JPH0640642B2 - Network control method - Google Patents

Description

The present invention relates to a network control method in a token bus type network system for transferring a communication right by a token which is a communication right transfer instruction.

[Prior Art] In recent years, a local area network system, so-called "LAN", in which a large number of communication control devices (hereinafter referred to as nodes) are commonly connected to one transmission line and data communication is performed between these nodes, has been developed. It is flourishing. Among various communication methods in the LAN, the token passing method is particularly excellent in that the communication service can be uniformly provided to all the nodes even when the network is in a high traffic state, and therefore the transmission efficiency is not deteriorated. It is a thing.

An example of the system configuration of this LAN is shown in FIG.

In the figure, reference numeral 1 denotes transmission lines 100 to 160, which are nodes A to G constituting a LAN. Each node A to G (100 to 160)
Host A to G (2
00 to 260) are connected. In this way, in general, one transmission line is shared in the bus LAN. Therefore, if transmission is permitted without control at each node, a state occurs in which transmission is performed from two or more nodes at the same time, and data on the transmission line is transmitted. A so-called "collision" phenomenon occurs in which the two interfere with each other.

One method for preventing this is the token passing method. In the token passing method, on the other hand, an arrangement for exchanging transmission right delegation commands called "tokens" between nodes via a transmission line and acquiring the right (transmission right) to be transmitted only by the node that received the token. As
The node that received this token performs a series of communication processing such as transmission processing at that point if necessary (for example, if there is a transmission request from the host), and when this processing is completed, or no transmission processing is necessary. When there is no token, the collision phenomenon is prevented by passing (transmitting) the token to the node to which the token should be delegated next.

The "token" is passed to the next node every time the transmission processing is completed at the node that has made a transmission request in this way, and is sequentially circulated among the nodes in the network, and each constituent node in the network. In this way, the opportunity for acquiring the transmission right, that is, the opportunity for the communication service is equally given.

In this way, in the token passing system, all nodes in the network can synchronize with each other and communicate without collision using the token code as a medium.

On the other hand, CSMA / C, which has existed for a long time as a network method
D (Carrier Sense Multiple Access / Collision Detectio
The n) method is based on the premise that transmission data will collide, and will allow each node to send data randomly unless data is sent out on the transmission path 1. In the case of data collision, there is a fixed interval. Then, the transmission is retried, and in a system with a large amount of data communication, collisions frequently occur and communication efficiency is impaired.

In this sense, the token system is a synchronous communication system, and also CSM.
The A / CD system can be called an asynchronous communication system, and the CSMA / CD system is not suitable for a LAN with a large amount of data communication, and the token system can be said to be suitable.

There are two types of token circulation control, a "token ring" system and a "token bus" system, depending on the shape of the network.
Transmission is formed by a single linear conductor, and transmission data transmitted from one node is transmitted to all other nodes connected to the network transmission line (transmission line 1 in FIG. 2) almost at the same time. Be received. Therefore, the destination node address is always added to the beginning of the data to be transmitted including the above token command, and this is compared with the address value uniquely assigned to each node, and the node assigned to the own node When it matches the address, the transmission data is taken as the data addressed to the own node, or after the transmission data is indiscriminately taken, the above address comparison is performed, and when it matches, the data is officially addressed to the own node. deal with.

In this token bus system, a node to which a token should be passed next (downstream node) is generally "a node that is the closest to its own node address and has a small (or large) address value. A node having a maximum (or minimum) address value is defined as a node having a (or maximum value) address.

FIG. 3 shows an example of token circulation in the LAN shown in FIG.
In the case of the operation in parentheses, the token circulation direction is only reversed. In addition, if there are inoperable nodes due to a failure or power down in the network, it is necessary to skillfully avoid them and perform token circulation. That is, if there is an inoperable node, remove this node from the network configuration, remove it from the token cyclic ring (that is, perform degenerate operation), select another appropriate node as the node to which the token should be passed thereafter, and select it. It is necessary to switch. FIG. 4 shows an example of token circulation when the node B 110 and the node F 150 are inoperable nodes in the system shown in FIG.

As shown in the figure, it is necessary to circulate the token while avoiding the inoperable node. Now, in order to start the token circulation, it is necessary to generate a token at any node in the network and pass it to the next node. Regarding this, in the general token bus type network system, at the time of start-up,
Alternatively, when the token disappears, a token is generated at each node, and the token is allowed to be transmitted freely so that data can be transmitted subsequently. Here, as a matter of course, a token collision may occur on the network transmission line 1.

Therefore, a method is adopted in which tokens are transmitted with a certain time difference in advance by using an address value or the like unique to each node, and collision of a transmission token with other nodes is avoided. FIG. 5 shows the token transmission permission timing for this conventional node address.

In FIG. 5, if the node G160 having the smallest address value (address "1") is still inoperable, the node F having the next address value (address "2") is the node F.
The token is first sent from 150 and circulated on the network system.

If the nodes with the addresses "1" and "2" are inoperable, the node E14 that is the node with the address "3"
The token is sent for the first time from 0. In this way, the token is first transmitted from any one node, and the transmitted token starts to circulate the network.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, the recognition of the passage of time of each node can be succeeded only when the tokens coincide with each other. It is possible to collide with tokens issued by other nodes,
As a countermeasure, the CSMA / CD system, which is an asynchronous communication system described above, is also equipped with a collision detector, so that a retry is performed when a collision occurs in the token transmission, and a painstaking measure is taken.

Further, when a node having a small node address is inoperable or is not connected, useless time elapses (results in deterioration of transmission efficiency).

Even if the token passing system is a network, it is possible that the token communication will not be synchronized until the token circulates. It shows a thing. And this asynchronous processing operation occupies a considerable proportion, which makes the control very complicated.

Therefore, in view of the above points, as in Japanese Patent Laid-Open No. 60-87534, a management station that controls the generation and transfer of tokens is provided in the network, and after the management station transfers the token to one node, a predetermined time is passed. It is known that when the token is not returned even after the lapse of time, a new token is generated and the token is transmitted to the next node to promptly generate the token when the token is lost.

However, the technique disclosed in Japanese Patent Laid-Open No. Sho 60-87534 has a drawback that the transfer of the token must always go through the management station, which takes time to transfer the token and the communication efficiency is poor. It was

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above problems, and includes the following configuration as one means for solving the above problems.

That is, in a network control method of a network system in which a transmission device that obtains a communication right by a token that is a communication right transfer command by connecting a plurality of transmission devices to each other via a communication medium obtains a transmission right, an error occurs in the network system. When the generated token is lost, the only specific transmission device among the transmission devices that make up the network enables the generation of a new token, and the specific transmission device uses the address value of its own device as an initial value, For the destination address setting means for setting the destination address by shifting the address values one by one from the initial value, and for the transmission apparatus having the address value set by the destination address setting means as the unique address value, the transmission apparatus is Transmitting means for transmitting a transmission frame for checking whether or not it is operable, and after transmitting the transmission frame by the transmitting means When a response signal is returned from the transmission device that transmitted the transmission frame, storage means for storing the address value of the transmission device that transmitted the transmission frame in a network configuration table, and setting of the address value by the destination address setting means A control means for repeatedly executing transmission of a transmission frame by the transmission means and storage of an address value in the storage means for all transmission devices; and an address value stored in the network configuration table And a sending means for sending a token based on an address value stored in the network configuration table, and a notification means for sending a notification to a plurality of transmission devices constituting the network. Each of the plurality of transmission devices that A token based on the content of the notified the net work configuration table is achieved by the configuration to be sent to another transmission apparatus from.

[Operation] In the above configuration, when the token is lost, the specific transmission device checks the states of all the transmission devices, notifies all the transmission devices, and newly generates and sends the token. Even if it is lost, the network can be reliably reconstructed.

Further, as a result, the normal token transfer can be performed directly between the transmission devices constituting the network, and the token transfer can be performed quickly without taking time.

First Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a node according to an embodiment of the present invention, which constitutes the network system shown in FIG. The description of FIG. 2 is omitted because it has been described above.

In FIG. 1, 1 is a network transmission line of a LAN, 2 is a node which is a transmission control device, and 3 is various computer equipment and office equipment (hereinafter referred to as a host) connected to the node 2.

The node 2 is a transmission circuit 12 that performs data communication with the transmission path 1, a reception circuit 11, a token determination circuit 4 that determines whether or not the reception data in the reception circuit 11 is a token, the overall control of the node and the transmission data. Control unit (hereinafter referred to as CPU) 5 for processing data, decoding received data, disassembling, timing control of communication operation, etc., memory circuit 6 for storing transmission / reception data, control procedure of CPU 5, interface with host 3. Ace circuit 7, address setting unit 8 including a switch for setting a unique address number (node address) for each node, network configuration table for storing network configuration such as address information of each configuration node of the network 9 and a destination address discriminating circuit 13.

The address value set in the address setting unit 8 and the node information in the network configuration table 9 are read by the CPU 5 and used as a destination address, a source address, etc. during transmission / reception.

Further, a master node described later is provided with a timer circuit 10 shown by a chain line, and when a token is not detected for a certain period of time, it notifies the CPU 5 of that fact.

The data to be transmitted by the host 3 can be transmitted to the transmission line 1 via the transmission circuit 12 only when the reception circuit 11 receives the token addressed to the own node and acquires the transmission right.

The data to be transmitted is temporarily stored in the memory circuit 6 in the node 2 and is converted into an appropriate format (packet) as communication data.
The destination node address is added as the destination address value, and the setting value of the address setting circuit 8 is added as the source address, and then sent to the transmission line 1.

To receive the transmission information, the communication circuit 1 receives the communication data on the transmission line 1.
1, the destination address discriminating circuit 13 checks the destination address value in the received data, and when it is determined that it is the set value of the address setting circuit 8 in the own node, that is, the data addressed to the own node, this is sent to the CPU 5. The CPU 5 informs this data, fetches this data into its own node, performs some disassembly and editing processing on the CPU 5, and then delivers it to the connected host 3 as necessary.

Based on the above hardware configuration and the principle of token passing described above, each node in the network transfers tokens to downstream nodes one after another, so that communication that shares one transmission line is performed. is there. When all the nodes in FIG. 2 are up, the token circulates as shown in FIG.

The network system configuration of this embodiment will be described below with the configuration shown in FIG.

The structure of the transmission frame circulating in the network system of this embodiment is shown in FIGS. 6 (A) and 6 (B).

In the figure, 200 is a token frame, 201 is a source address (hereinafter referred to as SA), 202 is a destination address (hereinafter referred to as DA), 203 is a token code representing a token frame, 205 is a transmission code representing a data frame, 206 is transmission information.

The data transmission control of this embodiment will be described below with reference to the flow chart of FIG.

When the node device is powered on, whether or not it is the only specific node (hereinafter referred to as a master node) in the network that can first generate a token in step S1 and send (transfer) it to another node. If it is a master node, the process proceeds to step S2, the network construction process is executed, and the timer circuit 10 is started in the following step S3.

When this network construction process is completed, the flow proceeds to step S4, where SA201 is set to the own node address, 203
The token code is set to the node, the downstream node address to which the token should be transferred is determined by referring to the network configuration table 9 constructed in step S3, set in DA202, and the token frame 200 is generated. Then, this is sent to the transmission line 1 via the transmission circuit 12, the transmission right is transferred to the downstream node, and then the process proceeds to step S5.

On the other hand, if the master node is not the master node in step S1, the process proceeds to step S5.

In step S5, it is monitored whether or not a transmission frame is received from the transmission line 1, and when the transmission frame is not received, the process proceeds to step S6 to check whether or not the node is the master node. Check whether there is a notification due to a timeout interrupt. The timer circuit 10 is set to a time sufficient for the token to complete one round of the network, or the maximum token holding time per node. Even if the predetermined time set in the timer circuit 10 has elapsed, the token discrimination circuit 4 If no token is detected, it is determined that the network configuration has been changed, and the process returns to step S2 to execute the network construction process. If it is not the time-out or if it is not the master node, the process proceeds to step S5 to wait for the reception of the transmission frame.

When the transmission frame is received in step S5, step S8
Then, the transmission code area (203, 205) in the transmission frame received by the token discrimination circuit 4 is examined to see if it is the token code 203 or not. If the token frame is received, the process proceeds to step S9, and if it is the master node, the timer of the timer circuit 10 is restarted. Then, in step S10, the destination address determination circuit 13 compares the DA 202 in the received frame with the own node address value set in the address setting circuit 8. If the two values do not match, that is, if the transmission frame is not addressed to the own node, the process returns to step S5 to prepare for reception of the transmission frame addressed to the own node.

In the case of the transmission frame addressed to the own node, the process proceeds to step S11 and the transmission right is acquired by receiving the token. Then, in step S12, it is checked whether or not there is data to be transmitted from the host 3 or its own node, that is, whether or not there is a transmission request, and if there is a transmission request, a transmission frame for transmitting data is generated in step S13.

Specifically, the node address (destination address) peculiar to the destination node is set to DA 202, and the own node address (source address) set by the address setting circuit 8 is set to SA.
201 respectively, followed by transmission code 205,
A data transmission frame 250 is generated by setting the transmission information 206. Then, in step S14, the data transmission frame 250 is transmitted to the destination node according to a predetermined transmission control procedure. This transmission control means is publicly known and will not be described.

When the data transmission process is completed, the process proceeds to step S4, the token frame 200 is generated, this is sent to the transmission line 1 via the transmission circuit 12, the transmission right is transferred to the downstream node, and then the process returns to step S5.

If the token frame is not received in step S8, the process proceeds to step S20, and the DA202 in the received frame is determined by the destination address determination circuit 13 as in step S10.
And the own node address value set in the address setting circuit 8 are compared. If the two values do not match, that is, if the transmission frame is not addressed to the own node, the process returns to step S5 to prepare for reception of the transmission frame addressed to the own node.

In the case of the transmission frame addressed to the own node, the process proceeds to step S21, the data transmission frame 250 addressed to the own device is received in the own node according to a predetermined transmission control procedure, and the transmission information received in step S22 is sent to the host 3. If it is the information to be sent to the host 3, it proceeds to step S23, and after some disassembling and editing of this information, it is sent to the host 3 connected to this node, and to step S5. Return Prepare for the next data transmission.

If it is not the data to be transmitted to the host 3, that is, if it is the communication data between the nodes, the process proceeds to step S30,
It is checked whether or not the network configuration table is sent from the master node by, for example, group broadcast communication, and if the network configuration table is received, step S26
Then, the received data is stored in the network configuration table 9.

If the network configuration table is not received in step S25, the process proceeds to step S27, the process corresponding to the received data is executed, and then the process returns to step S5 to prepare for the reception of the next transmission frame.

As described above, in the present embodiment, only the master node can first generate a token and send (delegate) it to another node, and the other node receives the token from the master node and then receives the token. Without it, tokens cannot be generated. That is, the token is generated from only one node, and the tokens do not collide with each other on the transmission line 1.

Next, the construction process of the network configuration in the above description will be described with reference to the flow chart of FIG.

In this embodiment, this network reconfiguration processing is performed only by the master node, and the other nodes receive the network configuration information from the master node, store it in the network configuration table 9, and transmit it according to the stored contents. To do.

This network reconfiguration process is performed when a token is lost at the time of system startup, that is, when a node that is part of the network is disconnected from the network due to power failure or failure. This is done when a node joins.

First, in step S40, the downstream node address, that is, the destination address is set to the set address of the own node, irrespective of the downstream node address held in the network configuration table 9 until now, and in step S41, the downstream node address is set. Decrement by one, and in step S42 it is checked whether or not the destination address and the setting value of the address setting circuit 8 are equal. If they are not equal, the process proceeds to step S43, a transmission frame is generated using this address as the destination address, and the transmission circuit 12 is set. It is transmitted from the transmission line 1 via This transmission frame may be a control frame between nodes.

Then, in a succeeding step S44, it is checked whether or not the transmission of the transmission frame has succeeded. The means for identifying this varies depending on the transmission control procedure of each network, but for example, ACK which is an acknowledgment at the node which has received the transmission frame.
It is identified by returning a response.

If the transmission frame is not normally sent to the destination node (if the transmission fails), the other node operates (communication).
Assuming that the node is not possible, the process proceeds to step S45, and it is checked whether or not the destination node address value is the minimum address value defined in the network. If it is not the minimum address value, the process returns to step S41 and the destination node address value is set to one again. It decrements and tries transmission frame transmission using this new address value as the destination address.

In this way, the address value is gradually subtracted, and then the transmission frame is tried to be transmitted to the node having the address value.

If the subtracted address value reaches the minimum address value defined in the network, step S4
From S5, the process proceeds to step S46, and the destination node address value is set as the minimum node address value determined in the network, and the process returns to step S43. After that, the transmission of the transmission frame and the subtraction operation of the address value are repeated.

If the transmission of the transmission frame is successful, the process proceeds from step S44 to step S47, and the node having the destination node address value at that time is stored in the network configuration table 9 as an operable node configuring the network. Then, the process returns to step S41, and it is checked whether or not another operable node exists.

If the destination address is equal to the own node address in step S42, it means that the transmission process of the transmission frame has been executed for all the nodes that compose the network. Therefore, the process proceeds from step S42 to step S50, In the process, it is checked whether or not there is a node that has successfully transmitted the transmission frame.

If there is no node that has succeeded in transmission, it means that all the nodes other than the master node of the network system are in an inoperable state. Therefore, the process returns to step S40 and the network is transmitted until one of the nodes becomes available for transmission. Execute the build process. As described above, in the present embodiment, the above-described processing is repeated until the transmission processing of the transmission frame to one of the nodes succeeds.

If there is a successful transmission node in step S50, the process proceeds to step S51, and the network configuration table stored in the network configuration table 9 is transmitted by group broadcast communication. The other nodes receive this broadcast communication, store it in the network configuration table 9 of their own node, and thereafter select a downstream node according to this network configuration table.

The above explanation is mainly about the recovery process when a node that falls out of the network occurs or when the network system starts up, but a node newly entering the network configuration asks its own node to circulate the token. There is a need. In order to realize this, the node that should enter must monitor the transmission frame on the transmission path 1 and immediately transmit it when it detects the token code 203 of the transmission frame (for example, when its own node address is between SA201 and DA202 of the transmission frame). It suffices to send data on the road, cause a “collision” with the token frame 200, generate a token disappearance state, and execute the processing from step S40.

Alternatively, this process may be performed at regular intervals.

Also, in the above description, a general transmission frame is transmitted,
Although the network configuration has been checked, the network configuration may be checked using a token frame instead of the transmission frame. In this case, first, only the master node may be designated as the network configuration table, the token is transmitted, and the transmitted token is returned to the own node.

[Second Embodiment] (FIGS. 9 and 10) As described above, the master node in this embodiment plays an important role in recovery processing at the time of network start-up and token loss. It is a thing. Therefore, it is necessary to take sufficient measures against the failure of the master node. Therefore, in this embodiment, a plurality of nodes to be the master nodes are prepared, that is, a duplicated system or a multiplexed system of the master nodes is configured.

As described above, when the token is normally circulating, the master node performs the same operation as other nodes (hereinafter referred to as slave nodes). In addition, the hardware configuration is such that the timer circuit 10 is simply added between the master node and the slave node, and the timer circuit 10 is added to all the nodes.
By including the above, any node can operate as a master node. Therefore, for example, as a communication control processing procedure (firmware) in the CPU of each node in the network, both a control operation as a master node and a control operation as a slave node are provided, and instructions from an external (host) are provided. It is desirable that either the control operation as the master node or the control operation as the slave node can be selected and executed. As the input means of the selection instruction of the control operation, for example, the CPU 5
This can be easily performed by providing a control operation mode selection switch at the input / output port of the.

FIG. 9 shows a configuration example of the node in this case. This is the first
A timer circuit 10 and an operation mode selection circuit 14 are added to the circuit configuration shown in the figure. The operation mode selection circuit 14 can be composed of, for example, a switching switch. FIG. 10 shows an external view of a node when a switching switch is used as the operation mode selection circuit 14.

As shown in FIG. 10, the switching switch 14a can be operated from the outside, and when the operating master node stops operating due to a failure or the like, another operating mode is switched to the master node as another slave mode. You can

[Third Embodiment] (FIG. 11) In the second embodiment, the master node function and the slave node function are selected by switching by the operation mode selection circuit 14, but this selection is performed according to the instruction input from the host 3.
You may switch.

Generally, the host 3 is equipped with a man-machine interface, such as a personal computer shown in FIG. 11, and is often equipped with a display section 31 and a key input section 32. It is possible to instruct to switch the slave node function.

As a result, it is possible to switch the processing function of the node 2 without the need for an operation on the node 2, which normally has little human intervention.

At this time, the node 2 sends the time-out information of the timer circuit 10 to the host 3 via the interface circuit 7, and when the host 3 receives the time-out information, for example, a "token" is displayed on the display surface of the display device 31 of the host 3. It may be controlled so that it is displayed as "disappeared" information 31a.
When the operator confirms the display 31a indicating that "token disappears", he / she inputs the node function switching instruction input key 32a arranged in the key input section 32, and operates the node connected to the own device as the master node. Then, the CPU 5 is designated to operate as the master node via the interface circuit 7 of the node 2 in accordance with the key input. Upon receiving this designation input, this node executes the control operation as the master node shown in FIG. 7, reconstructs the network, and sends the token to the downstream node. At this time, if the function of the node connected to the own device is displayed on the display surface of the display device 31 (3
1b) The operator can always confirm the connection node function.

[Fourth Embodiment] (FIG. 12) Further, in the host 3 connected to the network, which controls particularly important processing in the network, for example, in a file device, a central processing unit, a mass storage device, etc. , First
As shown in FIG. 2, a plurality (for example, 2
In many cases, the connection is made via a node (1) to improve reliability and enhance communication capability. In the case of such a configuration, it is desirable that one of the nodes connected to this central processing unit be made to function as a master node so that the state of the node can be managed by the host side. It is one of these nodes.

In this case, there is also a method of operating one of the nodes as a master node and the other as a slave node in the normal case, and switching the other slave node to the master node when one master node goes down. This eliminates the need to find out if the master node is connected to any host in the network, and even if the node that was functioning as the master node goes down, the master node that changes to it becomes the master node before that. It is possible to immediately recognize that it is in the vicinity of the functioning node, and it is possible to take quick and accurate countermeasures against failures.

Since any of the methods described above can potentially have a plurality of master nodes in the network, it is possible to build a robust network system against failures in the master node.

In the above description, the token bus type network is used as a reference, but the present invention is not limited to this, and the present embodiment can be applied to a token ring type network configuration.

As described above, according to the present embodiment, token transfer can be performed reliably in any case, and even if token transfer cannot be performed normally, the network transmission can be performed without substantially impairing the data transmission efficiency. Can be rebuilt.

As described above, in this embodiment, by providing the master node only in the network, there is no conflict and collision state at the time of generation and transmission of tokens in the past, and the token circulation start processing is executed synchronously. It has the advantage of saying that.

In addition, it eliminates the need for conventional collision detectors,
It can be cheap in terms of cost.

Furthermore, since the asynchronous processing is eliminated, the processing procedure can be made extremely simple, and the processing overhead such as the communication control procedure can be minimized.

Further, even if the master node goes down due to a failure or the like, another slave node can be easily made the master node, and a network resistant to the failure can be constructed.

[Effects of the Invention] As described above, according to the present invention, when a token is lost, a specific transmission device checks the states of all the transmission devices, notifies all the transmission devices, and newly generates a token. However, since it is transmitted, the network can be reliably reconstructed even if the token is lost.

Further, as a result, the normal token transfer can be performed directly between the transmission devices constituting the network, and the token transfer can be performed quickly without taking time.

[Brief description of drawings]

FIG. 1 is a block diagram of nodes constituting a network system according to an embodiment of the present invention, FIG. 2 is a network configuration diagram, and FIG. 3 is a token of a network token passing system shown in FIG. Cyclic transition diagram, FIG. 4 is a token transition diagram of the token passing method in the case where there is a partially inoperable node of the network shown in FIG. 2, and FIG. 5 is a conventional token re-sending timing when a token disappears. 6A, FIG. 6A and FIG. 6B are transmission frame configuration diagrams used in this embodiment, FIG. 7 is a general data transmission control flow chart in the node of this embodiment, and FIG. 8 is this embodiment. FIG. 9 is a block diagram of a node constituting a network system of another embodiment according to the present invention, and FIG. 10 is a flowchart of another embodiment of the present invention. External view of over-de, Figure 11 is an external view of a node and the host of another embodiment of the present invention, FIG. 12 is a block diagram of the net work of another embodiment of the present invention. In the figure, 1 ... Transmission line, 2,100 to 170 ... Node,
3 ... Host, 4 ... Token discrimination circuit, 5 ... CP
U, 6 ... memory circuit, 7 ... interface circuit, 8
...... Address setting circuit, 9 ...... Network configuration table, 10 ...... Timer circuit, 11 ...... Reception circuit, 12 ......
Transmission circuit, 13 ... Destination address discrimination circuit, 14 ... Operation mode selection circuit, 31 ... Display device, 31a ... Node function display, 32 ... Key input unit, 32a ... Node function switching instruction input key, 203 ... Token code, 2
05 ... Transmission code.

Claims (1)

[Claims] 1. A network control method of a network system, wherein a plurality of transmission devices are connected to each other by a communication medium and the transmission device which has acquired the communication right by a token which is a communication right transfer command obtains the transmission right. When a token is lost due to an error in the, the only specific transmission device among the transmission devices that make up the network enables the generation of a new token, and the specific transmission device sets the address value of its own device to the initial value. For the destination address setting means for shifting the address value one by one from the initial value and setting the destination address, and for the transmission device having the address value set by the destination address setting means as the unique address value, Transmitting means for transmitting a transmission frame for checking whether or not the transmitting device is operable; and a transmitting frame by the transmitting means. When the response signal from the transmission apparatus that has transmitted the transmission after the transmission frame is sent back,
Storage means for storing the address value of the transmission device that has transmitted the transmission frame in a network configuration table; setting of the address value by the destination address setting means, transmission of the transmission frame by the transmission means, and address to the storage means Control means for repeatedly executing storage of values to all transmission devices, notification means for notifying the address values stored in the network configuration table to a plurality of transmission devices constituting the network, and a new token And a token sending means for sending a token based on the address value stored in the network configuration table, each of the plurality of transmission devices constituting the network is Talk based on the contents of the network configuration table notified by the transmitter. Network control method, which comprises delivering to another transmission apparatus.