Do not treat OPC UA Part 8: Data Access as a replacement: the available evidence does not show that Part 8 defines ISA-88 batch, recipe, or procedural concepts. The unresolved design decision is how to map the ISA-88 model into OPC UA while a dedicated companion specification remains under investigation.
Separate the Batch Model from the Transport
OPC UA is the communication and information-modeling mechanism. These solve different layers of the system, so selecting OPC UA Data Access does not by itself establish a batch or recipe model.
| Layer | Supported role | Design implication |
|---|---|---|
| OPC UA Part 8: Data Access | Data-access services and representation | Do not assume it supplies ISA-88 semantics that are absent from its scope. |
| OPC UA companion specification | Potential standardized mapping for the batch domain | The evidence describes this mapping as under investigation, not available for immediate dependence. |
Evaluate the Legacy Batch Specification Carefully
The evidence does not establish that the older Batch specification has been withdrawn, superseded by OPC UA Part 8, or broadly implemented by current DCS and MES products. Treat those as open questions.
The cited standards work was active: a Part 1 revision was approaching publication, Parts 2 and 3 were being updated, and an OPC UA companion specification was being investigated. Because the evidence supplies no publication date or finalized companion specification, verify the current document status before fixing a product architecture.
Select an Implementable Integration Contract
- Define the required batch and recipe objects, procedures, states, commands, and ownership boundaries using ISA-88 terminology.
- Obtain the supported OPC UA information model and batch interface from each target DCS or MES vendor. Determine whether the interface uses a vendor-defined model, an older Batch interface, or another mapping.
- Document the mapping between every required ISA-88 concept and its exposed OPC UA object, variable, method, or event. Leave unsupported concepts explicitly unresolved rather than representing them as generic Data Access values without semantics.
Verify the Architecture
Test semantic interoperability, not only connectivity. The acceptance test should show that the DCS or MES and the product assign the same meaning to recipe identity, procedural structure, commands, states, and batch context. A successful OPC UA connection or readable value proves data exchange; it does not prove that both systems implement the same ISA-88 behavior.
Record which system owns recipe creation, approval, download, execution, and batch records. The evidence does not assign these responsibilities to the product, DCS, or MES, so make them explicit in the integration contract and verify each transition end to end.
FAQ
Does OPC UA Part 8 replace ISA-88 batch management?
No replacement is established by the evidence.
Is ISA-88 still valid for batch and recipe design?
Yes.
Is there an ISA-88 OPC UA companion specification?
The evidence reports that a companion specification was being investigated, but it does not confirm a published specification. Check the current standards status and the exact interfaces supported by the selected DCS or MES before implementation.
