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This document covers the general terms and corresponding definitions that support the design, development, implementation, testing, and application of vehicle networks. The terminology also covers some terms and concepts of distributed embedded systems, network hardware, network software, physical layers, protocols, and other related areas.

The Token Slot Data Link is intended to provide periodic, broadcast communications (communication that must occur on a regular, predetermined basis) within a vehicle system. The Token Slot protocol achieves this by implementing a masterless, deterministic, non-contention Token Slot sequence which is designed to offer a transmit token to all devices (or nodes) without requiring that they respond. After acquiring the token, messages may be sent and verified using a variety of built-in techniques. The token passing slot sequence is then reinitiated by the current token holder.

The Token Slot Data Link is intended to provide periodic, broadcast communications (communication that must occur on a regular, predetermined basis) within a vehicle system. The Token Slot protocol achieves this by implementing a masterless, deterministic, non-contention Token Slot sequence which is designed to offer a transmit token to all devices (or nodes) without requiring that they respond. After acquiring the token, messages may be sent and verified using a variety of built-in techniques. The token passing slot sequence is then reinitiated by the current token holder.

The Class A Task Force of the Vehicle Network for Multiplex and Data Communications Committee is publishing this SAE Information Report to provide insight into Class A Multiplexing. Multiplexed actuators are generally defined as devices which accept information from the multiplexed bus. A multiplexed actuator can be an output device controlled by the operator or an intelligent controller. A Multiplex actuator can also be a display device that reports the status of a monitored vehicle function. This document is intended to help the network system engineers and is meant to stimulate the design thought process. A list of multiplexed actuator examples is provided in Appendix A, Figure A1. Many other examples can be it identified.

The Class A Task Force of the Vehicle Network for Multiplexing and Data Communications Subcommittee is providing information on sensors that could be applicable for a Class A Bus application. Sensors are generally defined as any device that inputs information onto the bus. Sensors can be an input controlled by the operator or an input that provides the feedback or status of a monitored vehicle function. Although there is a list of sensors provided, this list is not all-inclusive. This SAE Information Report is intended to help the network system engineer and is meant to stimulate the design thought process.

This SAE Recommended Practice defines the information contained in the header and data fields of non-diagnostic messages for automotive serial communications based on SAE J1850 Class B networks. This document describes and specifies the header fields, data fields, field sizes, scaling, representations, and data positions used within messages. The general structure of a SAE J1850 message frame without in-frame response is shown in Figure 1. The structure of a SAE J1850 message with in-frame response is shown in Figure 2. Figures 1 and 2 also show the scope of frame fields defined by this document for non-diagnostic messages. Refer to SAE J1979 for specifications of emissions related diagnostic message header and data fields. Refer to SAE J2190 for the definition of other diagnostic data fields. The description of the network interface hardware, basic protocol definition, the electrical specifications, and the CRC byte are given in SAE J1850.

This SAE Information Report will explain the differences between Class A, B, and C networks and clarify through examples, the differences in applications. Special attention will be given to a listing of functions that could be attached to a Class A communications network.