Abstract : The operating principle and structural characteristics of maglev trains have led to their unique traction control method—long stator commutation technology. To study how this traction control method minimizes thrust loss during the switching process between two adjacent long stators, a frequency converter network control system based on the actual maglev train traction control system was constructed. In the STEP7 programming environment, various function modules provided by the system were used to complete data communication and system monitoring between the master and slave stations, and a preliminary simulation of the long stator commutation process was achieved. Keywords : Fieldbus; Maglev train; PROFIBUS-DP; STEP7; CT frequency converter. The main characteristics of the maglev train traction control system are: based on the motion principle of linear synchronous motors, considering efficiency and power requirements, it is a large-scale, complex, high real-time distributed electric drive control system using a long stator linear field motor with stator segment configuration. To avoid the interference problem of thrust loss during the typical switching process between two stator segments, two stator windings parallel to the train track are set up, and the segment switching method can solve the problem [LI]. In the actual operation control system of maglev trains, building a control system to realize data exchange between the master station and slave station in the network and monitoring the entire system is of great significance for studying and simulating the traction control of maglev trains based on the power switching logic sequence of the traction power supply system and the long stator converter method. [b]1 PROFIBUS-DP Network Structure of Analog Control System 1.1 PROFIBUS-DP Bus Control Characteristics with Frequency Converter[/b] PROFIBUS-DP is a high-speed byte-level device bus communication system for transmitting digital and analog signals of complex equipment. It generally operates in the form of periodic data exchange between the master station and slave station in an RS485 network. The slave station in this allocated master station polling network is a deterministic bus access technology. Its characteristics are: the data exchange between the master station and slave station is initiated by the master station device, the slave station has no bus access rights, and each slave station has the same priority. PROFIBUS-DP offers significant advantages in multi-frequency converter systems: 1) Different devices can utilize various transmission media in different applications, achieving interconnection of all devices with a single transmission medium; 2) Employing digital signal technology reduces signal interference and enables error detection, greatly improving the reliability and accuracy of signal transmission; 3) Enhanced intelligence and reliability of the frequency converters strengthen their field data processing capabilities and simplify data exchange between devices. The combination of distributed fieldbus functionality and the inherent intelligence of the frequency converters enhances the overall reliability of the control system; 4) The frequency converter control algorithm is implemented by the master controller, requiring only software redesign for different applications, thus improving system flexibility; 5) The open network allows different frequency converter products to be connected to the same network for collaborative control. [b][align=center]For more details, please click: PROFIBUS-DP-based Frequency Converter Network Control[/align][/b]