ISA-95 Model

The highest level of the hierarchy, encompassing enterprise-wide business activities. This level establishes the basic plant production schedule, material use, shipping, and inventory levels.

• Core Functions: Order processing, demand forecasting, procurement, long-term production planning
• Time Horizon: Months to years
• Key Systems: ERP (Enterprise Resource Planning), PLM (Product Lifecycle Management)
• Data Exchange: Communicates production plans and receives plant performance summaries from Level 3

The domain of workflow and recipe control that coordinates the execution of production on the plant floor. This level manages the detailed scheduling, quality assurance, and resource allocation to meet Level 4 objectives.

• Core Functions: Detailed production scheduling, dispatching, quality management, maintenance management
• Time Horizon: Days to weeks
• Key Systems: MES (Manufacturing Execution System), LIMS (Laboratory Information Management System), WMS (Warehouse Management System)
• Data Exchange: Translates business plans into operational commands; aggregates process data from Level 2 for reporting

The layer responsible for monitoring, supervising, and controlling the physical process through automated systems. This level executes the recipes and setpoints defined by Level 3.

• Core Functions: Supervisory control, data acquisition, alarm management, operator interfaces
• Time Horizon: Seconds to hours
• Key Systems: SCADA (Supervisory Control and Data Acquisition), HMI (Human-Machine Interface)
• Data Exchange: Sends setpoints to Level 1 controllers; collects real-time process data for visualization and historical logging

The direct sensing and manipulation of the physical process. This level executes closed-loop control algorithms to maintain process variables at desired setpoints.

• Core Functions: PID loop control, discrete logic execution, safety interlocks, analog and digital I/O processing
• Time Horizon: Milliseconds to seconds
• Key Systems: PLCs (Programmable Logic Controllers), DCS (Distributed Control Systems), RTUs (Remote Terminal Units)
• Data Exchange: Reads sensor inputs; writes actuator outputs; reports process values to Level 2

The actual physical equipment and material transformation occurring on the factory floor. This level represents the tangible reality that all higher levels seek to monitor and control.

• Core Functions: Material transformation, motion, chemical reaction, assembly
• Time Horizon: Real-time, continuous
• Key Components: Motors, valves, conveyors, reactors, robots, sensors, actuators
• Data Exchange: Generates raw sensor signals consumed by Level 1; receives actuation commands from Level 1 controllers

Beyond the physical hierarchy, ISA-95 defines standardized activity models and data structures for information exchange between levels. These models decompose manufacturing operations into generic, reusable functions.

• Part 1: Defines standard terminology and object models for resources, personnel, equipment, and material
• Part 2: Specifies B2MML (Business To Manufacturing Markup Language) , an XML schema implementing the object models for electronic data exchange
• Part 3: Details activity models for production, maintenance, quality, and inventory operations management
• Part 5: Establishes KPIs and metrics for measuring manufacturing performance across the hierarchy

A single source of truth for all industrial data, structured around the ISA-95 asset hierarchy. It enables decoupled, real-time data exchange between OT and IT systems by organizing information based on the Enterprise > Site > Area > Line > Cell model.

• Maps directly to ISA-95 physical asset hierarchy
• Enables contextualized data discovery without point-to-point integration
• Uses MQTT Sparkplug for stateful, topic-based communication

A reference architecture for industrial control system security that segments the network into hierarchical levels, from physical processes to the enterprise DMZ. It is the security-focused counterpart to ISA-95's functional hierarchy.

• Level 0/1: Physical process and basic control
• Level 2: Area supervisory control
• Level 3: Site manufacturing operations (MOM)
• Level 4: Business planning and logistics (ERP)

An extension of OPC Unified Architecture that decouples data producers from consumers using a publish-subscribe pattern, often over MQTT or AMQP. It enables scalable cloud and edge integration while preserving the rich information modeling that maps to ISA-95 equipment hierarchies.

• Supports JSON and binary encoding for efficiency
• Integrates with MQTT brokers for cloud-native architectures
• Maintains ISA-95 compliant asset modeling

A specialized time-series database designed for industrial environments to archive high-fidelity process data over long periods. Historians are the primary data repository at ISA-95 Levels 2 and 3, capturing sensor telemetry for compliance, analysis, and reporting.

• Optimized for lossless compression of analog signals
• Supports time-weighted averages and interpolation
• Foundation for predictive maintenance algorithms

A standardized digital representation of an industrial asset defined by Industry 4.0 (IEC 63278) . It provides a discoverable, interoperable interface for an asset's properties, capabilities, and lifecycle data, serving as the digital twin counterpart to ISA-95's physical asset model.

• Contains submodels for different lifecycle aspects
• Enables cross-vendor interoperability
• Complements ISA-95 hierarchy with semantic richness

A communication framework that connects traditionally siloed data throughout the product lifecycle, from design and manufacturing to service. It creates a closed feedback loop that traverses all ISA-95 levels, linking ERP, MES, SCADA, and physical processes.

• Links PLM data to operational performance
• Enables traceability from raw material to finished product
• Closes the loop between design intent and manufacturing reality