Multiple access data communication system
US4539677A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 28, 1983 |
| Grant date | Sep 3, 1985 |
| Priority date | — |
| Expiry date | Jul 28, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/413
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In this data communication system, stations linked to a single line bus exchange information in a bit-serial asynchronous format in which transitions between stop and start signals mark beginnings of information bytes. The stations use a modified CSMA/CD protocol (carrier sense multiple access with collision detection) to obtain sending access to the bus. During information transfers, durations of stop signals are less than a predetermined limiting time length, but long enough to allow general purpose processing equipment at a station to participate directly in the real time process of information reception, thereby avoiding the need for having complex and costly adapting equipment interface between the bus and such processing equipment. When any transmission concludes, the bus remains at the stop signalling level. By conditioning detection of bus availability on timeouts conducted while the bus is in this condition, stations then ready to transmit avoid interfering with on-going transmissions. After timing out, any station may begin transmitting. At this same time, all stations monitor the bus receptively. If a station not currently sending detects a start-stop transition, its pro…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.