USN ( Unique Serial Numbers)

A USN (Unique Serial Number) is a unique identifier assigned to each individual unit of a SKU, even when units are identical. It acts as a digital fingerprint for every unit, enabling precise tracking, traceability, and control at the unit level.

How is a USN Assigned?

• Pre-printed USNs: Manufacturers can pre-print unique serial barcodes on each unit. These are scanned and recorded during the GRN process.

• WMS-Generated USNs: If products do not come with a pre-printed serial, the WMS can generate a unique serial number during the GRN process. This ensures each unit received is tracked individually.

• Both options are configurable and can be set based on the business’s supply chain setup.

How USNs Get Tagged to Orders

During picking, the WMS suggests a bin containing multiple units with unique USNs. The picker scans any one unit’s USN from the bin. That USN is then uniquely tagged to that specific order, ensuring the exact unit is traceable until dispatch.

USN Audit Trail

The system maintains a complete audit trail of each USN from GRN to Putaway, Order Picking, Dispatch, and Returns if applicable. This can be checked under Inventory → USN Barcodes, showing:

• USN status (Used or Available)

• Linked SKU

• Related order number

The ‘Audit USN’ option provides the full movement history of a USN, including its bin location, linked orders, and any returns.

USN Reports

• USN Dump: Lists all USNs, showing which are used and which are available, with a SKU-wise breakdown.

• Not Found USN: If a picker cannot find a unit, they can mark that specific USN as Not Found. The WMS marks the USN as Not Found, removes it from available stock, and adjusts total SKU inventory. These entries appear under the Not Found Inventory section.

Returns Handling with USN

• Original Barcode Intact: The same USN barcode can be scanned during return QC, and the unit is recorded back into inventory under the same USN.

• Barcode Missing: If the returned unit does not have its original USN, the WMS can generate a new USN during return QC to maintain traceability.

Cycle Count with USN

When performing a cycle count, each physical unit must be scanned by its unique USN, not just by SKU. This ensures no duplicates, no missing units, and accurate bin-level reconciliation.