IEC 61158-4-19:2019

Overview - IEC 61158-4-19:2019 (Data-link layer protocol - Type 19)

IEC 61158-4-19:2019 is part of the IEC 61158 fieldbus family and defines the data-link layer protocol (DLP) elements for Type 19 fieldbus communication. The standard specifies procedures for the timely transfer of data and control information between peer data-link user entities, the structure of fieldbus DLPDUs (data-link protocol data units) and their representation as physical interface data units. Edition 4.0 (2019) supersedes the 2014 edition and introduces technical revisions focused on improved hotplug and redundancy, enhanced phase switching and error handling, and editorial clarifications.

Key Topics and Technical Requirements

• DLPDU structure and identification: Definitions for DLPDU headers, payloads, MAC addresses and EtherType usage for Type 19 elements.
• Cyclic communication and phases: Management of cyclic real‑time communication, communication phases (CP) and phase switching procedures.
• Connection and state machines: Producer/consumer and topology state machines to manage connections, configuration and transitions.
• Topology and redundancy: Support and procedures for ring and line topologies, redundancy handling, ring-break recovery and channel recovery.
• Hot-plug procedures: State machine and behavior for device insertion/removal without disrupting real‑time communication.
• Service channel (SVC) and RT channel: Mechanisms for non-cyclic service exchanges (SVC) and real‑time cyclic data (RT).
• Multiplexing and data containers: Techniques for multiplexing real‑time data with data containers (standard and extended) and diagnostics.
• Timing and telegram handling: Calculation and timing constraints for Type 19 telegrams and real‑time channel scheduling.
• Diagnostics and watchdog: Error handling, watchdog behavior, and diagnostic messages to maintain robustness.
• Advanced features: SMP session control, oversampling support and real‑time bit (RTB) handling for fine-grained data timing.

Applications and Who Uses This Standard

IEC 61158-4-19 is used by:

• Industrial automation device manufacturers (fieldbus interface, I/O modules, PLC/RTU vendors) implementing Type 19 data‑link behavior.
• Network and firmware engineers designing data‑link layer implementations and RT communication stacks.
• System integrators and control engineers deploying deterministic fieldbus networks requiring hot‑plug, redundancy and phase control.
• Test and certification laboratories validating conformance, timing, and topology behavior.

Typical applications include distributed control systems, factory automation networks, and process industries where deterministic, timely fieldbus communication and robust redundancy/hot‑plug behavior are required.

Related Standards

• Other parts of the IEC 61158 series (additional protocol layer and type specifications).
• Fieldbus profile guidance such as IEC 61784 (where applicable for application profiles and functional safety integration).

Keywords: IEC 61158-4-19:2019, fieldbus, data-link layer protocol, Type 19, DLPDU, hotplug, redundancy, phase switching, cyclic communication, SVC, RT channel, multiplexing.