In-Depth Analysis of Low-Latency Optimization Technologies (<10ms Solutions) for serial port to ethernet adapter in the 5G Era
In the wave of 5G network commercialization, low latency (Low Latency) has emerged as a core technical metric driving transformation across vertical industries such as industrial internet, autonomous driving, and telemedicine. Traditional serial port to ethernet adapter, acting as bridges between industrial equipment and networks, typically face bottlenecks with delays exceeding 100ms in the 4G era, struggling to meet the sub-10ms real-time requirements of 5G scenarios. This article explores how to achieve ultra-low latency in serial port to ethernet adapter through hardware-software co-design from three dimensions—technical principles, optimization pathways, and practical case studies—while analyzing their typical applications in 5G-connected factories.
Latency in serial port to ethernet adapter is not caused by a single component but results from the superposition of hardware transmission, protocol processing, and network communication. In a typical industrial scenario, the complete end-to-end latency from sensor data transmission to cloud processing can be broken down as follows:
Serial data transmission: RS-232/485 level conversion time (typically <1ms)
Network medium transmission: Wired Ethernet (0.1–1ms/100m), 5G wireless air interface (1ms theoretically, 2–5ms in practice)
Serial protocol parsing: Modbus RTU/ASCII frame decoding (0.5–2ms)
Network protocol encapsulation: TCP/IP handshake, IP fragmentation/reassembly (3–10ms)
Queue buffering: Packet queuing for processing (dynamic delay, reaching tens of milliseconds during peak periods)
OS scheduling: Linux kernel interrupt response, task switching (1–5ms)
Resource contention: Processing blockages caused by CPU/memory bandwidth occupation
Measured Data: A traditional serial port to ethernet adapter from a certain brand averaged 128ms latency from serial input to cloud reception under 4G networks, with protocol processing accounting for over 60% of the total delay.
To achieve a total latency target of <10ms, breakthroughs must be made in four areas: hardware architecture, protocol stack, network scheduling, and system optimization.
Traditional serial port to ethernet adapter adopt a general-purpose MCU + software protocol stack architecture, requiring multiple memory copies and CPU interrupt handling for data processing. Low-latency solutions demand hardware acceleration engines:
ASIC Dedicated Chips: For example, the USR-N540 integrates a custom network processor capable of parallel processing serial data transmission, CRC validation, and TCP/IP encapsulation, reducing CPU load.
DMA Direct Transmission: Memory mapping technology enables serial data to bypass the CPU core and be written directly into network buffers by peripherals, minimizing interrupt latency.
Time-Sensitive Networking (TSN) Support: Hardware timestamp modules integrate precise timestamps for each packet, facilitating subsequent latency analysis and compensation.
Effect: Hardware acceleration reduces protocol processing latency from 8ms to below 0.5ms.
Standard TCP/IP protocol stacks contain redundant features (e.g., congestion control, slow start) that become latency sources in industrial scenarios. Low-latency solutions require:
Replace TCP with UDP + reliable transport layer (e.g., QUIC protocol) to eliminate three-way handshake delays.
Adopt Modbus TCP Lite, removing non-essential fields and shortening frame length by 40%.
Avoid data copying between kernel and user spaces by using shared memory for "write-once, read-multiple" operations.
Eliminate input/output buffers, adopting a "send-on-arrival" model paired with traffic shaping algorithms to prevent packet loss.
Case Study: A car factory’s tests showed that protocol stack optimization reduced single-transmission latency from 15ms to 3.2ms.
Low latency in serial port to ethernet adapter relies not only on self-optimization but also on deep integration with 5G networks:
Allocate dedicated network slices for serial devices via the 5G core network to guarantee bandwidth and priority.
Enable PDCP (Packet Data Convergence Protocol) redundant transmission to reduce air interface retransmission probabilities.
Offload partial protocol processing (e.g., Modbus-to-OPC UA conversion) to MEC (Mobile Edge Computing) nodes, minimizing cloud round-trip delays.
Deploy lightweight AI models for localized anomaly detection, avoiding data upload for analysis.
Data: Combining 5G URLLC and edge computing stabilizes end-to-end latency below 8ms.
Traditional Linux systems struggle with hard real-time requirements due to unpredictable task scheduling, necessitating deep customization:
Replace the Linux kernel with VxWorks or FreeRTOS, reducing interrupt response times from milliseconds to microseconds.
Use static memory allocation to prevent latency fluctuations caused by dynamic memory fragmentation.
Pin serial processing threads to specific cores to reduce cache invalidation and context switching.
Dynamically adjust CPU frequency, entering low-power mode during idle periods and instantly ramping up to maximum clock speed under burst traffic.
Test Results: RTOS transformation reduced system jitter from ±5ms to ±0.2ms.
Take the intelligent production line upgrade of an electronics manufacturer as an example. Its original system faced two major pain points:
150ms latency in robotic arm control commands, causing motion trajectory deviations.
PLC status monitoring data update intervals exceeding 200ms, failing to trigger real-time alarms.
Solution: Deploy the USR-N540 low-latency serial port to ethernet adapter with the following optimizations:
Hardware Layer: Dual-core ARM Cortex-A72 processor with integrated hardware encryption engine and TSN support.
Protocol Layer: Custom Modbus TCP Lite protocol, disabled Nagle algorithm, and enabled fast retransmission.
Network Layer: Allocated 10MHz bandwidth via 5G private network slicing with QCI=6 low-latency bearer configuration.
System Layer: Migrated to FreeRTOS, disabled non-essential services, and set core thread priority to 99.
Verification Results:
Robotic arm control command latency dropped from 150ms to 7.2ms, improving trajectory accuracy by 300%.
PLC status data update intervals shortened to 8ms, enabling true real-time monitoring.
The system ran continuously for 30 days without packet loss, with latency fluctuations <1ms.
As 5G-Advanced and 6G technologies advance, low-latency optimization for serial port to ethernet adapter will evolve further:
AI-Driven Dynamic Optimization: Machine learning predicts traffic patterns to automatically adjust buffer sizes and QoS parameters.
Photonic Computing Integration: Explore optical interconnects to replace traditional copper cables, further reducing physical layer latency.
Semantic Communication Fusion: Introduce data semantics analysis at the protocol layer to transmit only critical information, minimizing redundant data transfers.
In the 5G era, millisecond-level latency is no longer a technical limit but a foundational capability for industrial control systems. Through integrated optimizations in hardware acceleration, protocol streamlining, network synergy, and system tuning, serial port to ethernet adapter are transforming from "data couriers" into "real-time communication hubs." As demonstrated by the USR-N540, when latency is compressed below human perception thresholds, scenarios like smart manufacturing, remote surgery, and vehicle-road collaboration will witness explosive growth. This technological race against time is redefining the future boundaries of industrial production.
