Glossary · Batch and process operations
ISA-88 physical model
Also known as: Batch physical model
German: Physisches Modell nach ISA-88
In ISA-88 batch control, the physical model is the hierarchical model of an enterprise's physical assets, with the levels enterprise, site, area, process cell, unit, equipment module and control module. The lower four levels are defined by engineering for batch control.
- Batch control
- Process industry
- Standards
In one sentence
The ISA-88 physical model structures assets as enterprise, site, area, process cell, unit, equipment module and control module.
Example
The plant's asset list is structured by the ISA-88 physical model: Site Basel, Area API production, Process cell PC2, Unit reactor R-201 and its equipment and control modules.
How it applies
- Engineering: The physical model sets the structure for tag names, control software modules and the equipment the batch system can allocate.
- Operation: Operators navigate HMIs by area, process cell and unit; alarms and events are attributed to the same objects.
- Integration: The upper levels align with the equipment hierarchy of ISA-95 hierarchy models, which helps exchange data between batch control and MES.
- Documentation: Organizing plant documentation by the physical model gives readers a stable map: one section per process cell and unit, with equipment and control module descriptions reused where types repeat. Metadata based on the model supports search and delivery of the right content for an asset.
Physical model vs. procedural model
The physical model describes the equipment. The ISA-88 procedural model describes the actions (procedure, unit procedure, operation, phase). Equipment control links them: phases are executed by equipment entities of the physical model.