Craig DiLouie, LC, CLCP recently had the opportunity to interview Charles Knuffke, Wattstopper Systems VP and Evangelist, and Jonathan Cartrette, Sr. Systems Architect, Legrand, on the topic of protocols for an article being developed for tED Magazine, the official publication of the NAED. Here’s the transcript.
DiLouie: What is a lighting control protocol and what is its purpose in a control system applied to a nonresidential building? Why should electrical distributors care about protocols?
Cartrette: Protocols are digital “languages.” There are only a few of these languages that are standard that only apply to lighting such as DALI or proprietary ones. Standards like ZigBee, Dotdot, OCF go broader than lighting. Bluetooth® and BLE mesh are trying to move beyond lighting too.
For a distributor, I think there would be two things that they care about when it comes to protocols: Do I have to only buy piece parts within a vendor specific product line in order to have it be interoperable? Or is knowing the protocol something that actually matters to me because somebody is going to try to assemble a system from interoperable pieces?
There are proprietary protocols that are vendor specific such as Acuity nLight AIR or Lutron Vive, but that matters to a distributor only in that they need to know that protocol.
If you’re buying aware of protocols because you’re assembling a system, then the distributor needs to make sure they have what their customers are likely to ask for on their shelf – and DALI, DMX, ZigBee, Dotdot/Thread, BACnet, and others are the sort of protocols that will allow interoperability off the shelf.
Knuffke: A protocol is typically interpreted as a set of agreed upon commands to provide interoperability between components of the system. There the deeper explanation is that this may expand to include electrical characteristics of the communication. But for most applications in lighting we typically don’t worry about that.
Not every manufacturer will support a protocol in its entirety and sometimes, will make changes to work around issues outside of a protocol to add features that the marketplace is demanding. One example is DALI or 0-10V, which is a simple protocol that everyone has used for years except when the requirement changed to get light levels from a fixture down to .1 percent. Some manufacturers started implementing procedures outside the protocol – and that would be a problem is that is not taken into account.”
DiLouie: What are the basic characteristics of a protocol that differentiate one from the next? Speed, size of communication, open vs. proprietary, version of open standard, etc. What rules of thumb should distributors use for recommending controls to customers?
Knuffke: The characteristics listed are correct, however, in general you typically don’t worry about speed. It’s important to know as base whether protocols are open versus proprietary. Open, interoperable, and certified protocols are probably more beneficial.
Cartrette: Don’t stray outside the bounds of recommending controls, and go to recommending controls based on protocol minutiae, unless you have the people on staff to own those recommendations.
DiLouie: What are the most common protocols used for nonresidential lighting control, and what are their relative pros, cons, and most common applications?
Cartrette: Proprietary protocols currently rule the roost in nonresidential. There are exceptions, but for the individual devices, the majority of systems use vendor-specific capabilities to guarantee functionality in high reliability commercial installs. BACnet, DMX, and DALI show up as well, but are usually integrated by a specific services persona.
Knuffke: While proprietary protocols currently rule in the nonresidential space, there are exceptions like DALI, 0-10V, BACnet, and DMX.
DiLouie: The most popular dimming method is 0-10V, though this is implemented as a method rather than a standardized protocol. What is the difference, and what effect does this have on dimming performance?
Cartrette: 0-10V is not a digital protocol, though it is an analog signaling convention nonetheless. It highlights how hard interoperability really is, but it has been incredibly helpful for the industry to have something to depend on that generally made arrays and drivers that work together in a usable way. The effect this has on dimming performance highlights the differences though. Controls at 0-10V scale connected to drivers that perform on a 1-8V scale can result in non-intuitive behavior from dimmers and photocells, and the only surefire way to avoid these subtleties becoming major issues is to calibrate all dimming – a costly services operation. Those who ask, “Why bother?” haven’t had to demonstrate an ADR (automated demand response) shed where a 15% reduction in the signal produces a 0% reduction in wattage. But otherwise it’s often unnoticed because users expect dimming performance to be limited.
Knuffke: However, we recognize that when California mandated dimming in its energy code, the fact that most manufacturers responded by providing 0-10V capable fixtures eliminated an immediate in flood of complexity that would have stymied the market had any other “protocol” had been used.
DiLouie: For control devices to communicate, they must be able to recognize and understand each other. What are typical scenarios where lighting control systems, and lighting control and other building systems, must be integrated, and how are protocol conflicts eliminated?
Knuffke: I can say that the bottom line is ensuring that the control system has the capability of controlling the lights that are called out in the fixture schedule with those different products – and hopefully, the protocol is called out. Additionally, where the lighting control system is going to integrate to somebody else’s equipment such as a building automation system, the distributor has to be capable of and be knowledgeable about those issues.
We understand that the lighting control system has value above and beyond controlling the lights, such as data about the occupants.
Cartrette: There are no typical scenarios here. Integration even like-to-like – e.g. DMX/DMX, DALI/DALI, BACnet/BACnet – is time consuming and costly. The short answer is that the conflicts are eliminated through time with the equipment – either a head of time or on the job site. Interoperability is always simpler than integration. It’s key to examine the fixture schedule and make sure that either the fixtures choses all use the same controls protocols, or that the services and front-end equipment account for the integration.
DiLouie: The second part of the article will describe what’s new in the world of protocols. Looking at both supply and demand, how has the marketplace for lighting control protocols changed in the last 3-5 years?
Cartrette: The emphasis on data, IoT, and integration is stressing proprietary systems and in particular, data transfer speed-limited sub-GHz protocols based on 900MHz and 400Hz range technologies. Two-way communication, and especially for things over the air updates and patching and logging / trending, are driving the market to 2.4GHz solutions and standards. The security regulatory momentum, with laws on the books in CA, WA, VA, CO, OR, FL, and proposed both nationally and in other states, are highlighting the need for standards-based security. Protocols that support standards have an advantage. IECC code option’s acceleration is requiring controls to be a part of the lighting and building platforms, so the data and stance on open methodologies must be viewed more broadly than just a lighting control sequence of operation in a room.
DiLouie: Bluetooth Mesh promised very strong potential for advanced integration, particularly for centralized intelligent lighting control and integration with Internet of Things strategies. Where does the market stand on acceptance of Bluetooth Mesh? Is it a savior or just another protocol?
Cartrette: Bluetooth mesh has more promises than installations to date and the larger players, like Casambi are making proprietary extensions and delivering a system – not interoperable components. The models and integration methods for non-lighting models are today by APIs. So, the systems that are being delivered are using vendor-specific systems and tools (ETC, Douglas, Xicato) and then to the market appear no different than brand-locked solutions.
DiLouie: Proprietary protocols are argued to provide stronger assurances of interoperability, while open protocols promise the economic benefits of competition, broader adoption, and a stronger role for lighting in the Internet of Things. Where is the market now in terms of acceptance of proprietary versus open, and where is the market headed in the coming years?
Cartrette: The market is headed to open, hands down. Even if the vendor silos are enforced in other ways like the security technologies, transparency is becoming important more quickly even than interoperability. Large companies will even find this transparency challenging to sustain as the security and privacy focused regulations get more specific. On a longer time frame it seems likely that both device manufacturers and installers can add value to their business by building and maintaining systems from a variety of best-in-class, interoperable, digital components vs. continuing to rely on vendor-locked implementations.
Knuffke: Trying to meet the ever-changing landscape of security standards will be difficult for any individual company including the conglomerate. We must look outside our pond to the bigger pond where security is de facto as opposed to where security is a bolt on.
DiLouie: Staying with the Internet of Things, are protocols a roadblock to lighting play a strong role in its implementation? What is required moving forward for that to happen?
Cartrette: Not necessarily. The “smart money” is on adding capabilities and services locally so that the expertise to be reactive is in front of the customer more often and more easily accessible. It’s important to pick manufacturers who can support you in doing this – training, local resources, troubleshooting, Interoperability solves so many problems but comes with the double edge sword of eventual commoditization. When the “smart” versions of all the components become the norm the business landscape may look very different than it does today.
DiLouie: Where do you see the world of controls headed in terms of protocol development and adoption? What should distributors be looking for?
Cartrette: Make sure you are using the right products that can adhere to your local codes. For the time being this may mean that the protocol landscape is a small factor but that will change.
DiLouie: If you could tell the entire electrical industry just one thing about lighting control protocols, what would it be?
Cartrette: Security, security, security, security!