System for monitoring switch locations
US4970508A · kind A · utility
Inventor
Key dates
| Filing date | Jun 5, 1989 |
| Grant date | Nov 13, 1990 |
| Priority date | — |
| Expiry date | Jun 5, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B25/14
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A system is provided for electronically monitoring a group of sensor switches employed at remote locations in security or alarm systems. To monitor the status of individual switches, a matrix of conductors is employed. The matrix has a predetermined number of send conductors by a predetermined number of return conductors. Switch circuits each having a diode connected in series with one of the sensor switches are connected at selected crosspoints of the matrix of conductors between respective send and return conductors. Line selection circuitry responsive to an input signal from a computer selectively permits the supply of a sourcing voltage potential to at least a selected one of the send and return conductors and the supply of a sinking voltage potential to at least a selected one of the remaining send and return conductors. Monitoring circuity senses current flow through the selected send and return conductors supplied with the sourcing and sinking voltage potentials to monitor the status or change in status of any selected switch or conductor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.