1.3 System Landscape & RACI

A manufacturing floor running on undefined system boundaries guarantees data corruption. When an ERP attempts to manage millisecond sensor data, or a PLC tries to query financial ledgers, the architecture suffers a "split-brain" failure where the financial view contradicts physical reality. You must strictly define architectural layers based on Data Granularity and Functional Domain, ensuring every data point has exactly one 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. Do not force 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

Do not rely on the table alone. You must implement the following logic gates to enforce the RACI.

1. Static Data (BOM & Routing)

• Owner (A): PLM.
• The Risk: Manufacturing Engineers often tweak routings directly in the MES to "make it work." This breaks the revision loop with Engineering.
• The Mandate:
  • If a process change is required → Then it must be released in PLM first.
  • If MES detects a BOM mismatch → Then enforce a "Stop Ship" until PLM pushes the 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:
  • ERP generates the Production_Order_ID.
  • MES is Responsible (R) for updating the status (Scheduled → In_Progress → Complete).
  • MES cannot create a WO. It can only consume one.

3. Material Lots & Inventory

• Owner (A): ERP (Financial Value).
• Executor (R): WMS (Storage) / MES (Consumption).
• The Logic:
  • If material is in the Warehouse → WMS controls location.
  • If material is issued to the Floor → MES takes custody.
  • If material is consumed/scrapped → MES triggers the deduction transaction.
  • Then ERP passively receives the inventory decrement signal. ERP never guesses consumption based on BOM (back-flushing is forbidden for high-value components).

4. Traceability (Serials & Defects)

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

  Pro-Tip: Do not push every single screw tighten result to ERP. Push a "Genealogy Summary" (Parent/Child link) only when the unit is shipped.

Data Flow Strategy: Push vs. Pull

Define data movement direction to prevent synchronization lag.

Master Data (Push)

Static data (BOMs, Part Numbers, Users) triggers a Push from Owner to Subscriber immediately upon release.

• If PLM releases a new BOM → Then PLM pushes the update to ERP and MES.

Transactional Data (Event-Driven)

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

• If Operator finishes a unit (MES Event) → Then MES instantly decrements local WIP.
• Then MES accumulates events and sends a bulk "Production Declaration" to ERP (e.g., hourly or per shift).

Shadow IT Containment

Well-meaning engineers often build isolated apps (PowerApps, SQL scripts) to solve local problems. These create "Dark Data" silos invisible to enterprise systems.

The Containment Rule:

• If an app generates data required for audits (Quality Pass/Fail, Traceability) → Then it must integrate directly with the MES.
• If an app is purely for visualization (Dashboarding) → Then it may Read-Only from the Data Lake.

Final Checklist

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 calc.
Equipment State	MES/SCADA	Maintenance	Do not rely on ERP for downtime tracking.