Use ISA-95 to separate control, supervisory, manufacturing operations and enterprise functions while keeping the real data path visible.
Physical process and basic control: sensors, actuators, PLCs and drives.
Supervisory control: HMI, SCADA and local operational visibility.
Manufacturing operations: MES, quality, production tracking and scheduling.
Business planning and logistics: ERP, finance, planning and enterprise workflows.
It helps define responsibilities and interfaces. Actual network architecture should still account for security zones, industrial DMZs, approved protocols and data ownership.