IEC 61784-2-21-2023 PDF

Full title and description

St IEC 61784-2-21: Industrial networks - Profiles - Part 2-21: Additional real-time fieldbus profiles based on ISO/IEC/IEEE 8802-3 — Communication Profile Family (CPF) 21. This part of IEC 61784 defines CPF 21, a set of Real‑Time Ethernet (RTE) communication profiles and related network component specifications that provide deterministic, low-latency, low-jitter communication for industrial applications while remaining compatible with standard Ethernet.

Abstract

IEC 61784-2-21 specifies the structure, conventions and conformance rules for CPF 21 (Communication Profile Family 21). It describes selected lower‑layer technologies (based on ISO/IEC/IEEE 8802‑3 and IEC 61158 Type 26), application and data‑link layer selections, addressing and port conventions, RTE performance indicators (latency, jitter, cycle times), dependency matrices for those indicators, and a conformance‑test methodology. The document also defines extended common memory area services and features to support deterministic cyclic and acyclic data exchange for industrial control, motion and I/O systems.

General information

• Status: Published
• Publication date: 5 May 2023
• Publisher: International Electrotechnical Commission (IEC)
• ICS / categories: 35.100.20 (Data link layer); 35.240.50 (IT applications in industry)
• Edition / version: Edition 1.0 (2023)
• Number of pages: 50

Scope

This standard establishes CPF 21 for Real‑Time Ethernet fieldbus profiles: it defines terminology, profile structure and conventions, the set of required and optional lower‑layer and application protocols, addressing and port conventions, and the performance indicators (PIs) and PI dependency matrices that allow matching device/network classes to application timing requirements. It provides guidance for conformance testing and coexistence with standard Ethernet services, and specifies extensions such as an expanded common memory area (CM3) and services for extended cyclic data and network parameter access.

Key topics and requirements

• Definition of Communication Profile Family 21 (CPF 21) and constituent communication profiles (CPs).
• Lower‑layer technology selections based on ISO/IEC/IEEE 8802‑3 and IEC 61158 (Type 26) for RTE.
• Performance indicators (latency, jitter, cycle time) and classes for expressing RTE performance requirements.
• PI dependency matrices relating device/network parameters to achievable performance.
• Conformance and test methodology for device certification and interoperability verification.
• Common memory area (CM) enhancements (e.g., CM3) and extended cyclic/acyclic services.
• Addressing, port and IP conventions for deterministic industrial operation alongside standard Ethernet traffic.
• Guidance on coexistence with non‑RTE Ethernet applications and use of timing/bridging standards where applicable (e.g., IEEE 802.1AS, IEEE 802.1Q).

Typical use and users

IEC 61784-2-21 is used by industrial network architects, control and automation engineers, device and network component manufacturers (ASIC/FPGA vendors), integrators designing deterministic Ethernet networks for factory automation, motion control and safety systems, and test laboratories/certification bodies performing conformance testing and interoperability verification.

Related standards

IEC 61784-1 (system and profile definitions), IEC 61784-2 (other CPF parts), IEC 61158 series (fieldbus protocols, Type 26), ISO/IEC/IEEE 8802-3 (Ethernet), IEEE 802.1AS (time synchronization), IEEE 802.1Q (bridging/VLANs), and other CPF family parts (CPF 20, CPF 3, etc.) that form the IEC 61784 family of industrial communication profiles.

Keywords

CPF 21, Real‑Time Ethernet, RTE, industrial networks, fieldbus profiles, deterministic Ethernet, latency, jitter, cycle time, conformance testing, common memory area, IEC 61784, IEC 61158, ISO/IEC/IEEE 8802-3

FAQ

Q: What is this standard?

A: IEC 61784-2-21 (CPF 21) is a part of the IEC 61784 family that defines additional Real‑Time Ethernet fieldbus profiles based on ISO/IEC/IEEE 8802‑3 to provide deterministic communication for industrial control systems.

Q: What does it cover?

A: It covers the specification of CPF 21 communication profiles, selections for lower and application layers, addressing and port conventions, RTE performance indicators (latency, jitter, cycle time), PI dependency matrices, conformance test methodologies, and extensions such as an expanded common memory area and services for extended cyclic data.

Q: Who typically uses it?

A: Network and control engineers, device vendors, system integrators, test labs and certification bodies involved in designing, implementing or certifying deterministic industrial Ethernet systems for factory automation, motion control, I/O and similar applications.

Q: Is it current or superseded?

A: IEC 61784-2-21 was published on 5 May 2023 and is a current part of the IEC 61784 series; the IEC record indicates stability to 2028 unless updated or replaced before that date.

Q: Is it part of a series?

A: Yes. It is Part 2‑21 of the IEC 61784 series (Industrial networks — Profiles). The IEC 61784 series contains multiple parts addressing different Communication Profile Families (CPFs) and associated conformance requirements.

Q: What are the key keywords?

A: CPF 21, Real‑Time Ethernet, fieldbus profile, determinism, latency, jitter, conformance testing, IEC 61784, ISO/IEC/IEEE 8802‑3.