Preface Currently, the manufacturing industry faces new challenges. Since the establishment of international safety standards, primarily ISO 12100, the systematic construction of safety systems on factory production lines worldwide has become a top priority. A safety system, designed to prevent accidents or workplace injuries during machine or robot operation, uses sensors to detect when workers enter hazardous areas and quickly bring the robot or equipment to an emergency stop. Therefore, safety systems absolutely cannot allow equipment to stop due to malfunctions or noise. However, the high cost of wiring and maintenance presents a significant burden. To ensure the safety system smoothly enters a stop state, safety sensors and emergency stop signal circuits must be connected to existing information communication circuits. The safety system circuit inevitably becomes a dual circuit. Furthermore, to achieve equipment reset and safety system monitoring, it requires a high degree of integration with the control system. Thus, the safety of fieldbus systems has become a focus of attention. Currently, the development of safety networks that can achieve both low-wiring safety systems and high integration with control systems is receiving considerable attention. The Necessity of Safety Networks When people work alongside machinery and robots, there is a potential risk of mechanical injury when they are within a certain distance. Therefore, safety systems that use sensors to detect the presence of people and can urgently stop mechanical devices when a person enters a dangerous area are essential. To prevent emergency stops from failing due to malfunctions or noise, safety systems are designed with dual processing and diagnostic functions, thus increasing wiring compared to general control systems. In recent years, safety networks have been increasingly promoted to reduce wiring in such safety systems. Safety networks not only have the function of detecting communication faults causing emergency stops but also have a fail-safe function that quickly transfers mechanical devices to a safe state when a communication fault is detected. Furthermore, safety devices such as light curtains and safety switches support safety networks, reducing the number and length of wiring and achieving cost reduction. Therefore, the variety and quantity of compatible products for safety networks are constantly increasing. Challenges of Safety Networks When introducing safety networks to build safety systems, the following challenges exist. Safety networks need to have the functionality and performance to solve these challenges. Reducing Introduction Costs Many factories already have extensive control networks. When introducing a new safety network, if the safety network is interchangeable with the existing network and equipment, the investment in new equipment can be reduced. Furthermore, network management and operation can be carried out on the existing basis without additional technical training costs. Therefore, everyone hopes that the security network is interchangeable with the FA network with a large market share to reduce the cost of implementation. Achieving High-Speed ​​and High-Reliability Communication Because the security network has error detection functions such as error detection symbols and redundant transmission, compared with general networks, it can store less application data in communication information. At the same time, detection and processing can worsen communication responsiveness, and the increase in communication speed will increase the proportion of communication errors per unit time. Therefore, the security implementation of high-speed networks has always been considered technically very difficult. However, the large-scale and high-speed requirements of security systems necessitate that the security network possess both high speed and high reliability. Enriching Configuration Management Functions To ensure the operation of the security system, configuration management of the security network is essential. That is, it requires functions that can manage information of products connected to the security network, prevent modifications or unintentional changes that compromise security, and prevent errors in configuration settings during modification projects. Enriching RAS Functions The security network system reacts sensitively to faults or abnormal situations, triggering fail-safe actions to stop mechanical equipment. To quickly restart production equipment from a stopped state, a fail-safe (RAS) function is needed to determine whether the cause of the fail-safe activation is a fault requiring repair or a temporary abnormality. In addition, engineering software that centrally manages the status and settings of network-connected devices also plays a crucial role in the rapid recovery of production equipment. The CC-Link Safety system was designed and developed to address these new challenges. Firstly, it is based on the CC-Link network, which holds a significant market share in Japan and worldwide, and features protocol-interchangeable safety features. Because it achieves data link layer interchangeability with CC-Link, it can utilize existing CC-Link cables and coexist with CC-Link compatible products. Therefore, for factories that have already implemented CC-Link, the equipment investment for introducing a safety system can be reduced. Products that can connect to CC-Link Safety include the CC-Link Safety master station (hereinafter referred to as the safety master station) and the CC-Link Safety slave station (hereinafter referred to as the safety slave station). The safety slave station refers to CC-Link Safety compatible products other than the safety master station, consisting of a safety remote I/O station and a safety remote device station. Figure 1 shows the CC-Link Safety configuration diagram. A safety master station is connected to the corresponding CPU, along with CC-Link Safety monitoring software for various settings and monitoring. Safety control-related devices such as light curtains, safety switches, and load power are connected to the safety I/O terminals of the safety remote I/O station. As shown in the diagram, using CC-Link Safety-compatible safety products, such as light curtain controllers that connect directly to CC-Link, can further reduce wiring costs. Products not directly related to safety control are connected to the (general) I/O terminals of the CC-Link (general) remote I/O station. For example, connecting an emergency stop button to the safety remote input station, a power source to the safety remote output station, and an action light to the general remote output station creates a safety system where pressing the emergency stop button stops the machinery and the warning light emits a signal. The main specifications of CC-Link Safety and CC-Link are shown in Table 1. Because their physical and data link layers are common, there is no difference in communication speed or transmission distance. However, the number of safety stations and safety remote register points for CC-Link Safety is more limited than that for CC-Link. However, since remote safety registers do not use analog values ​​in mechanical safety applications, they are not inherently limited. As long as the communication performance and number of points can be achieved, not only single mechanical devices but also large-scale safety systems consisting of multiple projects such as automobile assembly lines can be constructed into safety networks. A typical CC-Link Safety system: Figure 2 shows the structure of a typical CC-Link Safety application safety system. The CC-Link Safety system master unit acts as the master station, CC-Link Safety system remote I/O, and other safety devices such as light curtains and robots act as substations. CC-Link Safety transmits emergency stop signals to the safety devices connected to it. Other devices, such as warning lights, are connected via CC-Link standard remote I/O. CC-Link Safety not only ensures the control and monitoring of the safety system and prevents erroneous information from substations to the master station, but also achieves low-wiring in the safety network, helping to accelerate system development and improve maintenance efficiency. Conclusion: CC-Link Safety is a safety network that achieves interchangeability with CC-Link, high-speed and high-reliability transmission, safety functions, and simple maintenance. It can fully utilize existing CC-Link resources to construct IEC61508 SIL3 and ISO13849-1 Category 4 safety systems. Furthermore, CC-Link Safety has extended functions: in addition to collecting error information, it also collects various information from safety slave stations (parameters, switch status, etc.), allowing system users to perform simple checks through monitoring software. The application of safety systems in my country is receiving increasing attention. Reducing safety accidents in production and eliminating casualties requires not only sound management systems but also safety considerations from the design and construction of equipment. Moreover, CC-Link Safety is well-suited to my country's actual conditions, with low system construction costs, ease of use and maintenance, and stable and reliable operation, which will undoubtedly contribute to safe production in my country. Wu Qin's Personal Profile Wu Qin, male, born in October 1973, native of Hubei Province, Han nationality, member of the Communist Party of China, electrical engineer, currently working at the Shanghai Airport Construction Headquarters, Address: No. 300 Qihang Road, Pudong International Airport, Postcode: 201102, Contact Number: 68349159, 13918628307. He graduated from the Department of Electrical Engineering, Shanghai Railway University in 1997 with a Bachelor's degree and began working at Shanghai Hongqiao International Airport that same year. In 1998, he was transferred to Pudong International Airport to participate in its construction. In October 1999, the first phase of Pudong International Airport was completed and put into operation, and he transferred to the airport's operation and support work, serving as an assistant electrical engineer, electrical engineer, and head of the airport power supply support department. In August 2003, the second phase of Pudong International Airport commenced construction, and he was transferred to participate in the Pudong International Airport expansion project, mainly responsible for the airport's power supply supporting projects.