ISA-88 (batch control)

ISA-88 (ANSI/ISA-88 and IEC 61512) is the international standard that structures batch control systems. It defines a physical model (enterprise, site, area, process cell, unit, equipment module, control module) and a procedural model (procedure, unit procedure, operation, phase) that decouple the recipe from the PLC code. We systematically use it on multi-recipe or multi-product projects: sequencing logic (recipe) is managed separately from machine execution (phases), which radically simplifies maintenance and accelerates the OQ and PQ phases. Without ISA-88, every new recipe requires custom code and triggers requalification. With well-implemented ISA-88, adding a recipe becomes a documented configuration operation, without modification of validated PLC code.