Set up your devices in predefined groups and control each group with a single command, e.g., group exterior lighting. When you activate your wall switches, they too can transmit PLC messages. You could, for example, push a switch before leaving home and set the whole house in unoccupied mode, turning off all lights, triggering the security system, activating random light patterns to simulate your presence, adjusting temperature set points to save energy, etc. PLC-controlled electrical outlets are also an important HA actuator. This device plugs into standard electrical outlets along with the controlled load.
Actuators are, generally, simple devices and include a small amount of intelligence.
Unlike other popular PLC products, PLC-1 actuators may include analog functions. Yet, we want the lighting functions of a given HA system to be remotely accessed, controlled, and programmed through the Internet. Thus, actuators are generally designed as simple, low cost devices and execute PLC commands transmitted by one or many intelligent controllers. Transmission conditions may differ from one sensor or one application to the next. Some sensors will not transmit without first being polled, some transmit only when their input changes beyond a given threshold, others transmit at every t time unit, etc.