Equipment of a standard reverse osmosis unit with programmable logic controller (PLC) Siemens S7-1200 (this eliminates the microprocessor controller RO digital). The PLC is characterized by intuitive menu navigation and allows optimal control and evaluation of the plant operation. The use of standardised components and protocols in industrial standard facilitates the connection to on-site control systems with Siemens components. In contrast to microprocessor controllers, subsequent expansion or adaptation of the controller is possible at extra cost.