The traditional ethernet based on shared communication channels is not suitable for hard real - time control systems . a maths model of collision in the ethernet is provided and several technologies are adopted to make the ethernet real - time 针对传统共享型以太网难以胜任控制中硬实时要求的问题,建立以太网碰撞冲突模型,并提出一些确保以太网在工业控制中实时性的措施。