Offline Storage & Resync Architecture - Industrial PMR

Factory floors frequently encounter Wi-Fi dead zones, network switch restarts, access point congestion, or temporary ISP link disruptions. Industrial PMR implements a dedicated Non-Volatile Ring-Buffer on the edge node’s onboard SPI flash memory to guarantee zero production data loss.

The Zero-Data-Loss Ingestion Pipeline

Technical Specifications of the Edge Buffer

Parameter	Specification	Engineering Benefit
Storage Medium	Dedicated SPI NOR Flash Partition	Non-volatile; immune to sudden factory power cuts.
Hardware Clock (RTC)	Dedicated battery-backed Real-Time Clock	Guarantees microsecond timestamp accuracy even without internet NTP servers.
Buffer Capacity	Over 65,000 discrete records	Equates to over 72 hours of continuous offline production data at standard logging rates.
Replay Strategy	First-In, First-Out (FIFO) chronological batches	Backfills time-series databases in true chronological sequence.
Flow Control	Strict ACK callback confirmation	Read pointers advance only after the cloud ingestion worker confirms database commit.

Factory Resync Behavior on the Web Dashboard

When an offline edge node reconnects to the network:

Historical Backfill: Historical production counts and power profiles populate the dashboard’s hourly bar charts for the outage duration without leaving gaps.
Audit Trail Integrity: Shift handover reports compile accurate totals even if the network was down during shift boundary transitions.
No Duplicate Strokes: Unique transaction hashes prevent duplicate count registration if a retransmitted packet arrives twice.