Double-ring network system, method for determining transmission priority in double-ring network and transmission station device

Abstract

According to one embodiment, in a double-ring network, a master station includes a transmitting and receiving permission switch portion, a communication port A at an A-system side, a communication port B at a B-system side, a first receiving control circuit portion, a transmitting and receiving control circuit portion, a frame detection determining circuit portion, a frame data generating circuit portion, a logical address determining circuit portion, a live list setting circuit portion and an address list setting circuit portion. The master station determines a token order (a transmission priority, also called a logical address) using a shortest path function by the logical address determining circuit portion and the address list setting circuit portion such that the token order does not depend on physical addresses of transmission stations and is matched to a connection order of transmission stations to realize path optimization. This reduces a transmission time.

What is claimed is: 
     
         1 . A double-ring network system comprising one or more transmission stations each of which is connected to a double-ring network and includes two communication ports allowing two-way communication, wherein:
 any one of the one or more transmission stations functions as a master station;   a new transmission station, which enters into the double-ring network, transmits a connection request frame including a physical address of the new transmission station, according to a reception of a synchronous frame from the master station;   the master station associates the transmitted physical address with a logical address for determining a transmission priority of each transmission station connected to the double-ring network, to determine a transmission priority of the new transmission station; and   the master station comprises:
 a transmitting and receiving portion that controls a transmission and reception timing, transmits a generated frame from the two communication ports, and introduces therein a frame received via the double-ring network according to a transmission of a synchronous frame; 
 a frame detection determining circuit portion that determines whether or not the transmitting and receiving portion receives the connection request frame; 
 an address list setting circuit portion that includes transmission priority setting circuits to which logical addresses are sequentially assigned, and transmits a physical address of a transmission station set in each transmission priority setting circuit and a logical address of the each transmission priority setting circuit in which the physical address of the transmission station is set; 
 a logical address determining circuit portion that determines, when the frame detection determining circuit portion receives the connection request frame, a logical address whose a value corresponds to a connection number of the new transmission station such that transmission priorities of transmission stations match a connection order on the double-ring network, based on a communication port via which the connection request frame is received, and sets the physical address included in the connection request frame in a transmission priority setting circuit to which the determined logical address is assigned; and 
 a frame data generating circuit portion that generates a synchronous frame to which a physical address and a logical address from the address list setting circuit are added, and instructs the transmitting and receiving portion to transmit the generated synchronous frame. 
   
     
     
         2 . The double-ring network system according to  claim 1 , wherein:
 the master station further includes a live list setting circuit portion that has holding circuits corresponding to the transmission priority setting circuits; and   every time when the connection request frame is received and a physical address is set in a transmission priority setting circuit, the master station sequentially validates a holding circuit corresponding to the transmission priority setting circuit.   
     
     
         3 . The double-ring network system according to  claim 2 , wherein when a transmission station withdraws, a holding circuit corresponding to a transmission priority setting circuit in which a physical address is not set is invalidated. 
     
     
         4 . The double-ring network system according to  claim 1 , wherein the logical address determining circuit portion obtains logical addresses generated by adding one to each of logical addresses equal to or more than a logical address to be associated with a physical address included in the connection request frame, and sequentially shifts physical addresses set in transmission priority setting circuits to which the logical addresses more than or equal to the logical address are assigned, to transmission priority setting circuits to which the obtained logical addresses are assigned. 
     
     
         5 . A method for determining a transmission priority of a transmission station connected to a double-ring network system to which one or more transmission stations each of which is connected to the double-ring network and includes two communication ports allowing two-way communication are connected, wherein any one of the one or more transmission stations functions as a master station, the method comprising:
 generating, via the master station, an address list in which one or more logical addresses for determining one or more transmission priorities of the one or more transmission stations connected to the double-ring network are arranged in ascending order;   transmitting, via the master station, to the one or more transmission stations connected to the double-ring network a synchronous frame which includes therein the one or more logical addresses associated with one or more physical addresses of the one or more transmission stations;   transmitting, via a new transmission station to be connected to the double-ring network, to the master station a connection request frame which includes a physical address of the new transmission station;   setting, when each transmission station other than the master station receives the synchronous frame, a logical address included in the synchronous frame as a transmission priority of the each transmission station and transmitting, via the each transmission station, a frame data to the master station according to its own transmission priority;   associating, via the master station, on the address list the physical address included in the connection request frame transmitted from the new transmission station according to a transmission of the synchronous frame, with a logical address whose a value corresponds to a connection number of the new transmission station such that transmission priorities of transmission stations match a connection order on the double-ring network, based on a communication port via which the connection request frame is received;   obtaining, via the master station, when receiving the connection request frame in a state where physical addresses are assigned on the address list, logical addresses generated by adding one to each of logical addresses equal to or more than the logical address associated with the physical address included in the connection request frame, and associating with the obtained logical addresses physical addresses associated with the logical addresses equal to or more than the logical address; and   transmitting, via the master station, every time when a physical address is assigned on the address list, to the double-ring network the synchronous frame to which the physical address and a logical address associated with the physical address are added.   
     
     
         6 . The method according to  claim 5 , further comprising:
 adding, via at least one of the one or more transmission stations, when receiving the connection request frame from an adjacent transmission station, to the connection request frame a logical address which is associated with a physical address of the at least one of the one or more transmission stations in the master station, and relaying the connection request frame to the master station.   
     
     
         7 . The method according to  claim 5 , wherein at least one of the one or more transmission stations is a hub station or a branching station connected to the hub station. 
     
     
         8 . A transmission station device which is connected to a double-ring network and includes two communication ports allowing two-way communication, the transmission station device comprising:
 a transmitting and receiving portion that controls a transmission and reception timing, transmits a generated frame from the two communication ports, and introduces therein a frame received via the double-ring network according to a transmission of a synchronous frame;   a frame detection determining circuit portion that determines whether or not the transmitting and receiving portion receives a connection request frame from a new transmission station;   an address list setting circuit portion that includes transmission priority setting circuits to which logical addresses indicative of transmission priorities on the double-ring network are sequentially assigned, and transmits a physical address of a transmission station set in each transmission priority setting circuit and a logical address of the each transmission priority setting circuit in which the physical address of the transmission station is set;   a logical address determining circuit portion that determines, when the frame detection determining circuit portion receives the connection request frame, a logical address whose a value corresponds to a connection number of the new transmission station such that transmission priorities of transmission stations match a connection order on the double-ring network, based on a communication port via which the connection request frame is received, and sets the physical address included in the connection request frame in a transmission priority setting circuit to which the determined logical address is assigned; and   a frame data generating circuit portion that generates a synchronous frame to which a physical address and a logical address from the address list setting circuit are added, and instructs the transmitting and receiving portion to transmit the generated synchronous frame.   
     
     
         9 . The transmission station device according to  claim 8 , further comprising a live list setting circuit portion that has holding circuits corresponding to the transmission priority setting circuits;
 wherein every time when the connection request frame is received and a physical address is set in a transmission priority setting circuit, a holding circuit corresponding to the transmission priority setting circuit is sequentially validated.   
     
     
         10 . The transmission station device according to  claim 9 , wherein when a transmission station withdraws, a holding circuit corresponding to a transmission priority setting circuit in which a physical address is not set is invalidated. 
     
     
         11 . The transmission station device according to  claim 8 , wherein the logical address determining circuit portion obtains logical addresses generated by adding one to each of logical addresses equal to or more than a logical address to be associated with a physical address included in the connection request frame, and sequentially shifts physical addresses set in transmission priority setting circuits to which the logical addresses more than or equal to the logical address are assigned, to transmission priority setting circuits to which the obtained logical addresses are assigned.