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Browse Prior Art Database

Open-Line Local Area Network

IP.com Disclosure Number: IPCOM000043522D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 4 page(s) / 47K

Publishing Venue

IBM

Related People

Krumrein, W: AUTHOR

Abstract

Fig. 1 shows a number of stations G1 to Gm connected in series by a coaxial line K. The local area network (LAN) may be expanded by connecting further stations to one or both ends of line K which is not terminated by its characteristic impedance. Messages are transmitted from left to right and from right to left, with buffering being effected in the stations. In a particular section between two adjacent stations, two messages can be simultaneously transmitted, i.e., one message from left to right and the other from right to left. One of the stations Gi, comprising an interface controller INC-L for transmission from right to left and an interface controller INC-R for transmission from left to right, is shown in greater detail by way of an example. Gi is connected to line K by a sender S and a receiver R.

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Open-Line Local Area Network

Fig. 1 shows a number of stations G1 to Gm connected in series by a coaxial line K. The local area network (LAN) may be expanded by connecting further stations to one or both ends of line K which is not terminated by its characteristic impedance. Messages are transmitted from left to right and from right to left, with buffering being effected in the stations. In a particular section between two adjacent stations, two messages can be simultaneously transmitted,
i.e., one message from left to right and the other from right to left. One of the stations Gi, comprising an interface controller INC-L for transmission from right to left and an interface controller INC-R for transmission from left to right, is shown in greater detail by way of an example. Gi is connected to line K by a sender S and a receiver R. S and R are implemented as a bridge-type hybrid circuit, as described in greater detail in [*]. Signals applied by a particular sender S to line K are not received by the station's own receiver R. As line K is not terminated by its characteristic impedance at the two outer ends of the network, and as the hybrid circuit thus is not matched, signals transmitted by S of the first and the last station G1 and Gm, respectively, are received by R and retransmitted through the network in the opposite direction. Each station comprises equipment, such as a computer, an input/ output device, a measuring device, etc. Instead of using two interface controllers in each of the stations, a single interface controller may be employed, replacing the second controller, otherwise required, by a direct connection. In that case, a particular unit always sends its data in one direction, say, from left to right. Therefore, if G2 wishes to send data to G1, such data are sent to Gm from where they are returned to G1 in the opposite direction. Gm reflects the data received, as line K is not terminated by its characteristic impedance. However, if two interface controllers are used in each station, the transmission direction for ensuring the shortest transmission distance can be defined in the respective unit. An information block, transmitted on line K, consists of the following information: - start code - receiver address

- sender address

- information type (command, data, status)

- check byte

- stop code All stations have the same quartz-controlled transmission rate. With respect to the network, the tasks to be performed by each INC are: - Blocks not directed to the unit connected to the respective INC are passed on by switches T2 and T3

(Fig. 2) or must be buffered and then passed on. - Blocks directed to the unit connected to the respective INC must be completely retrieved from

the network and passed to the connected unit after

buffering. - Line K must be monitored to use free-time periods

1

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for passing on information blocks to other

stations. - A block not retrieved by any of the other stations

must be removed fro...