工业以太网在船舶发电机组测试系统中的应用及网络负载分析

Application of Industrial Ethernet in Marine Generator Set Testing System and Network Load Analysis

船舶发电机组测试系统作为一个监控系统,在控制器(PLCs)和上位机(触摸屏、监控PC)之间存在大量的数据传输;采用485总线,允许的最大波特率是19200bps,且为主从式通讯,同一总线只允许一个主站存在;为了提高系统的通信速率和响应速度,改进系统的性能,采用速率极快的100Mbps工业以太网,采用星型拓扑结构分割网段,隔离冲突域,解决非确定性;实践证明,系统响应速度快,实时性好,性能明显优于485总线,且允许多主站存在;为了从理论上验证系统的良好实时性,分析了控制器和上位机的网络负载,计算了网络占用率,结果分别是29.822%和26.448%,均满足工业以太网网络占用率低于30%～40%的要求。

As a monitoring system, the marine generator set testing system has large data to be transmitted among controllers （PLCs） and supervisory comPuters （touch screen and monitoring PC） . Using 485 buses, the maximum allowable baud rate is 19200bps. It is master-slave communication, only one master station is allowed in the same bus. In order to improve system＇ s communication rate and response speed, 100Mbps fast Industrial Ethernet is put into use. Using star topology to divide network segment, isolate collision domain, and solve the uncertainty. It has been found that the system responds more quickly, and has more excellent real time performance. Compared with 485 buses, the advantage is obvious. To confirm system＇ s excellent real-time performance in theory, network load is analyzed, network occupancy rate is calculated. The results are 29. 822% and 26. 448%, all below 30%.