Technical Disclosure of the Hardware Watchdog Function in Industrial 4G LTE Modems Automatic Restart within 30 Seconds After Program Crashes
1. Program Crash Crisis in Industrial Scenarios: Dual Challenges to Data and Production
In today's era of deep integration between industrial automation and the Internet of Things (IoT), industrial 4G LTE modem have become the core hub connecting on-site equipment to cloud platforms. However, the industrial environment is complex, with factors such as electromagnetic interference, temperature fluctuations, and mechanical vibrations constantly threatening equipment stability. When an industrial 4G LTE modem program gets stuck in an infinite loop or crashes due to abnormalities, traditional solutions rely on manual on-site restarts. This not only interrupts data collection and renders equipment control ineffective but may also trigger cascading failures, resulting in significant economic losses. For example, an automobile manufacturing company once experienced a production line shutdown for 2 hours due to an industrial 4G LTE modem crash, directly losing over one million yuan.
Core Pain Points:
Data Loss Risk: Crashes cause gaps in critical production data and equipment status information, affecting quality traceability and process optimization.
Disruption of Production Continuity: In automated production lines, a single-point failure can trigger a complete line shutdown, with high repair time costs.
Skyrocketing Maintenance Costs: Equipment in remote areas requires dedicated personnel for maintenance, with manual intervention being inefficient and posing safety hazards.
A hardware watchdog (Watchdog Timer, WDT) is an independent timer module embedded in the main control chip of an industrial 4G LTE modem. Its core logic can be summarized as "heartbeat monitoring + forced reset." When the industrial 4G LTE modem program runs normally, it must periodically send a "watchdog feed signal" (such as clearing the counter) to the watchdog. If the program stops responding due to abnormalities, the watchdog counter overflows and triggers a hardware reset, forcing the system to restart. This mechanism ensures that the industrial 4G LTE modem automatically resumes operation within 30 seconds without manual intervention.
In a blast furnace monitoring system at a steel company, the deployed USR-DR504 industrial 4G LTE modem continuously collects data from over 200 temperature and pressure sensors and uploads it to the cloud in real-time via 4G networks. During the initial system operation, electromagnetic interference caused occasional crashes in the industrial 4G LTE modem program, with data interruptions occurring as frequently as three times a week. After introducing the hardware watchdog function, the industrial 4G LTE modem automatically restarted within 28 seconds after a crash, reducing the data interruption rate to less than once a month and increasing system availability to 99.95%.
Key Data Comparison:
| Metric | Before Transformation | After Transformation (Hardware Watchdog) |
| Average Fault Recovery Time | 2 hours | 28 seconds |
| Data Integrity | 92% | 99.98% |
| Annual Maintenance Cost | 150,000 yuan | 30,000 yuan |
As a flagship industrial 4G LTE modem launched by URS IoT, the USR-DR504 has achieved multiple technological innovations in hardware watchdog design, becoming a model for highly reliable industrial communication equipment.
The USR-DR504 adopts a dual safeguard of "hardware watchdog + software watchdog":
Hardware Layer: An independent timer module monitors the main program heartbeat and directly cuts off the power to restart upon timeout, ensuring system recovery under extreme faults.
Software Layer: A Linux-based daemon process monitors the status of critical tasks in real-time. If task blocking is detected, it triggers a soft restart through system calls.
The dual mechanism covers all scenarios from single-thread freezes to system-level crashes, increasing the crash recovery success rate to 99.99%.
Traditional watchdogs use fixed feed intervals, which are prone to false resets due to task delays. The USR-DR504 introduces a dynamic watchdog feed algorithm:
Task Cycle Learning: The system records the main program loop cycle during operation and calculates the average and standard deviation.
Safety Interval Setting: The watchdog feed interval is set to "average cycle + 3 times the standard deviation," providing ample buffer time.
Real-Time Adjustment: If the task cycle continuously exceeds the safety interval, the watchdog feed interval is automatically shortened to accelerate response.
This strategy enables the USR-DR504 to avoid false resets in 99% of scenarios while still maintaining a restart within 30 seconds when faults occur.
Wide Voltage Input: Supports DC 9-36V wide-voltage power supply, tolerating voltage fluctuations of ±20%, adapting to unstable power scenarios in industrial settings.
Electromagnetic Compatibility: Passes IEC 61000-4-2/4/5/6-level anti-interference tests, enabling stable operation in strong electromagnetic environments.
Isolation Protection: The RS485 interface uses 1500V electrical isolation to prevent ground loop currents from damaging equipment.
The introduction of hardware watchdog technology not only solves the crash problem of industrial 4G LTE modems but also drives a transformation in customer maintenance models:
Achieving Zero Downtime Goals: In continuous production scenarios, the 30-second restart mechanism ensures that equipment failures do not affect production line operation, meeting the demand for 7×24-hour high availability.
Optimizing Maintenance Costs: Reduces the frequency of on-site inspections and the need for manual intervention, lowering maintenance costs for equipment in remote areas by over 60%.
Maximizing Data Value: A complete data chain supports real-time analysis and predictive maintenance, helping customers identify equipment degradation trends in advance and avoid unplanned downtime.
In the wave of Industry 4.0 and smart manufacturing, equipment stability has become a core element of enterprise competitiveness. The USR-DR504 industrial 4G LTE modem provides customers with "never-stop" communication guarantees through its hardware watchdog technology, dual protection mechanisms, and industrial-grade design. Whether in traditional heavy industries such as steel, power, and petrochemicals or emerging fields such as new energy and smart manufacturing, the USR-DR504 can assist customers in achieving digital transformation with ultimate reliability.
