Yokogawa SSB401-53 ESB Bus Interface Slave ModuleGENERAL The Optical ESB Bus Repeater Module converts ESB Bus signals, facilitating communication between the safety control unit, safety node unit, and N IO node, into optical signals. It extends the ESB Bus transmission distance by connecting the Optical ESB Bus Repeater Master Module (SNT411) and Optical ESB Bus Repeater Slave Module (SNT511) with an optical fiber cable. This extension allows for transmission distances of up to 50 km. STANDARD