双端口RAM在PROFIBUS-DP智能从站中的应用

Application of Double Ports RAM in PROFIBUS-DP Intelligent Slave Stations

随着企业信息化和自动化的需要,管理网络和底层控制网络实现无缝连接显得极为迫切和重要。以PC机和Profibus DP智能从站为基础构成的Profibus DP现场分布式测控系统可实现远程分布式数据采集、控制、通信、信息显示等功能。使分散在不同地理位置且具有不同功能的测试设备连接在一起。采用基于Profibus DP协议的从站芯片LSPM2配以双端口RAM和微处理器,用过程映象的方法,在内部存储区域中,划分I/O点的过程映象区,实现监控主站和底层I/O之间的数据交换。实际应用表明该方法能简化硬件设计思路,减轻CPU的负载工作,充分发挥单片机的处理、控制功能,还解决了单片机的I/O口无三态浮空与系统测控、数据采集和处理要同步的矛盾。使得分布式系统中,下位机中数据采集与通行之间的矛盾也得以解决,提高了系统速度和可靠性。

With the development of enterprise information system and automation system, the seamless connection between management network and bottom layer control network seems to be very urgent and important. The distributed field measurement ＆ control system of Profibus-DP, which is based on PC and intelligent slave stations of Prot：ibus-DP, can realize remote distributed data collection, control, communication, information display, and other functions. Thus, the measurement devices distributed in different places with different functions can be connected together. In the inner storage area, the secondary chip LSPM2 based on PROFIBUS-DP protocol with double ports RAM and MPU plots out the process reflection area of I/O point by means of process reflection. Data exchange between the primary station and the bottom I/O point is then realized. The practical application shows that this method can simplify the hardware design, lighten the load of CPU, and fully bring the processing and control functions of SCM into play. Also, it resolves the contradiction between I/O ports wilhout Tritate and the synchronization of system measurement and control, data collection and processing. Thus, the contradiction between data collection and communication of the single chip computer in the distributed system can be resolved, and the speed and reliability of the system can be improved.