ISO 27145-1:2012

Overview

ISO 27145-1:2012 - "Road vehicles - Implementation of World‑Wide Harmonized On‑Board Diagnostics (WWH‑OBD) communication requirements - Part 1: General information and use case definition" is the introductory part of the ISO 27145 series. It provides the structure, terminology and high‑level use case definitions for implementing a world‑wide harmonized OBD communication standard (WWH‑OBD). The document explains the relationship between the parts of ISO 27145, the intended migration path from CAN‑based diagnostics (DoCAN) to Ethernet/IP‑based diagnostics (DoIP), and how external test equipment initializes and identifies supported protocols and diagnostic services for emissions‑related systems.

Key topics and technical scope

• Scope and purpose: Establishes ISO 27145 as the single communication standard for access to OBD‑related information, while supporting a smooth migration from ISO 15765 (DoCAN) to ISO 13400 (DoIP).
• Use case clusters and definitions: Defines primary WWH‑OBD use cases (for example UC 1 - information about OBD system state; UC 2 - active/confirmed malfunctions; UC 3 - diagnostic data for repair) to guide external test equipment and in‑vehicle implementations.
• Terminology and data concepts: Standardizes common terms (e.g., CALID, CVN, continuous‑MI counters, DTC classes) used across the ISO 27145 series to ensure consistent interpretation.
• OSI layer mapping: Maps WWH‑OBD services to the OSI model - application/session/transport/network/data link/physical layers - and specifies references for each layer (e.g., ISO 14229 for UDS, ISO 27145‑4 for transport/network).
• Migration and extensibility: Initial DoCAN‑based concept (ISO 15765 series) with the intention to adopt DoIP (ISO 13400) and support future optional physical layers (including potential wireless extensions).
• Initialization behavior: External test equipment determines supported protocol and services during initialization to distinguish between legislated OBD (ISO 15031) and WWH‑OBD (ISO 27145).

Practical applications and users

ISO 27145-1 is useful for:

• Vehicle manufacturers and OEMs aligning OBD communications across markets.
• Diagnostic tool and external test equipment developers implementing WWH‑OBD initialization and service discovery.
• Aftermarket diagnostic software and service garage systems that need standardized access to emissions‑related diagnostic data.
• Regulatory bodies and type‑approval labs implementing or assessing WWH‑OBD GTR No. 5 compliance.
• Systems architects planning migration from CAN (DoCAN) to Ethernet/DoIP for vehicle diagnostics.

Related standards (normative and informative)

• ISO 27145 series: Part 2 (Common data dictionary), Part 3 (Common message dictionary), Part 4 (Connection between vehicle and test equipment)
• ISO 14229‑1/2 (UDS - Unified Diagnostic Services)
• ISO 15765 (DoCAN), ISO 13400 (DoIP)
• SAE digital annexes: SAE J1930‑DA, SAE J1979‑DA, SAE J2012‑DA, SAE J1939 families
• ISO/IEC OSI references (ISO/IEC 7498‑1)

Important: ISO 27145‑1 does not include country‑specific GTR No. 5 implementation cases; those are handled separately.