Product Description:

The CU1521-0000 is an EtherCAT junction manufactured by Beckhoff for the CU EtherCAT Junctions series. It terminates one electrical drop and one optical trunk, allowing EtherCAT telegrams to pass between cabinet-level copper wiring and plant-wide fiber links without adding an active switch. By providing a simple media transition in a 35 × 98.5 × 76.5 mm DIN-rail housing, the device supports decentralized motion or I/O clusters while maintaining protocol timing and galvanic isolation between network sections.

On the copper side, the junction provides 1 x RJ45, and that connector follows the Fast Ethernet signaling scheme 10BASE-T/100BASE-TX. The port runs at a fixed data throughput of 100 Mbit/s and permits cable distances up to 100 m when category-compliant twisted-pair cable is installed. Control voltage is supplied through the 3-pin push-in terminal, where a nominal 24 V DC powers the internal PHY and link diagnostics. With a protection rating of IP20, the unit is intended for closed cabinet environments rather than exposed machine areas. One electrical port and one optical port are integrated, allowing line extension without occupying additional address space on the EtherCAT ring.

The optical interface uses 1 x SC Duplex and follows the industrial fiber standard 100BASE-FX. It is optimized for multimode glass rated at 50/125 µm MM, launching a 1310 nm wavelength toward remote nodes. Link budgets accommodate runs up to 2000 m, and the receiver detects signals down to -31 dBm to help preserve data integrity on long spurs. Because the copper and fiber channels share the same 100 Mbit/s line rate, timing adjustments are unnecessary when segmenting an existing EtherCAT topology. This arrangement allows a direct transition between electrical and optical network segments while keeping the connection format simple.