To address the issue of poor real-time performance and low reliability in communication between the serial interface of distributed I/O devices and external systems,a design for an IO station device based on PROFINET real- time industrial Ethernet has been proposed.A dual-core model is presented,utilizing the PROFINET communication core chip and RS485 application core chip.The PROFINET communication core chip is an application-specific integrated circuit(ASIC),while the RS485 application core chip is based on the STM32 microcontroller.The dual-core model collectively handles the conversion between the PROFINET protocol and the RS485 protocol.The process of non-cyclic and cyclic data interaction between the main station controller and IO modules through the IO station device is analyzed. A generic station description(GSD)file for the IO station device and IO modules is designed.By integrating PROFINET network communication interfaces and RS485 communication interfaces into the IO station device,a complete PROFINET IO communication test platform is established,and system configuration is completed.The test results indicate that the designed IO station device achieves cross-network communication from PROFINET to RS485,providing a feasible and reliable solution for connecting traditional distributed I/O devices to the PROFINET industrial Ethernet in the field of technology.