How to Build a Control System

by Jeremy Day, Application Engineering Director

Building a control system for a modern lighting installation can seem like an impossibly complex task. To simplify it, a systematic approach to understanding the needs of the design, facility, and user can be employed. In this white paper, we aim to define the questions one must answer to construct an appropriate control system.

First, and perhaps counterintuitively, one must start with the control narrative. A lighting programming and control narrative is a document that is essential to coordinate the design/construction process with a fully realized final architectural product. It defines how lighting will integrate into the space and, ultimately, how humans will interact with that same space. (See Control Narrative Whitepaper.) With the direction of the narrative, the necessary functionality of the control system can be defined. Is the intent for lights to automatically turn on and off with an astronomical time clock? Should lights be dimmed via daylight harvesting? What kind of shows or effects are desired? The answers to these questions will directly determine the size and scale of the control system. Without this narrative, assumptions will have to be made. The balancing act will be between providing a highly flexible control system and a system that is adequately capable yet cost effective.

 

Secondly, the number of controllable zones must be determined. An outdoor façade installation may have a  floodlights-only zone, or it could also include linear grazing fixtures as well as direct view elements. Each of these zones will need to be controlled independently, and the control system must be sized appropriately. 

 

Of note, to create a dynamic lighting system, the number of channels needed to put the system together must be well understood. A channel is defined as a single controlled attribute. For simple dimming only lights, one channel would be needed to control that dimmed intensity. For tunable white lights, two or three channels would be needed to adjust intensity and color temperature, depending on the exact configuration of that fixture. A color changing RGBW light would most likely need four channels, one for each Red, Green, Blue, and White control.

A simple system comprised of only a white light fixture with a dimmable, static color temperature will need only one DMX channel per zone. A more complex system, such as a linear run of color-changing, RGBW fixtures, could potentially need four channels per foot (or even eight per foot in exceptional circumstances). Of course, if the control narrative is clearly defined as, "this linear run will only fade from Color 1 to Color 2 in unison," that would eliminate the need for individually addressed fixtures and could significantly reduce the cost of the control system.

 

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Another consideration is requirements for Input and Output (I/O) signaling and integration. Some common examples of these I/O's are:

  1. Fire alarms,
  2. Emergency conditions,
  3. Building automation systems,
  4. Occupancy and daylight sensors
  5. Shades
  6. Wind or other atmospheric sensors
  7. A/V integration

The control narrative will describe the necessary interactions, but the physical locations and quantities of I/O will determine the number of interfaces in the control system. A system comprised of only a few lights might still require a larger more sophisticated control system based purely on the complexity of the I/O needs.

 

 
 

The next key component to consider are User Interfaces: How will the users interact with the system, turn lights on and off, raise and lower, change colors, advance scenes, etc.? Where will these interactions take place? You might need a keypad at every office and door, but what about the exterior lights? Where will they be controlled? In addition to physical control stations like keypads and touchscreens, virtual control like web pages and smart devices need to be considered and allotted for. 

 

 
 

Figure 1 - A Touchscreen control station

 
 

Finally, a consideration to make is whether to base a control system off DMX/RDM (a digital, daisy chained system for smaller systems) or Ethernet (a highly flexible and scalable system for projects of all sizes and complexities). Below are some key advantages of each protocol.

 

Now that the requirements of the control system have been defined, the type, scale, and specifics of the control system can be chosen. Often tiers exist in control systems, sometimes defined by the number of universes, user interfaces, or I/O triggering. One specific requirement may bump the system up into a higher tier. Having a complete understanding of the scope of the control system will ensure that all requirements are covered by the capabilities of the control system. Lumenpulse Sales Engineers are experienced in the consultation and execution of control systems of all sizes and are available to consult on the needs, options, and budgets of this critical element of all lighting systems.

Understanding of the desired functionality of the lighting system will help right-size the control system to meet all needs without overspending and overcomplicated a project. Control systems come in many shapes and sizes, with tradeoffs in capabilities, cost, and complexity. Lumenpulse is here to help clients balance these elements and choose the correct system at the right price and feature set.