Abstract: A method and apparatus detect devices on a line in an alarm system that have been assigned a common or duplicate address, or that are located beyond the maximum allowable wiring distance on the line, or that are poorly connected to the line thus providing weak answers to communications from the control panel. The method and apparatus operate by polling suspect addresses of devices on the line while adjusting the sensitivity of the receiver. The sensitivity of the receiver is lowered by an amount corresponding to the test being performed. In duplicate address testing, the sensitivity of the receiver is lowered by an amount such that a single response from only one device having the polled address will not be sensed, but combined responses from more than one device having the same address are sensed.

Abstract: An output voltage supplied to alarm devices in an alarm system is adjusted according to either a standby condition or an alarm condition. In the standby condition, a power control circuit adjusts power so that a standby voltage is supplied to the alarm devices which allows the alarm devices to respond to poll messages regarding their alarm status. An alarm condition is triggered when an alarm device responds with an alarm status indicating an alarm condition. During an alarm condition, the power control circuit adjusts power to provide a higher voltage to the alarm devices in order to allow additional alarm device functions to be operated.