ISO 17356-4:2005

Overview

ISO 17356-4:2005 - "Road vehicles: Open interface for embedded automotive applications - Part 4: OSEK/VDX Communication (COM)" defines a uniform, message‑based communication environment for automotive ECU application software. The standard increases portability, reusability and interoperability by specifying a common Interaction Layer (IL) API and behavior for both internal (intra‑ECU) and external (inter‑ECU) communication, independent of specific bus protocols or network technologies.

Key topics and requirements

• Message-based model: Communication is organized around messages (signals) that carry application data. Messages are configured statically via OIL (ISO 17356-6).
• Interaction Layer (IL): Provides the COM API with services for initialization, data transfer and communication management. IL hides protocol/bus differences to improve portability.
• I‑PDUs and message packing: One or more messages are packed into Interaction Layer Protocol Data Units (I‑PDUs). Messages occupy contiguous, bit‑aligned regions within I‑PDUs and are sized in bits.
• Internal vs external communication: Internal communication delivers message data immediately within an ECU; external communication updates I‑PDUs and uses lower layers to transmit across the network.
• Message objects and identifiers: Sending and receiving message objects are configured at system generation and identified by message IDs. Supports m:n communication patterns.
• Queued vs unqueued receiving: Receiving message objects can be queued (FIFO, read removes the oldest message) or unqueued (last value readable multiple times). Queue sizes are defined per object.
• Transfer properties & transmission modes:
  • Triggered vs Pending transfer properties for external messages.
  • I‑PDU transmission modes: Direct, Periodic, and Mixed.
• Byte order conversion (endianess): IL performs network-to-local CPU conversion per message to ensure interoperability across heterogeneous ECUs.
• Non‑blocking send services & notifications: Transmit services are non‑blocking; the API includes notification mechanisms and deadline monitoring for transfer/reception status.
• Scalability & conformance classes: Multiple conformance classes allow implementations to scale to different hardware resource constraints.
• Lower-layer requirements: Clause 4 defines minimum requirements for Network and Data Link Layers to support IL features.
• Annexes: Guidance for using COM with non‑conforming OSes (Annex A), application notes (Annex B), and callout examples (Annex C).

Applications and who uses it

• Automotive software architects and embedded systems engineers designing ECU communication stacks.
• ECU and gateway suppliers implementing portable application modules across platforms.
• Tool vendors producing OIL/system-generation and COM configuration tools.
• Integration teams that require consistent internal/external message semantics across networks and ECUs. ISO 17356-4 is especially valuable where portability, interoperability and protocol‑independence are priorities (e.g., multi-supplier vehicle platforms, reuse of application software across models).

Related standards

• ISO 17356-1: General structure, terms and definitions
• ISO 17356-2: Binding OS, COM and NM
• ISO 17356-3: OSEK/VDX Operating System (OS)
• ISO 17356-5: Network Management (NM)
• ISO 17356-6: OSEK/VDX Implementation Language (OIL)

Keywords: ISO 17356-4, OSEK/VDX Communication, COM, automotive ECU communication, Interaction Layer, I-PDU, message-based API, embedded automotive applications, OIL, endianness, conformance classes.