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Commercial vehicle operators have many options available to them for managing their assets. Whether in an on-highway fleet, agricultural / off-road, construction, or military, available real-time vehicle information is growing. While accessing this data via applicable Wide Area Networks (WANs) is commonplace, new technologies are just beginning to develop to take advantage of all of the connectivity possibilities to further aid in delivery of goods and services. As an enabler to expanding these fleet management applications, vehicle on-board networks (commonly referred to as “in-vehicle” or simply “vehicle networks”) are expected to support a growing number of vehicle related technological solutions. This paper provides background on vehicle networks, including key terminology, an introduction to standards based protocols, and critical SAE vehicle network related standards.

The development of SAE J1939 was prompted by the Heavy Truck industry because of a need for a in-vehicle real time network operating capability (referred to as a “SAE Class C Network”). SAE J1939 has now been adopted for use in tractors and other off road equipment. This paper will outline SAE J1939 network development tools that are available to support hardware and software engineers. An example SAE J1939 network application done by Oklahoma State University will show how some of these tools could be used on tractors.

Now that the SAE J1850 recommended practice has essentially been completed, attention has turned to the message schemes which the network will be using. SAE J2178 has been developed to define the message strategy for SAE J1850 networks. This paper will describe the message strategy incorporated in SAE J2178 and possible transaction classes to drive SAE J1850 networks.

The purpose of this paper is to suggest a methodology for designing multiplex system software and defining the operational requirements of its hardware. The methodology will only study here the design phase of the software development cycle, a later paper will propose a complete design method. The goal of the methodology is to create reusable system objects which can be used again in future system applications. Reusing these objects in other systems will reduce the cost of multiplex system development. Cost savings will also result from decoupling the software from the hardware so software development can commence long before the hardware design has been completed and, using library objects that have previously been tested and proven to be reliable so software bugs are less likely to occur.

As multiplex hardware moves toward standardization, vehicle multiplex network devices will require increased software support for application specific services. The use of software engineering principles and the design of a Common Software Interface between the application program and the logical device (hardware and physical interface software) enables more efficient software development and allows for software reusability. This paper explores concepts for Software Services in lower data rate multiplex multi-master network architectures. As both Object-Oriented design and the C++ language are shown to offer advanced programming methods for implementing these services, a summary of how they aid in the overall application specific services is shown. Finally, a proposal for a Common Software Interface for multiplex applications is discussed.