DS486Q features quad beams, easy alignment (sounder, LEDs, and voltage readings) and two coverage ranges. It also provides four mounting options, environmental discrimination circuits, and multiple channel operations. The DS486Q detector has separate transmitters and receivers. The transmitter sends an invisible infrared beam to the receiver. If the beam is broken, the receiver signals an alarm. Multiple channel operation provides increased system flexibility. It features several functions, including environmental discrimination circuitry that monitors the gradual loss of signals due to dust, fog, rain, snow, and so forth. Normally-closed outputs open when the signal loss reaches 90 percent. Multiple channel operation configures the detectors for up to eight different channels. This also allows multiple units to be used near one another without the possibility of receiver cross-talk, and is particularly useful when stacking multiple beam sets.