Electronic Load Network Monitoring System Based on ARM

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Electronic Load Network Monitoring System Based on ARM [Copy link]

With the widespread application of electronic products, various power supply devices are used, and the reliability of power supply devices is directly related to the safety and accuracy of system operation, so the inspection of these power supply devices is very important. Electronic loads are devices that comprehensively test the output characteristics and reliability (aging discharge) of devices or conversion devices that output electrical energy in the power supply system, such as generators, AC/DC, DC/AC converters, batteries, rectifiers, and inductors, capacitors and other components. There are many shortcomings in the widely used electronic loads now, such as only being able to work in a single-machine panel operation mode, lacking the upper computer monitoring function, lacking a graphical interface for data display, and not being intuitive and user-friendly; the test process must be operated by personnel throughout the process, and programming control tests cannot be performed; there is no Ethernet network interface, and remote communication and control cannot be performed. Compared with traditional electronic load systems, network-based electronic load systems have the following outstanding advantages: (1) The test work is carried out centrally on the host computer. Through automatic testing, the labor intensity of testers is reduced, redundant personnel are reduced, and test efficiency is improved; (2) It is convenient to reflect the power supply test status in a timely, accurate, comprehensive, intuitive, efficient and continuous manner, which is conducive to scientific management; (3) Remote monitoring can save a large amount of work data for a long time, and use this as a basis for scientific test analysis. At present, traditional electronic loads usually use buses such as RS232, RS485 or CAN for network communication. However, the effective radius of these networks is short and they are isolated from the Internet network. It is impossible to use modern network management to achieve large-scale and efficient remote monitoring. In view of the above shortcomings, this paper uses Samsung's high-performance ARM processor S3C2440 as the core to develop an Ethernet-based electronic load monitoring system, which is of great significance for realizing remote automated testing of power supply equipment. 1 Overall structure of the monitoring system The electronic load monitoring system is a communication network with ARM as the core. The system structure is shown in Figure 1.

ARM is a node on the network as a server in Ethernet communication, with an independent IP address. The host computer, as a client, can access different IP addresses to communicate with ARM servers at different nodes on the network, and connect or monitor the electronic load on a certain node. The control command sent by the host computer to the load via Ethernet is received by the ARM network controller, and then sent to the electronic load via the RS232 bus through the ARM network controller. The electronic load uploads various data of the tested power supply and various parameters of the load operation to ARM via the RS232 bus according to the received control command. ARM uploads the data from the load to the host computer via Ethernet using the TCP/IP protocol. ARM can connect multiple loads by expanding the serial port, and expand the network through the router, so that multiple ARM systems can work in parallel, and improve the load capacity of the entire monitoring system. 2 ARM network controller hardware design The ARM system hardware uses Samsung's ARM chip S3C2440, which is based on the 32-bit ARM920T core, with a nominal operating frequency of 400 MHz, a 64 MBytes Nand Flash and two 32 MBtyes SDRAMs. The network chip uses DM9000A and is equipped with a MAX3232 expansion serial port to connect to the electronic load. The structure diagram is shown in Figure 2.

3 ARM network controller software design The operating system of the ARM embedded network controller uses Windows CE 5.0. Windows CE 5.0 is a 32-bit, multi-threaded, multi-tasking operating system. It is also a modular operating system. You can select, combine and configure the modules and components of Windows CE 5.0 to create a user version of the operating system. Windows CE 5.0 meets the real-time requirements of the measurement and control system through interrupt nesting and priority processing mechanisms. At the same time, it has a human-machine interface and application development tools similar to desktop systems. In the development of Windows CE 5.0, there are two important aspects, one is kernel customization, and the other is application development. 3.1 Customization of Windows CE Kernel Due to the diversity of application environments, different kernel customizations need to be made to the Windows CE system. Using Microsoft's PlatformBuilder integrated development environment, certain system modules are added, deleted and modified according to the characteristics of electronic load network monitoring, including adding serial communication support, Ethernet communication support, ActiveSync support (communication support during software debugging), etc. In addition, the registry mode is changed to HIVE mode, so that the data is stored in Flash after power failure to realize the functions of program self-starting and parameter power failure saving. 3.2 Development of ARM-side communication software The ARM network controller serves as a bridge between the load and the host computer, realizing the interconnection of RS232 bus and Ethernet to complete the remote network monitoring function of the electronic load. Therefore, the functions of the ARM-side communication software include: serial communication with multiple electronic loads; communication with the host computer based on TCP/IP protocol, providing a visual interface to display the current network connection parameters and status, and users can set network connection parameters such as baud rate and IP address through the touch screen, and the system provides connection logs for users to review. The core function is to realize the communication interconnection between RS232 bus and Ethernet. The interconnection module adopts multi-threaded calling mode to ensure the real-time communication of the system. The communication frame format is defined as 26 bits in length, with the following format: synchronization header, load address, command word, 4 to 25 bits for related information content, and check code. (1) The synchronization header is AAH, which occupies 1 bit; (2) The load address range is 0 to FE, which occupies 1 bit and determines the target load or receiving source load of the frame; (3) The command word occupies 1 bit and indicates the function of the frame; (4) 4 to 25 bits are command parameters and feedback parameters.