Fecha de publicación: 15/12/2022 Fuente: WIPO (eseential oils OR extracts) The purpose of the present invention is to provide a SCADA web HMI system capable of reducing the processing load of input/output signals in a large-scale system. An HMI server machine according to the present invention executes three filtering processes. A first filtering process extracts a set of input/output signals from received block data when the received block data corresponds to a screen currently displayed on a web browser. A second filtering process extracts, from the set of input/output signals extracted by the first filtering process, input/output signals having values changed from the previous values. A third filtering process extracts, from the input/output signals extracted by the second filtering process, input/output signals corresponding to display parts arranged on the screen currently displayed on the web browser.