The IRIO/TWS  has 4 ON/OFF lighting control circuits for on/off lighting control using mechanical Two Way Switches and 2 x 0-10V outputs for dimming. Each Lighting circuit consist of a Latching Relay to switch the light on/off and an internal Current Sensor to sense the state of the light when connected to a two way switch. Latching Relays remain at the last Open/Close state without requiring current in the relay coil, and saves energy.
The advantage of this method of control is the ability of the mechanical  two way switch to control the light even if the Comfort or IRIO is not working, as conventional Electrical/switch wiring is used.