ISO 11898-4-2004 PDF

Full title and description

Road vehicles — Controller area network (CAN) — Part 4: Time-triggered communication. Specifies a time‑triggered communication scheme for CAN networks used in road vehicles, defining the frame‑synchronisation entity (FSE), global time concepts and a system matrix to coordinate deterministic, scheduled message transmission between electronic control units (ECUs).

Abstract

ISO 11898-4:2004 defines time‑triggered communication services and mechanisms for Controller Area Network (CAN) systems in road vehicles. The standard describes how a time master and frame synchronisation entities provide a global time and a schedule (system matrix) that partitions bus access into time windows (exclusive, free and arbitrating), enabling deterministic periodic message transmission and optional arbitration for non‑scheduled traffic. Two implementation levels (Level 1 and Level 2) and related timing and transmission rules are specified.

General information

• Status: Published; international standard confirmed (status reviewed and confirmed in ISO systematic reviews).
• Publication date: August 2004 (commonly listed as 2004-08-05 / 2004-08).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 43.040.15 (Automotive informatics / vehicle computer systems).
• Edition / version: Edition 1 (2004).
• Number of pages: 32 pages.

Scope

This part of ISO 11898 applies to CAN networks in road vehicles where time‑triggered interchange of digital information is required. It specifies the frame synchronisation entity that coordinates logical link and media access control functions to support a time‑triggered schedule (system matrix), defines global time distribution and reference messages, and sets rules for time windows, arbitration behavior, and two levels of implementation. It is intended for use where deterministic, scheduled communication (and coexistence with event‑driven traffic) is needed.

Key topics and requirements

• Definition of time‑triggered CAN operation and objectives (deterministic scheduling for periodic messages).
• Frame Synchronisation Entity (FSE): role and behaviour in each CAN controller to implement schedule following.
• Global time distribution and reference message format (time master, Cycle_Count, Global_Sync_Mark).
• System matrix and transmission columns: basic cycle, matrix cycle, Cycle_Offset and Repeat_Factor concepts.
• Time window types and rules: exclusive, free and arbitrating windows; Tx_Enable windows and restrictions on retransmission in arbitrating windows.
• Two implementation levels (Level 1 and Level 2) with Level 2 as an extension of Level 1.
• Interoperability considerations with other ISO 11898 parts (linking logical link/media access rules to ISO 11898-1 and physical/media aspects in other parts).

Typical use and users

Used by automotive OEMs, ECU and ASIC/PHY vendors, embedded software and network architects, test and validation laboratories, and tool vendors implementing CAN schedulers and time‑synchronisation features. Typical applications include safety‑critical or timing‑sensitive vehicle subsystems where deterministic periodic messaging is required alongside conventional event‑driven CAN traffic.

Related standards

ISO 11898-1 (data link layer and physical signaling concepts), ISO 11898-2 (high‑speed physical media attachment), ISO 11898-3 (low‑speed fault‑tolerant MDI), and other vehicle/CAN-related standards such as ISO 15765 (diagnostics over CAN). ISO 11898-4 is one part of the ISO 11898 series addressing CAN protocol stacks and physical interfaces.

Keywords

CAN, time‑triggered, frame synchronisation entity (FSE), system matrix, transmission column, time window, global time, ECU, deterministic scheduling, ISO 11898.

FAQ

Q: What is this standard?

A: ISO 11898-4:2004 is the part of the ISO 11898 series that specifies time‑triggered communication for Controller Area Network (CAN) systems used in road vehicles, providing rules and mechanisms to implement scheduled, deterministic message exchange.

Q: What does it cover?

A: It covers the frame synchronisation entity, the concept and distribution of global time, the system matrix and scheduling constructs (basic cycles, transmission columns, time windows), message timing and arbitration rules, and two implementation levels for time‑triggered CAN operation.

Q: Who typically uses it?

A: Automotive manufacturers, ECU designers, embedded network engineers, standards implementers and test houses that require deterministic time‑scheduled communication in CAN networks.

Q: Is it current or superseded?

A: The 2004 edition (ISO 11898-4:2004) is published and has been subject to ISO systematic review activity; ISO records indicate the standard was reviewed and confirmed (i.e., remains the current edition) in recent ISO reviews. Users should consult ISO or their national standards body for the absolute current status and any amendments.

Q: Is it part of a series?

A: Yes — it is Part 4 of the ISO 11898 series addressing Controller Area Network (CAN). Other parts cover the data‑link layer and related physical/media interfaces (for example, Parts 1, 2 and 3).

Q: What are the key keywords?

A: CAN, time‑triggered communication, FSE, system matrix, time windows, global time, ECU, deterministic scheduling.