How do you implement ISA-88 batch control in a PLC/SCADA system?

ISA-88 implementation: define physical model (process cells, units, equipment modules, control modules), create procedural model (procedures, unit procedures, operations, phases), develop recipes (header, formula, equipment requirements, procedure). Implementation: equipment phases as reusable PLC function blocks with standard states (idle, running, complete, held, aborted), recipe management in SCADA batch server, phase interface for parameter passing, and report generation. Key features: concurrent phase execution, exception handling, equipment arbitration, and material tracking. Test each phase independently, then validate complete recipes. Support recipe versioning and audit trail.