EP0190060B1 — Method and apparatus for reliable message broadca…

Claim 1

Independent Claim 203 words

Process for reliable distribution of messages within a ring network between a transmitting station and several network stations to which a message contained in the information field (INFO) of a frame is liable to be sent by means of a destination address field (DA) and to be copied, comprising a stage for transmission by the transmitting station (EM) after a field (FT) indicating the end of the frame of a blank field (CV) containing no data at the start, characterised in that it further comprises a stage for modification of the information contained in a bit (D) of this blank field (CV) upon passing within each station, to indicate that the stations which had detected that they were being addressed by the destination address field (DA) and had copied the information, actually had sufficient memory capacity allocated to the destination address (DA) for copying the whole of the message, by comparison between a value (L) indicating the length of the message transmitted, the value (L) being provided by the first bits of the information field (INFO), and a value (C of F) stored in a memory of the station indicative of the spare memory of the station available for this destination address (DA).

Claim 2

Dependent Claim 203 words

Process for reliable distribution of messages within a ring network between a transmitting station and several network stations to which a message contained in the information field (INFO) of a frame is liable to be sent by means of a destination address field (DA) and to be copied, comprising a stage for transmission by the transmitting station (EM) after a field (FT) indicating the end of the frame of a blank field (CV) containing no data at the start, characterised in that it further comprises a stage for modification of the information contained in a bit (D) of this blank field (CV) upon passing within each station, to indicate that the stations which had detected that they were being addressed by the destination address field (DA) and had copied the information, actually had sufficient memory capacity allocated to the destination address (DA) for copying the whole of the message, by comparison between a value (L) indicating the length of the message transmitted, the value (L) being provided by the first bits of the information field (INFO), and a value (C of F) stored in a memory of the station indicative of the spare memory of the station available for this destination address (DA).

Claim 3

Dependent Claim 81 words

Process according to claim 1, characterised in that during the stage for modification of the blank field (CV), the bit (D) is kept at the binary value 0 if no preceding station had been addressed or if an addressed station lacked the means to pick up the whole message, and the bit (D) is modified or kept at the binary value 1 if all the preceding stations which had been addressed had the means for storing the message as a whole.

Claim 4

Dependent Claim 75 words

Process according to claim 1 or 2, characterised in that the stage for modification of the information of the blank field (CV) comprises the incrementation stage of a certain number of bits forming a counter field (CPT), the capacity of which is related to the number of stations of the network, and a stage for modification or recopying of at least one bit (A), indicating that the station had detected that it was being addressed.

Claim 5

Dependent Claim 50 words

Process according to claim 3, characterised in that the modification stage is provided as required with a stage for modification of at least one bit (C) indicating that all the stations addressed had safely recopied the current frame, or that at least one station addressed had not recopied this frame.

Claim 6

Dependent Claim 40 words

Process according to one of the claims 1 to 4, characterised in that the bits (A), (C) and (D) are two in number and that the stages for modification of these bits are doubled to allow an improvement of reliability.

Claim 7

Dependent Claim 52 words

Process according to one of claims 4 or 5, characterised in that it further comprises a stage for reading the modified information of the field (CV) upon return to the transmitting station (EM) to censure that the message had been picked up by all the stations and retained by the stations concerned.

Claim 8

Dependent Claim 65 words

Process according to claim 6, characterised in that it further comprises a stage for transmission by the transmitting station of a frame for cancelling the preceding frame, if the stage for reading the information of the modified field (CV) by the transmitting station indicates an anomaly, or the stage for reading a bit (E) of the field (FT) indicates an error in the frame transmitted.

Claim 9

Dependent Claim 168 words

Device for application of the process according to one of the preceding claims, characterised in that it is provided in each station with means (6) for transmission of a blank field (CV), means (7) for reception and storage of the information contained in a blank field and means for detection of the passage of the blank field, means (20) for recognition of the presence or absence of the address of the station and for consideration of the information (INFO) , means for extraction of the length of the message which is to be considered (for example expressed in octets) from the information field (first octet of the field (INFO); means (8) for modification of the information carried by the blank field (CV) as a function of the result provided by the address recognition means (20) and the means for comparison of the length of the information which is to be considered and of the space available in the memory (213) of the means (20) for considering the information.

Claim 10

Dependent Claim 90 words

Device according to claim 8, characterised in that it comprises means (5) for reading the information contained in the blank field (CV) permitting a comparison of the number of network stations recorded in a memory (50) with the number of stations traversed by the message and for indicating to the processing unit (20) of the station that the message had been considered by all the stations which had identified themselves and means for indicating that all the information transmitted has been considered by all the stations which had identified themselves.

Claim 11

Dependent Claim 49 words

Device according to claim 9, characterised in that it comprises means for storing the spare memory available in the station traversed for the destination address (DA) indicated, and field selection means indicating the length (L) of the information contained in the information field (INFO), (first octet of this field).

Method and apparatus for reliable message broadcasting in a ring network

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