ISO 15531-42:2005

Overview

ISO 15531-42:2005 - "Industrial automation systems and integration - Industrial manufacturing management data - Part 42: Time Model" defines a generic, one-dimensional time model for manufacturing-management and industrial-automation applications. The standard provides a universal, event‑independent framework for representing time (points, intervals, frequency and relations) so software can reference events or sequences accurately in the past, present or future. The model is specified in the EXPRESS language (with EXPRESS‑G diagrams) to ensure compatibility with ISO 10303 tooling and data-exchange practices.

Key topics and requirements

• One‑dimension domain framework: A generic domain property schema suitable for any one‑dimensional domain, with emphasis on the time domain.
• Time entities: Standardized constructs such as point_in_time, interval_of_time, frequency_of_event, and related relations and assignment entities.
• Topological properties: Definitions and constraints for domain types (continuous vs discrete, bounded vs unbounded, complete/composite domains).
• Relations and rules: Entities for rules of reference to origin, unit relations, and time unit relations that enable consistent time transformations and conversions.
• Formal definitions: EXPRESS schemas, entity and attribute definitions, and EXPRESS‑G diagrams as specified by ISO 10303‑11, providing machine‑readable data models.
• Scope limits: Explicitly excludes multi‑dimensional domains, measure theory, and event modeling under ISO 10303‑41; focuses solely on the time/topological model itself.

Practical applications and users

ISO 15531-42 is designed to support interoperability and consistent time referencing across manufacturing and enterprise software:

• Use cases:
  • Scheduling and production planning (synchronized start/stop and durations)
  • Manufacturing Execution Systems (MES) and process historians needing consistent timestamps and intervals
  • Maintenance management, procurement, delivery tracking and cost evaluation systems that coordinate timelines
  • Multi‑process and distributed control environments where consistent time references prevent conflicts and misalignment
• Typical users:
  • MES/ERP vendors, system integrators, automation engineers
  • Software architects implementing data exchange and integration between manufacturing subsystems
  • Standards bodies and implementers building ISO 10303 (STEP) compatible tools

Related standards

• ISO 10303‑11 - EXPRESS language reference (used for EXPRESS schemas in this part)
• ISO 10303‑41 - (event modeling - out of scope for this part)
• ISO/IEC 8824‑1 - ASN.1 referenced for identifier handling in SC4 standards
• Other parts of ISO 15531 (industrial manufacturing management data) provide complementary models for manufacturing data exchange.

ISO 15531-42:2005 is a foundational specification for consistent time representation in industrial automation, improving interoperability and reducing ambiguity in time-related manufacturing data.