Most WMS implementation delays originate not in the software or the integration but in the catalog: duplicate items, units of measure without a documented definition, cases with no barcode and lots captured on some products and not on others. When that data flows from the ERP to the warehouse, every error is replicated on the floor.
This is especially common when a US parent company's ERP feeds a new Mexican site: the item master was built for purchasing and finance in pounds and inches, and the warehouse needs kilograms, centimeters, Mexican tax codes and pack-level barcodes.
What product master data is
It is the data that describes a product and rarely changes: its code, description, how it is measured, how it is identified and how it is traced. It differs from transactional data (a purchase order, a sales order, a movement), which changes constantly and relies on it.
The fields the warehouse needs
| Field | What the warehouse uses it for | Common error |
|---|---|---|
| Item code | Identify the item in every system | Duplicates with different codes for the same item |
| Description | Confirm the item being picked | Abbreviated or identical descriptions for different sizes |
| Barcode per pack level | Scan the each, the inner pack and the case | One barcode for each and case |
| Unit of measure and conversions | Correct quantities at receiving and picking | Ordered in cases, stocked in eaches, no factor |
| Lot or serial control | Traceability and recalls | Lot captured on some items and not others |
| Expiration and minimum shelf life | Reject short-dated lots and pick FEFO | Perishables without required expiration |
| Weight and dimensions | Location capacity, package weight, freight | Empty fields or dimensions of the wrong pack |
| Mexican tax product and unit codes | Electronic invoicing and Carta Porte | Generic or outdated codes |
| Hazardous material | Segregation and transport documents | Item not flagged |
Which system owns each field
The rule that prevents most conflicts: each field has one owning system and the others receive it. In most companies:
- The ERP creates the item and owns the code, description, purchase and sales units, cost and tax codes.
- The warehouse completes the physical data: real weight and dimensions, barcodes for each pack level when the supplier does not provide them, preferred location.
- Quality defines lot or serial control, required expiration and minimum shelf life.
If two systems can change the same description or unit, the records eventually diverge.
Cleaning the catalog in four weeks
- Week 1: prune. Export the ERP catalog. Separate active items (movement in the last 12 months or stock on hand) from inactive ones. Only active items go to the WMS.
- Week 2: duplicates and units. Find items with the same description or barcode. Define one base unit per item (the one that is counted) and the conversion factors to purchase and sales units.
- Week 3: barcodes and control. Complete the barcode for each pack level with the manufacturer's or your company's GTINs; the GS1 General Specifications assign one per level. Decide, item by item, whether it is controlled by lot, by serial number or not at all.
- Week 4: measure and weigh. Measure and weigh the items that account for most of the movement. Measuring the whole catalog on day one is not necessary.
Units of measure in detail
It is the field that causes the most errors. An example: the ERP buys oil by the case of 12 bottles, sells it by the bottle and the warehouse stores it by the pallet of 60 cases. If the WMS receives a purchase order for "10" without knowing they are cases, it records 10 bottles. Before integrating:
- Define the base unit the warehouse counts.
- Record conversions: 1 case = 12 bottles; 1 pallet = 60 cases.
- Make sure documents from the ERP state the unit on every line.
- For bulk products, use a unit with decimals (kilograms, liters, meters), not pieces.
- If the ERP stores imperial units, convert before the data reaches Mexican documents, which use metric units.
The product and unit codes that Mexican electronic invoicing requires come from SAT catalogs, such as those of the Carta Porte supplement; assign them in the ERP when the item is created, not on shipping day.
How they load in Chainlink
In Chainlink WMS, the catalog loads from an XLSX or CSV template with item code and name (required), barcode, unit, whether the item uses lots or serial numbers (one or the other, not both), whether expiration is required, minimum shelf life in days and description. Chainlink shows errors by row and column before creating anything, and an existing code is updated instead of duplicated. Items in kilograms, liters or meters accept decimals. With the connectors available as an add-on to the Professional and Enterprise plans, items arrive from SAP Business One, Odoo, ERPNext, SAP S/4HANA or Microsoft Dynamics 365 Business Central, and what leaves the warehouse goes back to the ERP with its lots and serial numbers.
Frequently asked questions
What is master data in a warehouse?
The stable data on each product that the ERP and the WMS share: code, description, barcodes, units and conversions, lot or serial control, expiration, weight and dimensions.
Who should own master data?
Each field should have one owning system. Usually the ERP creates the item and its commercial and tax data, and the warehouse completes the physical data.
Must the whole catalog be measured before go-live?
No. Start with the items that account for most of the movement and complete the rest as they are received.
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