Overview - ISO 14229-3:2022 (UDSonCAN)
ISO 14229-3:2022, titled "Road vehicles - Unified diagnostic services (UDS) - Part 3: Unified diagnostic services on CAN implementation (UDSonCAN)", defines an application profile for implementing Unified Diagnostic Services (UDS) over Controller Area Network (CAN) in road vehicles. It builds on ISO 14229-1 and ISO 14229-2 and specifies implementation requirements and restrictions for diagnostic communication on CAN. The 2022 second edition restructures the document, introduces numbered requirements, and incorporates industry implementation feedback.
Key topics and technical requirements
- Scope and references
- OSI-layer mapping
- Defines how UDS services map to OSI layers (application, presentation, session, transport, network, data link, physical) for CAN.
- Service primitives and interfaces
- Specifies service primitives and interfaces such as A_Data.req / A_Data.ind / A_Data.conf, S_Data, T_Data, N_Data, and L_Data for consistent diagnostic messaging.
- Transport and network mapping
- Details mapping of transport PDUs (T_PDU) to network PDUs (N_PDU) and adaptation to DoCAN (diagnostic communication over CAN).
- Unacknowledged message types
- Defines UUDT (unacknowledged unsegmented data transfer) and USDT (unacknowledged segmented data transfer) behavior, including periodic transmission handling and related service primitives.
- Timing and session parameters
- Establishes timing parameters (e.g., P2, S3 timers and CAN-specific timeout values) and constraints for request/response and unsolicited messages.
- CAN identifier usage
- Specifies usage options for 11-bit (standard) and 29-bit (extended) CAN identifiers for enhanced diagnostics.
- Implementation restrictions
- Lists CAN-specific restrictions and additional requirements to ensure reliable diagnostic communication on in-vehicle networks.
Applications and who uses ISO 14229-3
ISO 14229-3 (UDSonCAN) is intended for organizations and professionals involved in vehicle diagnostics and ECU communication, including:
- Automotive OEMs and vehicle integrators
- ECU and embedded software suppliers
- Diagnostic tool and tester manufacturers
- Test and validation engineers (conformance and interoperability testing)
- In-vehicle network designers and system architects
Practical uses include implementing standardized diagnostic services on CAN buses, ensuring interoperability between diagnostic testers and ECUs, defining periodic diagnostic transmissions, and aligning transport/network behavior with DoCAN specifications.
Related standards
ISO 14229-3:2022 is essential for anyone implementing or validating UDS over CAN, providing the technical rules needed for robust, interoperable vehicle diagnostic communication.