PLC:
A PLC (Programmable Logic Controller) is an industrial digital computer designed to control machines and processes.
HMI:
HMI (Human Machine Interface) is a user interface that connects operators to machines, systems, or processes
SCADA:
SCADA (Supervisory Control and Data Acquisition) is an industrial automation system used to monitor, control, and analyze** real-time data from various machines and processes across a plant or facility.