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 J2057-2 REAF. SEP2006 SURFACE VEHICLE INFORMATION REPORT Issued 1994-02 Reaffirmed 2006-09 Superseding J2057-2 AUG2001 Class A Multiplexing Actuators RATIONALE This document has been reaffirmed to comply with the SAE
5、 5-Year Review policy. FOREWORD This SAE Information Report is the fourth in a series of Class A Multiplexing information reports. The intent of this document is to introduce the reader to Multiplexed Class A actuators. It is not a “Recommended Practice” report. The document is intended only to info
6、rm the reader of some of the issues involved in multiplexing Class A actuators. These actuators fall into two general categories: analog actuators and digital actuators. This document is not all-inclusive but is meant to be used as a tool for the system engineer designing and developing a Class A Mu
7、ltiplex network application. There are many SAE documents that define Class B and Class C technology (e.g., SAE J1850, J1979, and J2178). This document re-examines multiplexing to define Class A terminology which has some new issues as compared with the previously defined classes of multiplexing. Fo
8、r example, the resistive encoded steering-wheel switch assembly is a Class A Multiplex application. TABLE OF CONTENTS 1. Scope 2 1.1 Three Classes of Multiplex Networks . 2 1.1.1 A Class Multiplexing 2 1.1.2 B Class Multiplexing 2 1.1.3 C Class Multiplexing . 3 1.2 Analog as Well as Digital 3 2. Ref
9、erences 3 2.1 Applicable Documents 3 2.2 Related Publications . 3 3 Definitions . 3 3.1 Analog Actuator. 4 3.2 Digital Actuator 4 3.3 Engineering Units 4 3.4 Binary Resolution 4 3.5 Analog Resolution Requirement . 4 SAE J2057-2 Reaffirmed SEP2006 - 2 - 4. Typical Application 4 4.1 Analog Actuators.
10、4 4.2 Digital Actuators 4 5. Requirements 5 5.1 Network Requirements . 5 5.2 Electrical Requirements 5 5.3 Environmental Requirements 5 5.4 Latency 5 5.5 EMC Susceptibility and Radiation. 5 5.6 Reliability. 5 5.7 Actuator Failure. 5 5.8 Bus Failure 5 5.9 Diagnostics 5 6. Actuator Types and Parameter
11、s . 6 7. Conclusions. 6 8. Notes. 6 8.1 Key Words. 6 Appendix A Actuator Types and Typical Parameters. 7 1. SCOPE 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. Mult
12、iplexed 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 vehic
13、le 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. 1.1 Three Classes of Multiplex Networks The Vehicl
14、e Network for Multiplex and Data Communications Committee has previously defined three classes of vehicle data communication multiplexing: Class A, Class B, and Class C. A hierarchical relationship exists between the three classes. Class A multiplexing is a subset of Class B and Class B multiplexing
15、 is a subset of Class C. Definitions of all three classes are included in this document for reader convenience. 1.1.1 A Class Multiplexing Class A Multiplexing contains many of the direct operator controlled functions and the displays monitored by the operator. Some examples of actuator outputs woul
16、d be the operator control of powered convenience features such as power windows, door locks, and windshield wiper. 1.1.2 B Class Multiplexing Class B Multiplexing provides the data communications between different modules, internal and external to the vehicle, for the purpose of sharing common data
17、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. SAE J2057-2 Reaffirmed SEP2006 - 3 - 1.1.3 C Class Multiplexing Class C Multiplexing is used for real-time high-speed control, and
18、 normally requires a significant amount of data communication to function properly. An example is the hydraulic actuator for the Anti-Lock Brakes System. 1.2 Analog as Well as Digital The physical transportation of the information in a Class A Multiplex application can use analog or digital techniqu
19、es. The information can be transported by an encoded voltage, resistance, or other physical value impressed on the transportation media. The transportation media can be a wire, but is not limited to a wire. In some cases, it is difficult to identify an actuator as digital or analog. For example, a s
20、tepper motor can be used to control a flapper position in a heat exchanger. Although the motor has digital control, the intent of the control is analog as perceived by the vehicle operator. Hence, the Class A application of the flapper is identified as an analog function. In contrast, a door lock is
21、 a digital function. This concept is discussed further in the document. 2. REFERENCES 2.1 Applicable Publications The following publications form a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE,
22、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 J1850 Class B Data Communication Network Interface SAE J2057/1 Class A Multiplexing Application/Definition SAE J2057-4 Class A Multiplexing Architecture Strate
23、gies SAE J217812 Class B Data Communication Network Messages, Data Parameter Definitions 2.2 Related Publications The following publications are for information purposes only and are not a required part of this document. 2.2.1 SAE Publications Available from SAE, 400 Commonwealth Drive, Warrendale,
24、PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J1930 Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations, and Acronyms SAE J1979 E/E Diagnostic Test Modes 3. DEFINITIONS Class A actuators mostly fall into the area of op
25、erator convenience. They are typically characterized by moderate- to slow-communication times and are nontime critical. Actuators can be identified as either analog or digital. Actuators also can be classified by their engineering units and resolution. SAE J2057-2 Reaffirmed SEP2006 - 4 - 3.1 Analog
26、 Actuator Class A analog actuators convert some continuously varying output characteristic such as a continuously varying output value or magnitude. Although the communicated value may or may not be digitally encoded, the action taken is intended to provide a continuous range. An example of this is
27、the flapper position in the heat exchanger. The actuator has a continuum of positions between a maximum and minimum value. 3.2 Digital Actuator Class A digital actuators convert some output characteristic to discrete output states. The actuator has a maximum and minimum measurable range that corresp
28、onds to a fixed number of discrete output states. Examples of outputs that can have two states are the interior lights and parking lights. An output can have more than two states. For example, the blower fan is a digital actuator with possibly four or more states: off, low, medium, and high. 3.3 Eng
29、ineering Units Engineering units are the units of measure detected by and processed by the measuring system. Engineering units are a measure of Volume, Voltage, Displacement, Time, and other similar quantities. The engineering unit can be measured as an absolute value (i.e., volts), as a ratio (i.e.
30、, decibel), or as a percentage (i.e., gas tank gauge). 3.4 Binary Resolution Binary resolution is the number of bits, in base 2, required to represent the full scale value. A bit is a single unit of binary information which has only two states: On/Off, 1/0, HI/LO, or True/False. Binary bits may be c
31、ombined into groups of bits, representing values above two. 3.5 Analog Resolution Requirement Analog resolution requirement is the largest level change that cannot be perceived by an occupant or operator. The analog resolution of the system should not allow the occupant to perceive discrete change.
32、For example, “Opera Dimming” is an analog function. It can be achieved with discrete drive level changes that appear to the occupant as continuous dimming. The discrete drive resolution of this actuator should resolve to a level that is finer than required by the analog resolution of the function. 4
33、. TYPICAL APPLICATION Typical applications can be divided into analog and digital systems. A system is an analog system if the intent of the control is continuous. The system is considered digital if the intent of the control has discrete steps, locations, or values. 4.1 Analog Actuators Analog actu
34、ators are used where continuously varying data is required for display or actuation. For analog data to be communicated on the Class A network, it is usually, but not always, first converted to a digital format. Analog actuators provide continuous quantities as perceived by the occupant such as volt
35、ages, resistances, and pressures. For example, the location of a flapper can control temperature. The location of the flapper is controlled by an electric voltage, current output, or stepper motor. The temperature output signal is solely dependent upon the actuators transfer function to obtain a val
36、ue or magnitude. A second example of an analog actuator is a seat motor, since the location of the seat is not in discrete steps, this actuator is classified as an Analog Actuator. 4.2 Digital Actuators Digital actuators are used where discrete actuation is required. The information is represented b
37、y coded pulses or states based on discrete techniques. The information can be represented by two, three, or many states. The number of states are fixed and finite. For example, a door can be unlocked, locked, or bolted. SAE J2057-2 Reaffirmed SEP2006 - 5 - 5. REQUIREMENTS The following is a general
38、list of requirements and is not meant to be specific for any one application. The requirements in this report are for informational purposes only. The actual requirements for each specific actuator would be determined by the application and by the manufacturer. 5.1 Network Requirements The actuator
39、will be capable of interfacing to the Class A network through integral interface circuitry or through a stand alone interface module. Reference SAE J2057/1 for specific requirements. 5.2 Electrical Requirements The actuator must operate at all standard automotive voltages and survive the abnormal co
40、nditions, such as reverse voltage and load dump, as required by each user. 5.3 Environmental Requirements The environmental requirements vary depending on the application. Some of the requirements that should be identified are: temperature range, dust, humidity, shock, vibration, power dissipation,
41、conducted transients (load dump, etc.), double battery transients, low-voltage electrostatic discharge, and high-voltage electrostatic discharge. 5.4 Latency Refer to Table 2.2, Typical Class A Application, included in SAE J2057/1. 5.5 EMC Susceptibility and Radiation The EMC (Electro-Magnetic Compa
42、tibility) of actuators must meet the Requirements of the manufacturer and should meet the requirements of SAE J2057/1, paragraph 7.4. 5.6 Reliability The reliability of the actuator and its Class A network interface should not degrade the performance of the function or the network as compared to non
43、multiplexed vehicles. The actual actuator reliability requirement will be determined by the application and by the manufacturer. 5.7 Actuator Failure The failure of the actuator must not affect operation of the Class A Bus and should return to a known default value when appropriate. Reference SAE J2
44、057/1, paragraph 6.3. 5.8 Bus Failure The actuator should monitor bus activity to determine if there is active communication. During bus failures, this activity may be lost and can be used as an indication of a bus failure. If the actuator has the ability to initiate communication, the actuator can
45、test the bus by sending a status message. If the actuator detects a bus failure, it should move to a safe state as appropriate for the specific system affected. 5.9 Diagnostics The actuator should have the ability to be interrogated by a system to determine if failures are present in the actuator an
46、d transmit this information for appropriate action. In some actuators degraded performance could also be reported. SAE J2057-2 Reaffirmed SEP2006 - 6 - 6. ACTUATOR TYPES AND PARAMETERS Appendix A contains two lists of actuator types: analog actuators and digital actuators. Refer to SAE J2057/1 for a
47、dditional information. The lists are not all inclusive for all applications. 7. CONCLUSIONS The use of Class A actuators on a vehicle network should offer the manufacturer and the customer several benefits in several key areas: customer confidence, vehicle design, manufacturability, and service. a.
48、To the customer, the confidence that each system or function is working properly. If there is a failure, the vehicle can provide warning information and in some cases provide an alternative default function. b. To the design engineer, a minimized number of wiring harness variations to mechanize and
49、validate. c. To the assembly line worker, the installation of the wiring harnesses in the vehicle should be made simpler and easier due to minimized wiring harness size. d. To the service personnel, electrical problems can be diagnosed and repaired efficiently. e. To the component manufacturer, the “No Trouble Found” return rate should be lower. 8. NOTES 8.1 Key Words Multiplexing, Class A, Actuator PREPARED BY THE SAE VEHICLE ARCHITECTURE FOR
