1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2006 SAE International All rights reserved. No part of this publication m
3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J2057-3 REAF. SEP2006 SURFACE VEHICLE INFORMATION REPORT Issued 1993-06 Reaffirmed 2006-09 Superseding J2057-3 AUG2001 Class A Multiplexing Sensors RATIONALE This document has been reaffirmed to comply with the SAE 5
5、-Year Review policy. FOREWORD This SAE Information Report is the third in a series of Class A Multiplexing Information Reports. This sensors document is not a sensor definition report but intended to be a sensor multiplexing information report. The purpose of this document is to provide information
6、about the types of sensors that can typically be used to meet Class A Bus system requirements. These sensors fall into two general categories; analog sensors and digital sensors, including the operator controlled switches. This document is not all inclusive but is meant to be used as a tool for the
7、system engineer designing and developing a multiplexing network application. TABLE OF CONTENTS 1. Scope 2 1.1 Three Classes of Multiplex Networks . 2 2. References 2 2.1 Applicable Publications . 2 2.2 Related Publications . 3 3. Definitions . 3 3.1 Analog Sensor. 3 3.2 Digital Sensor 3 3.3 Engineer
8、ing Units 3 3.4 Binary Resolution 3 3.5 Engineering Resolution. 3 4. Typical Applications 4 4.1 Analog Sensors. 4 4.2 Digital Sensors 4 SAE J2057-3 Reaffirmed SEP2006 - 2 - 5. Requirements 4 5.1 Network Requirements . 4 5.2 Electrical Requirements 4 5.3 Latency 4 5.4 EMC Susceptibility and Radiation
9、. 4 5.5 Reliability. 5 5.6 Sensor Failure. 5 5.7 Diagnostics 5 6. Sensor Types and Parameters . 5 7. Conclusions. 5 8. Notes. 5 8.1 Key Words. 5 Appendix A 6 1. SCOPE The Class A Task Force of the Vehicle Network for Multiplexing and Data Communications Subcommittee is providing information on senso
10、rs 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 o
11、f 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. 1.1 Three Classes of Multiplex Networks The Vehicle Network for Multiplexing and Data Communications Committee has pre
12、viously identified three classes of vehicle data communication networks. 1.1.1 Class A Multiplexing Class A Multiplexing contains many of the operator-controlled functions and the monitored vehicle function status inputs. Some examples of sensor inputs would be the operator control of powered conven
13、ience features (power window switches) or the status of a fluid level (windshield washer fluid). 1.1.2 Class B Multiplexing Class B Multiplexing provides the data communications between different modules, internal and external to the vehicle, for the purpose of sharing common data about the vehicle.
14、 An example of this is the diagnostic information shared between an internal (on-vehicle) module and an external (hand-held) module for service repair. 1.1.3 Class C Multiplexing Class C Multiplexing contains systems that require real time, high-speed control, and normally require a significant amou
15、nt of information to function properly. An example is the wheel speed sensor for the Anti-Lock Brakes System. 2. REFERENCES 2.1 Applicable Publication The following publication forms a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. SAE J2
16、057-3 Reaffirmed SEP2006 - 3 - 2.1.1 SAE Publication Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J2057-1 Class A Multiplexing Application/Definition 2.2 Related Publication The follow
17、ing publication is provided for information purposes only and is not a required part of this document. 2.2.1 SAE Publication Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J1930 Electric
18、al/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, and Acronyms 3. DEFINITIONS Class A sensors fall into the areas of operator convenience, vehicle status, and vehicle message information for a monitored function. They are characterized by moderate to slow times of being read and ar
19、e non-time critical. 3.1 Analog Sensor A sensor that converts some measured continuously varying input characteristic as a continuously varying output value or magnitude. The sensor has a maximum and minimum measurable input range that corresponds to a maximum and minimum output represented value. 3
20、.2 Digital Sensor A sensor that converts some measured input characteristic as discrete output states. The sensor has a maximum and minimum measurable input range that corresponds to a fixed number of discrete output states. 3.3 Engineering Units Referred to as the units of measure detected by the s
21、ensor and processed by the measuring system. For example, Volume, Voltage, Displacement, Volume/Time, etc. 3.4 Binary Resolution The number of digits, in base 2, required to represent the full-scale numerical value measurable by a sensor. A bit is a single unit of information which has only two stat
22、es, On/Off, 1/0, HI/LO, or True/False. Binary bits may be combined into serial bits of data. 3.5 Engineering Resolution The smallest subdivision to which a sensors output must be resolved. SAE J2057-3 Reaffirmed SEP2006 - 4 - 4. TYPICAL APPLICATIONS 4.1 Analog Sensors Analog sensors are used where c
23、ontinuously varying measured data is required for display or mathematical calculations. Analog sensors continuously measure quantities such as voltages, resistances, pressures, etc., by representing the measured quantity with another type of continuously variable quantity, voltage or current. For ex
24、ample, in temperature measurement, input temperature is represented by an electric voltage or current output. The output signal is solely dependent upon the input signal and the sensors transfer function to obtain a value or magnitude to express the measured information. To extract the information,
25、it is necessary to compare the value or magnitude of the signal to a standard. For analog data to be transmitted on the Class A Bus, it is usually first converted to a digital format and then transmitted. 4.2 Digital Sensors Digital sensors are used where measured data is required for status informa
26、tion. Digital sensors measure a variable and represent it by coded pulses or states based on discrete numerical techniques. The discrete states can be a representation of numerical values; for example, the number of motor turns can represent a seat position distance from a maximum or minimum travel
27、point. The discrete states could represent other information based on the various combinations of the states. The information can represent an ON/OFF state, for example, is the door locked or not; or the information can represent a status, for example, if the fuel level is at FULL, 7/8, 3/4, ., EMPT
28、Y. The discrete states can be transmitted on the Class A Bus directly and no conversion is needed. Digital sensors can also be switch inputs that can be closed by the operator. For example the power mirror directional switches. 5. REQUIREMENTS This is only a general list of requirements and is not m
29、eant to be specific for any one application; that would be defined by the user. The requirements in this report are for informational purposes only, the actual requirements for each specific sensor would be determined by the application and by the manufacturer. 5.1 Network Requirements The sensor wi
30、ll be capable of interfacing to the Class A Bus through integral interface circuitry or through a stand-alone interface module. Reference SAE J2057-1 for specific requirements. 5.2 Electrical Requirements The sensor must operate at all standard automotive voltages and survive the abnormal conditions
31、, such as reverse voltage and load dump, as required by each user. 5.3 Latency Refer to Table 2.2, Typical Class A Applications, included in SAE J2057-1. 5.4 EMC Susceptibility and Radiation The sensors generation and susceptibility to EMI RFI noise must meet the requirements of the user and SAE J20
32、57-1, 7.4. SAE J2057-3 Reaffirmed SEP2006 - 5 - 5.5 Reliability The reliability of the sensor and its Class A Bus interface should not degrade the performance of the function or the network as compared to non-multiplexed vehicles. The actual sensor reliability requirement will be determined by the a
33、pplication and by the manufacturer. 5.6 Sensor Failure The failure of the sensor must not affect operation of the Class A Bus and should provide a known default value when appropriate. Reference SAE J2057-1, 7.3. 5.7 Diagnostics The sensor should have the ability to be interrogated by a system to de
34、termine if failures are present in the sensor and transmit this information for appropriate action. 6. SENSOR TYPES AND PARAMETERS Figure A1 in Appendix A contains two lists of sensor types: analog sensors and digital sensors. Refer to SAE J2057-1 for additional switches. The operator-controlled (ac
35、tuated digital) switches are a subset of the digital sensors. The lists are not all-inclusive for all applications. Each sensor has some information associated with it. This information is not stated to be recommended practice but only as useful information. The specifics for each sensor will be det
36、ermined by the application and by the manufacturer. 7. CONCLUSIONS The use of Class A sensors on a vehicle network should offer the manufacturer and the customer several benefits in several key areas: customer confidence, vehicle design, assembly operations, and service. a. To the customer, the conf
37、idence that each system or function is working properly and if it does not, the vehicle can provide warning information. b. To the design engineer, a minimized number of wiring harness variations to mechanize and validate. c. To the assembly line worker, the installation the wiring harnesses in the
38、vehicle should be made simpler and easier due to minimized wiring harness size. d. To the service personnel, any problems for which the vehicle is brought back, can be diagnosed and repaired efficiently. 8. NOTES 8.1 Key Words Multiplexing, Class A, Sensor PREPARED BY THE SAE VEHICLE ARCHITECTURE FOR DATA COMMUNICATIONS STANDARDS COMMITTEE SAE J2057-3 Reaffirmed SEP2006 - 6 - APPENDIX A FIGURE A1 - SENSOR TYPES AND TYPICAL PARAMETERS
