The “Economy plus“ version extends the existing PROFIBUS Bus Coupler series BK3xx0. The K-bus extension technology allows the connection of up to 255 spatially distributed Bus Terminals to one Bus Coupler. The BK3120 has been designed to accommodate automation requirements. The PROFIBUS protocols omit FMS operation in order to be able to transfer more user data in DP mode, which for this Bus Coupler type can be 128 byte inputs and 128 byte outputs. The BK3120 incorporates the PROFIBUS DP V1 services. These services allow direct access to the Bus Coupler register and the complex Bus Terminals in order, for example, to change the parameterisation or to set/correct limit values for analog Bus Terminals.