Lighting Control Protocol

Lighting has always been a prominent application of electricity since the time Thomas Edison invented the incandescent lamp. The lighting sector, over time, has witnessed many technological advances with the introduction of fluorescent lamps and LEDs. Regardless of the lighting element used, it is always fascinating to automatically control them to create the ultimate smart home.

As shown in the preceding image, a typical lighting control system includes a microcontroller unit (MCU) acting as the brain, sensors for control feedbacks, and some communication interface. These may be wired or wireless to make it controllable by external means. The lights are regulated by the MCU using control signals. This typically involves a pulse width modulation (PWM) or analog signal. There are also other drivers available which come with serial interfaces like I2C or SPI. The sensors are used to automate the lighting control and also for safety reasons. A simple control example may include gesture or motion control, whereas safety measures may include temperature sensors use to detect lighting panels get overheated.

The following portion of this document concerns different communication protocols available for lighting applications. If you want to learn about drivers in depth, refer to the LED Driver Selection document.

Zigbee IP

ZigBee IP pioneered the open standard for an IPv6-based full wireless mesh networking solution. It also provides seamless Internet connection to control low-power and low-cost devices. Dozens of different devices can be connected into a single control network. Zigbee IP was designed to support Zigbee 2030.5, previously known as Zigbee Smart Energy 2.

It comes with the following features:

  • Frequency bands: 2.4 GHz
  • Bandwidth: 2–100Mbps (Gigabit also available)
  • Topologies supported: Tree, Mesh
  • Range (in meters): 1–100

Wi-Fi

Wi-Fi is based on IEEE 802.11 standards and designed for wireless local area network (LAN).

It comes with the following features:

  • Frequency bands: 2.4 GHz
  • Bandwidth: 2–10 Gbps
  • Topologies supported: Tree
  • Range (in meters): 1–100

Bluetooth/BLE

Bluetooth is a short distance communication protocol targeted towards personal area networks (PAN).

It comes with the following features:

  • Frequency bands: 2.4 GHz, 915Mhz (Americas), 868Mhz (Europe) and 920 MHz (Japan)
  • Bandwidth: 1Mbps
  • Topologies supported: Tree
  • Range (in meters): 1–10
  • Max. Nodes per network: 7

Z-Wave

Z-Wave is a proprietary wireless communication protocol developed by Zensys and the Z-Wave Alliance. It is targeted towards low-power, low-bandwidth applications like home automation. The ITU-T recommendation G.9959 defines the PHY and MAC layer of the Z-Wave protocol. It uses GFSK as the modulation technique and comes with IPV6 support.

The following features are available:

  • Frequency bands: sub-GHz frequency band
  • Bandwidth: 100kbps
  • Topologies supported: Mesh
  • Range (in meters): 30
  • Max. Nodes per network: 232

ZigBee

ZigBee is a low-power digital communication protocol based on the IEEE 802.15.4 standard. It is designed for personal area networks or small networks. The protocol is targeted towards home automation and sensor networks.

It comes with the following features:

  • Frequency bands: 2.4 GHz, 868MHz, 915 MHz
  • Bandwidth: 20 to 250Kbps
  • Topologies supported: Star, tree, cluster tree, and mesh
  • Range (in meters): 1-75 and more
  • Max. Nodes per network: 65,000

6LowPAN/ Thread

Thread is an IPV6 based low-power mesh networking protocol designed for home automation. The thread is based on the broadly supported IEEE 802.15.4 radio standard.

It comes with following features:

  • Frequency bands: 2.4 GHz
  • Bandwidth: 20 to 250Kbps
  • Topologies supported: Mesh

Digital Addressable Lighting Interface (DALI)

DALI is an open, international standard protocol developed for lighting control applications. It enables two-way communications so that the status of a DALI enabled device can be queried or be reported. DALI is specified by technical standards IEC 62386 and IEC 60929. A typical DALI network consists of one or more slave devices, a controller and a power supply. Each device has a unique address between 0 and 63, thus limiting total number of devices to 64. However, DALI gateways can be used to extend the network. Data is transferred between the controller and devices using an asynchronous, half-duplex, serial protocol over a two-wire bus, with a fixed data transfer rate of 1200 bit/s. The bus is used for both data and power. It is polarity insensitive as each device comes with an input bridge rectifier. A wireless extension of DALI is also available via RF.

Digital Multiplex (DMX) Protocol

The DMX512 standard describes a digital data transmission method between lighting equipment and devices. The communication is unidirectional and does not have any error correction or detection schemes. In a typical scenario, the controller in the network sends packets between 24 and 512 data values which are consequently received by all the devices in the network. These devices are preconfigured to recognize the data value corresponding to them.

EnOcean

EnOcean is a proprietary wireless lighting control protocol. In the EnOcean network, the load switching is done locally at the device end. Every device in this network has a 32-bit serial number. Data packets are transmitted at a rate of 120kbps. Each packet is 14 bytes long with a 4-byte data payload. To avoid collision in the network, each packet is sent three times at pseudo-random intervals. The frequency used for the majority of the devices is 868.3 MHz. In the US, EnOcean devices increasingly use the 315 MHz frequency. A license from EnOcean is a must to use this proprietary protocol.

Konnex (KNX)

The KNX protocol is used extensively for lighting controls in continental Europe, especially in Germany, Austria and Switzerland. The KNX standard supports three modes of operation, namely ‘Automatic’, ‘Easy’ and ‘System’. In ‘Automatic’ mode, the device’s primary use is on/off. The ‘Easy’ and ‘System’ modes support intelligence and customizations. KNX uses twisted pair cables to connect devices in a daisy-chained fashion. The network supports 4800 and 9600 baud rates. The communication cable may also carry power to the devices if power line communication (PLC) is used. Alternatively, devices can communicate using RF communication. The KNX standard permits the use of wired and wireless Ethernet communication between networked controllers.

LonWorks

LonWorks is a peer to peer network protocol in which all the devices communicate with each other. Each node contains three microprocessors known as neuron cores. Of the three cores, two are used for communication, and the remaining one is used for node related applications. The microprocessors are typically, but not limited to, 8-bit, depending on the complexity of the project. The communication involves a twisted pair, Ethernet, power line, coax or fiber. A domain may contain up to a maximum of 256 groups. The groups are a collection of nodes within a domain and contain up to 64 nodes. Each node can accommodate up to a maximum of two addresses which allows for a total of 32,000 devices on a system.

Musical Instrument Digital Interface (MIDI)

MIDI enables electronic musical instruments, computers and other equipment to communicate, control and synchronize with each other. However, the actual audio signal is not transmitted by it. Instead, it transmits digital event messages, such as pitch and intensity of notes to play. The MIDI Manufacturers Association (MMA) was formed as an industry user group and now administers the standard. MIDI Show Control, an extension of MIDI. It is a real-time protocol that permits all 28 IES TM-23-11 types of entertainment control devices to talk with each other and with computers to perform show control functions in live and pre-recorded entertainment applications. Basic MIDI messages are either 2 or 3 bytes long (16 or 24 bits), and enable addressing of 256 different controls (128 using “Note Number w/Velocity” messages and 128 using “Controller Number w/Value” messages) on 16 different devices (4096 controls).

Society of Motion Picture and Television Engineers (SMPTE)

The interconnect cabling used is most commonly two-conductor, shielded audio cable. It can be either unbalanced (single-ended) or balanced (differential). It doesn’t matter which is used, or even if it is mixed in a given installation, as long as proper termination and impedance matching is observed. When it comes to limits/extents, most SMPTE reading devices support one input, while a source may support multiple outputs. The typical output will be +4 to +8 dBm, with a source impedance of 50 to 600 ohms. This is roughly a 1.2 to 2 volt, peak-to-peak signal. The total run length is difficult to determine due to the nature of the signal. However, audio compression/expansion, equalization, noise canceling and automatic gain control should be eliminated and the original waveform maintained to optimize clean signal transfer. Signal conditioning may be required, depending on installation. A number of conditioning techniques and devices are available.

Architecture for Control Networks (ACN)

ACN is a suite of protocols used primarily for theatrical lighting. The Entertainment Service and Technology Association maintain the standard. ACN is a bi-directional protocol with the ACN devices advertising themselves in order to be dynamically discovered by the controllers ACN equipment exposes “properties” that may have values read or written to. Upon receipt of a subscription request, ACN equipment will publish changes to “properties” back to the subscriber. ACN contains the definition of an XML based language (DDL) for describing the “properties” of equipment. Any ACN device will give out its DDL file upon request so that a controller can always find out how to control a device it hasn’t encountered before.

Building Automation and Control Networks (BACnet)

The BACnet standard defines a set of objects and services that are used to generically model-build control systems. Objects typically used for lighting control include the Binary Output Object (BO), used to represent a relay or a group of relays, and the Analog Output Object (AO), used to represent a dimmed lighting load. Each of the BACnet objects has a set of properties that describe its purpose and functions. A particularly useful object property for lighting control is the description property that allows a text string to be stored with the object to describe the function of the load represented by the object, such as the circuit number or room name where the lighting is located.