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, electrical specifications, and the CRC byte are given in SAE J1850.
SAE J1850 defines two and only two formats of message headers. They are the Single Byte header format and the Consolidated header format. The Consolidated header format has two forms, a single byte form and a three byte form. This document covers all of these formats and forms to identify the contents of messages which could be sent on a SAE J1850 network.
This document consists of four parts, each published separately.
SAE J2178-1, Part 1 of SAE J2178 (Titled: Detailed Header Formats and Physical Address Assignments) describes the two allowed forms of message header formats, Single Byte and Consolidated. It also contains the physical node address range assignments for the typical sub-systems of an automobile.
SAE J2178-2, Part 2 of SAE J2178 (this part, Titled: Data Parameter Definitions) defines the standard parametric data which may be exchanged on SAE J1850 (Class B) networks. The parameter scaling, ranges, and transfer functions are specified. Messages which refer to these parametric definitions shall always adhere to these parametric definitions. It is intended that at least one of the definitions for each parameter in this part match the SAE J1979 definition.
SAE J2178-3, Part 3 of SAE J2178 (Titled: Frame IDs for Single Byte Forms of Headers) defines the message assignments for the Single Byte header format and the one byte form of the Consolidated header format.
SAE J2178-4, Part 4 of SAE J2178 (Titled: Message Definition for Three Byte Headers) defines the message assignments for the three byte form of the Consolidated header format.
Rationale
The technical report covers technology, products, or processes which are mature and not likely to change in the foreseeable future.
The ever-increasing consumer expectations of vehicle internal functions and connectivity to the environment are outstripping the capability of current data communication architecture design. To address this vulnerability this committee will investigate and endorse new vehicle architectures that meet system requirements such as: ¿ Reliability ¿ System design metrics ¿ Data security ¿ Fault Tolerance ¿ Built in testability ¿ Validation/Verification ¿ Compatibility ¿ Redundancy This committee¿s mission is the investigation and development of vehicle architecture and data communication protocols and methods required to achieve the growth expected in the area of vehicle electronics. The committee shall continue to contribute to the understanding and use of semiconductor devices such as microprocessors, power devices, and other integrated circuits and the data transmission media used in these systems. Thus, all vehicle architectures (excluding aircraft) and devices used in these systems shall be included. Specific objectives shall include: ¿ Address the effect of electrical power environments (e.g., 42V, ground offsets) ¿ Sponsor forums to evaluate new technologies (e.g., MOST, Bluetooth, Firewire) ¿ Publish technical reports on vehicle architecture and system partitioning, interfacing, modes of operation, protocol standards, recommended conformance test methods, and evaluation methods of those standards ¿ Maintain the existing documents relevant to this committee (e.g., glossary of automotive electronics terms, SAE J1213/1) ¿ Encourage the applicable industries, government and educational institutions to support the efforts of this committee.
* Redlines comparisons are available for those standards listed in the Revision History that contain a radio button. A redline comparison of the current version against a revision is accomplished by selecting the radio button next to the standard and then selecting 'compare'. At this time, Redline versions only exist for some AMS standards. SAE will continue to add redline versioning with ongoing updates to SAE MOBILUS.
View/Annotate
Content Loading, Please Wait
Document Preview
Content Loading, Please Wait
Document Comparison
Content Loading, Please Wait
Download
A list of downloadable items.
Product Code
Document Title
File Type
Download
J2178/2_201104
Export Metadata
This modal will allow the user to download citation information or export specific fields of data into one of three file formats: Excel, comma-separated values, or text.
Sorry, this document is already saved to a project folder.
Share
Share this content via social media.
Share Via Email
Annotation Warning
You are currently not logged into your Dashboard account, which is required for annotating.
Please select Login to login or register for the Dashboard. Select Continue to view the content without the ability to annotate.
Class B Data Communication Network Messages - Part 2: Data Parameter Definitions
SAE Journal Subscriptions are available in a variety of options, which include electronic, electronic with back file, and archive. For detailed information and options, please complete the following:
Content Request
Check My Access!
You may already have access to the Ground Vehicle Standard, Class B Data Communication Network Messages - Part 2: Data Parameter Definitions
Subscription Access
If you have Subscription Access with a username and password, please login below.
Institutional Login
If you have Institutional Access to SAE MOBILUS, using a predetermined organizational login utilizing single-sign-on (Shibboleth), please login below. To request institutional access to SAE MOBILUS, please complete the institutional subscription information form.
Purchase
If you do not have access to SAE MOBILUS via username/password or institutional access, you can still purchase the Ground Vehicle Standard, Class B Data Communication Network Messages - Part 2: Data Parameter Definitions.
Search Tips: Search Operators:AND, OR, NOT; Wild Cards; Using Quotes
SAE MOBILUS® Search Tips
Please note: All terms not contained within quotes, will be evaluated using the OR operator. This means that your search results will contain all results that contain ANY of the entered terms.
AND, OR, NOT
SAE MOBILUS supports the use of the AND, OR and NOT BOOLEAN operators ONLY function with the Advanced Search.
Wild Cards
Using the asterisk, ( * ) allows you to search for a partial word. For example, entering a keyword search of aero* will search for any word beginning with aero.
Using the question mark, ( ? ) allows you to search for a word with a single character wildcard. For example, searching for t?re would match both tire and tyre
Using Quotes
Words in double quotes " " are treated as a phrase. Conducting a search for "heat model" will return all results in which the exact phrase "heat model" is found, while "heat modeling" would NOT be included.
A term combined with a phrase will be joined with an OR operator.
Searching for Standards
When searching for a standard please use the entire Document Number assigned, which includes the abbreviation. A space can be used, or omitted between the abbreviation and number.
