5 - Human Interface Subsystem

Abstract

This chapter discussed the functions of the human interface subsystem and its interface with the control system. Human interface is also called human–machine interface (HMI) or human–system interface (HSI) or operator panel, and is the means by which the operators or users manually interact with the process. The users can force an action to control the process or observe the parameters of interest in the process. The basic functions of the human interface system are to directly work with the process to manually control or to assess its state over and above the functions performed automatically by the control subsystem. The human interface subsystem is designed with active display and control components mounted suitably on a sheet metal or fiberglass base (panel) and wired up to the control subsystem. The panel is a passive element and is just the base of the human interface system. The role of the panel is to hold the mounted active components. There are two approaches to constructing the panel—basic and mosaic. No special interfacing equipment is required between the human interface subsystem and the control subsystem, as they both exchange compatible electronic signals.