Connecting Manufacturing Execution Systems to Core ERP

The integration boundary

The ISA-95 model separates enterprise planning from manufacturing execution. ERP holds the sales order, the material plan, the cost roll-up and the financial posting. MES holds the work order execution, the routing steps, operator actions, machine state and quality results.

Integration runs in two directions across that boundary. Downward, ERP releases work orders, material availability and due dates. Upward, MES reports consumption, production confirmation, scrap, downtime reasons and quality outcomes.

The failure mode is boundary erosion: someone starts reading ERP tables directly from a shop-floor terminal, or ERP starts calculating cycle times. Both create coupling that makes either system impossible to change.

Work order flow and machine telemetry

Work order flow should be event-based with explicit states. Release, start, pause, complete and close are distinct events with timestamps and operators, and the MES must be able to accept a work order update out of order without corrupting the record.

Machine telemetry is high volume and mostly noise. Capture at the edge, aggregate locally into meaningful intervals, and publish only state changes, counts and quality signals upward. Streaming raw sensor values to ERP is expensive, unhelpful and usually the first thing to be switched off.

Edge filtering also provides a natural resilience boundary. When connectivity drops, the local node continues to buffer and aggregates so production is unaffected.

Shop-floor resilience

A factory cannot stop because a planning system is being upgraded. Shop-floor systems must be able to operate independently for a defined period, buffering confirmations and consumption locally until connectivity returns.

The consequence is that conflict resolution must be designed: when a buffered confirmation arrives after ERP has already adjusted the order, the system needs a documented rule about which state wins. Reversal by exception is usually safer than silent overwrite.

Define and monitor a reconnection reconciliation process that compares MES buffered state with ERP state and reports differences, so drift is visible rather than discovered during a stock count.

• Allow the shop floor to run independently for a defined offline window.
• Buffer confirmations and consumption locally during outages.
• Define explicit conflict resolution for late arrivals.
• Reconcile after reconnection and report differences.

Traceability and genealogy

Traceability is a data capture problem, not a reporting problem. Genealogy must be recorded at the moment of production: which material lots, which equipment, which operators, which process parameters and which quality results produced a given serial or lot.

That data has to be attached to the physical unit as it moves. Retrofitting traceability after a recall is impossible, which is why regulated manufacturers treat it as a hard requirement rather than a reporting feature.

Once captured, genealogy enables forward and backward queries: what was in this finished unit, and where else did these components go. Both directions are required by most product safety regimes.

• Capture genealogy at execution time, not afterwards.
• Record material lots, equipment, operators and process parameters.
• Support both forward and backward trace queries.
• Keep traceability records immutable for the mandated retention period.