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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 therefr
2、om, 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. TO PLACE A DOCUMENT ORDER: +1 (724) 776-4970 FAX: +1 (724) 776-0790 SAE WEB ADDRESS h
3、ttp:/www.sae.org Copyright 2001 Society of Automotive Engineers, Inc. All rights reserved.Printed in U.S.A. SURFACE VEHICLE 400 Commonwealth Drive, Warrendale, PA 15096-0001 INFORMATION REPORT J2057-3 REAF. AUG2001 Issued1993-06 Reaffirmed2001-08 Superseding J2057/3 JUN1993 Class A Multiplexing Sens
4、ors ForewordThis Document has not changed other than to put it into the new SAE Technical Standards Board Format. Definitions have changed to Section 3. All other section numbers have changed accordingly. This SAE Information Report is the third in a series of Class A Multiplexing Information Report
5、s. 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 about the types of sensors that can typically be used to meet Class A Bus system requirements. These sensors fall into two ge
6、neral 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 system engineer designing and developing a multiplexing network application. TABLE OF CONTENTS 1.Scope. 2 1.1Three Classes of
7、 Multiplex Networks. 2 2.References. 2 2.1Applicable Publications 2 2.2Related Publications. 2 3.Definitions.3 3.1Analog Sensor 3 3.2Digital Sensor. 3 3.3Engineering Units. 3 3.4Binary Resolution . 3 3.5Engineering Resolution 3 4.Typical Applications 3 4.1Analog Sensors 3 4.2Digital Sensors . 3 5.Re
8、quirements . 3 5.1 Network Requirements. 3 5.2Electrical Requirements 4 5.3Latency .4 5.4EMC Susceptibility and Radiation 4 5.5Reliability 4 SAE J2057-3 Reaffirmed AUG2001 -2- 5.6Sensor Failure 4 5.7Diagnostics .4 6.Sensor Types and Parameters.4 7.Conclusions4 8.Key Words 4 Appendix A 5 1.ScopeThe C
9、lass 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 control
10、led 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
11、 process. 1.1Three Classes of Multiplex NetworksThe Vehicle Network for Multiplexing and Data Communications Committee has previously identified three classes of vehicle data communication networks. 1.1.1 CLASS A MULTIPLEXINGClass A Multiplexing contains many of the operator-controlled functions and
12、 the monitored vehicle function status inputs. Some examples of sensor inputs would be the operator control of powered convenience features (power window switches) or the status of a fluid level (windshield washer fluid). 1.1.2 CLASS B MULTIPLEXINGClass B Multiplexing provides the data communication
13、s between different modules, internal and external to the vehicle, for the purpose of sharing common data about the vehicle. 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 MULTIPLEXI
14、NGClass C Multiplexing contains systems that require real time, high-speed control, and normally require a significant amount of information to function properly. An example is the wheel speed sensor for the Anti-Lock Brakes System. 2.References 2.1Applicable PublicationThe following publication for
15、ms a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. 2.1.1SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J2057-1Class A Multiplexing Application/Definition 2.2Related PublicationThe following publ
16、ication is provided for information purposes only and is not a required part of this document. 2.2.1SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J1930Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, and Acronyms SAE J2057-3 Reaf
17、firmed AUG2001 -3- 3.DefinitionsClass 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 are non-time critical. 3.1Analog SensorA sensor that converts some
18、 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. 3.2Digital SensorA sensor that converts some measured input charact
19、eristic as discrete output states. The sensor has a maximum and minimum measurable input range that corresponds to a fixed number of discrete output states. 3.3Engineering UnitsReferred to as the units of measure detected by the sensor and processed by the measuring system. For example, Volume, Volt
20、age, Displacement, Volume/Time, etc. 3.4Binary ResolutionThe 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 states, On/Off, 1/0, HI/LO, or True/False. Binary bits may be combined into
21、serial bits of data. 3.5Engineering ResolutionThe smallest subdivision to which a sensors output must be resolved. 4.Typical Applications 4.1Analog SensorsAnalog sensors are used where continuously varying measured data is required for display or mathematical calculations. Analog sensors continuousl
22、y measure quantities such as voltages, resistances, pressures, etc., by representing the measured quantity with another type of continuously variable quantity, voltage or current. For example, in temperature measurement, input temperature is represented by an electric voltage or current output. The
23、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, it is necessary to compare the value or magnitude of the signal to a standard. For analog data to be transmitted o
24、n the Class A Bus, it is usually first converted to a digital format and then transmitted. 4.2Digital SensorsDigital sensors are used where measured data is required for status information. Digital sensors measure a variable and represent it by coded pulses or states based on discrete numerical tech
25、niques. 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 point. The discrete states could represent other information based on the various combinations of the states. The in
26、formation 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, ., EMPTY. The discrete states can be transmitted on the Class A Bus directly and no conversion is needed. Digital sensors c
27、an also be switch inputs that can be closed by the operator. For example the power mirror directional switches. 5.RequirementsThis is only a general list of requirements and is not meant to be specific for any one application; that would be defined by the user. The requirements in this report are fo
28、r informational purposes only, the actual requirements for each specific sensor would be determined by the application and by the manufacturer. 5.1Network RequirementsThe sensor will be capable of interfacing to the Class A Bus through integral interface circuitry or through a stand-alone interface
29、module. Reference SAE J2057-1 for specific requirements. SAE J2057-3 Reaffirmed AUG2001 -4- 5.2Electrical RequirementsThe sensor must operate at all standard automotive voltages and survive the abnormal conditions, such as reverse voltage and load dump, as required by each user. 5.3LatencyRefer to T
30、able 2.2, Typical Class A Applications, included in SAE J2057-1. 5.4EMC Susceptibility and RadiationThe sensors generation and susceptibility to EMI RFI noise must meet the requirements of the user and SAE J2057-1, 7.4. 5.5ReliabilityThe reliability of the sensor and its Class A Bus interface should
31、 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 application and by the manufacturer. 5.6Sensor FailureThe failure of the sensor must not affect operation of the Class A Bus and sh
32、ould provide a known default value when appropriate. Reference SAE J2057-1, 7.3. 5.7DiagnosticsThe sensor should have the ability to be interrogated by a system to determine if failures are present in the sensor and transmit this information for appropriate action. 6.Sensor Types and ParametersFigur
33、e 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 (actuated digital) switches are a subset of the digital sensors. The lists are not all-inclusive for all applications. Each sensor has some
34、 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 determined by the application and by the manufacturer. 7.ConclusionsThe use of Class A sensors on a vehicle network should offer the manufa
35、cturer and the customer several benefits in several key areas: customer confidence, vehicle design, assembly operations, and service. a.To the customer, the confidence that each system or function is working properly and if it does not, the vehicle can provide warning information. b.To the design en
36、gineer, a minimized number of wiring harness variations to mechanize and validate. c.To the assembly line worker, the installation the wiring harnesses in the vehicle should be made simpler and easier due to minimized wiring harness size. d.To the service personnel, any problems for which the vehicl
37、e is brought back, can be diagnosed and repaired efficiently. 8.Key WordsMultiplexing, Class A, Sensor PREPARED BY THE SAE VEHICLE NETWORK FOR MULTIPLEXING AND DATA COMMUNICATIONS STANDARDS COMMITTEE SAE J2057-3 Reaffirmed AUG2001 -5- APPENDIX A FIGURE A1SENSOR TYPES AND TYPICAL PARAMETERS SAE J2057
38、-3 Reaffirmed AUG2001 RationaleNot applicable. Relationship of SAE Standard to ISO StandardNot applicable. ApplicationThe 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 app
39、lication. 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-inclusiv
40、e. This SAE Information Report is intended to help the network system engineer and is meant to stimulate the design thought process. Reference Section SAE J1930Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, and Acronyms SAE J2057-1Class A Multiplexing Application/Definition Developed by the SAE Vehicle Network for Multiplexing and Data Communications Standards Committee