Human Machine Interface (HMI) panels are simply the operating screens and the visualization of the operating system. These operating screens make the interaction between human (operator) and machine possible. The PLC can be operated from this screen. The HMI shows relevant values, and basic settings of the system can be changed here.
HMI panels are usually made text-based. This means that lines of text are shown with the associated value. For more extensive systems, there are also graphically structured HMIs that have been developed. The installation can be shown schematically on these.
Next to a display of the monitoring of the system, an HMI also gives a notification when a system or parameter to be tracked, despite the automatic regulation, falls outside its defined permitted area. The HMI panel can then be used to intervene and to stabilize the process.