Before connecting MES and ERP, the most critical master data to align is material and product information. At minimum, you need a consistent material ID scheme, material descriptions, revision or version identifiers, and basic attributes such as type (raw, WIP, finished good, spare) and lifecycle status. If MES and ERP use different IDs or revision conventions for the same physical item, you will see order failures, mis-picks, and broken genealogy. In regulated environments, misalignment here also undermines batch records and product release decisions. Where PLM is the master for product data, you must decide which system is authoritative for which attributes and how changes propagate to MES and ERP under change control.
Bills of material, recipes, and routings (or process plans) must be semantically aligned, not just technically mapped. You need to ensure that the ERP production BOM or recipe that drives planning corresponds to the MES process definition used on the shop floor, including component list, quantities, and substitutions allowed. Differences in structure (e.g., phantom assemblies, alternates, options) and granularity (operation-level vs. step-level) are common and must be reconciled rather than ignored. In regulated industries, the released manufacturing BOM (mBOM) and routing usually trace back to engineering and regulatory approvals, so you cannot casually adjust them to fit an interface. Misalignment can cause incorrect material consumption postings, wrong batch compositions, and deviations between the as-planned and as-built records that are hard to justify in audits.
Work centers, equipment, and labor resource master data also need to be synchronized conceptually before integration. ERP often models work centers coarsely for capacity planning and costing, while MES models equipment and lines more granularly for execution and traceability. You must define a clear mapping between ERP work centers and MES equipment or lines, including which level is used for scheduling, costing, and performance reporting. If this mapping is inconsistent, planned orders may be scheduled to resources that do not exist in MES, or OEE and downtime metrics will be impossible to reconcile with ERP cost and throughput reports. Any long-lived assets with validation status (qualified, validated, decommissioned) must carry compatible status codes so that ERP does not plan production on equipment that MES correctly blocks due to qualification constraints.
Location and inventory master data—plants, warehouses, storage locations, and more granular bins—must be defined and mapped between systems. ERP typically manages financial and logistical inventory views, while MES tracks physical WIP locations and intermediate buffers. If the location hierarchy is not aligned, you risk inventory discrepancies, incorrect backflush postings, and broken material traceability between WIP and finished goods. In regulated contexts, the mapping must support clear, auditable movement histories from receiving through production to shipping. You should also harmonize any quarantine, hold, and restricted locations and ensure that their meaning (and related business rules) is consistent in both systems.
Units of measure, decimal precision, and conversion rules are frequently underestimated sources of integration failures. Before integration, you should agree on base units for materials (e.g., kg vs. g, pieces vs. boxes), permitted alternate units, and precise conversion factors that are consistent between ERP and MES. Differences in rounding rules or precision can cause cumulative inventory errors, yield miscalculations, and discrepancies in batch yields and potency calculations that are not easily explained in audits. For process industries, alignment on how you represent potency, concentration, and loss factors is particularly important, as MES often captures actual process data at a different granularity than ERP expects. These definitions should be under change control so that a unit or conversion change cannot silently corrupt historical comparability.
Status and lifecycle master data—such as material status, batch status, order status, and equipment status—must be aligned to avoid unsafe or non-compliant behavior. ERP may use simple codes like released, blocked, or restricted, while MES may have more granular states such as under inspection, on hold for deviation, or awaiting disposition. You must define explicit mappings and rules so that a blocked batch in MES cannot accidentally be consumed as available stock in ERP. Similarly, production order and operation statuses must be compatible so that completion, partial completion, and scrap are posted consistently. In regulated environments, misaligned statuses can compromise product release processes and make it impossible to prove that blocked materials were never used.
Customer and supplier master data, while often managed primarily in ERP, still affects MES through labels, batch records, and shipping documentation. You should ensure that customer IDs, supplier IDs, and any contract-specific attributes that drive labeling or documentation are consistently referenced where MES needs them. Batch and lot identification schemes are critical: lot numbers, serial numbers, and batch IDs must follow compatible formats and uniqueness rules across systems. If MES and ERP generate or interpret batch IDs differently, genealogy, recalls, and complaint investigations become much harder and less defensible. Any changes to numbering schemes must be planned with migration and coexistence in mind, as asset and product lifecycles can span many years.
Beyond the specific data elements, you must decide which system (or upstream system like PLM or a dedicated MDM solution) is the system of record for each master data domain. Without clear ownership, teams will make local changes in MES or ERP that diverge over time and quietly erode integration reliability. In brownfield environments, you often have to tolerate a period of dual maintenance and incremental cleanup rather than a big-bang master data re-design. Every change to master data that affects integration—IDs, structures, conversions, and statuses—should be subject to formal change control and, where required, validation. This governance work is often more challenging than the technical interface build, but skipping it usually leads to integration failures, rework, and audit findings.
Attempting to fully replace all existing master data structures to “standardize everything” before MES–ERP integration often fails in aerospace-grade and similar regulated environments. Long equipment and product lifecycles, historical qualification of routes and BOMs, and embedded integrations with legacy systems make wholesale redesign risky and expensive. Revalidating every impacted combination of materials, routes, and equipment can be prohibitive in both time and cost, especially when downtime windows are limited. A more practical approach is targeted harmonization: identify the minimal set of master data elements that must be strictly aligned to support safe, traceable integration, and then phase in further alignment over time. This approach acknowledges brownfield constraints while still reducing the risk of propagating bad or inconsistent data between MES and ERP.
Whether you're managing 1 site or 100, Connect 981 adapts to your environment and scales with your needs—without the complexity of traditional systems.
Whether you're managing 1 site or 100, C-981 adapts to your environment and scales with your needs—without the complexity of traditional systems.
