ISO 17458-2:2013

Overview

ISO 17458-2:2013 - Road vehicles - FlexRay communications system - Part 2: Data link layer specification defines the FlexRay data link protocol for dependable, high‑speed in-vehicle networks. The standard details how ECUs exchange deterministic, cycle‑based messages with guaranteed latency and jitter, supports synchronous and asynchronous frame transfer, and defines mechanisms for clock synchronisation, error detection/signalling and scalable fault tolerance. ISO 17458-2 is a core reference for implementing the FlexRay data link layer in automotive electronic control systems.

Key topics and technical requirements

ISO 17458-2 covers the data link layer behavior and includes normative requirements across these technical areas:

• Frame format and CRC: specification of header, payload (0–254 bytes), trailer and CRC calculation details.
• Coding and decoding: signal coding, bit strobing and wakeup pattern decoding.
• Media Access Control (MAC): deterministic and priority‑based access for time‑triggered (synchronous) and event‑triggered (asynchronous) traffic.
• Clock synchronisation: single or multi‑master synchronization, time representation, correction term calculation and sync frame configuration to maintain a common time base across nodes.
• Wakeup and startup: cluster wakeup procedures, autonomous startup and reintegration of nodes.
• Protocol operation control & frame processing: state machines and processes for reliable operation, error handling and signalling.
• Controller‑Host Interface: services and interfaces between FlexRay controllers and host ECUs.
• Configuration and conformance: system parameters, configuration constraints and wakeup application notes in normative annexes.

Practical applications

ISO 17458-2 is intended for applications that require deterministic, high‑speed communication with strong timing guarantees, for example:

• Advanced driver assistance systems (ADAS) and real‑time control loops
• Powertrain and chassis control requiring synchronized actuation sampling
• Safety‑critical subsystems where bounded latency and fault tolerance are mandatory
• Multi‑ECU distributed control architectures across one or multiple FlexRay clusters

Who should use this standard

• Automotive OEMs and system architects designing in‑vehicle networks
• ECU hardware and firmware engineers implementing FlexRay controllers or protocol stacks
• Semiconductor and IP vendors producing FlexRay PHY/MAC controllers
• Test and validation labs, and tool vendors developing conformance and interoperability tests

Related standards

• ISO 17458-1, -3, -4, -5 (FlexRay series covering use cases, conformance tests and physical layer)
• Diagnostic and higher‑layer standards referenced in the series (e.g., ISO 14229 series, ISO 10681-2)

ISO 17458-2:2013 is the authoritative reference for the FlexRay data link layer and essential for implementing deterministic, synchronized automotive networks.