One approach to the lighting control system is the use of intelligent control-
lers. These controllers are distributed throughout a facility and manage down-
stream relay panels. The controllers and the system server are networked via
an Ethernet network, usually sharing schedules and overrides. The controller
may have a user interface panel which can be used instead of a system work-
station to program and monitor the lighting control system (Fig. 4.1).
System controllers may be modular to allow for growth. The controller
may also have several communicationsinterfaces such as an Ethernet port
and ports for RS-232 and RS-485 communications. The system controller
communicates with each of the panels through an Ethernet connection or a
BACnet, LonTalk or Modbus protocol that is routed to a backbone IP
network.
Another emerging networking approach for lighting control systems is the
distribution of the intelligence and controls further downstream to each device.
Typically this would be a network interface for each lighting ballast. This
approach centralizes the control to the network server and allows for network
interfaces to specific devices.
ControllerRelay
PanelRelay
PanelRelay
PanelRelay
PanelRelay
PanelRelay
PanelGroup
Switch Switch DimmerPhoto-
electric
SensorOccupancy
SensorGroup
SwitchControllerEthernetControllerFigure 4.1 Typical lighting control system.
Lighting Control Systems 49