JP5586760B2 - Network system, network system control method, transmission station, transmission station program - Google Patents

Description

  The present invention is a dual ring network in which a plurality of transmission stations are connected to each other in a ring shape through a communication path capable of bidirectional communication, and each transmission station normally sends a transmission frame simultaneously in both directions of the ring. The transmission frame is related to a network in which each transmission station receives and relays the transmission frame to perform mutual communication with all the transmission stations in the ring.

  In particular, in order to prevent the transmitted transmission frames from continuing to circulate in the ring, the two adjacent transmission stations serve as termination stations and prohibit transmission of the transmission frames in both directions. The present invention relates to a control method for configuring a simple dual ring network.

  In addition, when a single-point failure occurs in a dual-ring network, the redundancy that changes the two transmission stations at the new location from the transmission station that maintains the sound function to the terminal station and avoids a full stop. The present invention relates to a control method for computerization.

  Further, transmission frames related to these control methods communicated between transmission stations and data frames and interfaces used in applications comply with the ISO / IEC8802-3 Ethernet (registered trademark) standard, and further, OSI (ISO / IEC7498). -1) As a physical layer, there is no limitation on a media access control method (MAC) for performing access control of a data link layer of an upper layer, in particular, a common transmission path for avoiding a collision between transmission frames on the common transmission path. The present invention relates to configuration control of a double ring network as a physical layer.

  In general, in a network system configured by sequentially connecting a plurality of transmission stations in a ring shape with a communication path capable of bidirectional communication, each transmission station transmits a transmission frame in both directions.

  In each of these transmission stations, one of the predetermined transmission stations serves as a control station so that transmission frames transmitted from the respective transmission stations do not continue to circulate in the ring.

  Japanese Patent No. 3461554 (Patent Document 1) is known as a conventional example of a method of blocking the transmission frame flow at this transmission station.

  In this Patent Document 1, when a failure occurs at any one place during operation, this transmission station mainly communicates with a transmission station in the network, particularly with a transmission station that detects the failure, as a central control station. The failure part is separated by the thing.

  In addition, the failure of the transmission frame that is regularly communicated is judged, the failure part is separated, and the two-way relaying of the transmission frame that has been blocked as a control station has been performed so There is a method for avoiding the entire down of the network system.

  A similar scheme is an IEEE 802.5 token ring network.

  On the other hand, each transmission station always sends a transmission frame in one direction on the ring, each transmission station relays a transmission frame sent by another transmission station, and a transmission frame returned around the ring is There is ANSIX3T9.5FDDI as a ring network that prevents the transmission frame from circulating in the ring by discarding it at the transmission station that sent the transmission frame.

  In this type of network, among communication paths capable of bidirectional communication between each other, a communication path in one direction is always used, and a communication path in the other direction is in a standby state.

  If a failure occurs at any one location during operation, the transmission frame will be cut off, and the communication between the central transmission station designated in advance and the transmission device adjacent to the failure location mainly communicates. By turning back the communication path between the two transmission devices on both sides of the faulty part and utilizing the communication path in the opposite direction that has been in the standby state until now, the communication path is doubled, but a new ring network Configure. This avoids the entire network going down due to a one-point failure.

  That is, in the conventional example, normally, the transmission flow is interrupted at one fixed point of the ring network.

  The part to be blocked is a central control station fixed in advance or a transmission station temporarily given a transmission right to send a transmission frame to a common transmission line, and while holding the transmission right The control station controls the transmission path.

Japanese Patent No. 3461954

  However, in these network systems, when a single failure occurs, communication is performed between the control station and the transmission station adjacent to the failure point in accordance with the procedure of the transmission path control method unique to those networks, Or, by synchronizing, in the former case, the transmission frame keeps circulating by avoiding the entire stop by turning back in the control station that has been disconnected, and in the latter case by turning back at two places so as to sandwich the failure point. Avoid that.

  Both methods depend on the transmission path control method, and there are problems that there is a limitation in versatility, and that even if applied, it takes time to control for recovery from a failure.

  Therefore, there is a problem that it is difficult to provide a general-purpose system from a one-point failure that provides a bus-type transmission path independent of the transmission control system.

  The present invention has been made in view of the above problems, and based on the fact that disconnection is performed at two locations, at the time of network initialization, two adjacent terminal stations are configured to recover from a single location failure. The purpose of this is to configure the terminal stations at new positions by distributing each of the transmission stations individually and operating in parallel.

  As a result, the time to recovery can be shortened to a very short time. In addition, for initialization, subsequent operation, and recovery from a single location failure, general-purpose applications can be used without depending on the upper layer transmission path control method. It can be used by using products distributed in the market and proven technology, and can be commercialized at a lower cost. Furthermore, it is a ring-shaped but double ring as a physical layer medium equivalent to the bus type. -A network can be provided.

In the network system of the present invention, a transmission station having a first communication port and a second communication port capable of bidirectional communication is connected in a ring shape via a transmission line, and a base point is established among these transmission stations. In a network system in which a station transmits a frame signal in a clockwise route and a counterclockwise route, and each of a terminal station in a clockwise route and a terminal station in a counterclockwise route returns a frame signal from the base station,
The transmission station, terminal station and base station are:
Means for determining whether or not the frame signal has been received from a first communication port capable of communicating via the clockwise route and a second communication port capable of communicating via the counterclockwise route;
Means for transmitting a route confirmation frame signal for route confirmation from the first and second communication ports to an adjacent transmission station when not received;
When there is no reception of the path confirmation frame signal from the adjacent transmission station , means for setting the own station as the terminal station;
The main point is that

Further, when the own station is a said terminal station, said frame signal when no input path of right-handed route or the left-handed, that is a means for releasing the setting of the terminating station The gist.

Further, the network system control method of the present invention connects a transmission station having a first communication port and a second communication port capable of bidirectional communication via a transmission path, and The base station transmits the frame signal in the clockwise route and the counterclockwise route, and each of the terminal station in the clockwise route and the terminal station in the counterclockwise route returns the frame signal from the base station, When an abnormality occurs in any of the transmission paths, it is a network system control method for newly setting a terminal station,
The transmission station, terminal station and base station are:
Determining whether the frame signal has been received from a first communication port capable of communication via the clockwise route and a second communication port capable of communication via the counterclockwise route;
When not received, a step of transmitting a route confirmation frame signal for route confirmation from the first and second communication ports to an adjacent transmission station;
When there is no reception of the route confirmation frame signal from the adjacent station , setting the own station as the terminal station;
When the local station becomes the terminal station on the clockwise route, the frame signal from the clockwise point from the base station is not transmitted to the adjacent right transmission station in the subsequent stage, or the local station is the terminal station on the counterclockwise route. When it becomes, the process of not transmitting to the adjacent left transmission station in the latter stage,
The gist is to do.

In addition, when the local station is the terminal station, a step of canceling the setting as the terminal station is performed when the frame signal is not input through a clockwise route or a counterclockwise route. .

The transmission station of the present invention includes a first communication port that is arranged between transmission lines of a dual ring network system, and that can communicate clockwise and a second communication port that can communicate counterclockwise. In the transmission station
Means for determining whether or not a frame signal has been received from the first communication port enabling communication on the clockwise route and the second communication port enabling communication on the counterclockwise route;
Means for transmitting a route confirmation frame signal for route confirmation from the first and second communication ports to an adjacent transmission station when not received;
When the route confirmation frame signal is not received from the adjacent station , means for setting the own station as a terminal station;
When the local station becomes the terminal station on the clockwise route, it does not transmit the clockwise frame signal from the base station to the adjacent right transmission station in the subsequent stage, or the local station and the terminal station on the counterclockwise route And a means for not transmitting to the adjacent left transmission station at the rear stage.

In addition, when the local station is the terminal station, a means for canceling the setting as the terminal station is provided when the frame signal is not input through a clockwise route or a counterclockwise route. To do.

Further, the transmission station program of the present invention is arranged between transmission lines of a dual ring network system, and a first communication port capable of communicating clockwise and a second communication port capable of communicating counterclockwise. A transmission station program controlled using
On the computer,
Means for determining whether or not a frame signal has been received from the first communication port enabling communication through the clockwise route and the second communication port enabling communication through the counterclockwise route;
Means for transmitting a path confirmation frame signal for path confirmation from the first and second communication ports to an adjacent transmission station when not received;
Means for setting the own station as a terminal station when the route confirmation frame signal is not received from the adjacent station ;
When the local station becomes the terminal station on the clockwise route, it does not transmit the clockwise frame signal from the base station to the adjacent right transmission station in the subsequent stage, or the local station and the terminal station on the counterclockwise route In this case, the gist is to execute a function as a means not to transmit to the adjacent left transmission station in the subsequent stage.

In addition, the computer
When the local station is the terminal station and the frame signal is not input through a clockwise route or a counterclockwise route, the gist is to execute a function as means for canceling the setting as the terminal station. To do.

  As described above, according to the present invention, on the basis of disconnecting at two locations, two adjacent terminal stations are configured at the time of network initialization, and each transmission is performed when returning from a single location failure. The stations were distributed individually and operated in parallel, and a terminal station was constructed at a new location.

  Therefore, it is possible to make the time to recovery in a very short time, and also to perform general-purpose applications without depending on the upper-layer transmission path control method for initialization, subsequent operation, and recovery from a single-point failure. It becomes possible. As a result, it is possible to use and distribute the products distributed in the market and the proven technology, and the product can be commercialized at a lower cost.

It is explanatory drawing of the positional relationship of the master station and both terminal stations in the double ring network system after initialization. It is explanatory drawing explaining that each transmission station in a double ring network system is mutually connected by the bidirectional | two-way transmission line. It is a hardware block diagram which becomes one Example (the 1) of the transmission station structure of a double ring network system. It is a hardware block diagram which becomes one Example (the 2) of the transmission station structure of a double ring network system. It is explanatory drawing explaining the switch state in both terminal stations after initialization. Each station switch state and each mode at the start of initialization are shown. It is explanatory drawing explaining the operation state in both terminal stations after initialization, and a normal station. It is explanatory drawing explaining each station mode transition from the initialization start. It is a sequence diagram of one Example (the 1) of INZ frame communication between transmission stations at the time of initialization. It is a flowchart explaining the initialization process (the 1) in #STj transmission station. It is a flowchart explaining the initialization process (the 1) in #STj transmission station. It is a sequence diagram (in the case of transmission stations ST1, ST2, ST8) of a communication example (part 1) between transmission stations at the time of initialization. It is a sequence diagram (in the case of transmission stations ST1, ST2, ST8) of a communication example (part 1) between transmission stations at the time of initialization. It is a sequence diagram of one Example (the 2) of INZ frame communication between the transmission stations at the time of initialization. FIG. 11 is a sequence diagram of initialization processing (part 2) in the #STj transmission station. FIG. 11 is a sequence diagram of initialization processing (part 2) in the #STj transmission station. It is a sequence diagram (in the case of transmission station-ST1, ST2, ST8) of the communication example (the 2) between the transmission stations at the time of initialization. It is a sequence diagram (in the case of transmission station-ST1, ST2, ST8) of the communication example (the 2) between the transmission stations at the time of initialization. It is explanatory drawing explaining the example which transmission abnormality generate | occur | produced between # ST10 and # ST9. It is explanatory drawing explaining the switch state of each station by reception abnormality detection and SYN non-detection after transmission abnormality generate | occur | produces between # ST10 and # ST9. It is a sequence diagram explaining one Example (the 1) of the reconfiguration | reconstruction from a single location failure of a double ring network system. It is a sequence diagram explaining one Example (the 2) of the reconfiguration | reconstruction from a single point failure of a double ring network It is explanatory drawing explaining an ISO / IEC 8802-3 Ethernet (trademark) transmission frame structure. It is a flowchart explaining the outline of the automatic termination station function of the double ring network system of this Embodiment. It is explanatory drawing explaining the setting of the terminal station in the initial stage. It is explanatory drawing explaining switching of a terminal station. It is a schematic block diagram of a transmission station.

  FIG. 2 is a schematic configuration diagram of a double ring network system (sometimes simply referred to as a double ring network) to which the present invention is applied.

  In FIG. 2, the eight transmission stations (transmission stations 1 to 8) are connected to each other via a bidirectional transmission path as shown in FIG. 2 to form a ring network. In FIG. 2, transmission station 1 is # ST1, transmission station 2 is # ST2, transmission station 3 is # ST3, transmission station 4 is # ST4, transmission station 5 is # ST5, transmission station 6 is # ST6, transmission station 7 Is denoted as # ST7, and the transmission station 8 is denoted as # ST8, indicating the address of each station on the network.

  For claim 1, FIG. 1 is an example of a dual ring network system according to the present invention. FIG. 1 shows an example in which the transmission station 1 (# ST1) becomes the master station (MS) and becomes the transmission station 5 (# ST5) and the transmission station 6 (# ST6) termination station. The aforementioned master station is, for example, the first started up.

  In FIG. 1, a total of eight transmission stations are interconnected in the same manner as the dual ring network system of FIG. 2, but in the dual ring network system of the present invention, the ring network system of FIG. Each transmission station has the above-described automatic terminal station function which is not described above.

  This local station automatic termination station function detects a transmission frame transmitted from the communication port of one transmission station and received from the communication port of the other transmission station connected via the transmission path, and converts it into a transmission frame. It responds according to the information contained, but does not relay from the received communication port to the other communication port.

  Accordingly, the transmission station having the function of not transmitting the transmission frame from the other communication port, as shown in FIG. 1, the transmission station 5 (# ST5) becomes the terminal station ST-TL, and the transmission station 6 (# ST6 ) Is the terminal station ST-T-R, and these two are included in a set.

  For this reason, it is possible to prevent the transmission frame transmitted from the transmission station from circulating in the network system configured in a ring shape.

  In FIG. 1, the terminal station ST-TL and the terminal station ST-TR are illustrated as # ST5 and # ST6, respectively, but are not limited to the network configuration of FIG.

  That is, FIG. 1 shows two or more transmission stations having two communication ports capable of bidirectional communication, each of which is connected to each other in a ring shape via a transmission line. A dual ring network system configured to allow mutual communication.

  The transmission station sends out transmission frames including information from two communication ports at the same time to adjacent transmission stations.

  Then, a transmission frame transmitted from another transmission station received from one of the two communication ports is detected, relayed to the other communication port, and the transmission frame is transmitted from the other communication port.

  Of two or more transmission stations connected to each other in a ring shape, in each of the two adjacent transmission stations, communication is transmitted from the communication port of one transmission station and connected via the transmission path to the other transmission station. A transmission frame received from the port is detected by the transmission station and responds according to information contained in the transmission frame, but is not relayed from the received communication port to the other communication port.

  Therefore, by transmitting the transmission frame from the other communication port so that the transmission frame is not transmitted to the further transmission station connected in a ring shape in the relay direction. Frames can be prevented from circulating in a ring-shaped network.

  For claim 2, # ST1 shown in FIG. 1 is a master station, and based on # ST1, the number of transmission stations (8 in this example) and the transmission path length between the respective transmission stations , # ST5 and # ST6 are uniquely determined as terminal stations.

  The procedure until the specific determination depends on claims 4 and 5 and the embodiment thereof, but the total number of transmission stations counted from the master station on the opposite side in the ring as seen from the transmission station selected as the master station. Each of the adjacent transmission stations located at half the number of counts becomes the position of the terminal station.

  That is, by configuring the terminal station whose position is determined when viewed from the master station, it is possible to prevent the transmission frame transmitted from the transmission station from circulating in the network configured in a ring shape.

  That is, as in FIG. 1, a plurality of transmission stations having two communication ports are connected to each other in a ring shape to form a double ring network. The transmission station also sends transmission frames from two communication ports at the same time, detects transmission frames from other transmission stations received from one communication port, relays to the other communication port, and relays to the other communication port. Send from port.

  Based on one transmission station, the total number of transmission stations constituting the ring network and the total length of the transmission path connecting the transmission stations among the two or more transmission stations connected in a ring shape. In each of the two transmission stations adjacent to each other, the transmission frame transmitted from the communication port of one transmission station and received from the communication port of the other transmission station connected via the transmission path is transmitted to the transmission station. , And further responds according to the information contained in the transmission frame, but does not relay from the received communication port to the other communication port.

  Therefore, by not transmitting the transmission frame from the other communication port, the received transmission frame is transmitted from the transmission station by being connected in a ring shape in the relay direction and not delivered to the further transmission station. It is possible to prevent the transmission frame from being circulated in the ring-shaped network.

  In claim 3, network components such as transmitters and receiver ICs, data transmission / reception LSIs and circuit components whose performance improvement and price decrease are remarkable, accessory products, media conversion devices, interface devices, test test devices, etc. Built-in communication protocol expansion procedure deployed on Ethernet (registered trademark), protocol processing firmware and middleware, general-purpose IT application software, test test procedure, etc.

  Before specifically describing the embodiment and procedure from claim 4, an example of the apparatus configuration of the transmission station of the dual ring network system of the present invention will be described.

  FIG. 3 and FIG. 4 show a hardware configuration as an embodiment (part 1) and (part 2) of the transmission station configuration of the dual ring network system of the present invention.

  The difference between the hardware configurations of FIGS. 3 and 4 is that, in particular, FIG. 4 is a configuration in which the RRR-DET-A and -B circuits and the RRR-RCV-ADRS circuit are omitted from the hardware configuration of FIG. This is referred to as a frame detection unit 45 for distinguishing from FIG.

  Port A, which is one communication port unit 10, includes a receiver (RVR-A) and a transmitter (TVR-A) so that bidirectional communication with the adjacent station can be performed. The other communication port unit 11, port B, includes a receiver (RVR-B) and a transmitter (TVR-B) so that bidirectional communication with a neighboring station can be performed.

  In the reception from the port A, the reception signal (SIG-RV-A) from the port A, which is the output of the RVR-A, is a repeater A (FW-A) 12 and a reception permission switch 18 (SW-RVC-A). ), Reception abnormality detection circuit 32 (RCV-ERR-A), SYN frame detection circuit 34 (SYN-DET-A), RRR frame reception detection circuit 37 (RRR-DET-A), RRR in the frame detection determination unit 31. The frame reception destination address holding circuit 38 (RRR-RCV-ADRS), the INZ frame reception detection circuit 40 (INZ-DET-A), and the INZ frame transmission source address holding circuit 41 (INZ-TX-ADRS-A) are guided.

  Similarly, in reception from port B which is the other communication port unit 11, a reception signal (SIG-RV-B) from port B which is an output of RVR-B is 15, repeater B (FW-B). , Reception permission switch 19 (SW-RCV-B), reception abnormality detection circuit 33 (RCV-ERR-B), SYN frame detection circuit 36 (SYN-DET-B), RRR frame reception detection circuit 39 (RRR-DET-) B), RRR frame reception address holding circuit 38 (RRR-RCV-ADRS), INZ frame reception detection circuit 42 (INZ-DET-B), INZ frame transmission source address holding circuit 43 (INZ-TX-ADRS-B) Led to.

  The transmission output from the transmission / reception control circuit 21 (MAC / DLC) that controls transmission and reception of transmission frames according to the Ethernet (registered trademark) procedure is a transmission permission switch 16 (SW-TX-A), a transmission permission switch 17 (SW -TX-B). When the transmission permission switch 16 (SW-TX-A) is in the ON permission state, the transmission output signal of the transmission / reception control circuit 21 (MAC / DLC) is sent to the TVR-A of the port A which is one communication port unit 10. Further, when the transmission permission switch 17 (SW-TX-B) is ON, it is guided to the TVR-B of the other communication port unit 11 and transmitted.

  When the switch state is OFF, the MAC / DLC transmission output signal is cut by the switch, and as a result, the transmission frame is not transmitted from the corresponding communication port.

  The transmission frame received from port A is guided to TVR-B of port B via the output of FW-A and relay permission switch 13 (SW-FW-A). When the relay permission switch 14 (SW-FW-A) is ON, the transmission frame received from the port A is relayed and sent out from the port B as a result.

  When it is OFF, it is cut by SW-FW-A and not relayed. Similarly, the transmission frame received from the port B is guided to the TVR-A of the port A via the output of the repeater 15 (FW-B) and the relay permission switch 14 (SW-FW-B).

  When SW-FW-B is ON, the transmission frame received from port B is relayed and sent out from port A as a result. When it is OFF, it is cut by SW-FW-B and not relayed.

  The transmission frame received from the port A is guided to the first arrival reception selection circuit 20 (RCV-SEL) via the SW-RCV-A. Similarly, the transmission frame received from the port B is guided to the RCV-SEL via 19 SW-RCV-B.

  In RCV-SEL, the reception signals from port A and port B are determined, and if there is an overlap, the transmission frame received from the port that has arrived first is preferentially switched until reception is completed.

  This RCV-SEL output is guided to the MAC / DLC and processed for reception. In the dual ring network system of the present invention, while operating in a healthy state, it is equivalent to a bus-type network even though it is in a ring shape. Depending on the positional relationship between the transmission station and the local station, a transmission frame is received from one of the ports at a time.

  In the terminal station, the transmission frame is received from both ports because of the ring-like connection state. Normally, the port side reception permission switch in the blocked state is turned OFF, and the port in the non-blocked state Receive input from the side.

  In the present invention, the ON / OFF state of these reception permission switch, transmission permission switch, and relay permission switch is controlled to be switched.

  The MPU 24 reads the necessary setting values according to the program procedure stored in the program memory (PROM, working RAM memory, RAM, PROM), and further writes the necessary data in the RAM to temporarily hold it. Alternatively, it is a core microprocessor that reads and processes the sequence procedure and the Ethernet (registered trademark) transmission procedure in the transmission station of the present invention.

  The IOC 22 is an input / output control circuit that receives write data from the MPU 24 and outputs a control signal to a necessary circuit, or receives a status input from each circuit unit and is read by the MPU 24.

  The dual port memory circuit, which is the DP-RAM 26, stores data of transmission frames transmitted / received from the MAC / DLC, and further, a host connection interface circuit 28 (via a HOST-IF) with an external host device 29 connected to the transmission station. A memory circuit for exchanging transmission / reception data and control commands / status. Since the DP-RAM 26 is accessed from the MPU 24, the HOST-IF 28, and the MAC / DLC 21, the DPRAM controller is read by the DPRC 27 and the write timing is controlled.

  The reception abnormality detection circuit 32 (RCV-ERR-A) and the reception abnormality detection circuit 33 (RCV-ERR-B) are circuits that detect reception abnormality corresponding to the ports A and -B.

  In the reception abnormality, a preamble pattern, which is a reception clock synchronization signal peculiar to Ethernet (registered trademark) exceeding a specified value, which is broken by a carrier signal of an incoming frame, is received.

  On the other hand, if the required preamble pattern cannot be detected, or if errors exceeding the specified value are detected continuously by checking the error detection code (FCS) of the transmission frame included in the Ethernet (registered trademark) transmission frame, the reception error continues. The detection circuit determines that a reception abnormality has occurred when it is detected more than the specified number of times, but the detection circuit has a range that excludes the FCS check means provided in the DLC / MAC and the resulting statistical processing by the MPU 24.

  The SYN frame detection circuit 34 (SYN-DET-A) and the SYN frame detection circuit 36 (SYN-DET-B) are circuits that detect the arrival of SYN frames corresponding to ports A and -B.

  On the other hand, the SYN break detection path 35 (NO-SYN-DET-A / -B) is a circuit that detects the occurrence of a long silence state without SYN.

  The RRR frame reception detection circuit 37 (RRR-DET-A) and the RRR frame reception detection circuit 39 (RRR-DET-B) are circuits for detecting RRR frame reception corresponding to the ports A and -B.

  The RRR frame reception address holding circuit 38 (RRR-RCV-ADRS) is a circuit that captures and holds the reception address (DA) portion in the received RRR frame. The RRR-RCV-ADRS has a circuit configuration capable of taking in the reception signals on both sides and taking in the reception destination address portion with timing.

  The INZ frame reception detection circuit 37 (INZ-DET-A) and the INZ frame reception detection circuit 38 (INZ-DET-B) are circuits that detect INZ frame reception corresponding to ports A and -B.

  The INZ frame transmission source address holding circuit 41 (INZ-TX-ADRS-A) and the INZ frame transmission source address holding circuit 41 (INZ-TX-ADRS-B) correspond to the received INZ corresponding to the ports A and -B. This circuit holds the source address (SA) portion in the frame.

  The interrupt signal detection circuit 23 (IRP) is an interrupt signal detection circuit that transmits an event occurrence detected by the transmission station circuit to the MPU 24 as an interrupt signal.

  The interrupt signal includes reception error occurrence detection (IRP-RE-A, -B), SYN disconnection detection (IRP-NO-SYN), SYN frame reception detection (IRP-SYN-A, -B), and RRR frame reception detection. (IRP-RRR-A, -B), INZ frame reception detection (IRP-INZ-A, -B), MAC / DLC transmission / reception completion detection (IRP-DLC), MPU processing request (IRP-HOST) and MPU Processing request (IRP-STN) to the host device.

  The C-BUS becomes a common data bus connected to the MPU 24, and the MPU 24 particularly detects the NO-SYN-DET-A / B detection state and the RRR frame held in the RRR-RCV-ADRS via the C-BUS. The destination address information and INZ frame transmission source address information held in INZ-TX-ADRS-A, -B can be read.

  In the present invention, as claim 11, it is assumed that a transmission frame conforming to the ISO / IEC 8802-3 Ethernet (registered trademark) standard is used.

  FIG. 23 shows a transmission frame format of the ISO / IEC 8802-3 Ethernet (registered trademark) standard.

    In FIG. 23, PRE is a 7-byte preamble pattern for synchronizing received signals, SFD is a 1-byte frame start pattern, DA is a destination address, SA is a source address, and LEN / TYPE is a transmission frame protocol type. A type code number indicating Inf is an information field of a transmission frame.

  RRR-RCV-ADRS is a circuit that takes in and holds the DA part, and each of INZ-TX-ADRS-A and -B takes in and holds the SA part.

  In the embodiment corresponding to claim 11, the transmission frame of SYN, RRR, INZ, and INZ-COMP used in this control method is not limited to the Ethernet (registered trademark) frame format that is specifically limited.

  Any format may be used as long as these control frames can be identified. In practice, there is a method of taking the LEN / TYPE number, but this requires the permission of the registration authority that manages the protocol type number of Ethernet (registered trademark).

  There is also a method of embedding identification information in an information field defined by a protocol type number that has already been acquired. A method of embedding identification information in a fixed position of a data field of a TCP header extension part or a TCP information part defined by a general TCP / IP protocol in Ethernet (registered trademark), or a dedicated format using a UDP protocol I can do it.

  According to the fourth to tenth aspects of the present invention, each switch of SW-FW-A, -B, SW-TX-A, -B, SW-REC-A, -B has the above-described transmission station apparatus configuration. This is one of the points according to the procedure that state control is implemented.

  In the network system utilizing the dual ring network of the present invention and its control method, the initial state of the dual ring network referred to in the present invention as the first layer media portion is assumed.

  FIG. 6 shows, for each of claims 4, 5, 6, and 7, each station switch state and station mode at the start of initialization. This is basically the same state as when the transmission station is powered on. The MS port indicates the port that first received and detected the INZ frame among the two communication ports A and -B.

  In the configuration of the transmission station of the present invention, since the hardware structure is symmetric between the transmission system and the reception system, there is no need to uniquely limit the communication ports A and -B to one of the communication ports. That is, no problem arises when either port is A or B in performing the procedure described in the claims.

  However, for the sake of convenience, the hardware configuration examples shown in FIG. 3 and FIG. 4 are used in each transmission station for the purpose of reducing the complexity and facilitating understanding and explanation in describing the following specific embodiments. The communication port on the left side is port A, and the communication port on the right side is port B.

  The station mode will be described later in correspondence with each claim. As shown in FIG. 8, the station mode is changed from the “undefined” state (start) in which the power is turned on to the “Not terminal station” through the intermediate mode. The state of the terminal station “ST-TL”, the relay station “Normal”, and the terminal station “ST-TR” is changed.

  As described above, according to the correspondence in the transmission station hardware configuration of port A and port B limited for convenience, the transmission station in which the port B side is in the block state is set as the termination station ST-TL, Hereinafter, a transmission station in which the port A side is in a block state will be described as a terminal station ST-TR.

  For claim 4, FIG. 9 shows a sequence of INZ frames communicated between the transmission stations.

  In the sequence diagram of FIG. 9, the master station MS transmits an INZ frame to the transmission station # ST1,... Transmission station # ST4, transmission station # ST8... Transmission station # ST5. Transmission station # ST1,..., Transmission station # ST4, transmission station # ST8,..., Transmission station # ST5, which has received the INZ frame, returns the INZ frame to an adjacent transmission station having a young address.

  When such initialization is completed, even if an INZ frame is transmitted to the transmission station but is not returned from the transmission station, an abnormality (disconnection) is established with the transmission station, and the INZ-COMP frame is transmitted. Transmit to the master station MS. In FIG. 9, the transmission station # ST5 does not send an INZ frame back to the transmission station # ST6.

  In the above description of FIG. 9, it is assumed that the INZ frame is returned to the adjacent transmission station with a young address, but the transmission station that has received the INZ frame may not return the INZ frame.

  10 and 11 show the initialization process in each transmission station excluding the master (MS) station.

  12 and 13 include the initialization process of the MS station ST1. In particular, the operation of the communication process in the transmission stations ST2 and ST8 that are adjacent to the MS station is shown based on the initialization process procedure in each transmission station shown in FIGS.

  The configuration example of the double ring network shown in FIG. 9 is in accordance with the example of FIG. 1, and there is no limitation on the total number of transmission stations and the numbering of transmission stations from # ST1 to # ST9. Furthermore, the configuration of one embodiment of the hardware shown in FIGS. 3 and 4 is applicable to claim 4.

  When # ST1 becomes the MS station as one base station, the MS station performs software control by the MPU 24 as shown in FIG. 9 and as shown in step S0 of FIGS. Start the ST timer.

  Further, the terminal station check of the neighboring station corresponding to ST2 and ST8 in this case is performed in step S1. Next, every time the ST timer is up, the MPU generates an INZ frame that designates initialization periodically by software control until step S3, which is initialization completion, is completed. Then, the MAC / DLC is activated, SE-TX-A and -B are held in the ON state, and are transmitted from both the ports A and -B.

  As shown in FIG. 6, each switch state at the initial point of the transmission station is in a blocked state and a reception-inhibited state at both ports. Therefore, in each processing step shown in FIGS. 12 and 13, INZ-DET-A Alternatively, the arrival of the INZ frame is detected by -B.

  Then, the reception of the INZ frame is confirmed by software processing of the MPU 24 by the interrupt signal of IRP-INZ-A or -B, and the receiving port from which port is received is confirmed.

  That is, the reception port of the first INZ frame for initialization is set as the MS port.

  Next, when the INZ frame from the master station MS is received in step S01 or S02 of FIGS. 12 and 13, the block state from the reception port to the other communication port is changed to SW-FW-A corresponding to the reception port. Alternatively, the non-blocking state is set by turning -B ON.

  Similarly, by setting SW-RCV-A or -B corresponding to the reception port to ON, reception of the transmission frame from the reception port is permitted thereafter.

  Further, only SW-TX-A or -B corresponding to the reception port is temporarily turned ON, a response confirmation INZ frame is transmitted from the reception port side, and the station mode is set to the not terminal station. Thereafter, when reception of the next INZ frame from the master station is detected in S11, an ST timer is started and an event in step S2 is awaited.

  Next, after sending the INZ frame in S01 or S02, in the state where the arrival of the next INZ frame is detected in S11, the response confirmation INZ frame sent by the adjacent station on the side opposite to the MS port side is sent. When the reception is confirmed in step S21 or S23, the blocked state from this receiving port to the other communication port is set to the non-blocking state, and reception of incoming transmission frames is permitted. As a result, in this transmission station, the station mode is set to Normal as a relay station that can receive and receive transmission frames received from the bidirectional communication port and relay to the other side. FIG. 9 shows an example in which ST2, ST3, ST4 and ST8, ST7 are in the normal mode.

  On the other hand, when the master MS station receives response confirmation INZ frames from ST2 and ST8 which are adjacent stations in steps S11 and S12 of FIGS. 12 and 13, the master MS station enters the normal mode. INZ-DET-A and -B simultaneously serve as means for reliably detecting response confirmation INZ coming from both directions.

  As described above, in this method, the normal stations are increased from the MS station one by one in both directions, so that the total number of transmission stations constituting the ring network and the transmission stations are connected to each other. A transmission station that receives an INZ frame transmitted by the MS station, which is determined according to the total length of the transmission path, from the communication ports on both sides of the time difference or simultaneously appears.

  In a situation where the MS port is determined in step S03 or S04 in FIG. 10, by receiving the INZ frame from the blocked port, the terminal stations ST-T-L and ST-T- R is determined.

  In step S03 or S04, the response confirmation INZ frame is not transmitted from the reception port side, so that the transmission station which is the other of the terminal stations, in step S24 corresponding to step S03 and step ST22 corresponding to step S04, If the response confirmation INZ frame from the other terminal station that has already been determined cannot be received within the specified time of up, ST-T-R and ST-T-L are the station modes of the opposite terminal station. .

  Furthermore, FIG. 9 shows a case where ST5 and ST6 are terminal stations as a result of the normal procedure described above. In step S22 or S24 of FIG. If the frame is not received, the terminal station ST-T-L or ST-T-R is selected at that time depending on the expected reception port.

  Similarly, in the case of the MS station, if there is an abnormality in the transmission path to the adjacent station, and the communication function including the adjacent station communication function and the transmission path from the adjacent station to the own station, steps S13 and S14 in FIG. Thus, the terminal station ST-T-L or ST-T-R and the station mode are determined.

  Note that the procedure step numbers of # ST2 and # ST8 in FIGS. 12 and 13 coincide with the step numbers in FIGS.

  As described above, it is possible to initialize the transmission frame transmitted from each transmission station constituting the dual ring network system so as not to circulate in the ring-shaped network.

  FIG. 5 shows the switch states of ST-T-L and ST-T-R that have become terminal stations due to initialization. FIG. 7 additionally shows the switch state at the normal station.

  Claim 5 will be described with reference to FIG. 14 showing a sequence of INZ frames communicated between the transmission stations. 15 and 16 show the initialization process in each transmission station excluding the master (MS) station.

  17 and 18 include the initialization process of the MS station ST1. In particular, the operation of the communication process at the transmission stations ST2 and ST8 that are adjacent to the MS station is shown based on the initialization process procedure at each transmission station shown in FIG.

  The configuration example of the dual ring network system shown in FIG. 14 is in accordance with the example of FIG. 1, and there is no limitation on the total number of transmission stations and the numbering of # ST1 to # ST9 of transmission station identification. .

  Further, the configuration of one embodiment of the hardware shown in FIGS. 3 and 4 is applied to claim 5.

  When # ST1 becomes the MS station as one base station, the MS station sends an INZ frame for specifying initialization as shown in FIG. 14 and step S0 in FIGS. Are sent in both directions, and the ST timer is started, and in step S1, the response confirmation INZ frames from the adjacent stations, in this example, # ST2 and # ST8, are waited for.

  As shown in FIG. 6, each switch state at the initial point of each transmission station is in a blocked state and a reception-inhibited state at both ports. Therefore, in each processing step shown in FIGS. 15 and 16, INZ-DET- The arrival of the INZ frame is detected by A or -B.

  Then, the reception of the INZ frame is confirmed by the software processing of the MPU 24 by the interrupt signal of IRP-INZ-A or -B, and the receiving port from which port is received is confirmed. The receiving port of the first INZ frame for initialization is set as the MS port.

  When the INZ frame from the master MS station is received in step S01 or S03 in FIGS. 15 and 16, the block state from the reception port (MS port) to the other communication port is changed to SW-FW- corresponding to the MS port. By setting A or -B to ON, a non-blocking state is set.

  Similarly, by setting SW-RCV-A or -B corresponding to the MS port to ON, reception of the transmission frame from the reception port is permitted thereafter.

  Also, the transmission source address information in the detected INZ frame is read from INZ-TX-ADRS-A or -B corresponding to the reception port and held as the MS port side neighbor station address. Further, the station mode is set to the not terminal station.

  Furthermore, in response to the MS port, in step S11 or S12, the response confirmation INZ frame is set as the receiving destination, the adjacent station address previously held is set, transmitted from both ports, and sent on the opposite side of the MS port. The reception of the transmission frame from the port is permitted, and the ST timer is activated to wait for the event of step S2.

  After sending the INZ frame in which the MS port side adjacent station address is set as the reception destination in S11 or S12, the response confirmation INZ frame designating the own station sent by the adjacent station on the opposite side to the MS port side is sent to S21 or When the reception is confirmed in step S22, the blocked state from this receiving port to the other communication port is set to the non-blocking state, and reception of the incoming transmission frame is permitted.

  As a result, in this transmission station, the station mode is set to Normal as a relay station that can receive and receive transmission frames received from the bidirectional communication port and relay to the other side.

  FIG. 14 shows an example in which ST2, ST3, ST4 and ST8, ST7 are in the normal mode.

  On the other hand, when the MS station receives a response confirmation INZ frame designating its own station from ST2 and ST8 which are neighboring stations in steps S11 and S12 of FIGS. INZ-DET-A and -B simultaneously serve as means for reliably detecting response confirmation INZ coming from both directions.

  As described above, in this method, the number of normal stations is increased one by one in both directions from the master MS station. Therefore, the total number of transmission stations constituting the ring network system and the mutual relationship between the transmission stations are increased. A transmission station that receives an INZ frame transmitted by the MS station, which is determined according to the total length of the transmission path to be connected, from the communication ports on both sides, or at the same time, appears.

  In steps S02 and S04 of FIGS. 15 and 16, when the INZ frame is received from the opposite port while the MS port has already been determined, the terminal station ST-T-L or ST-T-R Determine according to the MS port.

  Further, after becoming the terminal station, in step S11 or S12, a response confirmation INZ frame designating the MS port side adjacent station is transmitted. On the other hand, the transmission station B, which is opposite to the transmission station A for which ST-T-L or ST-T-R has been determined and is the other terminal station, transmits the INZ frame already transmitted by the transmission station B. While waiting for the reception of the response confirmation INZ frame designating the local station expected to be transmitted by the station A, the local station detects the reception of the INZ frame not designated as the reception destination before the ST timer is up. It will be.

  When receiving an INZ frame that is not designated as the receiving destination from the receiving port on the opposite side of the MS port, the terminal station ST-TR facing the transmitting station A in step S23 or S24. Or it becomes ST-TL.

  Furthermore, FIG. 14 shows a case where ST5 and ST6 are terminal stations as a result of the normal procedure described above. However, from steps S25 and S26 of FIGS. When the response confirmation INZ frame in which the local station is designated as the reception destination is not received, the terminal station becomes the terminal station ST-TL or ST-TR according to the expected reception port at that time.

  Similarly, in the case of the MS station, if there is an abnormality in the transmission path to the adjacent station, and the communication function including the adjacent station communication function and the transmission path from the adjacent station to the own station, the terminal station is terminated in step S13 or S14. ST-TL or AT-TR is determined.

  Note that the procedure step numbers of # ST2 and # ST8 in FIGS. 17 and 18 coincide with the step numbers of FIGS. As described above, it is possible to initialize the transmission frame transmitted from each transmission station constituting the dual ring network system so as not to circulate in the ring-shaped network.

  FIG. 5 shows the switch states of ST-TL and ST-T-R that have become terminal stations as a result of initialization as described above, and FIG. 7 additionally shows the switch states at the normal station. .

  For claim 6, the INZ frame communication sequence of FIG. 14, FIGS. 15 and 16 are the transmission stations excluding the MS station, and FIGS. 17 and 18 are the initialization processes of the MS station. 3 and 4 are configuration examples of the transmission station.

  The transmission frame includes a reception address indicating a reception destination and a transmission source address indicating a transmission source. In the Ethernet (registered trademark) transmission frame of ISO / IEC8802-3 shown in FIG. 23, DA and SA correspond to field information at a specified position in the transmission frame, respectively.

  In the embodiment corresponding to claim 5 described above, when the transmitting station other than the MS station receives the INZ frame for the first time within the initialization period, the receiving port is set as the MS port, and the source address (DA in the received INZ frame). ) And is stored as the address of the adjacent transmission station on the MS port side.

  Further, a response confirmation INZ frame in which the adjacent address on the MS port side that has been held is designated as the receiving destination is sent out in both directions. The adjacent station on the MS port side receives an INZ frame designating its own station as the receiving destination from the port on the opposite side of the MS port, but the source address is one ahead of the own station from the master MS station. That is, the address of the transmission station adjacent to the port opposite to the MS port.

  According to steps S11 and S12 in the master station MS in FIG. 17, and in a transmission station other than the master station MS in FIGS. 15 and 16, according to a series of procedures in steps S01 or S03 and S11 or S12 and S21 or S22 in FIG. In the process of transition to the normal mode, and in the process of transition to the ST-T-L or ST-T-R mode according to the steps S02 or S04 and S11 or S12 and S23 or S24, the MS port side and the opposite side port It is possible to acquire and hold the address information of the transmission station adjacent to.

  In addition, in this initialization method, in the process of incorporating the transmission stations one by one from the master station MS into the ring network system, in each transmission station, the soundness of the receiving system on the MS port side and the opposite side of the MS port If there is no abnormality in the transmission path to the transmission station adjacent to the port, the reception and transmission function of the adjacent station, and the transmission path returning from the adjacent station to the local station and the local station reception system, the response confirmation INZ frame from the adjacent station is sure. By detecting and receiving, the adjacent stations acquire and hold the addresses of the transmission stations adjacent to the MS port side and the opposite port while confirming the soundness of the bidirectional communication path between the adjacent stations. be able to.

  With respect to claim 7, in the embodiment of the initialization described in claims 4 and 5, the total number of transmission stations constituting the ring network system with the MS station as a base point, and between the transmission stations When two adjacent terminal stations ST-T-L and ST-T-R are configured at positions determined according to the total length of the transmission lines connecting the two or more, or in the middle of initialization, At the time when it is determined that the terminal station becomes the terminal station by not receiving the response confirmation INZ frame from the station, that is, in the initialization method of claim 4, steps S03, S04 or S22 in FIG. According to S24, and in the initialization method according to claim 5, ST-T-L, ST-T-R according to steps S02 or S04 or S23 or S24 or S25 or S26 of FIG. After the determination, each terminal station sends an INZ-COMP frame indicating the end of initialization including the terminal station address and the terminal station mode, so that a double ring It is possible to notify that network initialization is completed.

  Each transmission station that has completed initialization can transmit and receive transmission frames from both-side ports, generate INZ-COMP frames by MPU software control, and control transmission by MAC / DLC to both-side ports. The incoming INZ-COMP frame can be received and controlled by MAC / DLC, and can be detected, determined, and processed by MPU software control.

  However, since the initialization has been completed and the network is functionally a bus-type network, each transmission station has an opportunity to overlap reception when both end stations transmit INZ-COMP frames almost simultaneously.

  In that case, the first incoming INZ-COMP frame can be received and controlled by the MAC / DLC by RCV-SEL.

  Therefore, in the initialization method corresponding to claim 4, the communication procedure of the INZ-COMP frame specifying the MS station is shown as an example of the steps as steps S3 and S4 of FIGS.

  That is, the INZ-COMP frame can be reliably received by the MS station by the response confirmation sequence with the MS station. The retransmission process is continued until a reception confirmation INZ-COMP frame in which the own station is specified as the reception destination is received from the master station MS, but the waiting time for the retransmission is set to ST-T-L and ST-T-R station modes. Accordingly, the difference between ST1 and ST2 is an embodiment in which the overlap of the INZ-COMP frames at the MS station is avoided.

  In step S3 of FIG. 12 and FIG. 13, the MS station side can detect completion of initialization, and can stop transmission of periodic INZ frames.

  In addition, in the initialization method corresponding to claim 5, the communication procedure of the INZ-COMP frame in which the broadcast address is designated as the receiving destination is shown as an example of the steps as steps S3 and S4 in FIGS.

  When the master station MS receives the INZ-COMP frame in which the broadcast address is specified, the master station MS sends an INZ-COMP frame for confirming the response to the transmission source address destination, thereby ensuring a response confirmation sequence with the master MS. The INZ-COMP frame can be received by the master station MS.

  The retransmission processing is continued until the reception confirmation INZ-COMP frame in which the terminal station from the master station MS is specified as the reception destination is received, but the waiting time for the retransmission is set to ST-T-L and ST-T-R station modes. Accordingly, the difference between ST1 and ST2 is an embodiment in which the overlapping of INZ-COMP frames at the master station MS is avoided.

  In step S3 of FIGS. 17 and 18, the MS station side can detect the completion of initialization. It should be noted that the completion of initialization can be detected in all transmission stations by setting the receiving address of the INZ-COMP transmitted from the terminal station as the broadcast address.

  For claim 8, FIG. 3 and FIG. 4 are configuration examples of the transmission station. FIG. 19 illustrates a situation in which a transmission abnormality occurs in a communication path connecting # ST10 and # ST9 during normal operation in a dual ring network system configured as terminal stations facing # ST5 and # ST6. doing.

  The relationship between the location of occurrence, the number of transmission stations, the position of the synchronization station and the terminal station is not limited.

  FIG. 20 shows the state of each switch in each transmission station after a transmission abnormality has occurred in the communication path connecting # ST10 and # ST9.

  In the state where the above initialization is completed, in the general situation in which one or more of the transmission stations send out one or more transmission frames on the dual ring network system, it is set in advance. In a situation in which a SYN frame that includes specific information that meets the specified conditions and is used to determine arrival is periodically transmitted from any transmission station (synchronous station), the arrival of the SYN frame is SYN-DET. Discriminated and detected by -A, -B and output as IRP-SYN-A, -B.

  In addition, NO-SYN-DET-A / B which detects and detects for each communication port that the output of IRP-SYN-A, -B does not continue periodically that the reception of the SYN frame is not performed for a preset period. It is done at.

  Therefore, in NO-SYN-DET-A / B, the other communication is performed under the condition that the arrival of the periodic SYN frame continues continuously from one signal through the one communication port from the IRP-SYN-A, -B signal. It is also possible to detect that periodic arrivals do not continue over a predetermined period through the port, and from which communication port there is no periodic arrival reception of the SYN frame, the detection output of the SYN disconnection state The MPU can read out via the C-BUS at the time of the state change interrupt of the signal IRP-NO-SYN. Further, an abnormality in the reception signal state of the transmission frame received via the communication ports A and -B by the RCV-ERR-A and -B is detected based on the condition for monitoring the reception signal state and determining that it is abnormal.

  In response to the NO-SYN-DET-A / B and IRP-NO-SYN interrupt signals, MPU software controls the port-A or -B in the SYN disconnected state via each communication port. As the transmission frame to be transmitted, the above-described INZ frame and the RRR frame described later corresponding to the transmission station configuration of FIG. 3 are detected and responded, but the other communication is relayed from the communication port in which SYN disconnection is detected to the other communication port. Block state in which relay permission switch SW-FW-A, -B corresponding to the communication port in which SYN disconnection is detected is changed from ON to OFF so that relay between ports is prohibited so that no transmission frame is transmitted from the port To.

  Further, the reception and capture of the transmission frame from the port where the SYN disconnection is detected is changed from the ON to OFF state to the corresponding SW-REC-A, -B state to make the reception prohibited state. In the communication port in which the reception abnormality is detected in REC-ERR-A, -B, the corresponding SW-FW-A, -B is controlled to be in the block state, and SW-REC-A, -B is set in the block state. Control to disable reception. A control signal for each switch from the MPU 24 is output via the IOC.

  As described above, the communication port of the plurality of transmission stations can be maintained in the non-blocked state during the period from the detection of the occurrence of the failure to the recovery of the network function by the recovery procedure, so that the function of the terminal station can be performed by the plurality of transmission stations.

  For claim 9, FIG. 3 shows an example of the configuration of the transmission station. FIG. 21 shows a recovery procedure from detection of the corresponding failure occurrence. FIG. 19 illustrates a situation in which a transmission error occurs in a communication path connecting # ST10 and # ST9 during normal operation in a dual ring network configured as an end station facing # ST5 and # ST6. doing. The relationship between the location of occurrence, the number of transmission stations, the position of the synchronization station and the terminal station is not limited. FIG. 20 shows the state of each switch in each transmission station after a transmission abnormality has occurred in the communication path connecting # ST10 and # ST9.

  With the configuration of the transmission station in the embodiment of FIG. 3, the arrival of the RRR frame is discriminated and detected by RRR-DET-A, -B, and output as IRP-RRR-A, -B. When the RRR frame is received, the destination address information in the RRR frame is held in the RRR-RCV-ADRS, so that it passes through the C-BUS at the time of the IRP-RRR-A, -B state change interrupt. Then, the MPU can read out, and can determine and process from which communication port it is received.

  The local station address information serving as the local station identification information is set in advance in the PROM or set by a switch, and the address information of the transmission station adjacent to the ports -A and -B is further described above. Before starting the initialization procedure and the recovery procedure from the failure according to this method, the MPU reads and receives these information as adjacent station address information in the RAM, and receives them in the received RRR frame. The destination address information and the local station address information are compared, and a match or mismatch can be determined and processed by MPU software control.

  That is, the address match is determined and the RRR frame receiving port is changed to a non-blocking state, or the address mismatch is determined and the adjacent station address information corresponding to the RRR receiving port is read and designated as the receiving destination. An RRR frame is generated and transmitted immediately at the timing of completion of reception of the RRR frame via the RRR reception port.

  Furthermore, after sending the RRR frame, the process of starting the ST timer configured by the above-described software control and monitoring and detecting the reception of the RRR frame in which the local station is designated as the reception destination within the predetermined time is performed. It can be determined and processed by software control of the MPU.

  On the dual ring network system, in addition to the SYN frame from the synchronization station, a transmission frame periodically transmitted or a transmission frame transmitted once from each transmission station is not included in the present invention. # ST10 and #ST illustrated in FIG. 19 are transmitted in accordance with a transmission path control method for avoiding a collision between transmission frames on a dual ring network system that is an OSI upper layer that does not need to be specified. When a transmission error occurs in the communication path connecting ST9, as described above with respect to claim 8, # ST10 and each station # ST2, # ST3 on the path from # ST1 serving as a synchronous station to terminal station # ST5, In # ST4 and # ST5, since the periodic arrival and reception of the SYN frame from the synchronous station can still be detected, the SYN disconnection is not detected.

  On the other hand, in # ST9, # ST8, # ST7 and # ST6 on the path from # ST9 to terminal station # ST6, SYN disconnection is detected and reception abnormality is detected depending on the situation. Further, in # ST10, periodic arrival reception of the SYN frame is detected. As a result, reception abnormality is detected according to the above-described conditions.

  In the example of FIG. 19, in a situation where a transmission abnormality occurs in the communication path connecting # ST10 and # ST9, the state of each switch in each transmission station is as shown in FIG. In # ST9, # ST8, # ST7, and # ST6, therefore, turning off SW-FW-B and turning off SW-REC-B causes the port B side to be in a blocked state and a reception prohibited state. Become. In # ST10, the SW-FW-A and the SW-REC-A are turned OFF, so that the port A side is in a blocked state and the reception-prohibited terminal station ST-TR.

  Of the two terminal stations, in the # ST6 terminal station located on the path from the synchronous station # ST1 to the abnormal part, in step S-R0 shown in FIG. 21, the ST-TR shown in FIG. Switch state: In the TR-M0 mode, in addition to the port A side that was originally in the blocked state and the reception prohibited state, this time the port B is also in the same state, the switch state of the terminal station # ST6 shown in FIG. T-R-M1).

  Further, in # ST6, it is determined that an abnormality has occurred on the port B side, that is, on the path toward the synchronous station, by NO-SYN-DET-A / B, IRP-SYN-A, -B, and a SYN disconnection is detected. As a terminal station, immediately after step S-R1, the RRR frame designated as the receiving destination is read out from the RAM holding the address information of # ST5 that becomes the opposite terminal station ST-TL, and the port-A , -B is sent in both directions, and the ST timer with a pre-designated timer time is started, and the response confirmation RRR frame from the adjacent station on the port B side toward the synchronous station, in this case, # ST7 Waits for incoming arrival.

  In # ST5 of the opposite terminal station ST-TL designated as the reception destination of the RRR transmission frame, when the local station transmitted from # ST6 receives the designated RRR frame, in step S-L1, the terminal station When the port B side SW-FW-B in the blocked state is turned on and the SW-REC-B is turned on, the port B is set in the non-blocking state and the reception permitted state, and the relay station normal mode is changed from the terminal station state to the relay station normal mode. Become.

  In each of the normally functioning transmission stations from the ST disconnection termination station # ST6 to the location where the abnormality occurred, # ST7, # ST8, and # ST9 maintain the relay function in this direction. The RRR frames from the disconnection detecting terminal station # ST6 are received almost at once, although there is a delay on the transmission path.

  In each transmission station, when the arrival reception of the RRR frame is detected by RRR-DET-A in step S1, and it is determined that the local station is not the reception destination, the address of the adjacent station toward the SYN loss detection termination station is held. MAC / DLC transmission / reception control via port A, which is an RRR reception port, by generating an RRR frame that is read from the RAM that is designated and specified as the reception destination and temporarily turning off SW-TX-B To transmit immediately after the reception of the RRR frame.

  In the SYN loss detection terminal station # ST6, after sending the RRR frame designating the ST-T-L terminal station as the reception destination, the adjacent station # ST7 heading to the synchronous station sends the RRR frame designated by the local station to the step S -If reception is detected within the time until ST timer up by R2, after waiting for ST timer up, port B on the side toward the synchronous station that has been in the blocked state from the point of time of abnormality detection and ST-T- that was originally in the blocked state The port A facing L is set to the non-blocking state, and both ports are set to the reception-permitted state, and the relay station normal mode is set from the terminal station state.

  In each of # ST7, # ST8, and # ST9 functioning normally from the SYN loss detection terminal station # ST6 to the location where the error occurred, RRR reception is performed in step S1 with the RRR reception port side adjacent station designated as the reception destination. After sending from the port side, before the ST timer started at the time of sending is up, when the reception of the RRR frame in which the local station is designated from the adjacent station heading to the synchronous station is confirmed in step S21, after waiting until the ST timer is up, The port B, which has been in the blocked state from the time of the abnormality detection, is brought into the non-blocked state and returned to the relay station normal mode.

  On the other hand, the transmission station # S9 adjacent to the abnormal part heading toward the SYN loss detection terminal station # ST6 cannot receive the RRR frame designating its own station from # ST10 even if the ST timer is increased in step S22. The block state is maintained.

  Therefore, it becomes a new terminal station ST-TL. Similarly, if an abnormality occurs at a location adjacent to the SYN loss detection terminal station, the RRR frame designating the local station is not received even if the ST timer has expired after the predesignated time has elapsed. The blocked state of the port that was in the blocked state at the time of detecting the abnormality is maintained by S-R2.

  Further, the other communication port that was originally in the blocked state as the terminal station is set to the non-blocked state, and changes from the terminal station St-T-R to ST-T-L.

  As described above, when a transmission abnormal state occurs due to a failure at one location on the dual ring network system, the position of the terminal station is directed to the adjacent station from the location where the error occurred to the synchronization station, and from the location where the error occurred to the opposite side. By changing to an adjacent station, it is possible to avoid the entire network outage.

  In addition, when changing the terminal station, while confirming the soundness of the bidirectional communication with the adjacent station, it is also possible to establish a simultaneous transmission between a plurality of transmission stations on the path to the transmission station that becomes the new terminal station. It can sometimes be completed, and the recovery time from the abnormal state to return can be made very short.

  Furthermore, complicated communication procedures can be omitted by performing processing up to recovery by distributing between adjacent stations without the individual transmission stations exchanging with a special central station.

  For claim 10, FIG. 4 is an example of the configuration of a transmission station. FIG. 22 shows a recovery procedure from detection of the corresponding failure occurrence. FIG. 19 illustrates a situation in which a transmission error occurs in a communication path connecting # ST10 and # ST9 during normal operation in a dual ring network configured as an end station facing # ST5 and # ST6. doing.

  The relationship between the location of occurrence, the number of transmission stations, the position of the synchronization station and the terminal station is not limited. FIG. 20 shows the state of each switch in each transmission station after a transmission abnormality has occurred in the communication path connecting # ST10 and # ST9.

  Except for RRR-DET-A, -B and its detection output signals IRP-RRR-A, -B and RRR-RCV-ADRS described in claim 9, functions and operations of each circuit constituting the transmission station Are the same in function and operation such as setting and holding of own station address information and adjacent station address information.

    Further, as described in claim 9, on the dual ring network system, in addition to the SYN frame from the synchronous station, each transmission station transmits a transmission frame periodically transmitted or a single frame. The transmission frame is transmitted in accordance with a transmission path control method for avoiding collision between the transmission frames on the dual ring network system which is an OSI upper layer that does not need to be specified for the present invention. When a transmission error occurs in the communication path connecting # ST10 and # ST9 illustrated in FIG. 19, as described above with respect to claim 8, # ST10 and # ST1 serving as a synchronization station to terminal station # ST5 In each station # ST2, # ST3, # ST4 and # ST5 on the path of, it is still possible to detect the arrival and reception of a periodic and continuous SYN frame from the synchronous station, YN-off detection is not.

  On the other hand, in # ST9, # ST8, # ST7 and # ST6 on the path from # ST9 to terminal station # ST6, SYN disconnection is detected and reception abnormality is detected depending on the situation. Further, in # ST10, periodic arrival reception of the SYN frame is detected. As a result, reception abnormality is detected according to the above-described conditions.

  In the example of FIG. 19, in a situation where a transmission abnormality occurs in the communication path connecting # ST10 and # ST9, the state of each switch in each transmission station is as shown in FIG. That is, in # ST9, # ST8, and # ST7, SW-FW-B is turned off and SW-REC-B is turned off in step S0 of FIG. 22 and in step ST-R0 in # ST6. The OL-M1 state and the TR-M1 state shown in FIG. 20, respectively.

  In # ST10, SW-FW-A and SW-REC-A are turned OFF in step S-O1, and the terminal station becomes a new terminal station ST-TR. On the other hand, the terminal station # ST5 can periodically detect the arrival of the SYN frame from the port A serving as the synchronization station side port, but the port B facing the other terminal station # ST6 can receive the SYN frame. Since the detection is not possible, it is possible to detect that a transmission abnormality has occurred almost simultaneously with the terminal station # ST6 although there is a signal delay on the transmission path.

  In step S-L1, SW-REC-B is turned on to permit reception and reception at port B opposite to the synchronous station side port, and an ST timer by program control is started. The ST timer value set in step S-L1 is the maximum waiting time until # ST6 is permitted to send a transmission frame in accordance with a transmission path control method that does not specifically define a collision between transmission frames on a dual ring network. Set a value larger than the time.

  Of the two terminal stations, in the terminal station # ST6 located on the path from the synchronous station # ST1 to the abnormal part, the SW corresponding to the port A on the side facing the other terminal station is obtained in step S-R1. -Set REC-A from OFF to ON to enable reception of the transmission frame from port A.

  In this state, the transmission frame sequence transmitted from the other terminal station # ST5 is received by MAC / DLC, and judged by MPU program control to avoid collision between transmission frames on the dual ring network. According to the route control method, the transmission frame assigned to the own station is waited for. In step S-R2, when the transmission timing Tmac is in the true state, the SW-REC-A is turned from ON to OFF, the port A is again set in the reception prohibited state, and the SW-REC-B is turned from OFF to ON. As a result, the port B is set in the reception-permitted state, the RRR frame with the destination specified as # ST5 is transmitted from both ports, the ST timer is started, and the own station from the adjacent station # ST7 heading for the synchronous station is received as the destination. It waits for reception of the RRR frame specified in.

  In # ST5, which is a SYN normal terminal station, after detecting a transmission error, in step S-L21, when an RRR frame is received from the opposing SYN loss detection terminal station # ST6, the reception destination of the received RRR frame is At the reception port B of the RRR frame that is in the blocked state as the terminal station, the SW-FW-B is turned on to change to the non-blocking state, and the relay station normal mode is changed from the terminal station state to the relay station normal mode. . On the other hand, if there is no reception before the ST timer that has been activated earlier, SW-REC-B is returned to OFF and the terminal station ST-TL is maintained.

  In each of the normally functioning transmission stations from the SYN disconnection detecting terminal station # ST6 to the abnormal point, # ST7, # ST8, # ST9, the relay function in this direction is maintained, so in step S1, When the RRR frame sent by # ST6 is received all at once with a transmission line delay, the receiving destination is not its own station. Therefore, the RRR frame in which the adjacent station address on the port A side that becomes the receiving port of the RRR frame is designated as the receiving destination Is temporarily turned off from the port A for receiving the RRR frame, after the reception of the RRR frame is completed, and the ST timer is started.

  In # ST6, if the RRR frame designated by the local station from the adjacent station # ST7 on the port B side toward the synchronous station is received and detected before the ST timer is up in step S-R31, an error occurs after waiting until the ST timer is up. The terminal B that faces the synchronous station that has been in the blocked state from the time of detection and the port A that faces the ST-TL that was originally in the blocked state are set to the non-blocked state, and both ports are set to the reception-permitted state, and the terminating station From the state, the relay station is set to the normal mode.

  In each of # ST7, # ST8, and # ST9 functioning normally from the SYN loss detection terminal station # ST6 to the location where the error occurred, RRR reception is performed in step S1 with the RRR reception port side adjacent station designated as the reception destination. After sending from the port side, before the ST timer started at the time of sending is up, when the reception of the RRR frame in which the local station is designated from the adjacent station heading to the synchronous station is confirmed in step S21, after waiting until the ST timer is up, The port B, which has been in the blocked state from the time of the abnormality detection, is brought into the non-blocked state and returned to the relay station normal mode.

  On the other hand, the transmission station # S9 adjacent to the abnormal part heading toward the SYN loss detection terminal station # ST6 cannot receive the RRR frame designating its own station from # ST10 even if the ST timer is increased in step S22. Therefore, it becomes a new terminal station ST-TL. Similarly, if an abnormality occurs at a location adjacent to the SYN loss detection terminal station, the RRR frame designating the local station is not received even if the ST timer has expired after the predesignated time has elapsed. By S-R2, the blocked state of the port that was in the blocked state at the time of abnormality detection is maintained, and the other communication port that was originally in the blocked state as the terminal station is set to the non-blocked state, and from the terminal station St-TR ST-T-L.

  As described above, in the same manner as described above in claim 9, when a transmission abnormal state due to a single point failure occurs on the double ring network, the position of the terminal station is changed to the adjacent station from the abnormal point to the synchronous station. The entire network stoppage can be avoided by changing the station from the location where the abnormality has occurred to the adjacent station facing the opposite side. In addition, when changing the terminal station, while confirming the soundness of the bidirectional communication with the adjacent station, it is also possible to establish a simultaneous transmission between a plurality of transmission stations on the path to the transmission station that becomes the new terminal station. It can sometimes be completed, and the recovery time from the abnormal state to return can be made very short.

  Furthermore, complicated communication procedures can be omitted by performing processing up to recovery by distributing between adjacent stations without the individual transmission stations exchanging with a special central station.

  Therefore, according to the initialization method of the present embodiment, the transmission frames received by the two terminal stations are not relayed, so that the transmission station transmits the ring-shaped network. A logical bus type network can be configured so that transmission frames do not circulate.

  In addition, at the time of network initialization, the position of the terminal station can be uniquely determined according to the network configuration, as viewed from the master station for initialization, especially on the dual ring network.

  The transmission frame used in the control method is premised on the Ethernet (registered trademark) standard, but the SYN frame, the RRR frame, the INZ frame, and the INZ-COMP defined in this method are transmission frames that can identify each. It doesn't limit the special frame format.

  Furthermore, in the initialization method using this method, it is confirmed whether there is an abnormality in each direction in the transmission path to the adjacent station, and the communication function including the communication function from the adjacent station and the transmission path from the adjacent station to the local station. It is possible to configure a double ring network initially with a communication path without any abnormality.

  This is a process of incorporating transmission stations one by one from the MS station into the dual ring network. At each transmission station, the soundness of the receiving system on the MS port side and the transmission adjacent to the opposite port of the MS port are performed. If there is no abnormality in the transmission path to the station, the adjacent station reception and transmission function, the transmission path returning from the adjacent station to the local station and the local station reception system, the reception confirmation INZ frame from the adjacent station is always received and detected. Can integrally check the soundness of the bidirectional communication path between adjacent stations.

  In addition, the address information of the neighboring station of the own station can be acquired in the process of incorporation, and it becomes easy to grasp the connection state of the transmission stations constituting the network at the time of initialization by application.

  When a transmission error occurs due to a single failure on a dual ring network, the position of the terminal station is changed from the location where the failure occurred to the synchronous station to the adjacent station going from the location where the failure occurred to the opposite side. By doing so, it is possible to avoid the entire network outage.

  In addition, when changing the terminal station, while confirming the soundness of the bidirectional communication with the adjacent station, it is also possible to establish a simultaneous transmission between a plurality of transmission stations on the path to the transmission station that becomes the new terminal station. It can sometimes be completed, and the recovery time from the abnormal state to return can be made very short.

  Furthermore, complicated communication procedures can be omitted by performing processing up to recovery by distributing between adjacent stations without the individual transmission stations exchanging with a special central station.

(Replenishment explanation of automatic terminal station function)
The dual ring network system having the above configuration performs the processing described below.

  FIG. 24 is a flowchart for explaining the outline of the automatic termination station function of the dual ring network system of this embodiment.

  FIG. 25 is an explanatory diagram for explaining the setting of the terminal station in the initial stage. FIG. 26 is an explanatory diagram for explaining switching of a terminal station. In this embodiment, as shown in FIG. 25, a dual ring network system including nine transmission stations # ST1,..., Transmission station # ST9 is used, and # ST1 is the master station MS, and the above-described INZ frame A case will be described in which # ST5 and # ST6 are initially set as terminal stations by the INZ-COMP frame and the like.

  As shown in FIG. 24, the terminal stations # ST5 (hereinafter referred to as terminal station LT) and # ST6 (hereinafter referred to as terminal station RT) are virtually disconnected from the terminal station RT (S241, S243). That is, the terminal station LT receives the frame from the left transmission station # ST4, but does not transmit it to # ST6. The terminal station RT receives the frame from the right transmission station # ST7 but does not transmit it to # ST5.

  Also, the terminal station LT determines whether or not a SYN frame has been received from the left # ST4 (S245). The terminal station RT determines whether a SYN frame has been received from # ST7 on the right side (S247).

  Then, when the terminal stations RT and LT do not receive the SYN frame within a predetermined time, they are disconnected from the terminal stations (S249 and S251). That is, # ST5 and # ST6 deviate from the terminal station, # ST5 transmits a frame to # ST6, and # ST6 transmits a frame to # ST5.

  On the other hand, the master station MS (also referred to as a synchronization station) serving as a base point transmits a SYN frame to each transmission station in both directions (clockwise and counterclockwise transmission) (S253). This SYN frame is input and accepted at one communication port A and the other communication port of each transmission station (S255).

  Each of the other transmission stations determines whether a SYN frame has been received from both directions (S257).

  For example, as shown in FIG. 3, the reception of the SYN frame is determined by the SYN frame detection circuit 34 (SYN-DET-A) and the SYN frame detection circuit 36 (SYN-DET-B) provided in each transmission station. Detected and output as an IRP-SYN-A signal indicating reception from the right side and an IRP-SYN-B signal indicating reception from the left side.

  The SYN disconnection detection path 35 (NO-SYN-DET-A / -B) outputs IPR-NO-SYN when IRP-SYN-A / B is not continuously input.

  Therefore, when the IRP-SYN-A is continuously output, the MPU 24 knows that the SYN frames are continuously input via one communication port. In addition, when IPR-NO-SYN is output after IRP-SYN-B is output, it is understood that periodic arrivals are not continuously input over a predetermined period via the other communication port.

  In addition, the MPU 24 detects an abnormality in the reception signal state of the transmission frame received via the communication ports A and -B by the RCV-ERR-A and -B based on the condition for monitoring the reception signal state and determining the abnormality. To do.

  That is, in step S257, it is determined that the SYN frame has not been received from both directions. When the SYN frame is not received from both directions, the other transmission stations transmit the RRR frame in both directions (S259).

  In this embodiment, it is assumed that # ST8 cannot receive a SYN frame from # ST9, and # ST9 cannot receive a SYN frame from # ST8.

  # ST8 transmits an RRR frame to both # ST9 and # ST7, and # ST9 transmits an RRR frame to both # ST8 and # ST1.

  When transmission stations adjacent to # ST8 (# ST9 and # ST7) and transmission stations adjacent to # ST9 (# ST8 and # ST1) receive the RRR frame, they transmit the RRR frame in both directions, and the RRR frame Is not received, the RRR frame is not transmitted (S261).

  On the other hand, the transmission station # ST8 and the transmission station # ST9 monitor whether or not the RRR frame is received from the adjacent transmission station after transmitting the RRR frame (S263).

  In step S263, when # ST8 and # ST9 determine that no RRR frame is received from the adjacent transmission station that has transmitted the RRR frame, it is determined that there is an abnormality between the adjacent transmission stations # ST8 and # ST9 ( S265). By this determination, as shown in FIG. 26, # ST8 and # ST9 become terminal stations (S276).

  That is, it has a function of not transmitting a frame from the base point to an adjacent transmission station that does not send a reply even if an RRR frame is transmitted.

  Therefore, each transmission station of the dual ring network system according to the present embodiment includes the automatic termination station setting means 50 shown in FIG. In the present embodiment, # ST3 and # ST6 are representatively illustrated.

  The automatic terminal station setting unit 50 includes a local station terminal setting unit 52, a terminal station canceling unit 54, a frame transmitting unit 58, and the like.

  The local station termination setting means 52 determines whether or not the SYC frame is continuously input from the adjacent transmission station. If the SYC frame is not input continuously, the memory 56 determines that there is an abnormality with the adjacent transmission station. Set the flag. When a flag indicating an abnormality between adjacent transmission stations is set in the memory 56, the frame transmission means 58 transmits the RRR frame to both the adjacent transmission stations and transmits the RRR frame to the local station termination setting means. Tell 52.

  The local station termination setting means 52 determines whether or not an RRR frame has been received, and when no RRR frame has been received, sets it in the flag memory 56 indicating that the local station has become a terminal station.

  When the local station is the terminal station, the frame transmission unit 58 does not transmit the SYN frame from the base point to the subsequent transmission station even if it receives the SYN frame from the base point.

  Further, when the SYN frame is continuously input from both adjacent transmission stations, both end station cancellation means 54 causes the RRR frame to be transmitted from the frame transmission means 58 to the adjacent transmission station, and when the RRR frame is returned. In addition, the flag indicating that the own station in the memory 56 is terminated is deleted.

1 Transmission station (# ST1)
2 Transmission station (# ST2)
3 Transmission station (# ST3)
4 Transmission station (# ST4)
5 Transmission station (# ST5)
6 Transmission station (# ST6)
7 Transmission station (# ST7)
8 Transmission station (# ST8)
10 Communication Port Unit 11 Communication Port Unit 12 Repeater A (FW-A)
18 Reception permission switch (SW-RVC-A)
31 frame detection determination unit 32 reception abnormality detection circuit (RCV-ERR-A)
34 SYN frame detection circuit (SYN-DET-A)
37 RRR frame reception detection circuit (RRR-DET-A)
38 RRR Frame Recipient Address Holding Circuit (RRR-RCV-ADRS)

Claims (8)

A transmission station having a first communication port and a second communication port capable of bidirectional communication is connected in a ring shape via a transmission line, and the base station turns the frame signal clockwise in these transmission stations. In the network system in which each of the terminal station of the clockwise route and the terminal station of the counterclockwise route returns the frame signal from the base station,
The transmission station, terminal station and base station are:
Means for determining whether or not the frame signal has been received from a first communication port capable of communicating via the clockwise route and a second communication port capable of communicating via the counterclockwise route;
Means for transmitting a route confirmation frame signal for route confirmation from the first and second communication ports to an adjacent transmission station when not received;
When there is no reception of the route confirmation frame signal from the adjacent station , means for setting the own station as the terminal station;
A network system comprising: When the own station is a said terminal station, when the pre-notated frame signal does not enter the path of the clockwise route or counter-clockwise, and having a means for releasing the setting of the terminating station The network system according to claim 1. A transmission station having a first communication port and a second communication port capable of bidirectional communication is connected via a transmission path, and the base station of these transmission stations sends a frame signal clockwise. When the terminal station of the clockwise route and the terminal station of the counterclockwise route respectively send back the frame signal from the base station and an abnormality occurs in any of the transmission paths. A network system control method for newly setting a terminal station,
The transmission station, terminal station and base station are:
Determining whether the frame signal has been received from a first communication port capable of communication via the clockwise route and a second communication port capable of communication via the counterclockwise route;
When not received, a step of transmitting a route confirmation frame signal for route confirmation from the first and second communication ports to an adjacent transmission station;
When there is no reception of the route confirmation frame signal from the adjacent station , setting the own station as the terminal station;
When the local station becomes the terminal station on the clockwise route, the frame signal from the clockwise point from the base station is not transmitted to the adjacent right transmission station in the subsequent stage, or the local station is the terminal station on the counterclockwise route. When it becomes, the process of not transmitting to the adjacent left transmission station in the latter stage,
A method for controlling a network system, characterized in that: The step of canceling the setting as a terminal station is performed when the frame signal is not input through a clockwise route or a counterclockwise route when the local station is the terminal station. 4. A method for controlling a network system according to 3. In a transmission station having a first communication port arranged between transmission lines of a dual ring network system and capable of communicating clockwise and a second communication port capable of communicating counterclockwise,
Means for determining whether or not a frame signal has been received from the first communication port enabling communication on the clockwise route and the second communication port enabling communication on the counterclockwise route;
Means for transmitting a route confirmation frame signal for route confirmation from the first and second communication ports to an adjacent transmission station when not received;
When the route confirmation frame signal is not received from the adjacent station , means for setting the own station as a terminal station;
When the local station becomes the terminal station on the clockwise route, it does not transmit the clockwise frame signal from the base station to the adjacent right transmission station in the subsequent stage, or the local station and the terminal station on the counterclockwise route A transmission station having means for not transmitting to the adjacent left transmission station in the subsequent stage. And a means for canceling the setting as a terminal station when the frame signal is not input through a clockwise path or a counterclockwise path when the local station is the terminal station. 5. The transmission station according to 5. A transmission station program that is arranged between transmission lines of a dual ring network system and that uses a first communication port capable of clockwise communication and a second communication port capable of counterclockwise communication. And
On the computer,
Means for determining whether or not a frame signal has been received from the first communication port enabling communication through the clockwise route and the second communication port enabling communication through the counterclockwise route;
Means for transmitting a path confirmation frame signal for path confirmation from the first and second communication ports to an adjacent transmission station when not received;
Means for setting the own station as a terminal station when the route confirmation frame signal is not received from the adjacent station ;
When the local station becomes the terminal station on the clockwise route, it does not transmit the clockwise frame signal from the base station to the adjacent right transmission station in the subsequent stage, or the local station and the terminal station on the counterclockwise route A program of a transmission station for executing a function as a means not to transmit to the adjacent left transmission station in the subsequent stage. In the computer,
A claim for executing a function as means for canceling the setting as a terminal station when the local station is the terminal station and the frame signal is not input through a clockwise route or a counterclockwise route. 7. The transmission station program according to 7.

Images