Overview
IEC 61139-2:2022 is an international standard published by the International Electrotechnical Commission (IEC) that defines functional safety extensions for the Single-drop Digital Communication Interface (SDCI) specified in IEC 61131-9. This document focuses on enhancing SDCI to support safety-critical industrial network applications with a robust, lean communication protocol built over the standard SDCI black channel communication.
The standard specifies:
- A standardized OSSDe interface for redundant switching signals based on IEC 61131-2.
- Updates and extensions to state machines in SDCI to enable safety operations.
- Implementation of a functional safety communication protocol adhering to IEC 61784-3:2021 black channel principles.
- Protocol management features for device configuration, parameterization, and commissioning.
- Extensions for the IODD (IO device description) to cover functional safety.
- A dedicated device tool interface supporting safety-compliant dedicated tools.
IEC 61139-2:2022 excludes multi-point, multi-drop, multi-channel, encrypted, and wireless communication interfaces, as well as integration into upper-level fieldbus or functional safety communication profiles.
Key Topics
- Functional Safety Communication Protocol: A lean protocol layered on SDCI ensuring communication integrity and error detection in safety applications.
- OSSDe Interface: A standardized output switching signal device interface allowing redundant safe switching signals in compliance with IEC 61131-2.
- State Machine Extensions: Modifications to SDCI’s data link and communication layers to support safety operations and fault monitoring.
- Safety Device and Master Architectures: Defines roles and interactions for FS-Devices (safety devices) and FS-Masters (controllers), including power supply, wake-up coordination, and fast start-up procedures.
- Parameterization and Configuration: Protocol management functions are introduced for streamlined safety parameter configuration, device commissioning, and runtime management.
- IODD Functional Safety Extensions: Enhanced device descriptions support automation tools with critical safety parameters and diagnostic data.
- Safety Layer Manager (SLM): Manages safety communication states, error handling, and safety parameterization to maintain safe operating conditions.
- Process Data Exchange and Data Storage: Extensions ensure that safety-relevant process data and device states are managed securely and reliably.
Applications
IEC 61139-2:2022 applies primarily to industrial automation systems requiring high reliability and safety compliance such as:
- Safety-critical machinery control systems that use digital communication for monitoring and controlling safety functions.
- Redundant output switching systems in safety applications requiring fail-safe signal outputs.
- Functional safety device communication in manufacturing plants to meet strict safety integrity levels.
- Integration of safety-oriented dedicated tool interfaces for device diagnostics, configuration, and maintenance.
- Applications where point-to-point communication is preferred or mandated for safe operational architectures.
- Industries such as automotive manufacturing, process automation, robotics, and material handling where functional safety standards compliance is essential.
The standard is also a foundational building block for vendors and system integrators developing safety communication solutions that align with international best practices and IEC safety standards.
Related Standards
- IEC 61131-9: Single-drop digital communication interface base standard providing the core SDCI technology extended by IEC 61139-2.
- IEC 61131-2: Standard specifying digital input/output interfaces including OSSDe devices for industrial controllers.
- IEC 61784-3:2021: Defines communication profiles including black channel principles underlying the functional safety communication protocol in IEC 61139-2.
- ISO 13849 and IEC 62061: Functional safety standards for machinery control systems which can be supported using IEC 61139-2 safety communication features.
- IODD (IO device description) standards that are extended by IEC 61139-2 to include functional safety parameters.
- Other IEC functional safety standards that address safety device design and integration within industrial automation systems.
IEC 61139-2:2022 advances single-drop digital communication with essential functional safety extensions, enabling safer, more reliable industrial network deployments. By adopting this standard, manufacturers and system integrators can ensure compliance with international safety frameworks while benefiting from streamlined communication, configuration, and management of safety devices in automated environments.