Method of controlling the transmission/reception of data in a local communication network, and data transmission system for performing the method
First Claim
1. In a local data communication network, comprising a plurality of transmitter/receiver stations, each of which is connected to a transmission medium for the transport of data, said stations forming a logic communication loop, each station having its own address and comprising an address indicator, a method of controlling the transmission/reception of data in said network said method comprising the step of:
- (a) allocating the right to transmit to the station whose own address corresponds to the address indicated by the address indicator;
(b) transmitting a single message by the station having the right to transmit and, if this station has no information to be transmitted when it is allocated the right to transmit, transmitting a presence message by said station;
(c) incrementing said address indicators by one position by an end-of-message indication of the message transmitted by the station having the right to transmit;
(d) resetting said address indicators when each of said stations has had the right to transmit;
(e) detecting by a given station, referred to as the pilot station, of the absence of transmission of a message of any type by the station having the right to transmit;
(f) transmitting by said pilot station of a substitution message after the detection of said absence of transmission.
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Accused Products
Abstract
The method for use in a local network comprising a pilot station and local stations. Each station of the network is successively allocated the right to transmit a message on the transmission medium on which the messages are transported. This right to transmit is allocated to a station when its own address is indicated by its address indicator. The transmission of a message by the station having the right to transmit increments the address indicator of all stations, thus allocating the right to transmit to a next station. If a station remains silent when it has the right to transmit, the pilot station substitutes for the silent station. The method also concerns the detection of errors and the recuperation of incorrect messages. Each station of the system has a table which makes the state of the other local stations known at any instant.
20 Citations
10 Claims
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1. In a local data communication network, comprising a plurality of transmitter/receiver stations, each of which is connected to a transmission medium for the transport of data, said stations forming a logic communication loop, each station having its own address and comprising an address indicator, a method of controlling the transmission/reception of data in said network said method comprising the step of:
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(a) allocating the right to transmit to the station whose own address corresponds to the address indicated by the address indicator; (b) transmitting a single message by the station having the right to transmit and, if this station has no information to be transmitted when it is allocated the right to transmit, transmitting a presence message by said station; (c) incrementing said address indicators by one position by an end-of-message indication of the message transmitted by the station having the right to transmit; (d) resetting said address indicators when each of said stations has had the right to transmit; (e) detecting by a given station, referred to as the pilot station, of the absence of transmission of a message of any type by the station having the right to transmit; (f) transmitting by said pilot station of a substitution message after the detection of said absence of transmission. - View Dependent Claims (3, 5, 6)
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- 2. A method as claimed in the first claim, in which a message received by a station is stored in a memory having a limited capacity, and in which a rejection signal is transmitted on the transmission medium by said receiving station in the case of overflow of the memory, of limited capacity.
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7. A local data communication network, comprising a plurality of transmitter/receiver stations, each of which is connected to a transmission medium for the transport of data, said stations forming a logic communication loop, each station having its own address and comprising an address indicator, each station further comprising:
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allocation means for allocating the right to transmit to that station when its own address corresponds to the address indicated by its address indicator; transmission means for transmitting a single message, said transmission means having a control output connected to said allocation means and being activated under control of said allocation means, said transmission means being provided for transmitting a presence message if no information has to be transmitted by that station when it is allocated the right to transmit; each of said address indicators being provided with incrementing means for incrementing them by one position by an end-of-message indication of the message transmitted by the station having the right to transmit;
each of said address indicators being further provided with resetting means for resetting them when each of said stations has had the right to transmit;
said data communication network comprising a pilot station, said pilot station comprising an inactive-time counter for measuring the duration of the inactivity of a station having the right to transmit and for generating a substitution message when the inactive-time counter exceeds a predetermined value. - View Dependent Claims (8, 9, 10)
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Specification