HMI ( human man interface ) is normally a part of a SCADA ( supervisory control and data acquisition) system. HMI is a PC software or combination of software and hardware that makes a graphic tool/device/equipment. and both of this functions as an interface between the operator and the SYSTEM monitoring and control.
i never heard of a SCADA system that does not have an HMI. maybe when the time comes that the SCADA system are already super duper smart that it does not need human intervention anymore.