(1) Since the models are unified and modules can be used as spares, it is convenient for procurement and management of spare parts. (2) The models are unified and the functions and usages are the same, which contributes to the development of technical capabilities and improvement of technical level. (3) The models are unified, external devices are general-purpose, resources can be shared, communication with the network is easy, and a multi-stage distributed control system can be easily built by installing a host computer. In summary, Mitsubishi Corporation's FX-48MR series PLC was selected as the control host.