GB/T 39851.2-2021Road vehicles - Diagnostic communication over Controller Area Network (DoCAN) - Part 2: Transport protocol and network layer services (English PDF)

Foreword

GB/T 39851 "Road vehicles - Diagnostic communication over Controller Area

Network (DoCAN)'' has issued and plans to issue the following parts.

- Part 2.Transport protocol and network layer services;

- Part 3.Requirements for emission-related systems;

This Part is Part 2 of GB/T 39851.

This Part is drafted in accordance with the rules given in GB/T 1.1-2009.

This Part uses the redraft law to modify and adopt ISO 15765-2.2016 "Road

vehicles - Diagnostic communication over Controller Area Network (DoCAN) -

Part 2.Transport protocol and network layer services".

Compared with ISO 15765-2.2016, the structure of this Part has been adjusted

as follows.

- For the convenience of readers, the subclause composed of multiple

paragraphs is subdivided into several articles without title;

- According to the content added in Clause 5, add 5.1 "Open Systems

Interconnection (OSI) model", 5.2 "Diagnostic network architecture", and

1 Scope

This Part of GB/T 39851 specifies a transport protocol and network layer

services tailored to meet the requirements of CAN-based vehicle network

systems on controller area networks as specified in ISO 11898-1.2015.

2 Normative references

The following documents are indispensable for the application of this document.

For the dated references, only the editions with the dates indicated are

applicable to this document. For the undated references, the latest edition

(including all the amendments) are applicable to this document.

ISO/IEC 7498-1 Information technology - Open systems interconnection -

Basic reference model - Part 1.The basic model

3 Terms, definitions and abbreviated terms

Configures the maximum usable payload length in bytes of the data link layer

in the transmitter for the application that implements the network layer as

defined in this Part.

For the purposes of this document, the following abbreviated terms apply.

4 Conventions

This Part is based on the conventions discussed in the OSI service conventions

(ISO/IEC 10731) as they apply for diagnostic services.

5 Overview

The DoCAN protocol use cases are derived from the following areas of use for

diagnostic communications.

6 CAN data link layer extension

If a CAN FD protocol device is used, this Part can be configured to create

either CLASSICAL CAN or CAN FD type frames. When CAN FD type frames

are enabled for the data link layer, two new options need to be supported as

follows.

7 Network layer overview

The service interface defines a set of services that are needed to access the

functions offered by the network layer, i.e. transmission/reception of data and

setting of protocol parameters. Two types of service are defined.

8 Network layer services

Description. This parameter contains the status relating to the outcome

of a service execution. If two or more errors are discovered at the same time,

then the network layer entity shall use the parameter value found first in this list

when indicating the error to the higher layers.

9 Transport layer protocol

The payload data length CAN_DL of the received CAN frame has to match the

RX_DL value which was determined in the reception process of the FirstFrame

(FF). Only the last CF in the multi-frame transmission may contain less than

RX_DL bytes.

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