Lighting controls are an essential component of any lighting system, serve multiple purposes, and vary from simple user-activated switches to sophisticated scene controllers, automatic sensor controlled systems, and networked digital control systems. Apart from basic on/off control, they are used to tailor lighting to space functions, tasks, and user preferences while improving comfort, performance, aesthetic appeal, and energy savings. For tricolor systems, such as RGB LEDs, the control system can change source color. There are a wide selection of lighting controls on the market today covering anything from local controls to centralized approaches. On/off switching is frequently performed at the entrance to a space, as required by code, and at other areas of convenience to the users. Dimming control is more expensive than simple switching, but gives you flexible control of output down to the minimum level provided by the dimming hardware. Scene controls are a common control solution in spaces which are best served by pre-established settings of lighting control zones. Automatic control of electric light output in daylit areas can be achieved by switching or dimming the lighting equipment according to a photosensor reading that keeps track of either the daylight entering a space, or the combined level of daylight and electric light within that space. Electric lighting that remains on in spaces which are unoccupied is often a waste of energy. Occupancy sensors integrate motion sensors that detect occupancy and are able to switch lighting on when a person enters a space and off when the space is vacated. Time control takes the form of either a time-based schedule or timed switches. Time schedule control is a less forgiving technique of occupancy control, but useful in spaces that have a well-known and habitual operating schedule. When a dimming system is present, lighting conditions can be tuned to the tasks at hand. If a lighting system provides more illuminance than required for a specific task. Lumen maintenance involves adjusting lamp output over time to maintain constant light output as lamps age, and dirt accumulation minimizes luminaire output. During periods of peak electrical demand, it can be economical to reduce a building’s power consumption to prevent higher charges for electrical power.
Numerous types of lighting control systems are currently commercially available for controlling a wide range of lighting features from simple on/off switching to complex color adjustment and performance monitoring. Such systems also communicate according to an array of protocols over various communication channels. A simple system can be simply a triac dimmer and a single lamp. The 0-10V standard was one of the earliest and most basic lighting control signaling system, which is even now supported by many fluorescent ballasts. A complicated system could be a hierarchical campus wide network. In such a system, up to a whopping 64 intelligent fluorescent lamp ballasts inside a room or group of rooms could be wired together utilizing the Digital Addressable Lighting Interface (DALI) standard, for example, with an Ethernet enabled DALI controller. At the top layer of the hierarchy, the computer servers in different buildings within a campus could communicate online using Internet Protocol (IP). The DMX512 stands for "Digital Multiplex with 512 pieces of information" and is a standard for digital communication frequently used in theaters and production studios. DMX512 communicates over shielded twisted pair cable using EIA-485 standard voltages levels with node connected together in a daisy chain manner. The DALI standard, which is becoming relatively popular for commercial lighting systems, is similar to DMX512 in that various lamps can be singularly controlled employing a relatively low data rate digital control bus, however, there are lots of differences ranging from the type of communication cable and interconnections to data format and messaging requirements. While DMX512 communicates uni-directionally over shielded twisted pair cable between two nodes, DALI communicates bi-directionally over un-shielded twisted pair which can be tapped by up to 64 devices. While all DMX512 data frame include one start bit, 8 data bits, and two stop bits, DALI has different sized frames for communication in the varied directions with both acknowledge and data bytes in one direction and no acknowledge in the other direction. The DALI standard enables a digital communication lighting control system capable of fulfilling various user needs by allocating addresses to different combinations of lighting scenes. Unlike DALI, DMX512, 0-10v, and other protocols developed exclusively for lighting, X10 was developed for general home automation of which lighting is an important subset. LonWorks is a building automation protocol that typically makes use of either twisted pair cable at 78 kbit/sec or the power line at a few kilobits per second for the communication channel. The C-Bus Protocol targets home automation systems along with commercial lighting systems. Unlike the X10 protocol, C-Bus typically uses dedicated CAT5 cables and is believed by some to be more robust as a result. ZigBee comprises a group of high level communication protocols that typically take advantage of the IEEE 802.15.4-2003 standard for Wireless Personal Area Networks (WPANs) as the physical layer. Wi-Fi or 802.11 is a quite typical wireless network for data communication between computers. Wi-Fi has a plethora of different types of frames for communication management. In general, Internet Protocol (IP) and the associated Transport Control Protocol (TCP) run over Wi-Fi networks.
Wired lighting control systems require each luminaire in the system to be physically connected to its respective switch, controller and/or power source via a plurality of wires. Wireless lighting control systems, on the contrary, do not require physical connections between the controller, the switch and the light source. Rather, the light source often has a lighting controller coupled to it, and the lighting controller communicates wirelessly with the other components in the lighting control system. Some lighting systems come with a remote control for adjusting the brightness and/or color of the lighting. These remote controls offer buttons for an oeprator to press to be able to control the lighting and make use of standard infrared communication techniques to communicate with the luminaires or with a base station that then communicates with the luminaires or controls the luminaires directly.
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