The connection to the Modbus RTU is established via a 9-pin D-SUB socket. Up to 62 I/O modules can be connected per bus coupler. The modules are connected via an internal bus system. Up to 16 modules can be operated directly on the bus coupler, and the system can also be expanded with an additional power module. In the bus coupler, the areas of supply voltage, fieldbus and logic are galvanically isolated from each other. The system configuration consisting of bus coupler and I/O modules can be quickly determined via the button integrated in the front of the housing. Configuration and parameterization of the individual modules can be done via the fieldbus as well as via the SmartPort interface.