US3723971A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Serial loop communications system
Assignee: International Business Machines Corp
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Filing: 1971-12-14
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Granted: 1973-03-27
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Expires: 1991-12-14
Abstract
Abstract A communications system including a central station connected in a series loop with a plurality of remote stations and in which under control of said central station, the remote stations in the order of their physical position transmit data to the central station.
Inventors
- 👤 W Betts
- 👤 A Sawtschenko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:47
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/42; H04L12/423
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
289 words
A method of operating a serial loop communications network which includes a central station connected to the first and last stations of a plurality of serially connected remote stations for receiving data signals from said remote stations comprising the steps of: at said central station generating and transmitting to the first remote station of the serially connected stations a first unique serial multibit poll enabling signal and a plurality of second unique multibit serial framing signals when transmission of data from the remote stations to the central station is to be initiated; at each of said remote stations, monitoring the signals received via the network to detect the receipt of said first unique multibit poll enabling signal and said second unique multibit framing signal, when transmission of data to the central station is required generating and transmitting a third unique multibit control signal to a subsequent station upon receipt of a said first unique multibit poll enabling signal or upon receipt of a said second unique multibit framing signal received following receipt of the said first unique multibit poll enabling signal, initiating the transmission of data signals following transmission of said third unique multibit control signal only when a said second unique multibit framing signal is received immediately following transmission of the said third unique multibit control signal, and inhibiting further transmission of data signals following the transmission of one complete message when the remote station has data to send, or the receipt of a said first unique multibit poll enabling signal and a Following second unique multibit framing signal when the remote station has no data to send at the time of receipt of said signals until a subsequent first unique multibit poll enabling signal has been received.
Claim 2
Independent Claim
289 words
A method of operating a serial loop communications network which includes a central station connected to the first and last stations of a plurality of serially connected remote stations for receiving data signals from said remote stations comprising the steps of: at said central station generating and transmitting to the first remote station of the serially connected stations a first unique serial multibit poll enabling signal and a plurality of second unique multibit serial framing signals when transmission of data from the remote stations to the central station is to be initiated; at each of said remote stations, monitoring the signals received via the network to detect the receipt of said first unique multibit poll enabling signal and said second unique multibit framing signal, when transmission of data to the central station is required generating and transmitting a third unique multibit control signal to a subsequent station upon receipt of a said first unique multibit poll enabling signal or upon receipt of a said second unique multibit framing signal received following receipt of the said first unique multibit poll enabling signal, initiating the transmission of data signals following transmission of said third unique multibit control signal only when a said second unique multibit framing signal is received immediately following transmission of the said third unique multibit control signal, and inhibiting further transmission of data signals following the transmission of one complete message when the remote station has data to send, or the receipt of a said first unique multibit poll enabling signal and a Following second unique multibit framing signal when the remote station has no data to send at the time of receipt of said signals until a subsequent first unique multibit poll enabling signal has been received.
Claim 3
Dependent Claim
48 words
The method set forth in claim 1 in which at each of said remote stations following the transmission of data signals a said second unique multibit framing signal is generated and transmitted to the next station to thereby delineate the data signals when received at the central station.
Claim 4
Dependent Claim
257 words
A serial loop data communications system comprising: a central station adapted to transmit and receive data signals; a plurality of remote stations adapted to receive and transmit data signals; a transmission medium interconnecting said remote stations in series and said central station to the first and last remote station to thus form a serial transmission loop from the central station through the serially connected remote stations and back to the central station; said central station including means for transmitting to the first remote station a first unique serial multibit poll enabling signal followed by an uninterrupted plurality of second unique multibit serial framing signals when transmission of data signals from the remote stations to the central station is desired; each of said remote stations including, means for receiving and storing multibit signals received at the station via the transmission medium, decoding means responsive to the stored signals in the receiving and storage means for detecting said first and second unique multibit signals and providing first and second output signals upon detection of said first and second unique multibit signals, respectively, means responsive to said first output signal for transmitting a third unique multibit control signal when the station has data signals to transmit, means responsive to said first and second output signals for transmitting said third unique multibit control signal when the station has data signals to transmit, and means responsive to said second output signal for transmitting data signal when said second output signal is provided immediately following transmission of said third unique multibit control signal.
Claim 5
Dependent Claim
257 words
A serial loop data communications system comprising: a central station adapted to transmit and receive data signals; a plurality of remote stations adapted to receive and transmit data signals; a transmission medium interconnecting said remote stations in series and said central station to the first and last remote station to thus form a serial transmission loop from the central station through the serially connected remote stations and back to the central station; said central station including means for transmitting to the first remote station a first unique serial multibit poll enabling signal followed by an uninterrupted plurality of second unique multibit serial framing signals when transmission of data signals from the remote stations to the central station is desired; each of said remote stations including, means for receiving and storing multibit signals received at the station via the transmission medium, decoding means responsive to the stored signals in the receiving and storage means for detecting said first and second unique multibit signals and providing first and second output signals upon detection of said first and second unique multibit signals, respectively, means responsive to said first output signal for transmitting a third unique multibit control signal when the station has data signals to transmit, means responsive to said first and second output signals for transmitting said third unique multibit control signal when the station has data signals to transmit, and means responsive to said second output signal for transmitting data signal when said second output signal is provided immediately following transmission of said third unique multibit control signal.
Claim 6
Dependent Claim
72 words
A serial loop data communications system as set forth in claim 3 in which each of said remote stations includes, first means for inhibiting the transmission of data signals following the transmission of a complete message, when the station has data to send and second means for inhibiting the transmission of data signals upon receipt of said first and second output signals when the station does not have data signals to send.
Claim 7
Dependent Claim
49 words
A serial loop data communications system as set forth in claim 4 in which each of said remote stations includes means for generating and transmitting a said second unique multibit framing signal immediately following the last data signals to delineate the data signals when received at the central station.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |