Multiplex communications – Wide area network – Packet switching
Patent
1993-12-06
1994-12-27
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
370 856, 370 852, 3408255, H04J 302
Patent
active
053771893
ABSTRACT:
A hybrid data communication system comprises synchronous line cards(3) and asynchronous line cards(2) connected to a common data bus(1) includes a contention bus(7) arranged to communicate contention signals between the line cards(2,3). The synchronous line cards are arranged to transmit a high priority contention signal to suspend any outgoing transmission by an asynchronous card(3) and to gain access to the bus(1) of synchronous data. The contention bus includes an acknowledgement line(ACK) which is driven low by a receiving line card to indicate that it is receiving data. The receiving line card performs error checking and only receives the acknowledgement when the received data is determined to be error free. In a preferred example, the asynchronous line cards(2) are arranged to monitor the contention line(7) to detect the initiation of a contention cycle by a synchronous line card(3). Subsequently on the completion of the contention cycle the asynchronous cards(2) interrupt ant outgoing transmission of a data frame to allow the transmission of data by the synchronous card(3).
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British Telecommunications public limited company
Olms Douglas W.
Ton Dang
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