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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2012 SAE International All rights reserved. No part of this p
3、ublication may 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: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2497_201207SURFACE VEHICLE RECOMMENDED PRACTICE J2497 JUL2012 Issued 2002-10 Rev
5、ised 2012-07 Superseding J2497 DEC2010 Power Line Carrier Communications for Commercial Vehicles RATIONALE Replaced SAE J1113 references with equivalent CISPR 25 references. Updated the Intellectual Property section and removed the contact info. Added PID and PGN information for ABS Indicator Lamp S
6、tatus sections. Added missing abbreviations. FOREWORD This SAE Recommended Practice has been developed by the Truck and Bus Low Speed Communications Network Subcommittee of the Truck and Bus Electrical and Electronics Committee. The objectives of the subcommittee are to develop information reports,
7、recommended practices, and standards concerned with the requirements design and usage of devices which transmit electronic signals and control information among vehicle components. This document is intended as a guide toward standard practice and is subject to change so as to keep pace with experien
8、ce and technical advances. SAE J2497 Revised JUL2012 Page 2 of 22 TABLE OF CONTENTS 1. SCOPE 2 2. REFERENCES 3 3. ABBREVIATIONS . 4 4. INTELLECTUAL PROPERTY RIGHTS 4 5. NETWORK DESCRIPTION 4 5.1 PLC Network . 4 5.2 PLC Transceiver . 5 5.3 Coupling Examples . 5 6. POWER LINE MESSAGE . 6 6.1 Message F
9、ormat Between Host Microcontroller and PLC Transceiver 6 6.2 Message Format on the Power Line . 6 6.3 Message Encoding . 7 6.4 Message Timing 8 6.5 Contention Resolution . 8 7. TRANSMITTER CHARACTERISTICS . 8 7.1 Waveform Generation . 9 7.2 Amplitude 9 7.3 SUPERIOR1 to SUPERIOR2 Transition . 10 7.4
10、Conducted Emissions Limit . 10 7.5 ECU Isolation 11 8. RECEIVER CHARACTERISTICS . 11 8.1 SUPERIOR States Recognition 11 9. SOFTWARE FUNCTIONS 12 9.1 Cab Mounted Trailer ABS Malfunction Indicator Lamp Control 12 10. PLC NETWORK MESSAGE FORMAT DEFINITIONS . 14 10.1 Trailer ABS Indicator Lamp ON (MID10
11、) 14 10.2 Trailer ABS Indicator Lamp OFF (MID 11) . 14 10.3 Trailer ABS Active (MID 87) 14 11. PLC NETWORK MESSAGE FORMAT DEFINITIONS UNIQUE TO SAE J2497 15 11.1 Dynamic Claim to a Unique SAE J2497 MID 15 11.2 SAE J2497 MID Assignments . 17 11.3 Parameter Identification Assignments 18 11.4 Subsystem
12、 Identification Assignments . 18 11.5 Failure Mode Identifier Assignments 18 12. NOTES 18 12.1 Marginal Indicia . 18 SAE J2497 Revised JUL2012 Page 3 of 22 APPENDIX A SUPERIOR STATE WAVEFORM 19 APPENDIX B ECU ISOLATION 20 APPENDIX C TIMING DIAGRAMS . 21 FIGURE 1 EXAMPLE OF PLC NETWORK 5 FIGURE 2 PLC
13、 TRANSCEIVER. 5 FIGURE 3 POWER LINE COUPLING TECHNIQUES . 5 FIGURE 4 EXAMPLE OF PREAMBLE LOGIC SYMBOL ENCODING . 7 FIGURE 5 EXAMPLE OF DATA BODY LOGIC SYMBOL ENCODING 8 FIGURE 6 FREQUENCY SWEPT CARRIER WAVEFORM 9 FIGURE 7 OUTPUT DRIVER TEST CIRCUIT . 10 FIGURE 8 CONTROL OF CAB MOUNTED TRAILER ABS IN
14、DICATOR LAMP BY TRACTOR DEVICE . 13 FIGURE 9 EXAMPLE OF TRAILER DEVICE SET SUPPORTING DYNAMIC ADDRESSING . 16 FIGURE 10 EXAMPLE OF ADDING ECU TO TRAILER DEVICE SET SUPPORTING DYNAMIC ADDRESSING . 16 FIGURE C1 START OF MESSAGE TRANSMISSION TIMING AND CONTENTION ARBITRATION 21 FIGURE C2 END OF MESSAGE
15、 TIMING 22 TABLE 1 OUTPUT VOLTAGE . 9 TABLE 2 MESSAGE ID ASSIGNMENT LIST 17 TABLE A1 DIGITIZED 100 MS WAVEFORM360 INTERVALS (361 POINTS) 19 1. SCOPE This SAE Recommended Practice defines a method for implementing a bidirectional, serial communications link over the vehicle power supply line among mo
16、dules containing microcomputers. This document defines those parameters of the serial link that relate primarily to hardware and software compatibility such as interface requirements, system protocol, and message format that pertain to Power Line Communications (PLC) between Tractors and Trailers. T
17、his document defines a method of activating the trailer ABS Indicator Lamp that is located in the tractor. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publicati
18、ons shall apply. 2.1.1 SAE Publications Available from SAE International, 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 J1587 Electronic Data Interchange Between Microcomputer Systems In Heavy-Duty Vehicle
19、 Applications SAE J1708 Serial Data Communications Between Microcomputer Systems In Heavy-Duty Vehicle Applications SAE J1939 Recommended Practice for a Serial Control and Communications Vehicle Network SAE J2497 Revised JUL2012 Page 4 of 22 2.2 Related Publications The following publications are pr
20、ovided for information purposes only and are not a required part of this SAE Technical Report. 2.2.1 ANSI Publication Available from American National Standards Institute, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org. CISPR 25 Vehicles, boats and internal combustion
21、engines - Radio disturbance characteristics - Limits and methods of measurement for the protection of on-board receivers 3. ABBREVIATIONS ABS Antilock Brake System AC Alternating Current ASK Amplitude Shift Key modulation CISPR Comit International Spcial des Perturbations Radiolectriques; English: S
22、pecial international committee on radio interference) DC Direct Current ECU Electronic Control Unit FMI Failure Mode Identifier MID Message Identifier NRZ Non Return to Zero modulation PGN Parameter Group Number PID Parameter ID PL Power Line PLC Power Line Communications PRK Phase Reversal Keying m
23、odulation RF Radio Frequency SID Subsystem ID Tsd Start Delay Time 4. INTELLECTUAL PROPERTY RIGHTS By publication of this document, no position is taken with respect to the existence or validity of any third party patent rights in connection therewith. The SAE is not responsible for identifying pate
24、nts for which a license may be required. 5. NETWORK DESCRIPTION 5.1 PLC Network Figure 1 shows a typical PLC network. A typical network consists of Electronic Control Units (ECU) with, PLC transceivers, mounted on the tractor and trailer(s). These ECUs communicate to each other by sending Radio Freq
25、uency (RF) signals over the power line. These ECUs interface to the power line through a PLC transceiver. The tractor PLC ECU must provide control for the Tr ailer ABS Indicator Lamp that is mounted in the tractor cab. This can be done by either a direct connection to the lamp, or by providing an ap
26、propriate control message (for example, by SAE J1587 or SAE J1939) to another ECU which then controls the lamp. SAE J2497 Revised JUL2012 Page 5 of 22 FIGURE 1 - EXAMPLE OF PLC NETWORK 5.2 PLC Transceiver The microprocessor of an electronic module interfaces to the power line through a PLC transceiv
27、er. Refer to Figure 2. The microprocessor sends digital data (Tx) to a coding device in the PLC transceiver. This data is in the format described in SAE J1708. The coding device converts the digital data into a signal suitable for being transmitted on the power line. This signal will be described in
28、 later sections. This signal (Signal_out) is then passed through the appropriate amplifier and filters before it is coupled onto the power line. Conversely, a PLC signal (Signal_in) is taken from the power line, filtered, and decoded into digital data (Rx). This data is sent to the host microprocess
29、or in a format defined by SAE J1708. FIGURE 2 - PLC TRANSCEIVER 5.3 Coupling Examples The PLC transceivers will interface to the power line, relative to the negative line, through the appropriate coupling network. Figure 3 illustrates two possible coupling networks. One provides capacitive coupling
30、and the other provides transformer (inductive) coupling of the PLC signals onto the power line. FIGURE 3 - POWER LINE COUPLING TECHNIQUES SAE J2497 Revised JUL2012 Page 6 of 22 6. POWER LINE MESSAGE The message sent on the power line has two major parts, the preamble and the data body. Refer to Figu
31、res C1 and C2 in Appendix C for following descriptions. 6.1 Message Format Between Host Microcontroller and PLC Transceiver The communications between the host microcontroller and the PLC transceiver follows the SAE J1708 message format. The only exception to SAE J1708 message format is the characte
32、r gap between the first and second characters. The host microcontroller must wait 2 bit times after receiving the stop bit of the first character echoed back to the microcontroller before sending the second character. Refer to Figure C1 in Appendix C. 6.2 Message Format on the Power Line The format
33、of the message that is placed on the power line is as follows. Message: Preamble: Initial Symbol(s) Less than 2 symbols Start bit 1 Logic low, SUPERIOR2 symbol Data bits 8 Either Superior or Inferior symbol Stop bit 1 Logic high, Inferior symbol Data Body: Sync: 5 Logic high, SUPERIOR1 symbol Each d
34、ata character: Start bit 1 Logic low, SUPERIOR2 symbol Data bits 8 Either superior symbol Stop bit 1 Logic high, SUPERIOR1 symbol Character Gap 0 4 symbol times End of message 5 Logic high, SUPERIOR1 symbol A symbol is the signal, encoded on the power line, that is the representation of a binary sta
35、te. The symbols will be discussed in more detail in subsequent sections. The preamble is created by the PLC transceiver and uses the first character it receives, of the message to be sent, from the host microcontroller (i.e., the MID). After the preamble, the transceiver retransmits the first data c
36、haracter again in the data body. The host microcontroller SHOULD NOT resend the first data character again to the PLC transceiver. 6.2.1 Preamble format Refer to Figure C1 in Appendix C. The preamble starts with less than two complete initial SUPERIOR2 symbols. The initial symbol(s) are followed by
37、a start bit, 8 data bits, and 1 stop bits. The start bit is a SUPERIOR2 symbol and the stop bit is an Inferior symbol. The data bits are either symbol. 6.2.2 Data Body Format A sync segment follows the preamble. This sync segment consists of 5 SUPERIOR1 symbols. Following the sync segment is the fir
38、st data character. Data characters consist of a start bit, followed by 8 data bits, and 1 stop bit. These data characters in the data body are the same characters from the SAE J1708 message sent to the PLC transceiver by the host microcontroller. The start bit is represented by a SUPERIOR2 symbol, a
39、nd a stop bit is represented by a SUPERIOR1 symbol. The data bits can be either symbol. SAE J2497 Revised JUL2012 Page 7 of 22 The data characters are separated by character gaps of zero to four SUPERIOR1 symbols. The character gaps are required because the bit time (symbol time) of the message on t
40、he power line is different than the bit time of the message sent between the host microprocessor and the power line transceiver. The end of the message is terminated with five consecutive SUPERIOR1 symbols (logic highs) after the stop bit of the last (nth) character. Refer to Figure C2 of Appendix C
41、. 6.3 Message Encoding The preamble and data body are encoded onto the power line using different modulation techniques. 6.3.1 Preamble Encoding The preamble is encoded onto the power line using “Amplitude Shift Key” modulation (ASK). A logic “0” is encoded using a particular waveform. This waveform
42、 is a logic symbol known as a Superior State Phase 2 or SUPERIOR2. The characteristic of this waveform is described in a later section. The logic “1” is encoded by the absence of any signal. This logic symbol is known as an Inferior state. These symbols are illustrated in Figure 4. FIGURE 4 - EXAMPL
43、E OF PREAMBLE LOGIC SYMBOL ENCODING The bit time during the preamble is 114 s, whereas the time of the SUPERIOR2 symbol is 100 s. There are 14 s of idle time between two consecutive SUPERIOR2 symbols. This extra idle time increases the ability to detect the preamble. 6.3.2 Data Body Encoding The dat
44、a body is encoded onto the power line using “Non Return to Zero” (NRZ) “Phase Reversal Keying” (PRK) Modulation. There are two signals used to encode binary logic symbols “1” and “0”. Both are superior state. The signal for a logic “1” symbol is known as “Superior State Phase 1” or SUPERIOR1. The si
45、gnal for a logic “0” symbol is known as “Superior State Phase 2” or SUPERIOR2. The signal for a SUPERIOR2 has the same function as SUPERIOR1 except it differs in phase by 180 degrees (SUPERIOR2 = -SUPERIOR1). Examples of these symbols are shown in Figure 5. The SUPERIOR2 symbol is the same symbol us
46、ed in the coding of the logic “0” in the preamble. The characteristics of these waveforms are described in a later section. SAE J2497 Revised JUL2012 Page 8 of 22 FIGURE 5 - EXAMPLE OF DATA BODY LOGIC SYMBOL ENCODING 6.4 Message Timing Message between host microprocessor and PLC Transceiver: Bit tim
47、e is 104 s (9600 bits per second). Message sent on power line: Bit time of preamble is 114 s (8772 bits per second). Bit time of data body is 100 s (10 000 bits per second). Symbol time is 100 s. The tolerance is 0.5% over the operating temperature and humidity range of the PLC transceiver. 6.5 Cont
48、ention Resolution The preamble is used to resolve contention between two messages transmitted simultaneously. The ASK encoding method provides the means of arbitration. One preamble will have signal (SUPERIOR2) in a bit location that the contending preamble has no signal (INFERIOR). Thus, the SUPERI
49、OR2 symbol will overwrite the INFERIOR symbol. Refer to Figure C1 of Appendix C. As each transceiver sends out its preamble, it observes the preamble on the power line. When one transceiver detects a SUPERIOR2 symbol in the bit location where there should be an INFERIOR symbol, it will immediately stop transmitting and place itself in the receiver mode so as not to corrupt the preamble of the dominant
