IEC 61158-6-18:2010

Overview

IEC 61158-6-18:2010 specifies the application layer protocol for Type 18 fieldbus elements used in industrial communication networks. Aligned with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI application layer structure (ISO/IEC 9545), this standard defines the wire representation of FAL (Fieldbus Application Layer) service primitives (see IEC 61158-5-18) and the externally visible behavior associated with their transfer. Edition 2.0 (2010) is a technical revision of the 2007 edition and adds cyclic data segmenting, along with editorial corrections.

Key topics and technical requirements

• Application layer protocol definition - precise specification of messages, encoding and transfer semantics for Type 18 fieldbus.
• Wire representation of service primitives - mapping of IEC 61158-5-18 service primitives to on-the-wire PDUs (protocol data units).
• PDU types and encodings - detailed M1, M2, S1, S2 PDU abstract syntax and transfer syntax for device manager, connection manager, cyclic and acyclic transmission.
• Cyclic and acyclic transmission - support for both deterministic cyclic data exchange and on-demand acyclic messaging; includes the 2010 addition of cyclic data segmenting to handle larger or segmented cyclic payloads.
• Protocol state machines - definitions for AP-context, FAL service protocol machine (FSPM), AR protocol machine (ARPM), and DLL mapping protocol machine (DMPM), including state-event tables and mapping between layers.
• Device/Connection manager functions - attribute formats, command headers, system information, memory read/write and line test behaviors.
• Layer mapping - explicit mappings between application-layer primitives and the data link layer for deterministic fieldbus behavior and interoperability.
• Conformance requirements - normative references and conformance rules to ensure consistent implementations.

Practical applications and users

IEC 61158-6-18 is essential where deterministic, interoperable fieldbus communication is required:

• Embedded firmware and protocol stack developers implementing Type 18 fieldbus application-layer behavior.
• Device manufacturers creating fieldbus-enabled sensors, actuators, controllers and I/O modules.
• System integrators and control engineers designing industrial automation, process control and factory automation solutions using Type 18 networks.
• Test houses and certification bodies performing conformance and interoperability testing against IEC 61158 series requirements.
• Tool and middleware vendors building engineering, diagnostics, and commissioning tools that parse PDUs or simulate devices.

Related standards

• IEC 61158-5-18 - defines the corresponding service primitives (referenced for mapping in Part 6-18).
• Other parts of the IEC 61158 family and ISO/IEC 7498-1 / ISO/IEC 9545 for OSI model alignment.

By defining rigorous PDU encodings, state machines and layer mappings, IEC 61158-6-18:2010 helps ensure predictable, interoperable Type 18 fieldbus application-layer implementations for industrial communication networks.