Abstract: The development of new technologies has led to increasingly higher complexity and density of communication equipment, making its maintenance and support more difficult. This paper introduces how to construct the hardware component of a universal portable fault detection system for communication equipment to meet the needs of rapid fault diagnosis and location and on-site maintenance support. Keywords: Portable; Universal; Fault detection; PXI 1 Introduction The development of new technologies has led to increasingly higher complexity and density of communication equipment, resulting in high equipment costs. The strategy of replacing functional boards is constrained by economic factors. With the upgrading of communication equipment, spare boards may become obsolete before they are even used. Therefore, achieving rapid fault diagnosis and location for communication equipment is an important issue in on-site maintenance support. The hierarchical and related nature of the communication equipment structure determines that faults also have a hierarchical and related nature. Based on the universality and modular design of the equipment, a hierarchical diagnostic model for on-site maintenance support is established using a hybrid reasoning mechanism: from whole-machine diagnosis, module diagnosis to component diagnosis. Expert experience cases are presented in an intuitive diagnostic flowchart and related electronic data are displayed simultaneously to complete the fault diagnosis of the equipment. Repair solutions can be established in a short time, which has important practical significance for improving system survivability and life cycle, and improving equipment efficiency. 2. System Structure The system structure is shown in Figure 1. The testing instrument adopts a PXI virtual testing instrument. Virtual testing uses a computer as the hardware support for the instrument, fully utilizing the computer's intelligent functions such as computing, storage, display, and file management. It software-izes some or all of the specialized functions of traditional testing instruments, forming a completely new instrument system that possesses the functionality without the physical appearance of traditional instruments. On a general computer platform, flexible virtual instrument software and instrument soft panels better realize the instrument's measurement and control capabilities. Dynamic testing of equipment typically requires multiple instruments such as sensors, signal conditioners, and dynamic signal analyzers, resulting in bulky, complex, and expensive equipment. The emergence of virtual testing technology has brought significant challenges to traditional instruments, greatly reducing the time and complexity of operation and maintenance, and lowering the cost of testing instruments. Virtual testing technology is open to development, flexible, can synchronize with computers, has reusable configurations, and can communicate with surrounding instruments over long distances via network. The adoption of virtual testing technology in the system greatly improves the degree of automation. For details, please click: Hardware Solution for Portable Fault Detection System of Communication Equipment