Patent ID: 9747782
Date: 2017-08-29
CPC Classifications: G08B,H04L

Claim:
1. A wired data communications network for use in a building for the detection of fire or intrusion, comprising: a control unit connected by cable to a series of uniquely addressable transducers for the transmission and reception of data in a polling signal, wherein each transducer has a memory for control data and for its own unique address and is configured to respond to one or two predetermined start voltage pulses in the polling signal to clear any control data stored in its memory and then to respond to control data and address data in the polling signal to compare the address data with its own unique address and to store the control data if the addresses match and, only if they match, then to transmit data on the cable to the control unit representative of its own status; at least one of the transducers being further configured to determine whether the control data in the polling signal has a predetermined characteristic indicative of extended data and, only if so, to respond to the second one of the predetermined start voltage pulses received immediately after the control data and address data in the polling signal to retain in its memory the control data and address data as extended control data and extended address data, and then to respond to a sequence of further control data and further address data to compare its own unique address with a unique address represented by the combination of the further address data and the extended address data and, if and only if they match, to store the extended control data and the further control data, and then to perform the said transmission of data representative of its own status to the control unit and any other process dictated by the extended control data; and the control unit is configured to generate and to transmit the polling signal including the extended control data and the extended address data and to receive and process the data representative of its own status from the transducers that it has thereby addressed.