Autonomous terminal data communications system
US4471481A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 11, 1981 |
| Grant date | Sep 11, 1984 |
| Priority date | — |
| Expiry date | Feb 11, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F13/376
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A data communications system which includes a plurality of terminals TL.sub.1 -TL.sub.5) and a data bus (DB), wherein each of the terminals has autonomous access to the data bus. Each terminal includes a receiver (114) which is normally enabled to receive messages on the data bus and which provides a signal (ADA) signifying the absence of messages. A transmitter (120) within each terminal includes a protocol control unit (140) which enables the transmitter to initiate message transmission only upon (i) the detection of an absence of messages on the data bus whose duration substantially equals that of a sync gap that is common to all of the terminals, and (ii) the subsequent detection of an absence of messages on the data bus whose duration substantially equals that of a terminal gap that is unique to the terminal, with the duration of the sync gap being greater than the duration of any terminal gap. Within each protocol control unit, the sync gap is detected by a sync gap timer (160, 162, 164, 166, and 168) and the terminal gap is detected by a termial gap timer (190, 192, 194, 196, and 198) which is enabled (169) by the sync gap timer, with both timers being responsive to signal A…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.