IEC 61158-6-8:2007 PDF

Overview

IEC 61158-6-8:2007 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies the application layer protocol for industrial communication networks utilizing Type 8 fieldbus elements. This standard outlines the protocol elements required for both time-critical and non-time-critical messaging between application programs in automation environments, focusing specifically on the interoperability and behavior between remote applications.

IEC 61158-6-8 was developed to promote seamless integration of industrial systems, leveraging a robust application layer that conforms with the Open Systems Interconnection (OSI) Basic Reference Model (ISO/IEC 7498) and application layer structure (ISO/IEC 9545). The 2007 edition introduced technical revisions, notably the addition and removal of specific fieldbus types to reflect evolving market needs and to improve flexibility for industrial automation applications.

Key Topics

Application Layer Protocol Specification

• Provides common communication elements for Type 8 fieldbus systems.
• Specifies protocol data structures, encoding, and externally visible behaviors.
• Supports both time-critical and non-time-critical messaging, important for industrial safety and reliability.

Conformance with OSI Models

• Aligns with ISO/IEC 7498 (OSI Model) and ISO/IEC 9545 (application layer structure).
• Leverages ASN.1 (Abstract Syntax Notation One) and encoding rules per ISO/IEC 8824 and ISO/IEC 8825.

State Machine Definitions

• Describes the application context and relationship protocol state machines that manage the interactions between automation devices.
• Ensures consistent process automation communication flows, allowing robust industrial network implementations.

Wire Representation and Encoding

• Defines the wire-representation and encoding rules of service primitives (as per IEC 61158-5-8).
• Outlines abstract and transfer syntaxes for efficient and accurate protocol data unit exchanges, critical for interoperability.

Applications

IEC 61158-6-8:2007 is highly relevant to industries relying on industrial automation and process control where secure, reliable, and standardized communication protocols are critical. Practical uses include:

• Integration of Sensors and Actuators: Enables consistent communication protocols for integrating a diverse array of field devices such as sensors, controllers, actuators, and human-machine interfaces (HMI).
• Distributed Control Systems (DCS): Supports the deployment of DCS where components must exchange commands and data in both real-time and non-real-time conditions.
• Safety and Reliability Requirements: Utilized where completion of specific actions within designated time windows is vital to avoid process failures or safety risks.
• Vendor-neutral Interoperability: Facilitates procurement, testing, and deployment by ensuring compatibility across devices from different manufacturers, simplifying maintenance and future upgrades.

Related Standards

For comprehensive industrial communication solutions, IEC 61158-6-8 works in conjunction with several related standards:

• IEC 61158 Series: This overall series defines the complete stack for fieldbus technologies, including service definitions, data-link layers, and protocol specifics for various fieldbus types.
  • IEC 61158-5-8: Defines the application layer services for Type 8 fieldbus.
  • IEC 61158-3-8 & IEC 61158-4-8: Specify the data-link layer service and protocol for Type 8 fieldbus.
• ISO/IEC 7498: The OSI Basic Reference Model, fundamental to understanding and implementing the multi-layered approach taken by the IEC 61158 series.
• ISO/IEC 9545: Covers OSI application layer structure, providing the framework for implementing robust, standardized application protocols.
• IEC 60559: Outlines binary floating-point arithmetic for microprocessor systems, often applicable in fieldbus device implementations.

Practical Value

IEC 61158-6-8:2007 adds practical value by enabling reliable, standard-compliant communication in complex automation environments. By providing a detailed specification for the application layer protocol of Type 8 fieldbuses, the standard supports interoperability, system scalability, and lifecycle management for industrial networks. Adherence ensures legal certainty for deployments and streamlines integration, testing, and procurement for manufacturers and end-users in diverse sectors-including manufacturing, energy, transportation, and building automation.

Keywords: IEC 61158-6-8:2007, fieldbus, industrial communication networks, application layer protocol, automation, OSI model, industrial automation, process control, Type 8 fieldbus, interoperability, international standard.