Recently, a seminar on the present and possible future of LED lightsources occurred, and its results are worth sharing. The primary topic was lighting‘s “digital revolution,” which started in the 1970s with the concept of integrating multiple components on one “die” – the “integrated circuit“. Today, the keyword of “integration” of multiple parts impacts lighting components. Because LEDs are semiconductor devices, other semiconductor-based functions can be (and are already) integrated on the same chip. Temperature/brightness/current/voltage sensors, dimmer/drivers, motion sensors, video cameras and digital and/or wireless bus interfaces are examples.
Integration of lighting components in the sign industry’s sense primarily means lighting control. It all began with remote dimming from a central control room behind the stage in theatres. Currently, the most important wire-bound communication/lighting-control systems are:
• 0-10 VDC (or 1-10V), analog-control voltage. The end units aren’t addressable; each separate group of lamps needs separate control wiring.
• DMX, a three-wire, digital, daisy-chain protocol with, at maximum, 512 end units and one designated master controller. It originated from stage lighting, but it’s also now used in more complex, architectural-lighting applications. It’s only one-way communication; addressing occurs in the end unit (the controller puts out all channel settings in one common telegram periodically).
• DALI (Digital Addressable Lighting Interface), a two-wire, polarity-independent, serial, digital communication with 1,200 baud (slow). Each unit can be a transmitter and receiver, with up to 64 units on one bus. Larger systems need central controllers with multiple bus outputs. The DALI protocol first permitted a failsafe (in case of data-communication failure) setting of the end unit, and an interrogation of the end unit by the master for a status word to be transmitted. Its purpose was to centrally check any lamp failure without having to visually inspect every lamp periodically.
For DALI installations, the control bus wiring must be insulated for the full mains voltage (unit insulation between the control and power side doesn‘t comply with Safety Extra Low Voltage requirements), but it is permitted to pull the wiring through common conduit together with power wires.
• KNX (which evolved from the industrial EIB bus) is a building-control bus system initiated by the Konnex Group. Lighting control is only part of its function, and there are many parts manufacturers from which to choose. It requires two-wire, two-way communication, and a rather complicated addressing and routing structure that needs licensed software for the central controller and setup. Some end units can handle the controller function in smaller networks.
But today’s mobile world calls for remote control and surveillance (not only) by the owner. A few years ago, such projects always employed interfaces between a wired standard and the Internet as a communication platform.
I remember a request in the early 2000s from the Middle East, where a sheikh wanted to control the lighting color and intensity in his seven bedrooms from his cellphone (imagine the reasons yourself). At these times, wired control solutions were standard, and interfacing for cellphone Internet access remained custom-tailored.
The trend is accelerating, so now, wireless communication between the devices and the controller have evolved into many different standards, which often make use of standard Internet computer communication. The common keyword in all press releases is the “Internet of Things”.
Here, several companies initiated communication protocols (different from normal, computer-file transfer or website loading) to access existing, lighting-control devices from a central (or remote) building-control system. Thus, these interfaces mainly transported an existing protocol -like DMX – into another form of packet-data communication.
One example is the ArtNet protocol, which transfers standard DMX data packets onto the Ethernet/TCP/IP. This permits the use of existing data-network infrastructure in theaters and extends the addressing range far beyond the limits of the DMX-512 standard.
But then, in the computer world, the trend was to go wireless for network access, with portable devices like “smartphones“ or tablet computers. The lighting industry saw potential to go wireless too, especially for home or small-office applications. The integration has progressed so far that today’s power supplies include the controller, the communications devices and the sensor elements. This is not yet widespread, but first products are expected to have all these functions integrated on the LED module level.
Current products for wireless control are based on different, short-range, computer-communication platforms. Here are a few:
• WiFi – IEEE 802.11b/g/n protocol is actually an Internet-communication protocol for 2.4- and 5GHz, wireless-computer communication. Due to the low transmitting power permitted, the range is approximately 150 to 200 ft. All WiFi-based, lighting-control systems are based on standard TCP/UDP data packets (see graphics).
• Bluetooth – A short-range, wireless-communication standard for computer accessories, like keyboards, headphones, etc. (to avoid wires on your desk), but it‘s rarely used yet for lighting-device control. Security of the data connection is questionable; software (drivers) requires certain efforts to match the control computer and its operating system.
• zigbee – A wireless-communication standard similar to Bluetooth, intended for short-range networks with low, data-transfer rates, with the special “zigbee light link” profile. No coordination master or trust-center is intended in this standard; a fixed key is used for encryption. This master key can‘t be changed, so, as more devices are used, the more likely security is impaired. The manufacturers state “For lighting control, the security is not so relevant.“ I won‘t confirm this.
• Z-Wave – a system-on-a-chip initiated by the Sigma Design Company. It’s a mid-range, home-automation standard focused on the electrical-appliance industry (washing machines, HVAC units, etc.). Every mains-powered unit can act as an end unit and router/forwarder simultaneously; thus, its wireless range is extended by any other unit. Z-Wave is not yet widespread.
Because most systems are “protocols” based on available Internet and cellphone networking structures, or they form a separate network by themselves, it is never a “plug and play” system. Read: In most cases, a computer-network administrator is needed to assign addresses, functions and control elements to every device, even if software often is supplied by the manufacturer (user/application software is usually restricted to certain operating systems/devices).
In the sign industry, if sign and control devices (like PCs, smartphones or tablet computers) are supplied together by the signshop, this network configuration can be carried out in the shop before the sign is installed – but if the customer’s existing computer shall become the control center, the network specialist is needed onsite for setup. In rare cases, signshops employ their own network specialist; thus, such external cost needs to be considered when quoting a “smart” sign-lighting system.
The predicted future is that what today is part of the lighting controller – the digital interface with all sensors – will be integrated on a “COB – Chip on Board” base onto each LED module. Thus, LED modules will be available with integrated, infrared, motion sensors, or streetlights with intelligent cameras and image-recognition software that distinguish a rat or stray cat passing by from a pedestrian, so the light could be turned up from a dim, constant level to a normal, streetlight level only when needed by pedestrians.
However, modern streetlights are already equipped with surveillance cameras, police access to light, built-in cellphone repeaters, and, possibly, an optional siren/loudspeaker to address the public. George Orwell could not have better foreseen this in 1948.
Currently, every LED module measures its own brightness, regulates it to a given level, and reports when voltage, current temperature and light output is not within certain limits. “Change me; I will go bad soon”.
Control and report is all based on wireless Internet connections, and common end-user interfaces like smartphones or tablet computers. Signshops might like the ability to get reports from “their” signs so the signshop can tell the customer his sign needs service – before the sign owner sees the sign isn‘t functioning.
But what sign owner wants the signshop (or any other third party) to change brightness or switch the sign on/off remotely? Just re-read my article on smart electric meters (see ST, May 2013, page 28) – every “smart“ meter has a remote-control mains “off“ switch inside.
One could imagine an LED manufacturer building in a secret remote control for every LED module sold (like some Far East Internet routers had to have remote access built in upon a U.S. intelligence agency request to facilitate tapping Internet connections).
All this is not only possible, but already reality. (Darek Johnson‘s column [see ST, June 2015, page 16] addresses legal problems associated with buying material items, where you can‘t obtain ownership of, but only the function of, and you must depend on something you don‘t own.)
Smart sign lighting with all possible remote access is said to be the future of electrical signs. I don‘t want to paint technology‘s outlook as bleak, but my advice is: Always, always stay smarter than your sign, component or LED module.
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