Technical guide · Integration
WMS–SAP Integration and Movement Mapping
A successful integration is not just about moving messages. You need to design explicitly which system owns which data, when a warehouse event becomes an ERP movement, and how both sides are reconciled when something fails.
Integration scope
- Master data: items, units, plants/storage locations, customers, suppliers and batch rules.
- Inbound: purchase/production deliveries, expected receipts and actual quantities.
- Outbound: sales/transfer orders, allocation data and shipment confirmation.
- Stock: unrestricted, quality and blocked stock; differences and adjustment movements.
Document and interface options vary by SAP module and version. A project should not settle for “SAP integration: yes”; it should produce a real matrix of documents, fields and responsibilities.
What is movement mapping?
Movement mapping maps business events in the WMS to stock movements, documents or status changes on the ERP/SAP side. Not every internal location transfer needs to be an ERP movement; you define the boundaries that have a financial, ownership or storage-location impact.
| WMS event | Mapping decision | Check |
|---|---|---|
| Goods receipt | Quantity confirmation against the document | Over/short and lot |
| Internal location transfer | Can stay inside the WMS | Does the ERP storage location change? |
| Quality/blocked status | Mapped to stock type | Authorisation and reason |
| Shipping | Goods issue confirmation | Case, lot, serial and time |
| Count difference | Adjustment after approval | Accounting period |
Principles of a resilient integration
- Idempotency: if the same message arrives again, it must not create a second stock movement.
- Ordering: the outcome must be defined if a cancellation arrives before or after a confirmation.
- Error queue: business errors should be separated from technical errors; an authorised user must be able to reprocess them.
- Monitoring: you should be able to trace from a WMS task to the SAP document number and back.
- Reconciliation: produce regular difference reports by item, lot and stock status.
Testing before go-live
Besides the normal flow, test partial receipts, over-deliveries, cancellations, serial errors, closed periods, connection drops, duplicate messages, late messages and simultaneous stock changes. Performance tests should cover the campaign peak, not just average volume.
For the integration impact of count differences, see cycle count and full count; for the physical unit model, see pallet–case–location management.
Compare integration capability across candidate WMSs with document and exception scenarios.