Overview
ISO 17987-3:2025 - "Road vehicles - Local Interconnect Network (LIN) - Part 3: Protocol specification" defines the logical protocol requirements for LIN, the low-cost UART-based in-vehicle network used for low-speed control functions. The standard specifies signal management, frame transfer, schedule table handling, task behaviour, status management and the roles of commander and responder nodes. It also includes OSI layer 5 properties for UDS-on-LIN node configuration and identification services (per ISO 14229-7). Hardware-specific details are addressed in other parts of the ISO 17987 series.
Key topics and requirements
- Signal management: definition, types, packing, consistency, and transmission/reception rules for LIN signals.
- Frame transfer and structure: frame types, identifiers, transfer mechanics and frame length constraints.
- Schedule tables: deterministic, time-defined frame scheduling and slot handling for predictable communication.
- Task behaviour models: commander and responder state machines and task-level interactions.
- Status management: error detection, reporting, event-triggered frames and cluster reporting.
- Node configuration and identification: LIN product IDs (supplier, function, variant), serial numbers, memory model, responder configuration variants, PDU structure and services for node configuration.
- Transport and diagnostics: transport-layer support for larger PDUs and handling of diagnostic services (UDSonLIN).
- Auto-addressing: normative procedures for automatic node addressing (Annexes C–F).
- Standards alignment: OSI model mapping (ISO/IEC 7498-1) and interaction with ISO 14229-7 for UDS services.
- Inclusive terminology: replaces “master/slave” with commander/responder; updated from the 2016 edition.
Applications and users
ISO 17987-3:2025 is targeted at automotive and embedded-systems professionals implementing LIN-based communication for low-cost control modules such as:
- Door modules, window lifts and central locking
- HVAC and climate control units
- Seat control and mirror adjustment systems
- Body electronics and simple actuator/sensor clusters
Primary users:
- ECU firmware engineers and system architects
- Automotive communication-stack and tool vendors (LIN stack, diagnostics, node configuration tools)
- Test engineers and integrators validating schedule tables, frame timing and diagnostics
- OEMs and tier-1 suppliers specifying network behaviour and node conformance
Related standards
This standard provides the protocol-level foundation for deterministic, low-speed in-vehicle networks and is essential for implementing interoperable LIN nodes, diagnostics and configuration in modern automotive architectures.
