As an interface, interface relays connect the electronic control level, for example PLC, with the sensor/actuator level. They perform various functions: switching of direct or alternating voltage loads with different ohmic, inductive and capacitive components, switching in the voltage range from a few mV to 250 V, switching in the current range from a few mA to 10 A, amplifying weak control signals, potential isolation of control and load circuits and signal multiplication. The CR-U series has 12 different coil voltages with 2-3 changeover contacts. A built-in test button for manual actuation and locking of the output contacts can be removed if required. Relays can be ordered with and without a built-in LED. Two base variants are available: standard base and logical base. Plug-in function modules such as reverse polarity protection / freewheeling diode, LED module, RC elements, overvoltage protection or multifunctional time modules expand the areas of application of the plug-in universal relays.