Performance Bottlenecks of Serial to Ethernet Adapters in High-Concurrency Scenarios: An In-Depth Analysis of Load Testing with 100+ Devices Connected
In the fields of industrial IoT and automation control, serial to Ethernet adapters serve as the core hub connecting traditional equipment to modern networks, with their performance directly determining system stability. When a single serial to Ethernet adapter needs to connect to over 100 devices simultaneously, issues such as data conflicts, bandwidth saturation, and latency spikes will concentrate and erupt, here better translated as "become prominent". This leads to extended system response times and even service interruptions. Based on real-world load testing data, this article provides an in-depth analysis of performance bottlenecks in high-concurrency scenarios and offers targeted optimization solutions to help enterprises solve the "last mile" challenge of data transmission.
Traditional serial to Ethernet adapter testing is often conducted in ideal environments, such as scenarios involving single-device and low-frequency data interactions. However, the complexity of industrial fields far exceeds that of laboratories: A certain automobile manufacturing plant deployed 200 serial to Ethernet adapters to connect welding robots, resulting in a data packet loss rate as high as 15% during peak periods due to concurrent communication from multiple devices, directly causing production line shutdowns. Such cases reveal a critical issue: Laboratory performance metrics cannot be directly mapped to industrial high-concurrency scenarios.
Address Conflicts and Protocol Confusion: Traditional RS-485 buses adopt a master-slave communication mode, and when more than 32 devices share the same bus, the probability of address conflicts rises exponentially. A certain photovoltaic power plant once experienced a paralysis, better translated as "shutdown" of its data acquisition system due to repeated addresses of inverters, resulting in a loss of over 500 MWh of generated electricity.
Bandwidth Bottlenecks: Calculated at a baud rate of 115200 bps, a single device can only transmit approximately 14 KB of data per second. When 100 devices send data simultaneously, the total bus bandwidth demand reaches 1.4 MB/s, far exceeding the processing capacity of traditional serial to Ethernet adapters.
Timing Disruption: Differences in device response times lead to out-of-order data packets. In a certain intelligent warehousing system, when 120 barcode scanners and 80 PLCs were mixedly connected, the error rate in inventory data reached 3% due to asynchronous timing.
Based on a certain smart park project, a test environment was built containing 120 environmental monitoring devices (temperature and humidity sensors, PM2.5 detectors, etc.), with data aggregation achieved through USR-N510 serial to Ethernet adapters. Webbench was used as the testing tool for pressure simulation, focusing on monitoring the following metrics:
Throughput: The amount of data successfully transmitted per unit time (MB/s)
Latency: The time from when data is sent by a device to when the server responds (ms)
Error Rate: The proportion of data transmission failures caused by conflicts, packet loss, etc.
| Scenario | Number of Devices | Data Type | Trigger Condition |
| Basic Load | 50 | Periodic data (once every 5 seconds) | Simulating daily monitoring |
| Peak Load | 120 | Burst data (random intervals of 0.1-10 seconds) | Simulating device abnormal alarms |
| Mixed Load | 100 | Periodic + burst data | Simulating complex industrial scenarios |
In the 120-device concurrent test, the Cortex-M7 processor (400 MHz main frequency) of the USR-N510 demonstrated significant advantages:
Traditional Solution: A serial to Ethernet adapter with a low-frequency processor reached 95% CPU utilization when connecting to 80 devices, causing new connection requests to be discarded.
USR-N510 Solution: Through hardware-accelerated TCP/IP protocol stacks, even when fully loaded with 120 devices, the CPU utilization remained below 70%, ensuring immediate responses to new connections.
Technical Principles:
The deeply optimized protocol stack built into the USR-N510 breaks down the data packet processing flow into multiple hardware acceleration units, such as:
CRC Check Acceleration: Completes data integrity verification through dedicated hardware modules, with speeds 10 times faster than software implementations
DMA Transmission Engine: Direct memory access technology reduces CPU copy operations, increasing data throughput by 40%
In a 72-hour continuous stability test, memory management became a critical differentiator:
Dynamic Memory Allocation Defects: Traditional solutions adopt a "first-request, then-release" model, causing the memory fragmentation rate to exceed 30% after 48 hours, leading to system stuttering.
USR-N510 Static Allocation Mechanism: By pre-allocating fixed memory pools, the fragmentation rate is always kept below 5%, ensuring long-term operational stability.
Case Verification:
A USR-N510 deployed in a certain steel plant had a memory fragmentation rate of only 2.3% after 180 days of continuous operation, while similar products had an average fragmentation rate of 28%, requiring monthly restarts for maintenance.
In burst data tests, network congestion control strategies directly determine system recovery speed:
Traditional TCP Congestion Algorithms: Adopt a slow-start mechanism, requiring 6-8 RTTs (round-trip times) to recover from congestion, resulting in service interruptions lasting over 10 seconds.
USR-N510 Intelligent Congestion Avoidance: By monitoring queue depth in real time, it actively reduces the sending window when the queue length exceeds a threshold, shortening recovery time to within 2 seconds.
| Metric | Traditional Solution | USR-N510 Solution |
| Peak Throughput | 85 Mbps | 120 Mbps |
| 95% Latency (Peak Load) | 1200 ms | 350 ms |
| Data Packet Loss Rate | 2.3% | 0.07% |
Dual-Core Drive: The Cortex-M7 main processor (400 MHz) handles protocol processing, while an independent security coprocessor (100 MHz) manages encryption and watchdog functions, achieving functional isolation.
Dual-Socket Design: Supports two independent TCP connections, allowing simultaneous access to monitoring platforms and local servers, with automatic link switching in case of failure.
Industrial-Grade Protection:
Operating Temperature Range: -40°C to 85°C
EMC Protection Level: IEC 61000-4-5 standard
Power Supply Reverse Connection Protection and Wide Voltage Input (5-36V)
Virtual Serial Port Technology: A single device can map 256 virtual channels, completely solving address conflict issues. A certain charging pile operator achieved single-server connection to 200 devices using this feature, reducing deployment costs by 60%.
Priority Scheduling Algorithm: Based on QoS mechanisms, high-priority channels are allocated for alarm data. In a smart park project, the transmission delay for fire alarm data was reduced from 500 ms to 10 ms.
Edge Computing Capabilities: Built-in rule engines support data preprocessing, such as aggregating temperature data from 100 devices by region before uploading, reducing network traffic by 70%.
A certain automobile parts manufacturer's original system had two major pain points:
300 devices were connected through 8 traditional serial to Ethernet adapters, with a single device failure causing the entire bus to shut down,
200 GB of data was generated daily, but due to transmission delays, production report generation took 4 hours
After transformation with USR-N510:
Reliability Improvement: Through dual-socket design and virtual serial port technology, device connection success rates increased from 85% to 99.9%
Efficiency Leap: Edge computing capabilities compressed raw data by 40%, reducing report generation time to 15 minutes
Cost Optimization: The number of devices was reduced to 5, lowering annual maintenance costs by 120,000 yuan
| Metric | USR-N510 | Traditional Solution A | Traditional Solution B |
| Maximum Number of Connected Devices | 256 | 32 | 64 |
| Peak Throughput | 120 Mbps | 45 Mbps | 70 Mbps |
| Average Latency (Full Load) | 350 ms | 1200 ms | 800 ms |
| Operating Temperature Range | -40°C to 85°C | 0°C to 60°C | -20°C to 70°C |
| MTBF (Mean Time Between Failures) | 50,000 hours | 20,000 hours | 30,000 hours |
Small Systems (<50 devices): Basic serial to Ethernet adapters can be chosen, but 30% performance headroom should be reserved for future expansion
Medium Systems (50-150 devices): The USR-N510 is the most cost-effective choice, with its dual-socket design significantly improving system fault tolerance
Large Systems (>150 devices): It is recommended to adopt a USR-N510 cluster solution, achieving linear scalability through load balancing
With the popularization of 5G and edge computing, serial to Ethernet adapters are evolving from simple data forwarding devices to intelligent gateways:
AI Scheduling Engine: Predict device behavior through machine learning and dynamically adjust resource allocation
Protocol Fusion Capabilities: Support industrial protocols such as OPC UA and MQTT, breaking down protocol barriers
Security Enhancement: Integrate national cryptographic SM2/SM4 encryption algorithms to meet Class III requirements of the Cybersecurity Classification Protection 2.0
According to MarketsandMarkets predictions, the global market for intelligent serial to Ethernet adapters will reach $1.53 billion by 2026, with an average annual growth rate of 8.7%. In this transformation, the USR-N510 has been certified by the Industrial Internet Industry Alliance of the Ministry of Industry and Information Technology and has become one of the first products included in the "Catalog of Edge Computing Node Devices for the Industrial Internet."
In high-concurrency scenarios, the performance bottlenecks of serial to Ethernet adapters have evolved from simple hardware parameter competition to a comprehensive competition of system architecture design and ecosystem integration capabilities. The USR-N510, through triple breakthroughs in hardware innovation, software optimization, and ecosystem construction, provides a reliable foundation for data transmission in industrial IoT. For complete test reports or customized solutions, please contact us, and the PUSR technical team will provide you with one-on-one in-depth services.
