EP0093004A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Data communication system
Assignee: Fujitsu Services Ltd
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Filing: 1983-04-25
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Granted: —
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Expires: 2003-04-25
Abstract
Abstract In a ring network (1) messages sent from any one of a group of stations (3) to all the remainder include an acknowledgement field (ACK) holding a count preset to equal the number of expected destination stations. Each destination station that successfully receives the message acknowledges by decreasing the count by 1; acknowledgement is withheld if an error is detected in the message or the station cannot accept it. Acknowledgement is performed by a circuit (17) in a loop-through path (15) in an interface unit (4) connecting the station to the network (1). The originating station checks in a circuit (28) if the final value of the count on its return is zero. If so, the originating station is assured that each expected destination has made a positive acknowledgement of successful receipt.
Inventors
- 👤 Stuart Leslie Dean
- 👤 Donald Bell
- 👤 Stuart O'connor
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 09:34
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/12; H04L1/16; H04L1/18; H04L1/1829; H04L1/1858; H04L1/1607; H04L1/1671; H04L12/00; H04L12/02; H04L12/16; H04L12/18; H04L12/1863; H04L12/1877; H04L12/28; H04L12/42; H04L12/427; H04L12/433; H04L1/1867; H04L1/1874; H04L2001/0092; H04L2001/0093; H04L2001/0095
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
135 words
A method of data communication which comprises transmitting a message including an acknowledgement field (ACK) from a first station (3), passing the message successively through each of a plurality of other stations (3) some at least of which are second stations some at least of which perform an acknowledgement of the message, and returning at least the acknowledgement field (ACK) of the message to the first station for evaluation, characterised in that the acknowledgement field transmitted by the first station holds a count set at an initial value, the acknowledgement comprises changing the value of the said count in the acknowledgement field (ACK) of the message by an amount and in a direction that is constant and the same for every second station (3), and the evaluation is of the final value of the count.
Claim 2
Independent Claim
135 words
A method of data communication which comprises transmitting a message including an acknowledgement field (ACK) from a first station (3), passing the message successively through each of a plurality of other stations (3) some at least of which are second stations some at least of which perform an acknowledgement of the message, and returning at least the acknowledgement field (ACK) of the message to the first station for evaluation, characterised in that the acknowledgement field transmitted by the first station holds a count set at an initial value, the acknowledgement comprises changing the value of the said count in the acknowledgement field (ACK) of the message by an amount and in a direction that is constant and the same for every second station (3), and the evaluation is of the final value of the count.
Claim 3
Dependent Claim
46 words
A method as claimed in claim 1, characterised in that the evaluation of the final value of the count comprises checking whether the final value of the count equals a reference value corresponding to acknowledgement by every station (3) in a predetermined group of second stations.
Claim 4
Dependent Claim
47 words
A method as claimed in claim 3, characterised in that the initial value of the count is variable and is preset in dependence on the number of stations (3) in the said group to yield a reference value of a predetermined amount not dependent on that number.
Claim 5
Dependent Claim
39 words
A method as claimed in claim 3, characterised in that the initial value of the count is the number of stations (3) in the said group, acknowledgement comprises decreasing the count by one and the reference value equals zero.
Claim 6
Independent Claim
46 words
A method as claimed in any one of the preceding claims, characterised in that the first station (1) retains the right to transmit until it has carried out the said evaluation and then either employs or relinquishes that right depending on the results of the evaluation.
Claim 7
Dependent Claim
40 words
A method as claimed in claim 5 and any one of claims 2 to 4, characterised in that the first station relinquishes the right to transmit if the final value equals the reference value but otherwise conducts a recovery procedure.
Claim 8
Independent Claim
43 words
A method as claimed in any one of the preceding claims, characterised in that transmission is bit-serial and the acknowledgement field (ACK) comprises a sequence of bits together forming, in order of transmission, the binary representation of the count taken least-significant bit first.
Claim 9
Dependent Claim
49 words
A method as claimed in claim 7, characterised in that the acknowledgement field (ACK) comprises a sequence of consecutively transmitted bits divisible into pairs of consecutive bits in each of which pairs one bit is a bit of the said binary representation and the other bit is its inverse.
Claim 10
Independent Claim
42 words
A method as claimed in any one of the preceding claims, characterised in that acknowledgement is withheld by any second station (3) that would otherwise acknowledge the message if the station detects that there is an error in the message as received.
Claim 11
Independent Claim
37 words
A method as claimed in any one of the preceding claims, characterised in that acknowledgement is withheld by any second station (3) that would otherwise acknowledge the message if the station is unable to accept the message.
Claim 12
Independent Claim
41 words
A method as claimed in any one of the preceding claims, characterised in that the stations (3) are connected in sequence to provide a loop starting at and returning to the first station (3) and around which the said message passes.
Claim 13
Dependent Claim
42 words
A method as claimed in claim 11, characterised in that the first station (3) retains the right to transmit until it transmits a token enabling any station (3) that subsequently receives the token and is able to accept the token to transmit.
Claim 14
Dependent Claim
28 words
A method as claimed in claim 12, characterised in that the token contains a plurality of identical sequences of signals, which sequence does not appear in a message.
Claim 15
Dependent Claim
27 words
A data communication system comprising a network of stations (3) arranged to operate in accordance with a method as claimed in any one of the preceding claims.
Claim 16
Dependent Claim
165 words
A data communication system comprising a network of stations (3), at least one of the stations (3) being a first station capable of transmitting a message including an acknowledgement field (ACK), such a message in operation passing successively through a plurality of other stations (3) of the network and at least the acknowledgement field (ACK) returning to the first station (3), the said other stations (3) comprising second stations (3) each which has means (17) for performing an acknowledgement of such a message, and the, or each, first station (3) having means (28) for evaluating the returned acknowledgement field (ACK), characterised in that the means (17) for acknowledging such a message performs the acknowledgement by changing the value of the said count in the acknowledgement field (ACK) of the message by an amount and in a direction that is constant and the same for every second station (3) and the means (28) for evaluating the returned acknowledgement field evaluate the final value of the count.
Claim 17
Dependent Claim
165 words
A data communication system comprising a network of stations (3), at least one of the stations (3) being a first station capable of transmitting a message including an acknowledgement field (ACK), such a message in operation passing successively through a plurality of other stations (3) of the network and at least the acknowledgement field (ACK) returning to the first station (3), the said other stations (3) comprising second stations (3) each which has means (17) for performing an acknowledgement of such a message, and the, or each, first station (3) having means (28) for evaluating the returned acknowledgement field (ACK), characterised in that the means (17) for acknowledging such a message performs the acknowledgement by changing the value of the said count in the acknowledgement field (ACK) of the message by an amount and in a direction that is constant and the same for every second station (3) and the means (28) for evaluating the returned acknowledgement field evaluate the final value of the count.
Claim 18
Dependent Claim
43 words
A system as claimed in claim 15, characterised in that the evaluation means (28) comprises means for checking whether the final value of the count equals a reference value corresponding to acknowledgement by every station (3) in a predetermined group of second stations.
Claim 19
Dependent Claim
40 words
A system as claimed in claim 16, characterised in that the reference value is a predetermined amount not dependent on the number of stations (3) in the said group, the initial value of the count being in operation preset accordingly.
Claim 20
Dependent Claim
62 words
A system as claimed in claim 17, characterised in that the initial value of the count is in operation preset to equal the number of stations (3) in the said group, each means (28) for acknowledging a message comprises means for decreasing the count by one, and the means (28) for checking checks whether the final value of the count is zero.
Claim 21
Independent Claim
68 words
A system as claimed in any one of claims 15 to 18, characterised in that the, or each, first station (3) includes means (21) for transmitting, following receipt of a returned acknowledgement field (ACK), a signal pattern indicative of relinquishment of the right to transmit, which means is controllable in response to the evaluation means (28) to permit the transmission of the said signal pattern to be inhibited.
Claim 22
Independent Claim
68 words
A system as claimed in any one of claims 15 to 19, characterised in that in operation transmission is bit-serial and the acknowledgement field (ACK) comprises a sequence of bits together forming, in order of transmission, the binary representation of the count taken least-significant bit first, and each of the said means (17) for acknowledging a message comprises means for selectively inverting the said bits on the fly.
Claim 23
Dependent Claim
69 words
A system as claimed in claim 20, characterised in that the acknowledgement field (ACK) comprises a sequence of consecutively transmitted bits divisible into pairs of consecutive bits in each of which pairs one bit is a bit of the said binary representation and the other bit is its inverse, each means (17) for acknowledging a message inverting either both or neither of the bits of each of the pairs.
Claim 24
Independent Claim
44 words
A system as claimed in any one of claims 15 to 21, characterised in that each means (17) for acknowledging a message is controllable in response to an indication (FCS FAIL) that there is an error in the message as received to withhold acknowledgement.
Claim 25
Independent Claim
38 words
A system as claimed in any one of claims 15 to 22, characterised in that each acknowledgement means (17) is controllable in response to an indication (DONACK) that the station (3) cannot accept a message to withhold acknowledgement.
Claim 26
Independent Claim
45 words
A system as claimed in any one of claims 15 to 23, characterised in that the stations (3) of the network are interconnected in a ring (1), a message output by any station (3) circulating round the ring (1) and returning to that station (3).
Claim 27
Dependent Claim
64 words
A system as claimed in claim 24, characterised in that each station (3) includes means (21) for outputting a token enabling any station (3) that subsequently receives and is able to accept the token to transmit a message and means (18) controllable if the station (3) is about to transmit in response to a token to convert the token into a pattern distinguishable therefrom.
Claim 28
Dependent Claim
42 words
A system as claimed in claim 25, characterised in that the means (21) for outputting a token is responsive to an indication from the checking means (28) that the final value of the count equals the reference value to output the token.
Claim 29
Dependent Claim
81 words
A system as claimed in claim 25 or claim 26, characterised in that the means (21) for outputting a token includes means for receiving a signal pattern (FLAG) that does not occur in a message, the said means being operated a plurality of times in generating the token, and the means (18) for converting a token include means which while a token is being converted operate on the said signal pattern in an identical way each time the pattern is converted.
Claim 30
Dependent Claim
117 words
Interface apparatus suitable for use in providing the coupling between a second station (3) and a network (1) in a system as claimed in any one of claims 15 to 27, the interface apparatus (4) comprising means (11,24,25,26,27) for transferring to the remainder of the station data received from a transmission link of the network and addressed to the station (3), a loop-through path (15) permitting data received from the link (2) to be retransmitted onto a transmission link (2) of the network (1), and means (17) as specified in any one of claims 15, 18 and 20 to 23 for acknowledging a message, which means (17) is capable of modifying data travelling along the said path.
Claim 31
Dependent Claim
80 words
Interface apparatus as claimed in claim 28 and suitable for use in providing the coupling between a station (3) capable of acting as either a first or a second station and the network, the apparatus also including means (14) for selecting between the station (1) and the said loop-through path (15) as the source of data to be retransmitted and means (28) for evaluating the final value of a count as specified in any one of claims 15 to 18.
Claim 32
Dependent Claim
16 words
Interface apparatus as claimed in claim 30 and including the additional means specified in claim 19.
Claim 33
Dependent Claim
35 words
Interface apparatus as claimed in anyone of claims 28 to 30 for use in providing the coupling to a ring network and including the aditional means specified in any one of claims 24 to 26.
Claim 34
Independent Claim
25 words
A system substantially as hereinbefore described with reference to the accompanying drawings and as shown in Figures 1 and 5 to 19 of those drawings.
Claim 35
Independent Claim
25 words
A system substantially as hereinbefore described with reference to the accompanying drawings and as shown in Figures 1 and 5 to 19 of those drawings.
Claim 36
Independent Claim
12 words
A method substantially as hereinbefore described with reference to the accompanying drawings.
Claim 37
Independent Claim
12 words
A method substantially as hereinbefore described with reference to the accompanying drawings.
Claim 38
Dependent Claim
22 words
An interface unit substantially as hereinbefore described with reference to and as shown in Figures 5 to 9 of the accompanying drawings.
Claim 39
Dependent Claim
22 words
An interface unit substantially as hereinbefore described with reference to and as shown in Figures 5 to 9 of the accompanying drawings.
References Cited (Backward Citations)
No citation records indexed.
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