
               front axle, right 
             
             
               WHEEL 
               wheel 
             
             
               RELATIVE_SPEED —   
               Relative speed; 
               kph 
               −7.8125 
               7.8125 
             
             
               REAR_AXLE_1_LEFT —   
               rear axle #1, left 
             
             
               WHEEL 
               wheel 
             
             
               RELATIVE_SPEED —   
               Relative speed; 
               kph 
               −7.8125 
               7.8125 
             
             
               REAR_AXLE_1_RIGHT —   
               rear axle #1, 
             
             
               WHEEL 
               right wheel 
             
             
               RELATIVE_SPEED —   
               Relative speed; 
               kph 
               −7.8125 
               7.8125 
             
             
               REAR_AXLE_2_LEFT- 
               rear axle #2, left 
             
             
               WHEEL 
               wheel 
             
             
               RELATIVE_SPEED —   
               Relative speed; 
               kph 
               −7.8125 
               7.8125 
             
             
               REAR_AXLE_2_RIGHT —   
               rear axle #2, 
             
             
               WHEEL 
               right wheel 
             
             
               RATED_ENGINE —   
               Rated Engine 
               kW 
               0 
               32127.5 
             
             
               POWER 
               Power 
             
             
               RATED_ENGINE_SPEED 
               Rated engine 
               rpm 
               0 
               8031.875 
             
             
                 
               speed 
             
             
               RPM 
               RPM 
               rpm 
               0 
               8031.875 
             
             
               ENGINE_RETARDER —   
               Engine reatrder 
               % 
               0 
               100 
             
             
               SELECTION 
               selection 
               Torque 
             
             
                 
             
          
         
       
     
   
   Data value bit variables are those variables supported by the software package  100  that represent a single bit of storage, i.e. a logical value. All data values are of one, and only one, of two states, on or off. The definition of the variables in Table 2 includes a programmatic constant name and a description of the variable. Physical storage for any of these data values in the data link package  100  is provided by the VARIANT data type. In all cases, the data type shall be VT_BOOL. Data link clients may choose to assert this within their own code. Note that error indications typcially reflected in Boolean types on the vehicle network are captured in the data status fields returned to clients. 
   
     
       
         
             
             
           
             
               TABLE 2 
             
             
                 
             
             
               Name 
               Enumeration Name 
             
             
                 
             
           
          
             
               ABS 
               Anti Lock Brake System On 
             
             
               ABS_OFFROAD_SWITCH 
               ABS Offroad Switch 
             
             
               ACCELERATOR_PEDAL_ KICKDOWN_SWITCH 
               Accelerator Pedal Kickdown Switch 
             
             
               ACCELERATOR_PEDAL_LOW_IDLE_SWITCH 
               Accelerator Pedal Low Engine Idle Speed 
             
             
                 
               Switch 
             
             
               ANTI_LOCK_BRAKING_ABS_ACTIVE 
               Anti-lock Braking (ABS) Active 
             
             
               ASR_BRAKE_CONTROL_ACTIVE 
               ASR Brake Control Active 
             
             
               ASR_HILL_HOLDER_SWITCH 
               ASR Hill Holder Switch 
             
             
               ASR_OFFROAD_SWITCH 
               ASR Offroad Switch 
             
             
               BRAKE_FLUID 
               Brake Fluid 
             
             
               BRAKE_PRESS 
               Brake Press 
             
             
               BRAKE_SWITCH 
               Brake Switch 
             
             
               CENTER_RAIL_INDICATOR 
               Center rail indicator 
             
             
               CENTRAL 
               Central 
             
             
               CENTRAL_FONT 
               Central front 
             
             
               CENTRAL_REAR 
               Central rear 
             
             
               CHECK_ELECT_SYS 
               Check Elect Sys 
             
             
               CHECK_TRANS 
               Check Trans 
             
             
               CLUTCH_ACTUATOR 
               Clutch Actuator 
             
             
               CLUTCH_SWITCH 
               Clutch Switch 
             
             
               COOLENT_LEVEL 
               Coolent level 
             
             
               CRUISE_CONTROL 
               Cruise Control 
             
             
               CRUISE_CONTROL_ACCELERATE_SWITCH 
               Cruise Control Accelerate Switch 
             
             
               CRUISE_CONTROL_ACTIVE 
               Cruise Control Active 
             
             
               CRUISE_CONTROL_COAST_DECELERATE_SWITCH 
               Cruise Control Coast (Decelerate) Switch 
             
             
               CRUISE_CONTROL_ENABLE_SWITCH 
               Cruise Control Enable Switch 
             
             
               CRUISE_CONTROL_RESUME_SWITCH 
               Cruise Control Resume Switch 
             
             
               CRUISE_CONTROL_SET_SWITCH 
               Cruise Control Set Switch 
             
             
               DEFUEL_ACTUATOR 
               Defuel actuator 
             
             
               DISENGAGE_DRIVELINE_REQUEST 
               Disengage Driveline Request 
             
             
               DRIVELINE_ENGAGE 
               Driveline engaged 
             
             
               DRIVER_ALERT_MODE 
               Driver Alert Mode 
             
             
               ENGAGEMENT_INDICATOR 
               Engagement indicator 
             
             
               ENGINE_AND_RETARDER_TORQUE_MODE 
               Engine and Retarder Torque Mode 
             
             
               ENGINE_HAS_SHUTDOWN_BY_SYSTEM 
               Engine has shutdown by system 
             
             
               ENGINE_TEST_MODE_SWITCH 
               Engine Test Mode Switch 
             
             
               FORWARD_SWITCH 
               Forward switch 
             
             
               FRONT_AXLE_1 
               Front axle 1 
             
             
               FRONT_AXLE_2 
               Front axle 2 
             
             
               GEAR_ACTUATOR_1 
               Gear actuator #1 
             
             
               GEAR_ACTUATOR_2 
               Gear actuator #2 
             
             
               GEAR_ SHIFT_INHIBIT_REQUEST 
               Gear Shift Inhibit Request 
             
             
               HIGH_BEAM 
               High Beam 
             
             
               HIGH_RANGE_SENSE 
               High range sense 
             
             
               IDLE_DECREMENT_SWITCH 
               Idle decrement switch 
             
             
               IDLE_INCREMENT_SWITCH 
               Idle increment switch 
             
             
               IDLE_SHUTDOWN_TIMER_FUNCTION 
               Idle Shutdown Timer Function 
             
             
               IDLE_SHUTDOWN_TIMER_OVERRIDE 
               Idle Shutdown Timer Override 
             
             
               INERTIA_BRAKE_ACTUATOR 
               Inertia brake actuator 
             
             
               IO_CHANNEL_1 
               IO channel #1 
             
             
               IO_CHANNEL_10 
               IO channel #10 
             
             
               IO_CHANNEL_11 
               IO channel #11 
             
             
               IO_CHANNEL_12 
               IO channel #12 
             
             
               IO_CHANNEL_13 
               IO channel #13 
             
             
               IO_CHANNEL_14 
               IO channel #14 
             
             
               IO_CHANNEL_15 
               IO channel #15 
             
             
               IO_CHANNEL_16 
               IO channel #16 
             
             
               IO_CHANNEL_2 
               IO channel #2 
             
             
               IO_CHANNEL_3 
               IO channel #3 
             
             
               IO_CHANNEL_4 
               IO channel #4 
             
             
               IO_ CHANNEL_5 
               IO channel #5 
             
             
               IO_CHANNEL_6 
               IO channel #6 
             
             
               IO_CHANNEL_7 
               IO channel #7 
             
             
               IO_CHANNEL_8 
               IO channel #8 
             
             
               IO_CHANNEL_9 
               IO channel #9 
             
             
               LOCKUP_CLUTCH_ACTUATOR 
               Lockup clutch actuator 
             
             
               LOW_RANGE_SENSE 
               Low range sense 
             
             
               MOMENTARY_ENGINE_OVERSPEED_ENABLE 
               Momentary Engine Overspeed Enable 
             
             
               NEUTRAL_INDICATOR 
               Neutral indicator 
             
             
               NEUTRAL_SWITCH 
               Neutral switch 
             
             
               OVERRIDE_CONTROL_MODE_PRIORITY 
               Override Control Mode Priority 
             
             
               OVERRIDE_CONTROL_MODES 
               Override Control Modes 
             
             
               PARK_BRAKE 
               Park Brake 
             
             
               PARKING_BRAKE_ACTUATOR 
               Parking Brake Actuator 
             
             
               PARKING_BRAKE_SWITCH 
               Parking Brake Switch 
             
             
               PROGRESSIVE_SHIFT_DISABLE 
               Progressive Shift Disable 
             
             
               RAIL_ACTUATOR_1 
               Rail actuator #1 
             
             
               RAIL_ACTUATOR_2 
               Rail actuator #2 
             
             
               RANGE_HIGH_ACTUATOR 
               Range high actuator 
             
             
               RANGE_LOW_ACTUATOR 
               Range low actuator 
             
             
               REAR_AXLE_1 
               Rear axle 1 
             
             
               REAR_AXLE_2 
               Rear axle 2 
             
             
               REQUESTED_SPEED_CONTROL_CONDITIONS 
               Requested Speed Control Conditions 
             
             
               RETARDER_ENABLE_BRAKE_ASSIST_SWITCH 
               Retarder Enable - Brake Assist Switch 
             
             
               RETARDER_ENABLE_SHIFT_ASSIST_SWITCH 
               Retarder Enable - Shift Assist Switch 
             
             
               RETARDER_LOCATION 
               Retarder Location 
             
             
               RETARDER TYPE 
               Retarder Type 
             
             
               REVERSE_SWITCH 
               Reverse switch 
             
             
               RIGHT_TURN 
               Right turn 
             
             
               SEAT BELT 
               Seat Belt 
             
             
               SHIFT_IN_PROCESS 
               Shift in Process 
             
             
               SPLITTER_DIRECT_ACTUATOR 
               Splitter direct actuator 
             
             
               SPLITTER_INDIRECT_ACTUATOR 
               Splitter indirect actuator 
             
             
               TORQUE_CONVERTER_LOCKUP_DISABLE 
               Torque Converter Lockup Disable Request 
             
             
               REQUEST 
             
             
               TORQUE_CONVERTER_LOCKUP_ENGAGED 
               Torque Converter Lockup Engaged 
             
             
               TRQACTION_CONTROL 
               Traction Control 
             
             
               TRAILER_ABS 
               Trailer ABS 
             
             
               TRANSMISSION_OUTPUT_RETARDER 
               Transmission output retarder 
             
             
               TWO_SPEED_AXLE_SWITCH 
               Two speed axle switch 
             
             
               WAIT_TO_START 
               Wait to Start 
             
             
               WASH_FLUID_LOW 
               Wash fluid low 
             
             
               WATER_IN_FUEL_INDICATOR 
               Water in fuel indicator 
             
             
                 
             
          
         
       
     
   
   Table 3 contains definitions of data link variables that contain enumerations of values supported by the data link software package  100 . Included in the definition are a programmatic constant name, a description of the variable. 
   
     
       
         
             
             
           
             
               TABLE 3 
             
             
                 
             
             
               Name 
               Enumeration Name 
             
             
                 
             
           
          
             
               CRUISE_CONTROL_STATES 
               Cruise Control 
             
             
                 
               States 
             
             
               ENGINE_AND_RETARDER_TORQUE_MODE 
               Engine/Retarder 
             
             
                 
               Torque Mode 
             
             
               IDLE_SHUTDOWN_TIMER_STATE 
               Engine Idle Shut- 
             
             
                 
               down Timer State 
             
             
                 
             
          
         
       
     
   
   Network classes is one type of COM object used. Network classes is used by software  100  when explicit identification of the class of the underlying physical network is required, e.g. SAE J1939 or SAE J1587. DataValueStatus is used when explicit identification of the status of data communication is required. The values used are “MESSAGESUCCESS” which indicates that no exceptions occurred during a given network operation. Occurrance of MESSAGETIMEOUT indicates that a time out period expired during the course of a communication request. DATAVALUENOTSUPPORTED indicates that a given data value was requested from a remote device, but is not supported by the device. For example, suppose engine speed was requested from an anti-lock brake system (ABS) controller. DATAVALUERANGEERROR indicates that the data received from a reported remote device was out of range. DATAVALUEBITERROR can occur of devices reporting boolian (binary) values. 
   Another COM object is STATETRANSITIONS which is an enumeration used within explicit indication of a change in status is required. Enumerated values for this object include STATECHANGE which indicates that the mechanism for being notified for a particular value is on a state change basis. This means that if a client requests a given data value on a STATECHANGE basis, then the client will only be notified of a data value receipt when the state of the value has changed from what was initially specified. STATECONSTANT indicates that the mechanism for being notified for a particular value is on a continual basis until the state changes. This means that if a client requests a given data value on a STATECONSTANT basis, then the client will periodically be notified of a data value until the state of the value has changed from what was initially specified. Once the state of change is detected, the client will no longer be notified until the value again falls within the specified range. 
   Error Handling 
   A set of custom facility error codes that may be generated and returned by the software package  100 . Clients can determine, based on the HResult return code of all functions, whether a given function has failed or not. In addition to using the HResult, the client can retrieve additional data, possibly indicating why a particular function failed. For example, if a client invokes EnumerateNetworks  258  without first invoking, on at least an initial occasion, AcquireNetworks  270 , an HResult is returned indicating error. The actual error code may be extracted from HResult using the HResult_Facility and HResult_Code macros which are described in Microsoft documentation for the Win32 API. The custom error codes are as follows. 
   E_NO_NETWORKS_ACQUIRED. No successful network acquistions have occurred during an attempt to perform an enumeration. A successful network acquisition must occur before an enumeration can successfully complete. 
   E_NETWORK_CONFIGURATION_NOT-FOUND. This results from an attempt to acquire a network that would not resolve into something actually supported by the Software. This can result from the client specifying an instance number which is too high (e.g., not enough physical adaptors are connected to the host remote computer  44  to allow connection to the number of physical networks indicated, or a named network is of a class not supported by the software package  100 . 
   E_DRIVER_INITIALIZATION. An attempt was made to connect to a particular network and there were problems initializing an underlying physical device driver. 
   E_CANNOT_CLAIM_ADDRESS. The data link software package  100  is configured for the underlying physical network to reside at a particular node address. The error indicates a likely network topology problem. 
   E_NO_DEVICE_DETECTION_PERFORMED. An attempt was made to enumerate the devices found on a network before successful detection of the network has occurred. A successful network detection is defined as the client software having performed at least one network detection to completion and having issued a DetectionCompleted call on an IDetectDeviceNotify interface  438 . 
   E_NETWORK_NOT_CONNECTED. An attempt was made to perform some network specific operation that depended on the network being in a connected online state. This state is not reached until a successful network connection occurs. 
   E_DATA_VALUE_ALREADY_BEING_TRANSMITTED. An attempt was made to transmit a data value that is already in the process of transmission to a given remote device. Such attempts are disallowed because of the possibility of creating an inconsistency between what the client thinks it has set as a value for the remote device and what actually arrives at the remote device. Only one function should be allowed to transmit a given value to a given device. 
   E_UNSUPPORTED_DATA_VALUE_ID. An attempt was made to request or transmit a data value to or from a remote device that was not supported. For example, a client requested an engine speed data value from an ABS system. 
   Clients that require receipt of asynchronous notifications from the software  100  are required to implement COM objects that support public interfaces. Interfaces implemented by clients depend on the functionality of the notification that is being received. During the course of normal program execution, a given data link client may decide to use the same callback objects to satisfy the notification mechanism variables for some number of data link software requests. In such cases, the data link software does not guarantee that two callback events will not occur at substantially the same point in time. Thus client callback code may need to be reentrant. A case where such is required is where a client registers for raw message traffic from both a J1939 network and a J1587 network, allowing notifications of traffic to overlap. 
   Conclusion 
   Software development for vehicle networks is greatly aided by the increase level of abstractness provided by the translation model of the present invention. The flexibility and adaptability of the invention allows for the provision for new protocols as such become available. The system, based on the COM concept is readily extendible, which gives the system room for evolution of the system while maintaining robustness. Generalized function calls handle all data values which can be generated on a motor vehicle network by reference to a database supported by manufacturing codes, while higher level interfaces handle formatting depending on network class type and initiation of communication links through the automated loading of the required drivers. 
   While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.