Overview
IEC 61158-3-2:2023 defines the data‑link layer service (DLS) for Type 2 fieldbus elements in industrial communication networks. Part of the IEC 61158 fieldbus specifications and tied to the three‑layer fieldbus reference model (see IEC 61158‑1), this standard specifies the abstract services and primitives offered by the data‑link layer to the upper layer (in OSI terms). The document is architectural and service‑oriented - independent of physical implementation - and is essential for consistent interoperability of automation system components.
Key topics and technical requirements
- Data‑link service model: Definition of DLS instances, DLSAPs (data‑link service access points), DL‑addresses and group addresses; abstract queue models for peer and multipoint DLS.
- Connection‑mode and connectionless‑mode services: Primitives and parameters for both transfer modes, with sequences for successful and unsuccessful transfers.
- Queue management and QoS: Abstract receive/transmit queue concepts, queue maintenance primitives (flush, QoS‑based operations) and QoS features for traffic handling.
- DL‑management services: Link synchronization, synchronized parameter change (including coordinated countdowns), time distribution and related primitives.
- Operational controls and events: Moderator enable/disable, current moderator reporting, power‑up/online/listen‑only modes, event reporting, and Bad FCS indications.
- Primitives, parameters and sequences: Comprehensive definitions and time‑sequence diagrams for DLS primitives (requests/confirmations/indications) and their valid sequences at DLSAPs.
- Tag filtering and fixed tag services: Mechanisms for selective delivery and filtering of connectionless frames.
Practical applications
- Designing and implementing fieldbus data‑link protocols for industrial automation devices (PLCs, I/O modules, controllers).
- Ensuring interoperability between devices from different vendors by following a standardized DLS service interface.
- Developing firmware/stacks and test suites that conform to standard DLS primitives, parameters and timing.
- System integration and diagnostics where consistent event reporting, synchronization and QoS behavior are required.
- Use in safety‑critical and real‑time control networks where predictable link behavior and time distribution are vital.
Who should use this standard
- Automation and control system architects
- Protocol and embedded firmware developers
- Device manufacturers and fieldbus stack implementers
- System integrators and test laboratories
- Standards and compliance engineers
Related standards
- IEC 61158‑1 - fieldbus reference model and mappings (three‑layer model)
- Other parts of the IEC 61158 series (additional Type elements and protocol definitions)
For implementation or procurement, obtain the official IEC 61158‑3‑2:2023 document from the IEC webstore to ensure you use the latest normative text.
Open preview (PDF)Industrial communication networks - Fieldbus specifications - Part 3-2: Data-link layer service definition - Type 2 elements
