1.3 System landscape & RACI

A manufacturing floor operating with undefined system boundaries inevitably risks data corruption. When an ERP system attempts to manage millisecond-level sensor data, or a PLC tries to query financial ledgers, the architecture suffers a “split-brain” scenario where the financial records contradict physical reality. Therefore, it is critical to clearly define architectural layers based on Data Granularity and Functional Domain, ensuring every data point has exactly one designated Master Owner.

The system RACI protocol

In a digital ecosystem, RACI does not apply to people; it applies to Databases.

• Accountable (A): The System of Record. This holds the “Golden Copy.” If this database is corrupted, the truth is lost. There can only be one Accountable system per object.
• Responsible (R): The system executing the transaction or generating the raw data.
• Consulted (C): Systems providing validation or constraints (e.g. PLM providing limits to MES).
• Informed (I): Systems that subscribe to data updates (Read-Only).

The RACI matrix

Data Object	ERP	PLM	MES	QMS	WMS
Bill of Materials (BOM)	I	A	I	C	–
Routing / Process	–	A	I	C	–
Production Order (WO)	A	–	R	–	I
Material Lots (Inventory)	A	–	R	–	R
Serial Numbers (UIDs)	I	–	A	–	–
Defects / NC	–	C	R	A	–
Rework Loops	–	C	A	I	–

The core trinity: ERP, MES, PLM

Modern manufacturing relies on three pillar systems. It is important to utilize each system for its intended purpose rather than forcing one tool to perform the function of another.

ERP (enterprise resource planning)

• The Domain: Finance, Inventory, Procurement, Order Management.
• The Question: “Why are we building this, and how much does it cost?”
• The Boundary: ERP stops at the warehouse door. It manages aggregate inventory (e.g. “1,000 screws available”) but lacks visibility into which specific screw was installed in which specific product.

PLM (product lifecycle management)

• The Domain: Engineering Design, BOM, CAD, Revision Control.
• The Question: “What are we building?”
• The Boundary: PLM owns the definition. It creates the “Digital Twin” and pushes specifications to ERP and MES. It never executes production.

MES (manufacturing execution system)

• The Domain: Production Control, Quality, Genealogy, Machine Connectivity.
• The Question: “How is it being built right now?”
• The Boundary: MES executes the work. It acts as the bridge between the digital definition (PLM) and the physical reality.

Critical logic & boundaries

The table above provides a framework, but the following logic gates should be implemented to enforce the RACI model effectively.

1. Static data (BOM & routing)

• Owner (A): PLM.
• The Risk: Manufacturing Engineers will often adjust routings directly within the MES to “make it work” on the floor. This severs the revision loop with the Engineering team.
• The Mandate:
  • Any requisite process change must be formally released in the PLM system first.
  • When the MES detects a BOM or Routing mismatch, it should enforce a “Stop Ship” condition until the PLM pushes the authorized Revision update.

2. Demand & work orders (WO)

• Owner (A): ERP.
• The Risk: Production planners creating “phantom orders” in MES to keep lines running without financial approval.
• The Mandate:
  • The ERP generates the Production_Order_ID.
  • The MES is Responsible (R) for updating the status (Scheduled → In_Progress → Complete).
  • The MES does not create a Work Order; it only consumes them.

3. Material lots & inventory

• Owner (A): ERP (Financial Value).
• Executor (R): WMS (Physical Storage) / MES (Shop Floor Consumption).
• The Logic:
  • When material is located in the Warehouse, the WMS controls its location and status.
  • When material is issued to the shop floor, the MES assumes custody.
  • When material is consumed into an assembly or scrapped, the MES actively triggers the deduction transaction.
  • Consequently, the ERP passively receives the inventory decrement signal. The ERP should not assume or guess consumption based solely on the BOM (back-flushing high-value components should be avoided).

4. Traceability (serials & defects)

• Owner (A): MES.
• The Risk: Storing serialization data in ERP bloats the database and slows down financial closing.
• The Mandate:
  • The MES generates the unique serial number (UID).
  • The QMS is Accountable for the disposition of a defect (Use As Is / Scrap), but the MES is Responsible for effectively blocking the unit from progressing.

Pro-Tip: Every single screw tighten result must not be pushed to ERP. A “Genealogy Summary” (Parent/Child link) should be pushed only when the unit is shipped.

Data flow strategy: push vs. pull

Data movement direction must be defined explicitly to prevent synchronization lag.

Master data (push)

Static data (e.g. BOMs, Part Numbers, User Profiles) requires a Push methodology. The Owner transmits the data to Subscribers immediately upon release.

• When the PLM releases a new or updated BOM, the PLM system actively pushes that update down to both the ERP and the MES.

Transactional data (event-driven)

Dynamic data (e.g. Inventory Consumption, Machine Status Updates) operates on Event-Driven logic.

• When an Operator finishes a unit (triggering an MES Event), the MES instantly decrements local WIP.
• The MES then accumulates these events and transmits a bulk “Production Declaration” to the ERP at defined intervals (e.g. hourly or per shift).

Shadow IT containment

Resourceful engineers frequently build isolated applications (PowerApps, SQL scripts, Excel macros) to solve localized problems. These quickly mutate into “Dark Data” silos, entirely invisible to enterprise systems and compliance audits.

The Containment Rule:

• When a localized application generates data required for audits (e.g. Quality Pass/Fail records, Traceability links), it should integrate directly with the MES to ensure the data is secured in the official system of record.
• When an application is intended purely for visualization (e.g. a custom Dashboard), it may execute Read-Only queries against the Data Lake.

Final Checkout: System landscape & RACI

Data Object	System of Record (Owner)	Consumer (Subscriber)	Critical Rule
Sales Order	ERP	MES	MES cannot create or delete orders.
BOM / Route	PLM	ERP, MES	Engineering Change Orders (ECO) start in PLM.
Inventory ($)	ERP	MES	ERP owns asset value; MES owns location.
Unit Traceability	MES	ERP (Summary)	MES owns unique Serial Number history.
Quality Limits	PLM/MES	Machines	Machines execute limits; they do not define them.
Costing	ERP	Sales	MES sends “Time Spent” to ERP for cost calculation.
Equipment State	MES/SCADA	Maintenance	Do not rely on ERP for downtime tracking.