Overview
ISO 15765-5:2023 - part of the ISO 15765 series for Diagnostic communication over Controller Area Network (DoCAN) - specifies the OSI layers 4 to 1 (transport, network, data link and physical) requirements for the connection between external test equipment (via the diagnostic link connector, DLC) and the in‑vehicle CAN network. The standard defines how an external tester and the vehicle CAN/CAN FD network establish, maintain and terminate diagnostic communication using communication profiles referenced by application‑type standards. Signal improvement capability (SIC) transceiver options from ISO 11898-2 are explicitly out of scope.
Key technical topics and requirements
- OSI layer mapping (TL → PHY): Detailed mapping of service primitives and interface parameters for the Transport Layer (ISO 15765-2), Network Layer, Data Link Layer (ISO 11898-1) and Physical Layer (ISO 11898-2).
- Transport layer (TL): T_Data primitive parameter mapping, message segmentation and ISO 15765-2 segment flow control rules (REQ examples: OSI4.1, OSI4.2, OSI4.3).
- Network layer (NL): Network services, timing parameters, uniqueness of diagnostic node addresses and supported addressing formats (REQ examples: OSI3.1–OSI3.7).
- Data link layer (DLL): Mapping of network addressing into 11‑bit and 29‑bit CAN identifiers, device acceptance filters and DLL service interface requirements (REQ examples: OSI2.1–OSI2.5).
- Physical layer (PHY): Classical CAN and CAN FD requirements, PCS/PMA/PMD sub‑layer constraints, bit timing and sampling methods, and PMA/connector/cable requirements (REQ examples: OSI1.1–OSI1.5).
- Compatibility and backward compatibility: Annex A describes compatibility between external test equipment and in‑vehicle networks, including backward compatibility to classical CAN.
- Document provenance: Second edition (2023), replacing ISO 15765-5:2021; main changes include clarifications on network address translation between OSI layers and editorial corrections.
Practical applications and who uses it
ISO 15765-5:2023 is essential for:
- Vehicle OEMs and system integrators who must ensure vehicle diagnostic ports comply with CAN/CAN FD diagnostic access rules.
- Diagnostic tool and external test equipment manufacturers designing hardware and firmware that connect to the DLC.
- ECU and transceiver developers implementing compliant PCS/PMA/PMD interfaces and CAN controller behavior.
- Workshop and repair environments deploying diagnostic scanners and service tools that rely on standardized communication profiles.
- Vehicle network architects and safety engineers ensuring robust diagnostic connectivity and address mapping across OSI layers.
This standard enables reliable diagnostics, emissions testing, repair workflows and aftermarket tool interoperability across modern CAN FD vehicle architectures.
Related standards
- ISO 15765-2 (Transport protocol and network layer services)
- ISO 11898 (all parts) (Controller Area Network - PCS, PMA, PMD)
- ISO 15031-3 (Diagnostic connector and electrical circuits)
- ISO 15765-4 (Requirements for emissions-related systems)
Keywords: ISO 15765-5:2023, DoCAN, diagnostic link connector, CAN FD, transport layer, network layer, data link layer, physical layer, vehicle diagnostics.