Relay outputs are wired to ROx or ROy.x and COM screw terminals and serve for switching two-states devices. They are capable of switching AC or DC voltage. The COM terminal (which can be shared by two relays) serves for connection of the switched voltage (and others) by the relay to the ROx, or ROy.x terminal. Relays are connected in NO (normally open) states, meaning that by default there is no contact between COM and RO.

The state (On/Off) of each relay is indicated by a LED with a corresponding label. Overload and overvoltage protection should be provided externally by a circuit breaker (ideally one for each output). Nominal current and circuit breaker type should be selected according to the load and its characteristics concerning the maximum current on the output.

Caution:
If an inductive load is connected (e.g., electric motors, relay coils, contactors, or even the cables in extensive electric installations), it is necessary to protect the relay outputs with a corresponding external element (e.g., varistor, RC circuit or a suitable diode).

If a capacitive load is connected (e.g., power sources of LED lights), it is necessary to protect the relay contacts against inrush current by connecting a corresponding thermistor to the relay's output.

Connection

The following image illustrates the connection of a resistive AC load to a relay output: