1. Introduction In real-world industrial control systems, poor product compatibility, high prices, and slow low-level communication speeds are the reasons why fieldbus technology has not been widely adopted. The emergence and rapid development of industrial Ethernet technology has not only effectively solved these problems but also opened up a broader space for the development of fieldbus technology. Furthermore, embedded technology applied to intelligent measurement and control systems has the following characteristics: it can complete multiple tasks such as data measurement, data processing, and process control; it can ensure the real-time performance of some tasks; it has certain self-diagnostic and self-correcting functions; and it is easy to connect to industrial Ethernet for remote monitoring and data communication. These features greatly improve the performance of measurement and control systems. 2. Characteristics of Industrial Ethernet Compared with other fieldbuses or industrial communication networks, industrial Ethernet has the following advantages: Wide Application: Ethernet is currently the most widely used computer network technology with broad technical support. Almost all programming languages ​​support Ethernet application development, such as Java, Visual C++, and Visual Basic. These programming languages ​​have excellent development prospects due to their widespread use and high importance placed on them by software developers. Therefore, using Ethernet technology ensures a variety of development tools and environments to choose from. Low Cost: Due to its widespread application, Ethernet has received significant attention and support from hardware developers and manufacturers, offering a variety of hardware products for users to choose from. Moreover, its widespread use has resulted in relatively low hardware prices. Currently, Ethernet network cards cost only one-tenth of fieldbus products such as PROFIBUS and FF, and this price is expected to decrease further with the development of integrated circuit technology. High Communication Speed: Ethernet communication speeds have evolved from 10M to 100M Fast Ethernet, 1000M Ethernet technology is already in use, and 10G Ethernet is under research. Its speed is much faster than current fieldbuses, meeting higher bandwidth requirements. Abundant Hardware and Software Resources: Having been used for many years, Ethernet has accumulated considerable experience in design and application, and its technology is well-understood. Abundant software resources and design experience can significantly reduce system development and training costs, thereby significantly reducing the overall system cost and greatly accelerating system development and deployment. High Potential for Sustainable Development: The widespread application of Ethernet has consistently attracted significant attention and substantial technological investment for its development. Furthermore, in this era of rapid information change, the survival and development of enterprises will largely depend on a fast and effective communication management network. The development of information and communication technologies will be more rapid and mature, thus ensuring the continuous advancement of Ethernet technology. It is easy to connect to enterprise intranets and the Internet, enabling seamless integration of information between office automation networks and industrial control networks. However, Ethernet also has its shortcomings in real-time industrial control systems. These are mainly because: Ethernet uses CSMA/CD collision detection, which leads to uncertainty in network communication under heavy load (greater than 40%), failing to meet the real-time requirements of industrial control. Traditional Ethernet connectors, hubs, switches, and cables are designed for office applications and do not meet the requirements of harsh industrial environments. In factory environments, Ethernet has poor EMI immunity. If used in flammable, explosive, or other hazardous environments, Ethernet lacks intrinsic safety characteristics, and it also lacks the ability to supply power to field instruments via signal lines. 3. Industrial Ethernet Communication Protocol Industrial Ethernet is Ethernet technology applied in the field of industrial automation. Corresponding to the International Organization for Standardization's Open Systems Interconnection (ISO/OSI) reference model, the Industrial Ethernet protocol adopts the IEEE 802.3 standard at both the physical and data link layers. At the network and transport layers, it uses the TCP/IP protocol suite (including UDP, TCP, IP, ARP, ICMP, IGMP, etc.), considered the "de facto" standard on Ethernet. These constitute the lower four layers of Industrial Ethernet. In higher-layer protocols, Industrial Ethernet protocols typically omit the session and presentation layers, defining only the application layer. Some Industrial Ethernet protocols also define a user layer. Their communication protocol model is shown in Figure 1. Currently existing Industrial Ethernet protocols include: Modbus/TCP (Schneider, 1999), Interbus (Phoenix, 1999), Ethernet/IP (ODVA, 1999), IDA (Vendor Alliance, 2000), HSE (Foundation, 2000), and Profinet (Profibus, 2001). Figure 1. Industrial Ethernet Communication System Protocol Model 4. System Analysis and Hardware/Software Selection 4.1 System Analysis The key to developing industrial Ethernet intelligent devices is to implement Ethernet technology, i.e., embedded Ethernet, in embedded systems. The implementation of various network protocols on Ethernet places high demands on the operating speed and system resources of embedded systems. Therefore, in system design, in addition to considering conventional factors, the requirements of network functions must also be met. The design of industrial Ethernet intelligent devices is centered on high-performance microprocessors and embedded operating systems, so this section mainly discusses their selection. 4.2 Microprocessor Selection Currently, the mainstream 32-bit microprocessors on the market include PowerPC, 68000, MIPS, and ARM. When selecting a microprocessor, factors such as performance, power consumption, price, supporting development tools, and market availability need to be considered. ARM has advantages in all these aspects. ARM has an industry-leading RISC architecture, offering various performance levels and versions to choose from, with compatibility between different products, facilitating system upgrades. Support from major companies ensures high product cost-effectiveness and a stable and smooth supply channel. Furthermore, ARM and its partners provide complete technical support, corresponding operating systems, and hardware/software design and development tools. Given the numerous advantages of ARM microprocessors, using them to develop hardware platforms is undoubtedly an ideal choice. However, due to the existence of over a dozen core architectures, dozens of chip manufacturers, and countless combinations of internal functional configurations for ARM microprocessors, further comparisons are necessary. Based on the characteristics of industrial Ethernet network applications, and considering the microprocessor's operating speed and on-chip peripheral circuitry, the Samsung S3C4510B chip was selected. This chip belongs to the ARM7 series, with a typical processing speed of 0.9 MIPS/MHz and a system clock speed of up to 50MHz, which is sufficient for most application requirements. The S3C4510B integrates an Ethernet MAC layer controller on-chip, simplifying network interface circuit design and improving system reliability. Furthermore, this chip features synchronous dynamic memory (SDRAM) control logic, enabling convenient and cost-effective expansion of large-capacity memory space to run an operating system. 4.3 Embedded Operating System Selection Although embedded system applications can run entirely on "bare metal," with the increasing functionality of measurement and control equipment, the tasks that embedded systems need to perform are becoming increasingly complex, the program code is becoming increasingly large, and the number of peripherals that need to be managed is increasing, making traditional software development models inadequate. Using an embedded operating system as a software development platform allows the operating system to manage tasks and allocate system resources, enabling development to focus on improving the performance of the actual application system. Furthermore, an operating system allows for standardized programming, resulting in better readability and portability, and improved development efficiency. Embedded operating systems are generally divided into commercial and free categories. Commercial embedded operating systems include Wind River's VxWorks and pSOS, ATI's Nucleus Plus, and Microsoft's Windows CE. Free embedded operating systems include embedded Linux and uC/OS. Commercial operating systems are stable, reliable, and offer comprehensive technical support and after-sales service, but they are often expensive. Free operating systems have the advantage of open-source code and no royalties, but they also present development difficulties. The choice of embedded operating system depends on the user's hardware platform and actual application. This system uses embedded uClinux as the software development platform. uClinux is a free operating system, a branch of embedded Linux. It has been successfully ported to various microprocessor platforms without an MMU, such as the S3C4510B, and has shown excellent performance in stability and other aspects. More importantly, uClinux has a complete TCP/IP protocol, allowing for direct application layer protocol development, greatly accelerating the software development process. Of course, the system is not perfect; its non-real-time nature limits its applications to some extent. However, there are currently two different solutions to provide real-time support for uClinux: RTLinux (RTL) and RTAI, which allow modification of the kernel to make uClinux applicable to applications with high real-time requirements. 5 Key Technology Introduction 5.1 ARM Microprocessor ARM (Advanced RISC Machines) is a general term for a class of 32-bit microprocessors based on the RISC (Reduced Instruction Set Computer) architecture. These microprocessors are named after the intellectual property (IP) of the British company ARM. ARM was founded in 1991 and is a company specializing in the design and development of chips based on RISC technology. As an intellectual property supplier, ARM itself does not directly engage in chip manufacturing, but mainly sells licenses for chip design technology. Major semiconductor manufacturers worldwide purchase ARM microprocessor cores designed by ARM and add appropriate peripheral circuits for their respective applications, thus creating their own ARM microprocessors for the market. ARM microprocessors are widely used in many fields due to their advantages such as high performance, low cost, low power consumption, and small size. To date, their applications have spread to industrial control, consumer electronics, communication networks, and wireless communication, accounting for more than 75% of the 32-bit RISC microprocessor market share. ARM's leading position in the 32-bit microprocessor field is similar to that of the 51 series microcontrollers in the 8-bit microcontroller field. Furthermore, dozens of large semiconductor companies worldwide use ARM licenses, allowing ARM technology to receive more support from third-party tools, manufacturing, and software. ARM microprocessors are typical RISC architectures, proposed to address the shortcomings of traditional CISC (Complex Instruction Set Computer) architectures. CISC architectures have large instruction sets, variable instruction lengths, and varying instruction execution cycles, making instruction decoding and pipeline implementation extremely complex in hardware, posing significant challenges to chip design, development, and cost reduction. ARM microprocessors employ a RISC architecture combined with unique technologies, resulting in the following characteristics: fixed-length, single-cycle instructions and flexible, simple addressing modes, leading to high execution efficiency; extensive use of registers, with data processing instructions operating only on registers, resulting in fast instruction execution; support for both 32-bit ARM and 16-bit Thumb instruction sets, ensuring good compatibility with 8/16-bit devices; batch data transfer using load/store instructions to improve data transfer efficiency; the use of barrel shifters in hardware, allowing for simultaneous logic processing and shifting within a single data processing instruction; and automatic address increment/decrement in loop processing to improve operational efficiency. Currently, ARM microprocessors mainly include the ARM7, ARM9, ARM9E, ARM10E, SecurCore, and Intel's Xscale and StrongARM series. Each series, while sharing the common characteristics of the ARM architecture, has its own unique features and application areas. 5.2 uClinux Embedded Operating System uClinux is a branch of embedded Linux, specifically designed for microprocessors without a memory management unit (MMU), and is a Linux system for the microcontroller field. uClinux is derived from the Linux 2.0/2.4 kernel. It is a highly optimized and compact embedded Linux operating system created by miniaturizing, optimizing, and rewriting the code of standard Linux. Although the uClinux kernel is very small, it still retains most of the characteristics of the Linux system, ensuring better operation of various programs on hardware platforms. The uClinux embedded operating system has the following characteristics: it follows the GPL copyright agreement, its source code is completely open, and abundant software resources can be obtained and used for free, greatly shortening the software development cycle; it is a powerful, efficient, and stable multi-tasking embedded operating system; its kernel is small (around 512k) and adopts a modular design, allowing for flexible kernel customization and functionality tailored to application needs; it has a mature and complete network protocol stack, supporting all standard Internet protocols, enabling rapid development of network applications for embedded systems; it supports multiple architectures and has been successfully ported to various hardware platforms; its API functions are consistent with standard Linux systems, and it is almost unaffected by the absence of an MMU; it has a complete set of development tools, making it easy to set up an embedded system development environment, and allowing direct use of a kernel debugger for debugging and error checking; it supports major file systems such as FAT, EXT2, ROMFS, and JFFS; while it does not inherently have real-time capabilities, existing solutions allow for kernel modifications to be applied to applications with higher real-time requirements. The basic architecture of uClinux is shown in Figure 2: Figure 2 uClinux Basic Structure Boot Loader: The code responsible for starting the Linux kernel, used to initialize system resources to establish the Linux kernel runtime environment and load the initial ramdisk from Flash memory. Kernel Initialization: The entry point of the kernel is the start_kernel() function. It initializes other parts of the kernel, including capture, IRQ channels, scheduling, device drivers, calibration delay loops, and most importantly, it can fork the "init" process to start the entire multitasking environment. System Call Functions/Capture Functions: After executing the "init" program, the kernel no longer has direct control over the program flow. Its role thereafter is only to handle asynchronous events (such as hardware interrupts) and provide processes for system calls. Device Drivers: Device drivers occupy a large part of the uClinux kernel. Like other operating systems, device drivers provide interfaces between the hardware devices they control and the operating system. File System: The file system allows users to view files and paths on storage devices without considering the actual physical file system type. uClinux transparently supports many different file systems, presenting various installation files and file systems to the user as a complete virtual file system. 6. Conclusion With the rapid development of Ethernet technology, the obstacles to its application in the industrial field have been largely removed. Firstly, Ethernet communication speeds have been continuously improved. The main cause of latency in Ethernet is collisions, and the probability of collisions is determined by network load. Increased communication speeds mean reduced network load and transmission latency for the same data throughput. Secondly, the adoption of a full-duplex star network topology and Ethernet switching technology. Ethernet switches achieve collision domain isolation, freeing data frame input and output between ports from the constraints of the CSMA/CD mechanism. Furthermore, the full-duplex communication mode allows simultaneous reception and transmission of data on both pairs of twisted-pair cables (or two optical fibers) between ports, ensuring the determinism and real-time performance of Ethernet communication. Simultaneously, many companies have developed Ethernet devices suitable for industrial environments. Companies such as Synergetic Microsystems in the United States and Hirschmann and Jetter AG in Germany have specifically developed and manufactured DIN rail hubs and switches, mounted on standard DIN rails, equipped with redundant power supplies, and featuring robust DB-9 connectors. NETsilicon, Inc. of the United States, developed a low-cost industrial Ethernet communication interface chip using the NET+ARM architecture. The IEEE-802.3af standard published in 2003 defined the bus power supply specification for Ethernet. All of these factors created conditions for Ethernet to enter the field of real-time control. For this reason, the authoritative American research institution ARC (Automation Research Company) predicted that Ethernet will not only continue to monopolize the upper-level network communication market of commercial computer network communication and industrial control systems, but will also lead the development of future fieldbuses. Ethernet and TCP/IP will become the basic protocols of device buses and fieldbuses. A survey report by the American VDC (Venture Development Corp) also pointed out that the application of Ethernet in the field of industrial control will become more and more widespread, and its global market share will increase from 11% in 2000 to 23% in 2005[3]. The S3C4510B and uClinux system together form an embedded intelligent device with an industrial Ethernet interface. By using TCP sockets to achieve data communication over industrial Ethernet, this approach combines the advantages of uClinux embedded system and industrial Ethernet. It can meet the requirements of current industrial control for measurement and control tasks, ensuring the real-time performance and reliability of measurement and control tasks. This approach will be increasingly widely used in the field of industrial control.