Overview
ISO 14229-4:2012 - "Road vehicles - Unified diagnostic services (UDS) - Part 4: Unified diagnostic services on FlexRay implementation (UDSonFR)" defines how the UDS diagnostic services are implemented for diagnostic communication over FlexRay networks in road vehicles. It references ISO 14229-1 and ISO 14229-2 and focuses on additional FlexRay-specific implementation requirements and restrictions. The standard does not prescribe in-vehicle FlexRay architecture.
Key topics and technical requirements
- Scope and purpose
- Specifies the subset of UDS services applicable to FlexRay (see Table 2 in the standard).
- Defines FlexRay-specific behavior where required; otherwise UDS follows ISO 14229-1/-2.
- Service-specific requirements
- Several services have FlexRay-specific requirements (e.g., CommunicationControl 0x28, ResponseOnEvent 0x86, LinkControl 0x87, ReadDataByPeriodicIdentifier 0x2A) and are documented in clauses 6.3–6.6.
- Services marked “No FlexRay specific requirements” are implemented per ISO 14229-1/-2 without change.
- CommunicationControl (0x28)
- Defines sub-functions for enabling/disabling Rx and Tx in static and dynamic FlexRay segments (e.g., enableRxAndDisableTx).
- Notes that disabling Tx must not harm basic network functions (for example synchronization).
- Layer mapping and OSI model
- Uses the OSI reference model: application (ISO 14229-1), presentation (vehicle-specific), session (ISO 14229-2), transport/network (ISO 10681-2), data link and physical (ISO 17458-2/-4).
- Identifies how UDS layers map to FlexRay transport/network and physical layers.
- Normative references
Practical applications and who uses it
- Vehicle OEMs and system architects - to specify and integrate ECU diagnostic functionality over FlexRay.
- ECU and software suppliers - to implement compliant UDS services and ensure correct behavior for FlexRay communication segments.
- Diagnostic tool vendors and workshop equipment manufacturers - to build tools that communicate with vehicles using UDSonFR.
- Test and verification engineers - to validate service behavior, timing, and restrictions when UDS runs on FlexRay.
- Regulatory and compliance teams - to ensure diagnostic implementations adhere to international standards.
Typical uses include on-board diagnostics, engineering access sessions, periodic data reporting, event-triggered responses, and controlled enabling/disabling of communication for service or programming operations.
Related standards
Keywords: ISO 14229-4, UDSonFR, UDS on FlexRay, FlexRay diagnostics, vehicle diagnostic standard, ECU diagnostic communication.