Kuhnke's FIO is a system of I/O modules for interconnecting the process signals in an EtherCAT network. It consists of the bus coupler and a range of I/O modules. The bus coupler converts the physical transfer technology (twisted pair) to LVDS (E-bus) and generates the system voltages required by the LVDS modules. The standard 100 Base Tx lines used for office network communications connect to the one side, the I/O modules for the process signals connect to the other. This is how the EtherCAT protocol is retained right through to the last I/O module. At the end of the modular unit, the feed and return loops are terminated automatically.