Single-wire loop alarm system
US4751498A · kind A · utility
24Cited by
6References
110Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1986 |
| Grant date | Jun 14, 1988 |
| Priority date | — |
| Expiry date | Mar 11, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B25/018
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A single-wire loop alarm system in which an identification module is placed across each alarm switch. Any module which is across an open switch is powered by the loop current and, in response to a pulse count in the loop representing its address, changes the loop impedance in order to report on its status. The loop current may alternate in direction so that oppositely poled modules may be used, thus allowing a larger number of powered modules to accommodated at the same time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.