This content was originally published on the OSRAM Digital Systems blog. You can read the original blog post here.
Selecting a smart lighting system can be daunting partly because you need to have a basic understanding of networking. How will the luminaires, sensors and controls connect and reliably communicate with each other on your smart lighting network?
Does this sound complicated? It really isn’t, but understanding a few basics before you get started is essential. There are two major decisions you will need to make; the first is the system architecture and the second is the communications protocol. Let’s break it down a bit.
System Architecture Options - Wireless, Wired, or Hybrid
Lighting control systems can be wired, wireless or a combination of the two (hybrid). The system architecture refers to how control signals are communicated and not how a control device receives power.
In a typical wired lighting control system, control signals travel over communication wires. In a wireless system, control devices communicate through the air using radio-frequency RF waves without the need for wires. Hybrid solutions use wired for areas where it is feasible (such as new construction), and wireless as an extension of the wired network to provide coverage in hard-to-reach areas or where it is too expensive to wire.
Choosing the right architecture for a particular site is influenced by many factors including whether it is new construction or an existing building, the space or building itself, installation requirements, and overall costs. Let’s take a look at the advantages and challenges of each architecture type.
Factors that Influence System Architecture Decision
Building Status - Is your building already built or in the process of being built? If it is in the construction phase or under development, it is the most opportune time to integrate a wired lighting control system. For a pre-existing building, a wireless lighting control solution will probably be your best option.
System Reliability - Although wireless technology has come a long way, there are some situations where a wired solution is still the most reliable. In some applications, building materials and technology interference can cause wireless systems to be less reliable. To mitigate this issue, a wireless mesh network topology can be used. In this case, each network node (connection point on the network that can send, receive or store data) can communicate with every other device, and can relay messages for its neighbors. Mesh networks are self-healing, in that if any disruption occurs, data is automatically re-routed helping provide better coverage and reliability.
Scalability - A wireless system requires more nodes/repeaters (hardware) in a given radius to keep the signal strong as compared to a wired system. The range, or maximum transmission distance of a signal, is dependent on a number of factors including the wireless communications protocol used, building structure, and line-of-site obstructions. A wired system uses less hardware because it can support long cable runs (for example, 2500 ft.). Both are scalable, however as building size increases, the cost of wiring can exceed the cost of a wireless installation.
Budget - Equipment and installation costs are generally higher for wired systems.
Once you have decided on your system architecture, it is now time to determine the communications protocol that runs on the network.
Choosing a Network Control Protocol
A network protocol defines rules and conventions for communication between network devices and is classified as proprietary or open. Proprietary protocols are developed by a single vendor and are used specifically for the devices that they manufacture. Other vendors may or may not support the proprietary protocol so special gateway equipment likely will be needed in multi-vendor environments.
Open or standard protocols are not vendor specific and are embraced by the industry. Standard protocols are often developed by a collaborative effort of experts from different organizations.
ZigBee is a standard protocol defined by the IEEE standards body. It was designed to be a low power, low-data-rate, proximity wireless mesh network protocol, with the intention of being simpler and less expensive than other wireless network protocols such as Bluetooth or Wi-Fi. It offers a high level of security with 128-bit encryption.
Bluetooth Low Energy (BLE) offers 1-Mbps bandwidth and a range of up to 100 meters. The key advantages include consumer familiarity, a widely established ecosystem and a multi-vendor supply chain. Although it is considered a standard protocol, BLE is not open, as it must be licensed from the Bluetooth Special Interest Group.
EnOcean is a standard that uses energy harvesting to power sensors and switches to operate without batteries or a wired energy source. Although it is considered a standard protocol, it is not open, as it must be licensed from EnOcean.
Wi-Fi provides a higher bandwidth capacity than ZigBee, Bluetooth or EnOcean, but is typically more expensive and consumes more power than the alternatives.
0-10V is a standard analogue control protocol. It applies a DC voltage signal from<0V (minimum light output 0%; control wires short-circuited) to 10V (maximum light output 100%; control wires open) to produce a varying intensity level. Since the current through the LED remains unchanged, there is no color shift at different dimming levels. 0-10V protocols are typically used for ballasts and LED power supplies to control dimming functions, where the dimming range of the power supply or ballast is limited.
DALI is a non-proprietary, bi-directional protocol specified by international technical standard IEC 62386. It provides a single interface for all light sources and lighting control devices. This protocol not only permits devices to be individually addressed, but also allows multiple devices to be addressed simultaneously via multicast and broadcast messages. The DALI is used for communications and control of lighting equipment; not just ballasts, but also LED drivers, switching devices, emergency inverters, color control, etc.
GreenBus II is a DALI-based proprietary control protocol developed for the Osram Encelium networked light management system. It enables individual dimming control for thousands of fixtures in a building and integrates peripheral devices such as occupancy sensors, photo sensors, relay-based controls, switch packs and low voltage wall controls into the Encelium system.
DMX is a digital control protocol that can be used for a variety of devices to control options such as light levels, focus, light color or rotation of lights. In a standard configuration, DMX control interfaces can provide up to 512 addresses, are programmable via software and/or mixing desks, and are suitable for complex lighting scene sequences. DMX is typically used for stage lighting and theatrical effects, but also can be used to control color-changing LED applications.
With benefits like significantly reduced energy consumption and related operating expenses—along with increased employee productivity, workplace satisfaction and improved occupant health and wellness—smart connected lighting is here today, and here to stay.
(The article is from LED inside.)