Abstract: This paper introduces a multi-functional safety monitoring system for cranes based on the ADSP2105 digital signal processor and fieldbus technology. The system consists of modules such as a minimum system node, intelligent node, and master node. Communication between modules is achieved via a Controller Area Network (CAN). The system features a user-friendly interface, comprehensive protection functions, high reliability, and a certain degree of self-diagnostic capability. Keywords: Safety monitoring, Digital signal processor ADSP2105, Controller Area Network (CAN) Cranes are essential equipment in engineering construction and are widely used. However, cranes also present numerous potential hazards, making them prone to serious accidents. The State Bureau of Technical Supervision has successively formulated and issued standards such as the "Crane Design Code" (GB3811-83), the "Safety Technical Specification for Overload Protection Devices of Lifting Machinery" (GB12602-90), and the "Crane Safety Regulations" (GB6067-85), requiring all types of lifting machinery to be equipped with safety protection devices. Therefore, developing a new multi-functional safety monitoring and protection system for cranes is essential. Based on this, in recent years, various crane safety protection devices have been developed both domestically and internationally, such as load limiters, torque limiters, lifting height gauges, anti-collision devices, and wind speed alarms. However, these devices have limited functionality. If multiple protection functions are required, multiple instruments must be installed, which is not only expensive but also inconvenient for maintenance and use. Crane users urgently need a multi-functional safety monitoring system that integrates multiple functions and hopes that the crane has strong automatic control and self-diagnostic capabilities to reduce the labor intensity of operation and maintenance and ensure crane safety. The safety-related operating parameters that crane users are concerned about mainly include: the lifting load and lifting height of the main hook and auxiliary hook, the lifting torque and lifting angle of the main boom and auxiliary boom (tower boom), the working radius, the condition of the wire rope, the wind speed (force), the load vibration during lifting, and various information from the lower stage (such as the pressure of the luffing cylinder, the pressure and temperature of the hydraulic transmission system, engine speed parameters, and oil temperature). How to collect these operating parameters in a cyclical manner, process them using algorithms, and output control and prompts in real time is the key to the design of this system. [align=center][/align] In recent years, the continuous development and increasing maturity of fieldbus technology and digital signal processing technology, as well as the emergence of various new large-scale integrated devices, have laid the technical and material foundation for the realization of this system. Fieldbus standards and technologies are a hot topic in the international automatic control field. For industrial control, the biggest advantage of using fieldbus is that it can significantly reduce connection wires, maintenance costs, and installation costs. Simultaneously, fieldbus can transmit multiple process variables. Controller Area Network (CLAN) falls under the category of fieldbus. It is a serial communication network that effectively supports distributed controller or real-time controller control. Developed by Bosch in early 1980 to solve the data exchange problem between numerous control and testing instruments in modern automobiles, it is a serial data communication protocol with a communication rate of up to 1 Mbps (Multiple Master Multiple Slave, M3S). The CAN bus communication interface integrates the physical layer and data link layer functions of the CAN protocol, and can perform frame processing of communication data. It ensures the dynamic nature of the number of nodes within the network by encoding communication data blocks, and allows different nodes to receive the same data simultaneously. The maximum data segment length is 8 bytes, guaranteeing real-time communication; while the protocol utilizes CRC checks to provide corresponding error handling functions, ensuring the reliability of data communication. This system utilizes these characteristics of the CAN bus to solve the communication problem between numerous modules (nodes). The advent of the Digital Signal Processor (DSP) revolutionized the field of digital signal processing. It adopts a Harvard bus architecture, separating the data bus and program bus, allowing simultaneous instruction reading and data computation. Instructions can be executed essentially within one machine cycle. It features on-chip multiplier hardware with a pipelined bus connecting multipliers and accumulators, enabling high-speed continuous multiplication and accumulation operations. Therefore, its computing power is extremely strong, suitable for processing large amounts of high-speed signals. Since its introduction, it has developed rapidly and gained widespread application in less than 20 years. For example, Texas Instruments' TMS series has now reached its fifth generation. 1. System Overall Structure Diagram The basic components of this system are shown in Figure 1. The system consists of a master node (central processing unit), a smart node, and eight minimum system nodes. The minimum system nodes include tension sensor node 1 (sub-hook), angle sensor node 2 (sub-arm), tension sensor node 3 (main hook), angle sensor node 4 (main arm), wind sensor node 5, anti-collision sensor node 6, height sensor node 7 (main hook), and height sensor node 8 (sub-hook), etc. Each node is responsible for collecting different signals and performing A/D conversion (some nodes do not require A/D conversion, such as the incremental photoelectric encoder of the height node, which can directly obtain digital signals), and then communicating with the master node via a fieldbus. The maximum bus length between modules does not exceed 130 meters, the bit rate is set to 500kbps, and the bus timing is: BTR0, 01H; BTR1, 1CH. 1.1 Master Node (Central Processing Unit) The schematic diagram of the system master node is shown in Figure 2. The central processing unit uses an ADSP2105 manufactured by Analog Devices, Inc. It is a high-performance, cost-effective, and mature DSP device that can perform the following operations within a 100ns cycle: fetch two operands, modify the address units pointing to the operands, multiply the two operands, and accumulate the result into a 40-bit sum. Since the program loop is completed within the hardware, these high-level instructions can be executed once every 100ns. WSI's PSD311 programmable peripheral device effectively integrates programmable logic, I/O ports, and memory onto a single chip, enabling the peripheral functions of this system. The ADSP2105 provides significant timing flexibility in communicating with peripheral devices such as the PSD311. It can allocate a separate number of wait states for each of the four separate memory spaces to accommodate a wide range of timing differences. We have arranged one wait state (200ns cycle time) in the ADSP2105's "Wait Register" for the strobe pulses of the EPROM, RAM, and external memory to meet the timing requirements of the PSD311's 120ns device. Since the bus path is located inside the ADSP2105, the data lines of the PSD311 are connected to D15-D8. The ADSP2105's "D22" line provides the PSD311's "A14" address line. /BMS (Boot Memory Select) acts as the EPROM chip select and is connected to the PSD311's "A19" input. The SJA1000 is selected as the CAN controller, and the driver uses the CAN controller interface chip PCA82C250. The EEPROM is used as data RAM to store key input data to prevent loss during power failure. 1.2 Intelligent Node The schematic diagram of the intelligent system node is shown in Figure 3. The Philips 80C592 chip is an 8-bit high-performance microcontroller, a functional combination of the existing 80C522 and the CAN controller PCA82C200, featuring a 10-bit A/D converter with 8 analog input channels and 15 interrupt sources with two priority levels. The PSD311 is used as its peripheral ROM, RAM, and decoding chip. The 80C52 uses its built-in ADC to convert various analog/digital signals collected by the off-vehicle sensors into digital signals (analog signals only), which are then sent to the system master node via the CAN component. It also receives output signals from the master node to control various electrical relays and solenoid valves on the off-vehicle. 1.3 Minimum System Node The minimum system node uses the ISO/DIS11898 standard connection method, as shown in Figure 4. The P82C150 is a single-chip 16-bit I/O device with automatic bit rate detection and correction, including a CAN protocol controller. The direction and digital/analog modes of its 16 I/O lines are programmable. Its built-in 10-bit A/D converter with 6 analog input channels has an accuracy of 0.1%, which fully meets the system's accuracy requirements. 2. System Functions and Features The system can sample signals from various sensors in real time, calculate the actual operating parameters of the crane under corresponding working conditions, and compare them with standard operating parameters. A pre-alarm is triggered when the limit value is reached (90%), and an alarm is triggered when it exceeds 100%, forcibly stopping control. At this point, the crane cannot continue to move in a dangerous direction, such as lowering the boom, extending the arm, or lifting. The system also provides a user-friendly human-machine interface, allowing users to easily complete specific working parameter settings, debugging, calibration, and other auxiliary functions. Users can understand relevant operating parameters in real time through the display screen and voice prompts to take timely action. The system's most significant feature is its ability to dynamically add or remove nodes (CAN monitoring module) based on the specific conditions of the crane. High-performance DSP and peripheral PSD devices ensure the system's flexibility, robustness, and scalability. Integrated crane safety monitoring systems represent the future trend of crane safety monitoring systems. They will gradually replace single-function safety protection devices, such as load limiters, torque limiters, lifting height gauges, anti-collision devices, and wind speed alarms, becoming the mainstream product in the market.