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3.2 Serialization and Identity Lifecycle

A Serial Number (SN) is not a sticker; it is the primary key for your physical reality. If two units share an ID, traceability is mathematically impossible. Manage the lifecycle of these identities with cryptographic rigor, ensuring that every number generated is unique, readable, and immutable from cradle to grave.

The Generation Strategy (Source of Truth)

Who creates the number? There can be only one generator. Decentralized label printing (e.g., local spreadsheets) guarantees duplication.

The "Cloud-First" Rule

  • Bad: Print software generates the sequence locally.
  • Good: MES/ERP generates the SN and "issues" it to the printer.

Logic: Pre-Printed vs. On-Demand

  • If using Pre-Printed Labels (Vendor Supplied) → Vendor must provide a Manifest File (CSV/XML) containing all SNs. MES imports this file and marks them "Available."
  • If using Print-on-Demand → Printer requests next SN from MES API. MES marks it "Printed" immediately.

Syntax and Format (The Structure)

Random numbers are useless to humans; sequential numbers are guessable. Use a structured hybrid approach.

[Product Family] - [Date Code/Rev] - [Sequence]

  • Example: A01-2401-00123
    • A01: Product Type A.
    • 2401: Jan 2024.
    • 00123: Base-10 or Base-36 Counter.

Format Rules

  • Avoid: Ambiguous characters (O, 0, I, 1, Q).
  • Avoid: Intelligent logic in the sequence itself. Do not embed "Color" in the serial number. If the color changes (Rework), the SN becomes a lie.
  • Barcode: Use DataMatrix (ECC200) for PCB/Components (Small, robust). Use Code 128 for Cartons (Readable by legacy scanners).

Identity Lifecycle States

An ID exists in defined states. Transitions must be strictly controlled.

State Definitions

  1. Generated: Number exists in DB. Not yet physically assigned.
  2. Printed: Physical label created. (Risk zone: Label might be lost before sticking).
  3. Commissioned (Birth): Label scans at the first station. Digital Link created between SN and Work Order.
  4. Scrapped (Death): Unit destroyed. SN is "Burned" and cannot be reused.
  5. Shipped: Unit left the building. Ownership transferred to Customer.

Duplicate Protection Logic

  • If Operator scans SN 123 at "Start" station → Check State.
  • If State = "Commissioned" (Already Active) → Block (Duplicate).
  • If State = "Shipped" (Ghost Unit) → Block (Return Merchandise Authorization required).

Label Printing & Validation

Printing is the bridge between the digital and physical worlds. It is the most common point of failure.

The "Print-Verify" Loop

Never assume a label is readable just because the printer didn't jam.

  • Equipment: Use printers with internal verifiers (ODV) or place a fixed scanner immediately after the print head.
  • Logic:
    • Action: Print Label.
    • Action: Scan Label.
    • If Scan Fail → Void SN in System + Reprint New SN. Do not retry the same SN if the physical label is bad.

Pro-Tip: For container tracking (Trays/Pallets), use "License Plates." A License Plate (LPN) is a temporary Parent ID that contains 50 Child SNs. Moving the LPN moves all 50 Children digitally.

Final Checklist

Category

Metric / Control

Threshold / Rule

Generation

Source

100% Centralized (MES/ERP). No local counters.

Format

Symbology

DataMatrix (ECC200) for products < 10cm.

Format

Ambiguity

Exclude characters O, 0, I, 1, Q.

Lifecycle

Duplicates

Hard Block on scanning an active SN at Start Station.

Printing

Validation

100% Scan Verification immediately after print.

Scrap

Re-use

Scrapped SNs are "Burned." Never reassign to new hardware.

Storage

Capacity

Ensure Sequence range > 10 years volume.

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