KM2614 by Beckhoff

The KM2614 relay terminal is produced by Beckhoff for the KM Bus Terminals series. It is a field I/O component that contains electromechanical changeover relays, giving a PLC the ability to switch line-voltage loads directly from a DIN rail assembly. When mounted beside a bus coupler, the unit participates in the internal K-bus, allowing its four relay channels to appear in the controller's process image. This arrangement eliminates the need for external interface boards and converts low-level control signals into circuits suitable for motors, heaters, or indicator devices. The four independent channels allow several loads to be controlled from one compact terminal while remaining individually addressable by the PLC.

Each relay can interrupt a load of up to 16 A and withstand a startup inrush of 30 A. The maximum switching voltage is 400 VAC, while the rated switching voltage is 250 VAC for AC loads and 30 VDC for low-voltage circuits. The IP20 protection rating limits installation to closed control enclosures that prevent direct contact with live components. For inductive equipment, the AC-3 motor rating supports a single-phase motor load of up to 550 W without causing the relay contacts to weld. A minimum load of 10 V at 5 mA helps prevent contact oxidation during low-power switching. Each energized relay draws 50 mA from the coil supply, and the four changeover contacts are mapped to four outputs in the PLC process image for straightforward addressing.

The relay has an electrical endurance of 1 × 10^6 cycles at rated load and a mechanical endurance of 5 × 10^6 cycles when the contacts operate without current. The relay coils are powered by 24 VDC, while the terminal draws only 15 mA from the K-bus for its status LEDs and logic communication. These separate power paths allow the switching coils to operate without placing their full current demand on the communication bus. A front lever supports manual operation of individual relays without requiring software commands. This feature provides direct control at the terminal when checking connected circuits or verifying relay movement inside the control panel.