基于VC++的S7-300PLC高速采集系统设计

Design of High Speed Data Acquisition System of S7-300PLC Based on VC++

由于进行疏浚实验时,泥泵扬程、真空和管道流速、浓度等关键参数的变化较快,为了更为准确地研究泥泵性能和管道输送特性,需要进一步提高泥砂输送实验平台的数据采集和存储速度;下位机S7-300PLC控制系统选择了利用逐次逼近法进行采样的高速采集模块,使其AD转换速度缩短至μs级,同时采用中断定时技术,保证了传感器数据每隔50 ms更新、缓存一次,并通过OPC通讯协议将采样信号传送至上位机;上位机软件采用多线程技术保证采集的连续性和可靠性,同时采用顺序存储标志位确保Excel中存储的数据顺序与实际变化完全一致,解决了存储时易造成的数据重复、跳变等问题;通过对多个传感器的长时间采集、存储实验发现,在生成的Excel报表中数据的采集次数恒定为20次/秒,且无重复、跳变现象,满足了疏浚泥沙实验对数据采集系统的要求。

In order to study the performance of the pump and the characteristics of transporting slurry through pipeline more accurately, the speed of data acquisition and storage of the sand transport test stand should be increased with quick change of the key parameters, such as pump head, vacuum degree, velocity in pipeline and concentration during dredging experiment. In ST-300PLC control system, the time of AD conversion can be shorten to microsecond by using high speed acquisition modules, which sampling by successive approximation method. The timer interruption is used for updating and saving sensors＇ data every 50 ms. Then the communication protocol of OPC is used to trans mit the signals to the host computer. The multi thread technology is used in the PC software to keep the process of collecting data continuously and reliably, and the sequential storage flag is used to ensure that the sequence of data stored in Excel is consistent with the actual chan ges, then the problems such as data duplication, jumps, can be solved in the host computer. Through long time collection and storage experiment by multi-sensors, the results show that the stable data collection and storage with the speed of 20 times per second in Excel can be achieved in the improved system.