Abstract: This paper describes the characteristics of embedded Ethernet structure and designs a new network testing system. The system includes the development of embedded Ethernet control board and the network topology of peripheral circuit. It provides a network testing environment that can realize data acquisition, transmission and processing more quickly and multi-tasking. The system has been well applied in air conditioner production testing. Keywords: Embedded system, Ethernet, mClinux, testing 1 Introduction The development and application of embedded systems is a hot topic at present. With the development of embedded technology, its applications have made it possible to develop miniaturized and multi-tasking embedded controllers. This paper combines the characteristics of Ethernet structure and independently develops an embedded controller with ARM and mClinux as the development environment. It has been successfully applied to the online real-time detection of various performance parameters of air conditioner control board. 2 Embedded Ethernet System Structure [sup]【1】[/sup] The system structure is shown in Figure 1. The embedded Ethernet system is roughly a three-layer architecture: 1) The remote terminal is mainly used for remote data management. Generally, senior management of enterprises can call online detection data through the Internet for decision analysis, or send instructions to the local terminal to control the detection process in real time. 2) Local servers or terminals in the workshop or testing center can access data in a timely manner through the local Ethernet gateway and store valid data in the local database server. 3) On-site testing can collect parameters of the test object (such as current, voltage, pulse, and temperature) through the self-developed embedded controller, and can adjust the testing accuracy and perform data processing according to requirements. This part will be explained in detail later in this paper. 3 Embedded Ethernet Controller Design [sup]【2】【3】【5】[/sup] Figure 2 shows the hardware structure diagram of the controller. In the development of the embedded Ethernet controller, the CPU is the core part of the system, responsible for memory allocation, thread calling, and control of all devices. RAM and FLASH are the storage parts of the system, used for data storage and address allocation. The ports include the most popular Ethernet interface, USB interface, and RS232/485 interface. In addition, the bus technology adopts the most advanced PXI bus standard, which can realize high-speed acquisition and reliable output of on-site data. In addition, it is equipped with HMI (human-machine interface) to facilitate parameter adjustment and process control in on-site testing. The operating system of the controller adopts ARM loaded with mclinux architecture. mClinux was chosen because it has the following characteristics: 1) It eliminates the Memory Management Unit (MMU), providing complete network functionality. 2) It offers comprehensive file system support, using the romfs file system as the root file system, requiring less space compared to the typical ext2 file system. 3) It uses the flat executable file format: the ELF format has a large file header, while the flat file simplifies the file header and some segment information. 4) It is small in size and highly portable. During development, a cross-compilation environment was also established, connecting the local terminal and controller to the local area network via Ethernet debugging. This was achieved by installing the Red Hat Linux 9.0 operating system on the local terminal, along with the arm-elf-tools toolchain for ARM development. This allows user programs edited and compiled on the local terminal to be downloaded to the controller's CPU via Ethernet for execution. This embedded Ethernet controller has been debugged and is running normally, exhibiting high integration and real-time performance. 4 Application Scheme [sup]【4】[/sup] The network test system diagram for commercial air conditioners is shown in Figure 3. Commercial air conditioners are generally composed of a main unit and several sub-units, and their structure is more complex than that of ordinary household air conditioners. There are many parameters that need to be measured, including the overall current, voltage, compressor current, wind speed pulse, temperature and frequency of each unit, as well as the communication protocols between them. All these parameters are collected by the data acquisition card on the local industrial control computer, and the data is downloaded to the CPU of the embedded controller in real time through the PXI bus for calculation and data analysis. The database server can store the data transmitted from the controller via Ethernet, and can also respond to the instructions sent by the remote server, perform detection and data retrieval according to the process, and generate reports for user management to make decision analysis. In addition, as shown in Figure 2, the embedded controller is also compatible with many interfaces, such as USB interface, RS232/485 interface, etc., which can meet the various special data communication interfaces required by different models of air conditioners. Local operation can also be performed through the HMI human-machine interface on the periphery of the controller, such as parameter setting and calibration, test process control and data monitoring. 5. Conclusion The application of Ethernet in embedded systems and control networks is a current trend in intelligent testing. The innovation of this paper lies in its use of embedded technology as the core, employing a high-speed, multi-channel data acquisition system, high-precision, high-interference-resistance, modular signal acquisition and analysis technology, and fault diagnosis technology, demonstrating technological novelty. Through data fusion technology, combined with Ethernet technology, the automatic testing device for the intelligent home appliance control motherboard in the production site is connected to the embedded controller, forming a unified automatic measurement and control system. Since its commissioning, this system has demonstrated reliable and stable performance, meeting the manufacturer's testing requirements for air conditioning products and improving the efficiency of network testing by 30%-40%. Furthermore, this paper, by applying embedded Ethernet technology to a network testing system and exploring a beneficial application scheme, provides valuable reference and guidance for in-depth research on embedded Ethernet. References [1] Wang Tianmiao. Embedded System Design and Example Development. Beijing: Tsinghua University Press, 2002 [2] Tao Bo et al. Industrial Control Based on Embedded Internet. Measurement and Control Technology, 2002.20.(8) [3] Cui Tao. DMA Programming Based on PCI Controller under Linux System. Microcomputer Information (Measurement and Control Automation), 2006.1 [4] Lei Lin. Microcomputer Automatic Detection. University of Electronic Science and Technology Press, 1998 [5] Zhang Jingli et al. Implementation of High-Performance Data Acquisition System Based on PXI. Computer Measurement and Control, 2004.12(9), 885-887.