Feb 23, 2026
What is Store and Forward in IIoT?
Network outages in manufacturing are inevitable. Learn how the Store and Forward mechanism in Edge Computing prevents critical data loss during cloud disconnections.
The Myth of 100% Factory Uptime
In an ideal world, every machine on the factory floor maintains a flawless, multi-gigabit connection to the cloud 24/7/365. In the real world of manufacturing, forklifts sever Ethernet cables, factory Wi-Fi degrades near massive metal presses, telecom providers suffer 5G micro-outages, and IT departments occasionally misconfigure firewalls.
When your Industrial IoT (IIoT) architecture relies entirely on pushing data straight from the PLC to the cloud (direct-to-cloud), a network outage doesn't just mean a temporary loss of visibility—it means permanent data loss. If a machine produces 5,000 units during a 30-minute internet outage and that telemetry isn't recorded, your OEE, traceability, and shift reports are permanently corrupted.
This is exactly the disaster that the Store and Forward architectural pattern was invented to prevent.
What is Store and Forward?
Store and Forward is a resilient networking and data management technique used heavily in industrial Edge Computing.
Instead of a sensor or PLC attempting to send data directly to a remote server, it sends the data to a local Edge Gateway sitting right next to the machine. Under normal conditions, the Edge Gateway immediately forwards this data to the central Historian or Unified Namespace (UNS).
However, if the connection to the central server goes down, the Edge Gateway automatically switches to "Store" mode. It buffers incoming telemetry locally onto its internal hard drive. Once the network connection is restored, it automatically "Forwards" all the saved data to the central server in the exact chronological order it was received.
How the Store and Forward Mechanism Works
A robust Store and Forward system operates continuously through three distinct phases:
Phase 1: The Disconnection (Store)
The moment the Edge Gateway detects that the central broker or cloud database is unreachable, it halts all outbound transmission attempts. Instead of discarding the incoming 100-millisecond PLC data, it writes every single payload—complete with localized, high-precision timestamps—into an internal, high-speed disk buffer.
Phase 2: Local Autonomy
While disconnected, the factory isn't necessarily blind. Because the Edge Gateway has local compute capabilities, local HMI screens and localized dashboards can continue to display real-time machine statuses by querying the Edge Gateway directly. Critical safety rules and local alarms continue to trigger independently of the cloud.
Phase 3: The Reconnection (Forward)
When the network link is re-established, the system doesn't just dump all the saved data at once (which could overwhelm the network or crash the central database). Instead, it enters a structured Replay phase. It streams the buffered historical data sequentially while simultaneously weaving in the new, real-time data. To the central database, it appears as if the outage never happened.
Why Store and Forward is Critical for IIoT
Implementing this pattern provides three non-negotiable benefits for enterprise manufacturing:
- Zero Data Loss: Regulatory compliance (like FDA 21 CFR Part 11 or aerospace traceability) requires an unbroken chain of data. Store and forward guarantees that historical logs are whole, regardless of IT infrastructure hiccups.
- Time-Series Integrity: In predictive maintenance, the sequence of events is everything. If data packets arrive out of order, anomaly detection algorithms will fail. A proper store and forward mechanism replays data chronologically, preserving the exact timeline of a machine failure.
- Bandwidth Management: By storing data locally, the edge can also compress or aggregate it before forwarding, saving massive amounts of GSM/LTE bandwidth.
How Proxus Handles Disconnections at the Edge
When designing the Proxus Edge Computing platform, we built Store and Forward deeply into the core architecture, rather than bolting it on as an afterthought.
A Proxus Edge Gateway utilizes an incredibly fast, internal Write-Ahead Log (WAL). This means:
- Massive Buffering: It can survive days—or weeks—of continuous network disconnection, buffering gigabytes of high-frequency PLC data locally without running out of memory.
- Stateful Replay: When the connection to the Proxus Central Platform is restored, the Gateway intelligently resumes pushing MQTT payloads to the Unified Namespace exactly where it left off.
- Zero-Configuration: You don't need to write complex Python scripts to handle disconnections. It is a native, out-of-the-box feature of the Proxus Edge orchestration engine.
Never rely solely on in-memory buffers (RAM) for critical data. If the server loses power during a network outage, RAM buffers are erased. Always ensure your Edge Gateway persists its Store and Forward buffer to a physical solid-state drive (SSD).
Conclusion
Hoping that your factory's internet connection will never drop is not an engineering strategy.
In industrial environments, network volatility is a guarantee. By deploying Store and Forward architectures via robust Edge Gateways, manufacturers can decouple their local machine reliability from their wide-area network stability. The result is a highly continuous, resilient, and trustworthy data pipeline—no matter what happens to the cloud.