The Q4C is a multi-channel controller display and alarm unit that utilizes digital communications to interface with a maximum of four remote digital QEL transmitter/sensors. These are used to measure a wide variety of toxic gases such as CO, NO , NH , H S, SO , Refrigerants, and Combustibles. The RS-485 communication is connected via a 4-wire 2 3 2 2 multidrop daisy chain configuration to reduce the overall installation costs of the system. Alarm setpoints are set through

the front keypad or through QEL supplied software that is downloaded to the controller from a PC or laptop computer. Common relay configurations include voting, averaging, delay on actuation and de-actuation, normally or not-normally energized and latching. The audible alarm has three buzzer settings, continuous, intermittent and double-tap intermittent.