9.3 Input / output level (I/O system)All signal modules and functional modules (also those in the control cabinet!) are to be designed as a modular I/O system consisting of electronic modular terminal blocks from Beckhoff using an ELxxxx type EtherCAT terminal system.The configuration has to be carried out according to manufacturer specifications.In cases in which no EtherCAT terminals are provided for specific applications, Beckhoff standard bus terminals (KLxxxx) are to be used.The connection from the EtherCAT level to the communication bus level is to be established by means of the BK1250.Step 7-based control technology is to be connected up via the bus couplers:• CPU with a Profibus interface: Beckhoff EK3100As long as the Beckhoff EK3100 bus coupler has not been approved yet, a CX8031 is to beused as bus coupler. • CPU with a Profinet interface: