IEC 61784-5-21:2018

Overview

IEC 61784-5-21:2018 (consolidated with AMD1:2024) defines the installation profiles for CPF 21 (FL‑net) within industrial communication networks. It specifies which requirements of the reference installation standard IEC 61918 apply to CPF 21 and where those requirements are supplemented, modified, or replaced. The standard is intended to be read together with IEC 61918 and related amendments, and organizes CPF‑specific guidance into a single annex (Annex A) covering planning, implementation, verification, administration and maintenance of fieldbus installations.

Key topics and technical requirements

The CPF 21 installation profile (CP 21/1 - FL‑net) addresses practical, installation‑level requirements including:

• Installation planning
  • Planning requirements and network capabilities (supported data rates, topology constraints)
  • Selection and use of cabling components (balanced copper and optical fibre)
  • Documentation and verification of cabling plans
• Installation implementation
  • Cable routing and installation best practices
  • Connector, terminator and device installation rules
  • Coding, labelling, earthing and bonding of equipment and shielded cabling
  • As‑implemented cabling documentation
• Verification and acceptance testing
  • On‑site installation verification and acceptance test procedures
• Administration, maintenance and troubleshooting
  • Operational administration, maintenance guidance and fault investigation

Notable technical updates in Amendment 1 (2024) include:

• Addition of 1 000 Mbit/s as a supported data rate and inclusion of Category 5e in cabling/connectors tables.
• Revisions to single‑mode silica fibre parameters (bandwidth and optical power budget) for CP 21/1.

Standards referenced in the profile include IEC 61918, IEC 61784‑2, IEC 61158, and cabling norms such as ISO/IEC 11801‑3.

Applications and who uses this standard

IEC 61784-5-21 is targeted at professionals involved in industrial fieldbus and factory automation installations:

• System planners and network designers - to define network capabilities and select appropriate cabling and connectors.
• Installers and commissioning engineers - to follow implementation, termination, earthing and labelling rules.
• Verification and validation personnel - to perform installation acceptance tests and verify conformity to CPF 21 profiles.
• Maintenance teams and integrators - for troubleshooting, administration and lifecycle documentation.
• Device manufacturers and vendors - to ensure hardware and cabling compatibility with CPF 21 installation requirements.

Typical use cases include deploying FL‑net fieldbus segments in manufacturing lines, process automation, and retrofit projects requiring consistent, standards‑based cabling and test procedures.

Related standards

• IEC 61918 - Installation of communication networks in industrial premises (primary reference)
• IEC 61784‑2 - Communication profiles (CP definitions)
• IEC 61158 - Fieldbus standards (background on profiles)
• ISO/IEC 11801‑3 - Cabling categories and connector classes

Keywords: IEC 61784-5-21, CPF 21, FL‑net, installation profiles, IEC 61918, fieldbus installation, industrial communication networks, cabling, Category 5e, optical fibre, installation verification.