ISA-88: Batch Control Standard for Manufacturing

What is ISA-88?

ISA-88 (also called S88, IEC 61512 / DIN EN 61512) is an international standard for batch control. It provides models and terminology to describe equipment and recipes in a structured way—independent of manufacturer, controller, or software.

Important point: ISA-88 is not a concrete software specification but a design philosophy for structuring processes, equipment hierarchies, and recipes.

Goals of ISA-88:

• Uniform language for batch control
• Separation of procedure (recipes) and equipment
• Reusability and modularity of control functions
• Easier integration between control systems, MES, and automation

Originally developed for batch processes (pharma, chemicals), ISA-88 is now used beyond batch as a reference model for many industrial processes.

Core Models of ISA-88

ISA-88 defines several hierarchical models that together provide a complete picture of process, equipment, and recipe.

1. Process Model

The process model describes the procedural workflow—independent of equipment. It consists of:

• Process → entire process
• Process Stages → main sections
• Process Operations → logical work steps
• Process Actions → elementary process actions

This model forms the basis for "equipment-independent" process definitions (e.g., in general or site recipes).

2. Physical Model

The physical model describes the equipment hierarchy:

• Enterprise
• Site
• Area
• Process Cell
• Unit (mandatory level)
• Equipment Modules
• Control Modules

Essential is the strict separation of procedure and equipment: Process logic is not hard-coded into a single controller but mapped to a reusable structure of units, equipment modules, and control modules.

3. Procedural Control Model

The procedural control model describes how a batch is executed—the sequential control of a recipe:

• Recipe Procedure
• Unit Procedures
• Operations
• Phases

Phases are the executable building blocks mapped to equipment/control modules. This is where modularity emerges: same phase logic, different equipment—or vice versa.

4. Recipe Model

ISA-88 distinguishes four recipe types:

• General Recipe
• Site Recipe
• Master Recipe
• Control Recipe

A recipe consists of:

• Header (master data)
• Formula (material and production data)
• Equipment Requirements
• Recipe Procedure
• Other relevant information

This allows recipes to be cleanly broken down from product definition (general/site) through equipment-specific master recipes to the running control recipe (for individual batches).

Why ISA-88 is Relevant for MES and Cloud MES

Although ISA-88 originated in the batch world, its principles are now best practice for MES and Cloud MES architectures—even in discrete manufacturing:

Separation of Recipe/Procedure and Equipment

• Procedural logic (unit procedures, operations, phases) is not hardwired to a PLC
• Same process logic can run on different machines/units

Modularization & Reusability

• Phases, operations, and equipment modules are reusable building blocks
• Changes are made to central modules—not in hundreds of individual scripts

Clear Equipment Hierarchy

• Enterprise/site/area/process cell/unit structure directly maps to MES/ISA-95 models

Better Communication & Specification

• Engineering, automation, quality, and IT speak about the same models and terms
• Specifications and MES modeling become more consistent

ISA-88 in Context of ISA-95 and Digital Factory

ISA-95 extends ISA-88's model world to the enterprise and operations management level (Level 3/4), e.g., for MES functionality, production planning, and information models.

Combined, ISA-88 and ISA-95 provide:

• Clean OT models (equipment, recipe, batch, phases)
• Clean IT models (operations, orders, material, personnel, equipment)
• A blueprint for MES, MOM, and digital factory architectures

For modern Cloud MES approaches, this separation is crucial to:

• Offer standard functions (OEE, traceability, batches, recipes) generically
• Still cleanly model plant and equipment-specific characteristics
• Avoid reinventing integrations to control systems, ERP, and PLM every time