JP4655733B2 - Receiving method and apparatus in ring-type duplex network - Google Patents

Description

  The present invention relates to a duplex network configured in a ring type, and in particular, a duplex network configured in a ring type in which a plurality of nodes are configured in a ring type using two transmission media or lines whose transmission directions are opposite to each other. The present invention relates to a method for receiving a first transmission frame and a first frame reception apparatus used in a network.

  Conventionally, in a network, there are connection forms such as a star network, a bus network, and a ring network. The star type network is a connection form in which all terminals are connected to one hub, and the bus type network is a connection form in which all terminals are connected to one line in which terminal devices are connected to both ends. . On the other hand, the ring network is a connection form in which each terminal is connected in a ring shape. In particular, a duplex network configured in a ring shape is a connection form that is excellent in reliability and transfer efficiency in a network connection form.

  In this dual-type network configured in a ring shape, conventionally, the network is configured by a transmission path having a master system and a slave system, and the first system using the master system and the slave system separately, and the network transmission path Is a second system consisting of two equivalents (referred to as A system and B system). In the first method, the network performs communication using the main system when it is normal, and performs communication using the sub system when an abnormality occurs, for example, when the main system fails. On the other hand, in the second method, a transmission frame and the same transmission frame are simultaneously transmitted from nodes A and B by nodes in opposite directions, and another node is transmitted from opposite directions. Receive a frame.

  In a duplex network configured in a ring shape, for example, even when a part of the transmission line of the network is disconnected, there is an advantage that another transmission line can be used. At this time, the second method has an advantage that the transmission delay is small because the node receives the first transmission frame as compared with the first method, but the frame is received in duplicate. There is. In particular, if the memory is rewritten from the CPU in the node between the memory update by the first frame and the memory update by the second frame, the memory rewrite from the CPU is invalidated by the second frame. . For this reason, when the second method is used, it is necessary for the receiving node to appropriately select a transmission frame from the redundantly received transmission frames.

In order to achieve the above object, for example, Patent Document 1 discloses a conventional ring-type duplex network. In this conventional network, when a node transmits a transmission frame including a management number, the receiving node can receive the transmission frame and store the management number of the transmission frame. Next, when the node receives a new transmission frame, the node compares the management number of the new transmission frame with the management number of the stored transmission frame. Then, when both management numbers are the same management number, the node determines that the same transmission frame has already been received, and discards the new transmission frame. On the other hand, if they are not the same, the node receives a new transmission frame. However, in the network of Patent Document 1 that uses a transmission frame including a management number, for example, when the management number of the transmission frame changes in the transmission path due to noise or the like and is subsequently stored in the node, the nodes are the same A frame received later including the management number is discarded. To cope with this, in Patent Document 1, when the management number of the transmission frame received earlier is the same as the management number of the transmission frame received later, the node immediately deletes the transmission frame received earlier. In this case, it is described that the data is checked for correctness by comparing with a transmission frame received later. However, in the network of Patent Document 1, the node cannot determine whether the transmission frame including the wrong management number is the previous transmission frame or the subsequent transmission frame, and the transmission frame to be originally received is not determined. There is a problem that it cannot be received. Furthermore, in the network of Patent Document 1, there is a problem that a delay occurs by comparing the previous transmission frame and the subsequent transmission frame.
Japanese Patent Laid-Open No. 5-145569

  In order to solve at least one of the above-mentioned problems, the present invention appropriately receives a first-arrival transmission frame while preventing reception of a duplicate transmission frame in a ring-type duplexed network, noise, etc. It is an object to perform appropriate transmission / reception even if there is a message.

  In order to achieve the above object, according to the present invention, there is provided a method for receiving a first-arrival frame in a ring-type duplex network, wherein at least one receiving node included in the ring-type duplex network includes a source node number, a frame A transmission data memory for storing a communication frame including an identification number and a check code; a communication frame search database capable of addressing a combination of the transmission source node number, the frame identification number, and the received transmission system; and A reception determination unit that receives a check code and can access the communication frame search database; and a primary buffer that can temporarily store the communication frame and transfer the communication frame to the transmission data memory. . Furthermore, using the above-described components, at least a part of the communication frame is temporarily received from the first transmission system, and at least a part of the communication frame is transferred to the primary buffer and the reception determination unit. Determining whether the communication frame of the first transmission system is normal using the check code by the reception determination unit, the determination result of the first transmission system, and the communication frame Depending on the source node number in the search database and the determination result of the second transmission system in the frame identification number, the communication frame stored in the primary buffer is transferred to the transmission data memory, Or a first-come-first-serving determination step for determining whether or not to delete. In the present invention, receiving means transferring a transmission frame from the primary buffer to the transmission data memory. On the other hand, temporarily receiving means a state where a transmission frame is stored in the primary buffer.

  In order to achieve the above object, a first-arrival frame receiving device in a duplex network configured in a ring shape according to the present invention stores a communication frame including a transmission source node number, a frame identification number, and a check code. A transmission data memory, a communication frame search database that can be addressed in combination with the transmission source node number, the frame identification number, and the received transmission system, and the check code is input to access the communication frame search database A reception determination unit; and a primary buffer capable of temporarily storing the communication frame and transferring the communication frame to the transmission data memory. Furthermore, at least a part of the communication frame from the first transmission system is transferred to the primary buffer and the reception determination unit using the component, and the reception determination unit uses the check code. To determine whether the communication frame of the first transmission system is normal, the second result of the determination result of the first transmission system, the source node number and the frame identification number in the communication frame search database. It is preferable to determine whether to transfer or delete the communication frame stored in the primary buffer to the transmission data memory according to the determination result of the transmission system.

  In addition, in the method for receiving a first-arrival frame in a ring-type duplex network according to the present invention and the first-arrival frame receiving device, the communication frame search database is designated by the source node number and the frame identification number. It is preferable that information indicating that the communication frame has been temporarily received from the first and second transmission systems and that the communication frame has been received can be stored at a predetermined address.

  The method for receiving a first-arrival frame in a duplex network configured in a ring type and the first-arrival frame receiving apparatus of the present invention can prevent the same communication frame from being received repeatedly. Furthermore, in the present invention, each node can selectively receive only the first communication frame, and even if an abnormal communication frame is transmitted on the first arrival, a normal arrival frame having the same identification number is transmitted. Can be received. In the present invention, since the communication frame search database of each node is referred to, for example, the arrangement of each node in the network, the position of the noise source, the position of the disconnection, and the like can be checked.

  Hereinafter, a receiving apparatus and a receiving method according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the structure of the duplex network 10 comprised in the ring type of embodiment of this invention is shown. The duplex network 10 configured in a ring shape includes nodes 11, 13, 15 and 17, and two transmission media or lines 21 and 23 whose transmission directions are opposite to each other. Each of the nodes 11 to 17 is connected to another node by a transmission medium 21 and a transmission medium 23, respectively. In the duplex network 10 configured in a ring shape, each of the nodes 11 to 17 transmits a communication frame simultaneously using the A-system transmission medium 21 and the B-system transmission medium 23. Further, a source node number is assigned to each of the nodes 11 to 17, and each node can be identified by this source node number.

  FIG. 2 shows the configuration of the communication frame 30 transmitted by each of the nodes 11 to 17 in the ring type duplex network 10 of the present embodiment. In addition to the packet data 39, the communication frame 30 can have a transmission source node number 33, a frame identification number 35, a data size 37, and a check code 41. In the present embodiment, using the transmission source node number 33, the frame identification number 35, and the check code 41, it is determined which received communication frame is the first frame. The communication frame can include other elements such as a start delimiter 31 and an end delimiter 43, for example.

  FIG. 3 is a block diagram illustrating the configuration of each of the nodes 11 to 17 in the duplex network configured in the ring type according to the embodiment of this invention. Hereinafter, a node according to an embodiment of the present invention will be described with reference to FIG. First, the nodes 11 to 17 receive communication frames at the reception control units 27A and 27B. The communication frame is subsequently transferred to the primary buffers 51 and 55 and the reception determination unit 53. Here, the primary buffers 51 and 55 are buffer memories for temporarily storing communication frames. The reception determination unit 53 uses the check code 41 on the communication frame from the reception control units 27A and 27B to check whether the communication frame is a normal frame. Further, the reception determination unit 53 accesses the communication frame search database 57 and updates the communication frame search database 57 based on the transmission source node number 33 and the frame identification number 35 on the communication frame.

  FIG. 4 shows the configuration of the communication frame search database 57 in the present embodiment. The communication frame search database 57 is configured by using the transmission source node number 33 and the frame identification number 35 as addresses, and stores data indicating whether each communication frame has been received or has been temporarily received. It is. The number of elements in the communication frame search database 57 is the product of the number of nodes connected to the network 10 and the number of frame identification numbers (FIG. 4). Further, each element of the communication frame search database 57 indicates that it has been temporarily received from the A system 61, received from the A system 63, temporarily received from the B system 65, and received from the B system 67. Each flag value can be stored (FIG. 4). Further, the contents of the communication frame search database 57 can be deleted at regular intervals. In this way, if the communication frame search database 57 is configured, the maximum value of the frame identification number is obtained by adding a margin to the maximum value of the number of communication frames that will be transmitted to one node in the certain period. be able to. For example, in the case of a protocol in which a token is used as a transmission right, the certain period of time uses a timing at which a node has obtained a transmission right after a round of the token. Thus, the present invention can be implemented without increasing the capacity of the communication frame search database 57 more than necessary.

  Each element of the communication frame search database 57 is configured as follows. For example, when a node receives a communication frame from the A system, the communication frame is normal from the check code 41, and when the communication frame is received, it is temporarily received from the A system and received from the A system. Store in communication search database 57 (system A temporary reception flag 61 and system A reception flag 63 are stored as ON). On the other hand, the reception determination unit 53 confirms the check code 41 of the communication frame, and when the communication frame is abnormal, stores that it is temporarily received from the A system and stores that it is not received from the A system. (The system A temporary reception flag 61 is stored as ON and the system A reception flag 63 is stored as OFF). The B system is similarly configured.

  Returning to FIG. 3 again, the configuration of each of the nodes 11 to 17 will be described. The reception determination unit 53 of each of the nodes 11 to 17 combines normality determination processing using the communication frame check code 41 temporarily stored in the primary buffers 51 and 55 and reception determination based on the communication frame search database 57. Then, it is determined whether or not the frame at that time should be received.

  FIG. 5 shows a flowchart of a first-arrival frame receiving method in the duplex network 10 configured in a ring shape according to the embodiment of the present invention. Here, a case where a communication frame is received from the A system will be described as an example. First, the node temporarily receives a communication frame from the A system (step 71). The reception determination unit 53 turns on the A-system temporary reception flag of the communication frame search database 57 (step 73). Next, the reception determination unit 53 confirms whether the received communication frame is normal based on the check code of the communication frame (step 75). If the received communication frame is normal, the reception determination unit 53 turns on the A-system reception flag in the communication frame search database 57 (step 77). Further, the data of the address corresponding to the communication frame is searched from the communication frame search database to check whether or not the B-system reception flag is OFF (step 79). When the B system reception flag is OFF, the primary buffer transfers the communication frame from the A system to the transmission data memory (step 81). On the other hand, when the communication frame is abnormal in step 75, or when the B-system normal reception flag is ON in step 79, the primary buffer deletes the communication frame (step 83).

  Thus, the reception determination unit 53 can check which frame has arrived first by searching the data in the communication frame search database 57. For example, if the B-system reception flag is ON when a communication frame is temporarily received from the A-system, the A-system frame is considered to be a late arrival frame, assuming that the frame has already been received from the B-system. be able to. Further, when the B-system reception flag is OFF, it is considered that the A-system is the first frame.

  If this property is used, for example, it is possible to know the arrangement of node numbers on the network by collecting information on which frame arrives for each node multiple times and collecting the information at all nodes. it can. In addition, the reception status can be confirmed by reading the entire elements of the communication frame search database 57. When both the temporary reception flag and the reception flag are ON, it can be recognized that a normal communication frame has been received. When the temporary reception flag is ON and the reception flag is OFF, it can be recognized that an abnormal communication frame has been received. The temporary reception flag and the reception flag are both OFF when the communication frame has not yet been received, when there is any disconnection, or when the identification number has changed due to noise, and another address of the communication frame search database 57 It can be considered that this is a case of accessing. Utilizing these effects, it is possible to return an error when an abnormal frame is transmitted from both AB systems, or to collect abnormal reception logs in the communication frame search database. Processing such as estimation can be performed.

  In addition, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the process shown in FIG. 5, the step of turning on the A-system reception flag (step 77) is described immediately after step 75. However, as another aspect, step 77 is not performed in this order. It may be performed immediately after the step of transferring the communication frame to the transmission data memory (step 81). If the first frame reception device in the ring type duplex network is configured in this way, for example, reception is performed using the same transmission node number and the same frame identification number before the communication frame search database 57 is cleared. Also, it is possible to appropriately determine the first-arrival frame.

It is a block diagram of the duplex network comprised by the ring type in embodiment of this invention. 2 shows a format of a communication frame in an embodiment of the present invention. The functional block diagram which shows the structure of the node in embodiment of this invention is shown. It is explanatory drawing which shows the structure of the communication frame search database in embodiment of this invention. The flowchart of the duplex network comprised by the ring type in embodiment of this invention is shown.

Explanation of symbols

10 Ring-type redundant network 11 Node 0
13 Node 1
15 Node 3
17 Node 2
21 A system 23 B system 27A, 27B Reception control unit 51, 55 Primary buffer 53 Reception determination unit 57 Communication frame search database 59 Transmission data memory

Claims (6)

A method of receiving by a ring-type duplex network having a first and a second transmission system,
At least one node included in the ring-type duplex network includes a transmission data memory for storing a communication frame including a transmission source node number, a frame identification number, and a check code, the transmission source node number, and the frame identification number. A communication frame search database that can be addressed in combination with the received transmission system, a reception determination unit that is inputted with the check code and can access the communication frame search database, and temporarily stores the communication frame, A primary buffer capable of transferring the communication frame to the transmission data memory;
Temporarily receiving at least part of the communication frame from a first transmission system and transferring at least part of the communication frame to the primary buffer and the reception determination unit;
Determining by the reception determination unit whether the communication frame of the first transmission system is normal using the check code;
Depending on the determination result of the first transmission system and the determination result of the second transmission system in the transmission source node number and the frame identification number in the communication frame search database, it is stored in the primary buffer. A first-come-first-served determination step for determining whether to transfer or delete the communication frame to the transmission data memory ;
The communication frame search database temporarily receives the communication frame from the first and second transmission systems at an address specified by the transmission source node number and the frame identification number; and And receiving a first frame in a ring-type duplex network. Temporarily receiving at least part of a communication frame from the first transmission system and transferring at least part of the communication frame to a primary buffer and a reception determination unit , wherein the communication frame is transmitted A step including an original node number, a frame identification number, and a check code ;
Determining whether the communication frame of the first transmission system is normal by using the check code included in the communication frame by the reception determination unit;
Stored in the primary buffer according to the determination result of the first transmission system and the determination result of the second transmission system in the transmission source node number and the frame identification number in the communication frame search database. A first arrival determination step of determining by the reception determination unit whether to transfer or delete the communication frame to a transmission data memory;
The communication frame search database temporarily receives the communication frame from the first and second transmission systems at an address specified by the transmission source node number and the frame identification number; and And receiving a first frame in a ring-type duplex network.   The method of receiving a first-arrival frame in a ring-type duplex network according to claim 2, wherein the communication frame search database is addressable by combining the transmission source node number, the frame identification number, and the received transmission system. A receiving device connected to a ring-type duplex network having first and second transmission systems,
A transmission data memory for storing a communication frame including a source node number, a frame identification number, and a check code;
A communication frame search database capable of addressing a combination of the source node number, the frame identification number, and the received transmission system;
A reception determination unit that receives the check code and can access the communication frame search database;
A primary buffer capable of temporarily storing the communication frame and transferring the communication frame to the transmission data memory ;
A communication frame search database capable of addressing a combination of the transmission source node number, the frame identification number, and the received transmission system, wherein a first address is designated by the transmission source node number and the frame identification number. And a communication frame search database capable of storing that the communication frame has been temporarily received from the second transmission system and that the communication frame has been received.
At least a part of the communication frame from the first transmission system is transferred to the primary buffer and the reception determination unit, and the reception determination unit uses the check code to transmit the communication of the first transmission system. It is determined whether the frame is normal, and according to the determination result of the first transmission system and the determination result of the second transmission system in the transmission source node number and the frame identification number in the communication frame search database A first frame receiving apparatus in a ring-type duplex network, which can determine whether the communication frame stored in the primary buffer is transferred to the transmission data memory or deleted. A primary buffer to which at least a part of a communication frame from the first transmission system is transferred , wherein the communication frame includes a source node number, a frame identification number, and a check code ;
A reception determination unit to which the part of the communication frame is transferred;
A transmission data memory capable of storing a communication frame from the primary buffer;
The fact that the communication frame has been temporarily received from the first and second transmission systems and that the communication frame has been received are stored in the address specified by the source node number and the frame identification number. A communication frame search database that can
The reception determination unit determines whether the communication frame of the first transmission system is normal using a check code included in the communication frame, and the determination result of the first transmission system and the transmission source node Determining whether to transfer or delete the communication frame stored in the primary buffer to the transmission data memory according to the number and the determination result of the second transmission system in the frame identification number The first frame receiving apparatus in a ring-type duplex network capable of performing the above. 6. The first-arrival frame receiving apparatus in a ring-type duplex network according to claim 5 , further comprising a communication frame search database that can be addressed by combining the transmission source node number, the frame identification number, and the received transmission system.

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