ISO 14229-2-2021 PDF

Full title and description

Road vehicles — Unified diagnostic services (UDS) — Part 2: Session layer services. Specifies common session-layer services and the abstract service-primitive interface between the UDS application layer and underlying transport/network protocols so that ISO 14229-1 UDS services can operate independently of the chosen transport (e.g., DoCAN, DoIP, DoK-Line, FlexRay, CXPI).

Abstract

This part of ISO 14229 defines session-layer service primitives, requirements and behavior that provide independence between UDS application services and transport/network protocols. It specifies the service request/indication/confirmation primitives and timing/interaction rules needed for session control, multiplexing, and interaction with transport-layer protocols.

General information

• Status: Published
• Publication date: 12 October 2021
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 43.180 (Diagnostic, maintenance and test equipment)
• Edition / version: Edition 2 (2021)
• Number of pages: 53.

Scope

Specifies common session layer services and requirements to decouple unified diagnostic services (ISO 14229-1) from transport and network layer protocols; defines a common service-primitive interface between OSI layer 5 (session) and layer 4 (transport) so UDS can be implemented over DoIP, DoCAN (ISO 15765-2), DoK‑Line, FlexRay, CXPI and other transport mechanisms.

Key topics and requirements

• Definition of session-layer service primitives (request/indication/confirmation) that present a transport‑independent API to ISO 14229‑1 (UDS application layer).
• Mechanisms for session control, including diagnostic session selection, session timing and transition rules.
• Requirements to support independence from multiple transport protocols (CAN/ISO‑TP, DoIP, FlexRay, K‑Line, CXPI, etc.).
• Timing and flow-control considerations connecting session behavior to transport-layer constraints (P1/P2 timers, flow control coordination).
• Requirements and guidance to enable seamless implementation of UDS services across different network technologies and to support implementation profiles such as UDSonCAN.

Typical use and users

Used by automotive OEMs, Tier‑1 suppliers, ECU firmware architects, diagnostic‑tool and test‑equipment vendors, and software engineers implementing UDS application and session layers; it guides how diagnostic services are exposed to test tools regardless of underlying vehicle network.

Related standards

Part of the ISO 14229 UDS family; key related documents include ISO 14229‑1 (UDS application layer), ISO 14229‑3 (UDSonCAN implementation/profile), ISO 15765‑2 (DoCAN / ISO‑TP transport for CAN) and ISO 13400‑2 (DoIP transport profile). These referenced standards define the application‑level services, CAN implementation profiles and the transport/network specifications used together with ISO 14229‑2.

Keywords

ISO 14229, UDS, unified diagnostic services, session layer, service primitives, transport independence, DoCAN, DoIP, ISO‑TP, diagnostics, ECU, automotive diagnostics

FAQ

Q: What is this standard?

A: ISO 14229‑2:2021 specifies the session layer services for Unified Diagnostic Services (UDS), defining a transport‑independent interface between the UDS application layer and transport/network protocols.

Q: What does it cover?

A: It covers session‑layer primitives (request/indication/confirmation), session control behavior, timing/flow considerations, and the requirements needed so UDS can run over multiple transport protocols (CAN/ISO‑TP, DoIP, FlexRay, K‑Line, CXPI, etc.).

Q: Who typically uses it?

A: Automotive OEMs, Tier‑1 suppliers, ECU and embedded software developers, and test/diagnostic tool vendors use it to implement or interoperate UDS across vehicle networks.

Q: Is it current or superseded?

A: ISO 14229‑2:2021 is the current published edition (edition 2, published October 2021), which replaces the withdrawn 2013 edition.

Q: Is it part of a series?

A: Yes — it is Part 2 of the ISO 14229 series (UDS). Other parts include Part 1 (application layer) and Part 3 (UDSonCAN implementation/profile), among related transport standards referenced by the series.

Q: What are the key keywords?

A: UDS, session layer, service primitives, ISO 14229, transport independence, DoCAN, DoIP, ISO‑TP, ECU diagnostics.