流程工业数据采集中的流量控制

Flow Control in Data Acquisition of Process Industry

数据采集系统对数据库服务器需要进行非常频繁地读写,因此要考虑进行流量控制,尽可能地减少通信流量。提出一种group机制,按照已定义的数据点顺序直接发送其数据值序列,而不再重复传输数据点编号信息。通过优化传统数据传输方式中位号点信息(如节点编号)的传送来大幅减少数据流量,从而提高数据传输速度,更突出实时性。研究中使用DTD对数据请求和应答进行规范化定义,并使用xm l文档进行数据传递示例说明。group方式最适用于在数据点数目比较多,所属数据点变化不是很频繁的情况下,它能减少至少一半的网络流量。

Because data acquisition system often write to database server frequently, it is necessary to consider flow control, and to reduce the flow of communication as much as possible. A group mechanism was given which could send the value of the data sequence directly according to the defined data points order, avoid sending the ID information of each data point to reduce the transmission of data traffic, increasing the speed and real-time of data transmission. The data request and response were standardized with DTD and took xml files for examples of the data transfer. This method is appropriate for the large number and little change of data points. It can reduce at least half of the network traffic.