Overview
IEC 61158-3-24:2023 is part of the IEC 61158 fieldbus specifications and defines the data-link layer service for Type 24 elements. The standard specifies, in an abstract and vendor‑neutral way, the externally visible services used for basic time‑critical messaging between devices in industrial automation. It describes primitive actions and events, their valid sequences and interrelationships, and the parameters associated with each primitive. The scope explicitly addresses time‑windows in which actions must complete to avoid risks to equipment, plant operation or personnel.
Key topics
- Data‑link layer services (DLS): Abstract service definitions that the Type 24 data‑link layer provides to upper layers (DLS‑user).
- Time‑critical messaging: Concepts and constraints around messages that must be delivered or acted upon within defined time windows.
- Service primitives and events: Detailed lists and semantics for primitives (e.g., Write, Read, Send Data with Acknowledge (SDA), Send Data No‑Acknowledge (SDN), Event, Get Status).
- Service sequencing and interactions: Valid sequences and interrelationships between primitives and events (including diagrams and sequence descriptions).
- DL management (DLMS) services: Management primitives such as Reset, Set/Get Value, Evaluate Delay, Set Communication Mode, Start Communication, Clear Error Status and corresponding events.
- Parameters and data types: Definition of parameters for each primitive, permitted value ranges and the form in which parameters are exchanged.
- Conformance and normative references: Conformance rules and references to related IEC documents.
Applications and who uses it
IEC 61158-3-24 is intended for implementers and stakeholders in industrial communication and automation who require standardized, time‑deterministic data‑link behavior:
- Device manufacturers (PLCs, field devices, sensors, actuators) implementing Type 24 data‑link behavior.
- Network and firmware engineers designing low‑level communication stacks and drivers.
- System integrators and automation architects specifying deterministic messaging for control loops.
- Functional safety and compliance teams assessing timing behavior and conformance to standards for safety‑critical systems.
Practical uses include time‑sensitive control messaging in process and factory automation where missing time windows can cause equipment failures or safety hazards.
Related standards
- IEC 61158 (other parts) - broader fieldbus protocol and type definitions.
- IEC 61784‑1 / IEC 61784‑2 - profiles and protocol type combinations referenced for permitted protocol combinations and IP/licensing considerations.
Keywords: IEC 61158-3-24:2023, fieldbus, data-link layer, Type 24, time-critical messaging, industrial communication networks, fieldbus specifications, DLS, DLMS.