Persechini Maria Auxiliadora Muanis, Mendes Luiz Themystokliz Sanctos
Department of Electronics Engineering, Federal University of Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte, MG, 31.270-901, Brazil.
Department of Electronics Engineering, Federal University of Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte, MG, 31.270-901, Brazil.
ISA Trans. 2020 Feb;97:86-92. doi: 10.1016/j.isatra.2019.08.003. Epub 2019 Aug 7.
Data acquisition systems are crucial when implementing control and automation strategies correctly and on time. The knowledge of the sampling time is one of the relevant features to ensure that the sampled data properly represent the process variable. This paper describes the development of a performance index to measure continuously and in real-time the sampling time behavior of typical control and automation systems. To test this index two different architectures are used. The first one uses a data acquisition board plugged directly into the computer bus, and the second one uses a Programmable Logic Controller communicating with a computer through either Industrial Ethernet with OPC or the serial Modbus RTU protocol. In all cases, a custom software application is implemented to calculate the performance index when the sampling time is provided by the Operating System's timer interrupt service. The analysis of the experimental results shows that the proposed performance index can be useful to assess the sampling time behavior or to assist in decision-making about hardware and software choices.
在正确且按时实施控制与自动化策略时，数据采集系统至关重要。采样时间的知识是确保采样数据能恰当代表过程变量的相关特性之一。本文描述了一种性能指标的开发，用于连续实时测量典型控制和自动化系统的采样时间行为。为测试该指标，使用了两种不同的架构。第一种使用直接插入计算机总线的数据采集板，第二种使用通过工业以太网与OPC或串行Modbus RTU协议与计算机通信的可编程逻辑控制器。在所有情况下，当操作系统的定时器中断服务提供采样时间时，都会实现一个自定义软件应用程序来计算性能指标。实验结果分析表明，所提出的性能指标可用于评估采样时间行为或辅助有关硬件和软件选择的决策。
