ISO 14230-2:2016

Overview

ISO 14230-2:2016 - Road vehicles - Diagnostic communication over K-Line (DoK-Line) - Part 2: Data link layer - specifies the data link layer services for UART-based vehicle communication over the K-Line (DoK-Line). The standard defines an unconfirmed communication protocol and a service-primitive interface compatible with ISO 14229-2. It is designed to work with ISO 14230‑1 (physical layer) and is aligned with diagnostic services in ISO 14229‑1 and ISO 15031‑5, while remaining compatible with many other in-vehicle communication needs. ISO 14230-2 clarifies initialization differences between K-Line protocols (ISO 9141 vs ISO 14230) and supports application-layer uses such as enhanced diagnostics and emissions-related OBD.

Key Topics and Technical Requirements

• Data link services & primitives: Defines service primitives (e.g., DL_Data.request, DL_Data.indication, DoK-Line_Init.request) and the standardized interface to higher layers.
• Message structure: Specifies header fields and Service Data Units (SA = Source Address, TA = Target Address, FMT, LEN, MessageData, CS).
• Initialization procedures: Details protocol determination and initialization modes including 5‑BAUD_INIT and FAST_INIT, and clarifies differences with ISO 9141 and ISO 14230 implementations.
• Timing and timing parameters: Defines inter-byte, inter-message, and initialization timing requirements essential for reliable UART/K-Line operation.
• Key bytes & addressing: Describes protocol-specific key bytes, server/client addresses and format for protocol selection and ECU identification.
• Communication services: Includes StartCommunication, StopCommunication, AccessTimingParameter and SendData services.
• Error handling & collisions: Covers error handling during and after initialization, collision detection/mitigation, and fault responses.
• Physical bus topology: Guidance on wiring and K-Line physical arrangements as it affects data link behavior.

Applications and Who Uses It

ISO 14230-2 is aimed at:

• Automotive OEMs and ECU suppliers implementing K-Line diagnostics
• Diagnostic tool and scan tool manufacturers (diagnostic analyzers, testers)
• Software engineers building diagnostic application layers (UDS or ISO 14229 based)
• Test laboratories, vehicle service centers and regulatory bodies for OBD compliance Practical applications include enhanced vehicle diagnostics, non-emissions and emissions-related OBD services (including interaction with SAE J1979-DA / SAE J2012-DA), ECU boot/init procedures, and multi-protocol tool compatibility.

Related Standards

• ISO 14230-1 (DoK-Line - Physical layer)
• ISO 14229-1 / -2 (Unified Diagnostic Services / service primitives)
• ISO 14230-4 (FAST_INIT specifics)
• ISO 15031-5 (OBD data protocols)
• ISO 9141 (legacy K-Line initialization)
• SAE J1979-DA, SAE J2012-DA (OBD diagnostics)

Keywords: ISO 14230-2, DoK-Line, K-Line, data link layer, diagnostic communication, 5-BAUD_INIT, FAST_INIT, UART, ECU, OBD, ISO 14229.