EP0006325A1
Expired / Lapsed
EP
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Data transmission system for interconnecting a plurality of data processing terminals
Assignee: FMC Corp
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Filing: 1979-06-05
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Granted: —
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Expires: 1999-06-05
Abstract
Abstract A data bus system is disclosed which includes a plurality of interconnected active terminals (1, 2, 3, 4), i.e., terminals which receive serial data from one terminal and retransmit it or transmit new data to another terminal. The data is transmitted within a continuous series of time frames of predetermined length with each time frame being initiated by a control word transmitted by one of the terminals designated the controller terminal (e.g. 1 or 3). Each terminal includes a counter which counts the bits between control words, and each control word identifies the controller terminal so that each terminal can synchronize its counter with the counter at the controller terminal in accordance with the propagation time of data from the controller terminal. Logic circuitry at each terminal enables one (e.g. 1 or 3) of a plurality of the terminals to assume the function of the controller terminal should the presently designated controller terminal fail to generate control words. The system can therefore continue to operate in the event of partial interruption of the bus. Within each time frame, the terminals initiate data at times in accordance with the counts of their counters, and the transmitted data identifies each receiving terminal which directs it to users tied tothat terminal.
Inventors
- 👤 Keith S. Champlin
- 👤 Ernest C. Preimesberger
- 👤 Larry A. Meyer
- 👤 George W. Miller
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 22:03
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/0078; H04L1/0083; H04B; H04B1/00; H04B1/74; H04L12/00; H04L12/28; H04L12/42; H04L12/427; H04L12/43; H04L12/437
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
184 words
A data bus system, comprising a plurality of terminals (1, 2, 3.....) interconnected in a continuous chain for distributing serial digital data in a format which includes a continuous series of time frames of predetermined length, each time frame including data preceded by a control word which defines the start of the time frame and which is provided by one of the terminals (1, 2, 3.....) designated as the controller terminal (e.g.l or 3), characterised in that each terminal (1, 2, 3.....) includes circuitry (30) for receiving the data and the control word from one terminal (1, 2, 3......) and re-transmitting it to another terminal (1, 2, 3 .....) in the chain, in that a plurality of the terminals (1, 2, 3 .....) are broadcast terminals (1, 2, 3 ....) each capable of initiating and transmitting the data within the time frames to all of the other terminals, and in that each broadcast terminal includes circuitry (42a, 42b, 48a, 48b) responsive to the control word to determine whether or not that broadcast terminal is to initiate and transmit data within a given time frame.
Claim 2
Dependent Claim
184 words
A data bus system, comprising a plurality of terminals (1, 2, 3.....) interconnected in a continuous chain for distributing serial digital data in a format which includes a continuous series of time frames of predetermined length, each time frame including data preceded by a control word which defines the start of the time frame and which is provided by one of the terminals (1, 2, 3.....) designated as the controller terminal (e.g.l or 3), characterised in that each terminal (1, 2, 3.....) includes circuitry (30) for receiving the data and the control word from one terminal (1, 2, 3......) and re-transmitting it to another terminal (1, 2, 3 .....) in the chain, in that a plurality of the terminals (1, 2, 3 .....) are broadcast terminals (1, 2, 3 ....) each capable of initiating and transmitting the data within the time frames to all of the other terminals, and in that each broadcast terminal includes circuitry (42a, 42b, 48a, 48b) responsive to the control word to determine whether or not that broadcast terminal is to initiate and transmit data within a given time frame.
Claim 3
Dependent Claim
138 words
A system according to claim 1, characterised in that the control circuitry at each broadcast terminal (1, 2, 3 .....) comprises a counter (88, Fig.ll), a synchronising arrangement (96a, 96b) for synchronising the counter (88) with a corresponding counter (88) at the controller terminal by adding to the counter (88) at the broadcast terminal (1, 2, 3 ....) a base count which is representative of the propagation time to that broadcast terminal (1, 2, 3.....) for data coming from the controller terminal (e.g.l or 3), a source of clock pulses for counting the counter (88) from the base count, and circuitry (92) for determining, in dependence on a comparison of the actual count in the counter (88) with a predetermined count particular to that broadcast terminal (e.g.2 or 4), when the broadcast terminal should initiate and transmit data.
Claim 4
Dependent Claim
53 words
A system according to claim 1 or 2, characterised in that a plurality (e.g.l or 3) of the terminals (1, 2, 3.....) are each selectively capable of acting as a controller terminal, and by logic circuitry (48) to select which controller terminal (e.g.l or 3) shall produce control words at any given time.
Claim 5
Dependent Claim
87 words
A system according to claim 3, characterised in that the controller terminals respectively have different and predetermined priorities, and in that each controller terminal (e.g.l or 3) includes circuitry (40a, 40b) connected to monitor each received control word to determine the identity of the controller terminal represented in that control word, whereby each controller terminal (e.g.l or 3) maintains itself operative for so long as it is itself identified by each control word but renders itself inoperative when it is not identified in a received control word.
Claim 6
Dependent Claim
87 words
A system according to claim 4, characterised in that the logic circuitry in each controller terminal (e.g.l or 3) includes a counter (94, Fig.11) operative to count the number of control words not received by that terminal, and circuitry (e.g.FF-24 or FF-25) operative to cause that controller terminal (e.g.l or 3) to assume control of the system when the count of the counter (94) reaches a predetermined count which is different for each of the controller terminals (e.g. 1 or 3) and depends on their relative priorities.
Claim 7
Independent Claim
17 words
A system according to any preceding claim, characterised in that the continuous chain comprises a closed loop.
Claim 8
Dependent Claim
47 words
A system according to claim 6, characterised in that the continuous chain comprises a pair of complementary closed loops, each broadcast terminal including circuitry for simultaneously transmitting data over each of said loops with the data moving from the broadcast terminal in opposite directions in each loop.
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