**4.1.1 Master Terminal Unit (MTU)**

The Master Terminal Unit (sometimes called SCADA center, SCADA server, or master station) may be considered as the heart of a SCADA system. It manages all communications, gathers data of RTUs, stores obtained data and information, sends information to other systems, commands system actuators that are connected to RTUs, and interfaces with operators. Indeed, MTU is a device, which is located in the control center and it acts as master, while RTUs are placed in remote sites and act as slaves (Stouffer et al., 2008).
