September 16, 2025 
In today’s omnichannel retail landscape, ERP-WMS is no longer just a technical link—it’s a strategic enabler of operational intelligence. Supply chain disruptions cost companies an average of $184 million annually, yet 73% of organizations still struggle with inventory visibility across their ERP and WMS systems. As supply chains become more dynamic and customer expectations more unforgiving, brands must ensure seamless data exchange between enterprise resource planning (ERP) systems like SAP and specialized warehouse management systems (WMS) such as Vin WMS. This integration enables real-time visibility into a centralized pool of inventory, order status, and fulfillment workflows—critical for maintaining agility, accuracy, and trust across the value chain. From SKU creation and procurement to order orchestration and shipment confirmation, each touchpoint between ERP and WMS plays a vital role in synchronizing operations and delivering consistent customer experiences.
Core integration Points and Data Flow
Synchronization of Master Data
The foundation of any ERP-WMS integration is synchronization of master data that represent non-transactional information. The master data includes products, vendors and customers consistent across systems. There is a single authoritative source for maintaining system integrity and in many cases, the ERP- SAP is the system of record and this data is typically maintained and managed in SAP. Many progressive enterprises use specialized software such as Vin PIM for maintaining product information since there is a variety of product information that needs to be managed.
Data Flow for Product/SKU and Catalog Management
Product and SKU are fundamental elements to all warehouse operations. When a new product is created in SAP’s Material Management (MM) module or if it is created in a PIM software, this information must be made available to the other systems. When created in a PIM, that information is sent to an OMS (order management system) and a WMS. A WMS needs a unique SKU code, a description of the product, unit of measure, and any associated attributes or bar codes to accurately process goods within the warehouse inbound and outbound operations and to manage the inventory within a WMS.
Data Flow for Vendors and Customer Masters
In addition to products, the vendor and customer masters must be synchronized between SAP and WMS. Vendor data created in the SAP MM module is synchronized with data in WMS and vice-versa. This information is used in receiving materials from vendors during the inbound process of a WMS. Similarly, customer data from SAP SD module (Sales and Distribution module) or if created in a OMS is used in the outbound process of a WMS when the customer orders are fulfilled and invoices are generated. This information in a WMS is transmitted to logistics and transporter partners and without the customer master information in sync with the SD module, any verification and reconciliation is not possible.
Figure 1 shows the data flows of products/SKU, vendors and customers.
Inbound Logistics Integration: From Purchase Order to Goods Receipt
The inbound logistics operation involves the receipt of goods from a vendor in the warehouse. A vendor could also be created in an OMS, which flows into a WMS. Integration between SAP and a WMS is essential to ensure the information on inventory is updated in real time and the different systems are kept in sync.
PO Creation in SAP and ASN Creation in WMS
In many enterprises, a PO (Purchase Order) is created in the SAP MM module and issued to a supplier to supply the goods. Alternatively, the PO is created in an OMS and data synched with a WMS and then pushed to SAP to maintain consistency. When the supplier dispatches the goods, advance shipping notification (ASN) is sent to the warehouse to enable the warehouse operations staff to prepare for the goods to be received and stored in the warehouse.
Process Flow: Goods Receipt and GRN Posting
After receiving goods at the warehouse, the warehouse staff update the WMS software with information on the goods received (that includes whether the goods match the quantity mentioned in the ASN and quality is as per the required standards) and where they are stocked for use in serving the customer orders. A goods received note (GRN) is generated that shows the goods and the quantity received. This information is exchanged with SAP to update the ERP system on inventory count and for financial transactions to be updated in SAP based on GRN.
Figure 2 shows the process by which PO is issued, goods are dispatched with a ASN and a GRN is issued after counting the goods received at the warehouse.
Outbound Logistics Integration: From Sales Order to Shipment Confirmation
Customer orders — whether from ERP, webstores, or marketplaces — trigger the outbound process in a WMS. The data required for a WMS to fulfill an order regardless of its source includes order number, customer information, line items, quantities required. When the orders are consolidated and transferred to a WMS from an OMS, there is a single view of the order to be fulfilled.
Process Flow: Order Fulfillment, Shipping, and Invoice Generation
When the order details are received in the WMS, the process of fulfillment starts with picking, packing and shipping of the items. When these physical activities are completed, this updated status information is updated into various systems such as OMS and SAP and the source from where the order originated (it could be a website or a marketplace). The details transmitted include order status, tracking information such as AWB (airway bill that shows the goods and the quantity shipped) so that the financial entries are posted in SAP for billing and revenue recognition.
Figure 3 shows the process flow of consolidation of orders, routing of orders and fulfillment status of orders.
Real-time Inventory Management and Reconciliation
Maintaining consistent and accurate inventory is essential across the operational systems since decisions are taken based on these counts for availability of goods, reorder points and to ensure correct quantities are displayed for sale and customer orders are taken properly based on available inventory.
Mechanisms for Live Inventory Visibility
Real-time inventory synchronization is a core feature of WMS, enabling a “central pool of inventory” that is accessible for orders originating from any sales channel and helps prevent overselling and stockouts while reducing excess inventory costs. Every physical movement of stock within the warehouse, such as receiving, picking, or a stock transfer, immediately updates the inventory count in the WMS. Inventory changes must be instantly reflected in the ERP to prevent overselling or stockouts. By ensuring this bi-directional, near-instantaneous communication, accurate inventory is available across the relevant transactional systems. Additionally, features should be available to ping WMS to get periodic updates to verify data.
Data Flow for Stock Transfers, Adjustments, and Cycle Counts
Beyond the standard inbound and outbound flows, other transactions that alter inventory must be synchronized with SAP. Scenarios include stock transfers between different warehouse locations and other storage locations such as stores, manual inventory adjustments due to damage or loss, and the results of cycle counts. Inventory adjustments due to this are initiated within the WMS, and the system is responsible for pushing the updated data to SAP in near real time to ensure accurate inventory counts.
Figure 4 shows the data flow for stock transfer, inventory adjustments and cycle count adjustments.
Reverse Logistics Integration: Managing Returns and Restocking
Reverse logistics, the process of handling returns, is a complex workflow that requires deep integration between the WMS and SAP. When a customer initiates a return, the WMS manages the physical movement of the item back into the warehouse, either for restocking or for return-to-vendor (RTV) processing. The financial and inventory impact of the return, including any necessary restocks or credits, must then be communicated back to SAP. Discrepancies in this process, such as returned goods not being updated in the ERP, can lead to significant financial and operational risks, particularly when reconciling with external platforms. For a detailed view of the challenges involved such as inventory mismatches, orders fulfillment showing as fulfilled in one system but has a different status in another, returns not updated in SAP, etc are typical problems. For a more comprehensive view of the challenges, please refer to this blog post.
Figure 5 shows the reverse logistics process flow that includes handling of RTV and damaged goods/restocking flow.
Conclusion
ERP-WMS integration isn’t just about syncing systems —it is about aligning operations with business outcomes and achieving operational intelligence. Whether it’s minimizing reconciliation errors, accelerating fulfillment, or enabling real time visibility of inventory, the integration touchpoints outlined here form the backbone of scalable, customer-centric supply chain execution. As retail and supply chain leaders evaluate and review their tech stack, the ability to orchestrate real-time, bi-directional data flows between ERP and WMS will shape both operational efficiency and long term competitive advantage.
