The EtherCAT I/O system enables greater distances to be bridged through the use of optical fibre technology. Using the EK1501 EtherCAT Coupler and the EK1521 junction terminal, flexible topologies are also possible with glass fibre technology. Whereas standard Ethernet cables allow a distance of up to 100 m between stations, the distance between two optical fibre devices can be up to 2 km (1.24 miles) with multimode glass fibre connection – and even up to 20 km (12.4 miles) with singlemode glass fibre connection.