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
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.