Mission-critical data in PLCs: Why your logs matter more than you think 

Imagine your automotive production line stalls because a programmable logic controller (PLC) missed its timing—just a few seconds off, and the conveyor doesn’t sync with the robots. The entire line stops. For some manufacturers, that’s $2.3 million lost every hour. Or picture a chemical plant where a missed pressure reading triggers a costly emergency shutdown. 

These aren’t hypotheticals but realities in industrial environments where PLCs collect and act on critical operational data, every second of every day.   

In production environments, the focus often falls on large systems like robots and industrial machinery. But it’s the smaller, distributed PLCs running quietly in the background that serve as the data hub of your production system. Each log on its own may seem minor, but together they form the complete picture that guides system planning and key decisions. If your PLCs fail, that picture disappears, and the whole production line could come to a halt.  

Let’s dig into why PLC data is so critical and why logging it safely and reliably is more important than ever.  

What data do PLCs log? 

PLCs control industrial automation equipment—like robots, drives, actuators, and entire production processes—while continuously logging operational data. This includes: 

• Process variables: Temperature, pressure, and flow rates—the key indicators of system performance  
• Digital I/O states: Sensor activations, relay outputs, and motor statuses 
• Alarms and events: System warnings, safety tips, and failure flags  
• Diagnostics: CPU load, memory usage, and network health  
• Operational metrics: Production counts, cycle times, and throughput statistics 

In a nutshell, PLCs capture what’s happening in your production line, how it’s working, and when something’s off.  

How PLC data flows through your ecosystem 

PLCs first receive input signals from sensors and field devices. Based on this data and your programmed logic, they send output signals to actuators, motors, and drives.  

Logging doesn’t stop with PLCs—they’re just the first node in a broader industrial data flow. Data moves from your PLCS through your control system—either a supervisory control and data acquisition (SCADA) system or a human-machine interface (HMI)—into your data historian or manufacturing execution system (MES), and all the way to your cloud or business-level systems. 

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This data powers everything from the predictive maintenance algorithms that keep your equipment running to the dashboard your operators use.  

Why PLC data is mission-critical to your production line 

You can’t fix what you can’t see. And in manufacturing, visibility starts with your PLC logs. Here’s why they’re mission-critical: 

• Safety: In pharmaceutical or food manufacturing, missed temperature logs could mean unsafe products in the market. 
• Compliance: Clear, auditable logs are essential for meeting FDA, ISO, and IEC standards. 
• Uptime: Logs enable preventive maintenance and root-cause analysis to help avoid costly shutdowns.  
• Efficiency: Logs help optimize cycle times, reduce waste, and reveal bottlenecks.  

If your PLCs fail, the financial impacts are huge. Every second and every byte count, especially in regulated industries like food & beverage, energy, medical devices, and aerospace. Large manufacturers can lose up to 11% of their annual revenue to unplanned downtime—roughly $253 million per facility, per year.  

Hourly costs vary by sector, but it’s generally in the six-figure to seven-figure range, with costs climbing due to inflation and higher capacity utilization. Beyond hourly rates, a single downtime event can cost millions once all losses are tallied.  

With UK and European manufacturers projected to lose over $100 billion to downtime in 2025, unplanned downtime has become one of the costliest drains on profitability in industrial operations. 

Is your PLC data safe?   

PLC logs are often written to flash memory, which is vulnerable to corruption during power loss or brownouts. A sudden shutdown mid-write can compromise not just new data but existing logs as well. Other common risks include flash wear that quietly degrades data over time, and lack of rollback mechanism to recover from errors. 

With so much at stake, it’s clear you need reliable PLC data solutions. It’s easy to assume the file system that came with your controller is good enough. But in high-frequency, high-stakes environments, that assumption can be expensive. Ask yourself: 

• Will your current file system survive a sudden power loss? 
• Is it designed for high-frequency, small-packet logging? 
• Can it guarantee file integrity, even in the event of failure? 

If you’re unsure, your mission-critical logs—and the operations that depend on them—could be at serious risk.  

For context, consider this: just one Siemens S7-1500 logging 10 variables at 1 Hz generates approximately 207 MB of data per day. When you scale that across dozens of devices in an AI-driven production line, your file system becomes the backbone of your operational resilience.  

Choosing the right file system: A checklist  

When evaluating or upgrading your PLC logging strategy, look for a file system that offers:  

• Power-fail safety (e.g. atomic commits and journaling vs. transactional approach)
• Flash-optimized architecture for NAND/NOR flash  
• Real-time operating system (RTOS) compatibility (e.g. VxWorks, QNX, and FreeRTOS)  
• Portable Operating System Interface (POSIX) compliance or lightweight API  
• Low footprint with high reliability  
• Atomic operations that complete fully, or not at all 
• Copy-on-write/journaling to preserve original data  
• Flash-aware behavior (wear leveling, error correction code, bad block handling)

Purpose-built solutions like Tuxera EdgeFS are designed to provide deterministic fail-safety and optimize flash memory for embedded systems. While consumer-grade SD cards typically handle around 10,000 write cycles, industrial-grade SLC flash memory can endure more than 100,000. By using a wear-leveling file system, you can extend the lifespan of your memory by up to 10 times. 

Final thoughts: Respect the logs 

Your logs are more than just diagnostic tools—they’re your operation’s memory, foresight, and first line of defense. They support every dashboard, audit trail, and preventive fix that helps you avoid costly downtime. 

When disruptions can cost millions per hour, even the smallest devices on your production line need robust, reliable embedded software.  

Ready to boost your industrial systems with reliable data solutions? Learn more about our industrial automation solutions.