This piece was originally published in the February 2017 issue of electroindustry.
Robert Hick, Vice President of Engineering, Lighting, and Energy Solutions, Leviton Manufacturing Company
Over the past 20 years or more, several control protocols have become popular for indoor and outdoor lighting systems. In North America, only a few “open” basic dimming protocols have been favored within the general lighting industry; the more complex digital communications have been handled by proprietary digital protocols developed by the United States–based control manufacturers.
Times are changing, with the advent of flexible light-emitting diode (LED) and high-tech initiatives such as the Internet of Things and networked lighting controls. Just as a pioneering spirit characterized the 19th-century, a new manifest destiny has emerged as many organizations and consortiums have staked their claims in the new Wild West of lighting protocols. The protocols fall nicely into categories I call the pioneers, early prospectors, and gold rushers
The first settlers arrived in the half of the last century and ran the town until LEDs showed up.
Phase-cut: While some may not call it a true protocol, phase-cut dimming was the first practical, commonly used method of controlling general lighting. Phase-cut dimming became popular in the 1960s and most homes in the United States continue to use it. Phase-cut dimming works by chopping each cycle of the alternating current (AC) line voltage waveform.
There are two basic types of phase-cut protocols. The original and most popular in the U.S. is the leading edge (forward phase) dimmer, also known as a triac dimmer, which turns on the current to the light load for a variable amount of time during each AC cycle. The other is the trailing edge (reverse phase) dimmer that turns off the current for a time during each cycle. Trailing edge became popular for general use in Europe and elsewhere. In the U.S., these were called electronic low voltage (ELV) dimmers and only used for dimming special types of low voltage lighting.
Life was grand when phase-cut dimmers were used with incandescent lamps. Since incandescent lamps all had the same basic electrical characteristics, standardization was not necessary and manufacturers invented many variations of dimmers that are fully compatible with the venerable lamp.
Fluorescent lamps, however, presented challenges, but since there was a limited group of ballast manufacturers, solutions were generally available. Trouble arrived with the light-emitting diode (LED) revolution. New manufactures of LED lamps and drivers appeared overnight with no standardization. Incompatibility and mayhem reigned until 2013 when NEMA rode into town with SSL 7A Phase-Cut Dimming for Solid State Lighting—Basic Compatibility, which is bringing order to this ruckus.
0–10 V Dimming: The 0–10 V (also known as 1–10 V) dimming protocol showed up around 1990 as a way to control electronic ballasts. This protocol was standardized first in IEC 60929 AC and/or DC-supplied electronic control gear for tubular fluorescent lamp—Performance requirements and then in ANSI C82.11 American National Standard for Lamp Ballasts—High-Frequency Fluorescent Lamp Ballasts. Both standards have minimal performance requirements. At the same time, a fundamentally different version of a 0-10 V protocol became popular in the theatrical industry.
The IEC 60929 and ANSI C82.11 standards do not specify such details as the direct current (DC) control voltage-to-light level curve. Initially, this was not a big problem since the number of electronic ballast manufacturers was small and variations were not significant.
Again, the LED revolution brought trouble, with confusion between the very different theatrical and ballast versions of 0–10 V protocol and very different dimming curves causing incompatibility and unexpected performance. NEMA supports a proposal for ANSI C137.1 0–10V Dimming Interface for LED Drivers, Fluorescent Ballasts, and Controls, which ropes in the performance of 0–10 V LED drivers and controls.
DMX: DMX-512 was the first popular digital control protocol for lighting, standardized in 1990 by the United States Institute of Theatrical Technology. By today’s standards, it is a very simple serial protocol that involves repeatedly sending data over a special type of twisted pair wire at 250,000 bits per second. Since the data rate is relatively high, the wiring type is very specific and must be wired in a daisy-chain fashion. The data consisted of a start byte, followed by up to 512 bytes, called channels, representing lighting levels for a number of electronic dimmers controlling the lighting fixtures.
As moving and color-changing fixtures became popular, DMX channels controlled the position and color attributes of these fixtures in a non-standardized manner that was casually shared between control and fixture manufactures. Although DMX was mostly used in the theatrical industry, it still provides basic control for many general lighting products including many LED systems worldwide.
DALI: DALI, which stands for digital addressable lighting interface, was standardized in 2002 by the IEC as an annex to the IEC 60929 electronic ballast standard. Later it was separated into its own standard, IEC 62386 DALI Part 101: General requirements—System components. It has grown significantly, with many new parts added to keep up with new lighting technology, including LEDs. DALI uses a pair of wires to send two-way digital communications from control devices to the ballasts and drivers. Since the data rate for DALI is 1200 bits per second, the wire type is very flexible, with wiring varying from 18 AWG to 12 AWG standard building wire.
DALI’s compatibility is due to maturity, a high level of standardization, an extensive set of lighting commands, and continuous evolution. It is widely accepted for lighting controls in most parts of the world, except North America. Its growth in the U.S. has been slow but expected to improve as manufacturers rely more on open protocols versus proprietary protocols. Last year, DALI version 2 was published, adding specifications for control devices and multi-master capability. New standardization projects are underway for wireless DALI and extensions such as demand response and energy measurement.
The Wild West of lighting protocols heated up when the original wireless bunch came to town. Z-Wave, ZigBee, EnOcean, and a few proprietary cowboys shook things up.
Z-Wave: This was one of the first technologies to enable simple mesh networking in early 2000 and resulted in a spurt of wireless lighting products for the early days of smart homes. The protocol was widely compatible, due not to standardization but to a special Z-Wave chip that was required in all products. Z-Wave was used primarily in homes and did not gain much commercial usage.
ZigBee: This mesh network had a slow start in lighting control, as it took many years to work out an open standard that could provide most of the needs for automation and lighting markets. As ZigBee matured, it was adopted in both residential and commercial markets. ZigBee, like DALI, is constantly evolving and is becoming a mature and proven protocol.
EnOcean: EnOcean started in Germany as a solution for a very low-power wireless protocol that can be used with energy harvesting controls. EnOcean is a simple protocol that sends a very small data packet, only when needed, using very little energy. It is mainly used for commercial lighting control endpoints, including wireless occupancy sensors, photo sensors, and switches using energy harvesting such, as solar cells for power or very long-life batteries.
EnOcean protocol’s low-power and non-mesh architecture limit its range. ZigBee Green Power and other new wireless protocols are reaching very low power levels and may be a challenger for the energy-harvesting powered devices.
Proprietary wireless: Several manufacturers have developed proprietary wireless protocols, some modifying IEEE 802.15 (a communication specification) radios similar to ZigBee, while others have fully proprietary radios and protocols. Some have been very successful; others may ride into the sunset as open wireless protocols become more capable and mature.
The arrival of the Internet of Things (IoT) created a gold rush, and a frenzy of prospectors now seeks to make it big in all sectors of the high tech industry. New protocol consortiums are springing up like boom towns and shooting it out in the smart home frontier. The Design Lights Consortium specification for networked lighting controls has been successful in bringing this gunfight to commercial lighting lands as manufacturers look for solutions.
This following list is not complete, as protocols are popping up and disappearing as fast as prairie dogs.
Bluetooth/Bluetooth mesh: Bluetooth wireless protocol’s inclusion on almost every smart phone gives the protocol a natural key position for control and configuration of lighting systems. The original Bluetooth protocol is mature, easy to use, and can establish a point-to-point connection. Coupled with a smartphone app, it provides a powerful and ubiquitous tool to make residential and commercial lighting systems easier to set up and operate. A standard for a mesh version of Bluetooth will be released soon, and proprietary versions of Bluetooth mesh are already showing up in commercial lighting systems.
Thread: Thread is a wireless protocol proposed by Thread Group (composed of Nest/Google, Samsung, and others) that uses a protocol known as 6LoWPAN, which is easily addressable by computer systems. It is a similar radio to the ZigBee protocol. ZigBee Alliance and Thread Group have recently announced that they have demonstrated interoperability.
AllJoyn: AllSeen Alliance is a consortium of Qualcomm, LG, Sharp, and others that is promoting the AllJoyn Framework as a contender for appliance control protocol and have also developed models for basic lighting control. AllJoyn primarily uses TCP/IP Ethernet and Wi-Fi for communication transport but also claims wireless and power line carrier transports.
HAP: Apple’s HomeKit Accessory Protocol uses Bluetooth LE or TCP/IP (Wi-Fi) for transport. Of course, lighting is a big part of HomeKit. The details of the protocol are only shared with partners.
EchoNet: This protocol was originally designed for home audio/visual and appliance control. A consortium of Japan-based manufacturers is promoting this IEC standardized protocol for residential and commercial lighting control. Transports include TCP/IP Ethernet and Wi-Fi, infrared, and power line carrier.
CoAP: The Constrained Application Protocol (CoAP) is promoted by Cisco and others for power over Ethernet (PoE) lighting applications. This, of course, runs on Ethernet, and its simplicity and security make it a contender for the wired Ethernet and Wi-Fi space.
LoRaWan and Sigfox: Long-range and low-power 900 MHz protocols for city coverage may be used for outdoor lighting such as LoRaWan and Sigfox.
Cellular: LTE, 3G, and GPRS protocols are being promoted for outdoor lighting control.
Proprietary Modules: Several manufacturers now package proprietary wireless protocols into modules used by lighting partners as a cohesive but proprietary platform.
Taming the Frontier
The Wild West was a place of opportunity for the exploration of untamed territories. Rules were few and conflicts abounded. With the disruption caused by LED lighting, new wireless technology, and the IoT, lighting has become a new Wild West. As winners emerge and the promises of IoT take shape, this new frontier remains exciting.