Display backlight units are controlled with a signal. A message has an address header specifying one of an array of backlight units, and instructions for individually controlling each of the backlight units, particularized accordingly. The message is routed from a controller to a first controllable backlight unit of the display, which controllably responds to its corresponding particularized instructions. The message is sequentially routed in order from each backlight unit to the next in a chained ring configuration. Data from the backlight units is similarly routed back to the controller.