Multilevel signaling system and method

摘要

A fire detecting system can mix fire detectors, such as smoke, flame, or, thermal detectors on a common loop, or zone, with gas detectors. Signals indicative of gas can have one amplitude while those indicating fire can have a different amplitude. Duty cycles can be varied to indicate other conditions, such as trouble conditions.

主权项

1. A detector comprising:
an ambient condition sensor; and control circuits coupled to the sensor; wherein the control circuits include an interface that interacts with a control panel through a two-wire loop having a plurality of other associated ambient condition sensors, where the control circuits are coupled between the ambient condition sensor and the two-wire loop, where, in response to a first condition, the interface transmits a first signal having a first amplitude and a first duty cycle, the first duty cycle being less than a predetermined value, where, in response to a detected ambient condition, the interface transmits a second signal having the first amplitude and a second duty cycle, the second duty cycle being greater than the predetermined value, and where the first amplitude is between a normal open circuit voltage of the two-wire loop and a minimum operating voltage of the other associated ambient condition sensors, the detector relating signaling of the first and second signals is transparent to operation of the other associated ambient condition sensors.