JP2504130B2 - Bus type LAN - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus-type LAN, and more particularly to a token-passing bus-type LAN that is transmission-controlled based on a logical ring that represents the order in which tokens are sequentially transferred.

<< Outline of the Invention >> The present invention detects a fault occurring in an application unit provided in a node configuring a bus-type LAN by a transmission unit and temporarily collects the obtained fault data in a management station.
By sending a simultaneous broadcast notification to each normal station, each node station can grasp the failure occurrence of other stations, including the occurrence location.

<< Prior art and its problems >> As a transmission control method for a bus-type LAN, only a station having an access right to the transmission line, a so-called token, transmits data, and the token circulates through each station connected to the transmission line. There is a token passing method.

In general, the configuration of each node in this system can be divided into a transmission unit that performs transmission control by token passing and a so-called application unit that uses this transmission unit.

Conventionally, when a failure occurs in these nodes, the answer to the polling that is regularly performed is whether an abnormal frame is returned or nothing is returned. As a result, other nodes only recognize that a failure has occurred, and it is not possible to identify whether the failure location is in the transmission section or the application section. There was a problem that it was not possible to take appropriate countermeasures.

<< Object of the Invention >> The present invention has been made in order to solve the above problems, and an object of the present invention is to, even when a node fails, cause another node to cause the failure to occur. It is to provide a bus-type LAN that can be understood including.

<< Structure and Effect of the Invention >> In order to achieve the above object, the present invention has a plurality of communication nodes including a transmission unit that realizes a communication function and an application unit that performs various application processes by using the communication function of the transmission unit. A bus-type LAN for performing data communication between two or more communication nodes, a management station transmitting a polling frame for failure information collection, and a plurality of normal stations transmitting polling response frames in response to the polling frame. When the normal station detects a fault occurring in the application section of its own station and receives the polling frame from the management station, the fault information is put in the polling response frame and the management station Meanwhile, the management station periodically transmits the polling frame to a predetermined number of normal stations, and the predetermined number of normal stations is transmitted. Receives a polling response frame from the polling response frame, detects a fault in the transmission unit in the predetermined number of normal stations based on the presence or absence of the polling response frame, and determines the fault based on the fault information in the polling response frame. It is characterized in that the failure of the application unit in a certain number of normal stations is detected, and the failure information of the transmission unit and the failure information of the application unit in the predetermined number of normal stations are distinguished and notified to all the normal stations.

Therefore, according to the present invention, by the regular polling performed by the management station, the failure of the application unit and the transmission unit of the predetermined number of normal stations is distinguished by the management station, and the classified failure information is Since all the normal stations are notified from the management station, the management station and the normal station have either the application section or the transmission section causing the failure of the other station where the failure occurs. It is possible to obtain the effect of being able to understand even the location of the failure, such as a fault.

<< Description of Embodiments >> FIG. 1 is a diagram showing an overall configuration of a bus LAN according to the present invention.

In the figure, a bus-type LAN is configured by connecting a management station 1 and ordinary stations 2 to N, which form a communication node, to a transmission line 10 formed of a coaxial cable or the like. The inside of the management station 1 and the normal stations 2 to N is composed of a transmission unit a that realizes a communication function and an application unit b that uses the communication function of the transmission unit a. The management station 1 is a communication node in the bus type LAN and collects various management information including the operation status of the application section of the other stations by polling the other normal stations 2 to N, and broadcasts the management information. It has a function. Normal stations 2 to N are
It has a function of notifying the management station 1 of various management information including the operating status of the application section b of its own station in response to periodical inquiries.

FIG. 2 is a block diagram showing the internal structure of the node.

As shown in the figure, the node is divided into a transmission unit a and an application unit b. The transmission unit a includes the CPU21 and the ROM2.
2, a RAM 23, a transmission controller 24, and an internal bus 18 connecting these. Application part b is CPU26, ROM27, RAM28, I / O interface 2
9 and an internal bus 19 connecting them. Further, the transmission unit a and the application unit b are configured to exchange data with each other via the shared RAM 25.

The CPU 26 of the application section b executes various application processes according to the programs stored in the ROM 27,
When a communication function is required, the transmission unit a via the shared RAM 25
To send and receive data.

The CPU 21 of the transmission unit a controls the transmission controller 24 according to the program stored in the ROM 22, and the transmission controller 24
Various frames are transmitted / received to / from the transmission path 10 connected to.

The RAM 23 of the transmission section a is provided with a network management information table 30 and a local station information area 33, which will be described later.

Further, the shared RAM 25 is provided with a monitoring area 40 for monitoring whether the operation of the application section b is normal.

FIG. 3 is a diagram showing the configuration contents of the network management information table 30 and the own station information area 33 provided in the RAM 23.

The table 30 stores various management information about the nodes 1 to N on the network.
The memory area address in the table corresponds to the node numbers of the nodes 1 to N. The structure of each memory area is composed of a communicable bit 30a, a no-response bit 30b, an application monitoring bit 30c, and another area 30d, as shown in the memory area 30-2, for example.

The communicable bit 30a indicates whether communication is possible or not depending on the logical ring joining state of the corresponding node. This bit
When 30a is set to ON, it indicates that the corresponding node has joined the logical ring, and tokens are delegated in the order of the address of each node that is set to ON.

The no-response bit 30b indicates whether the normal station node responded or did not respond to the polling from the management station.If this bit is set to on, some failure occurred in the corresponding node. It is possible that the power is on or the power is off.

The application monitoring bit 30c indicates whether or not an abnormality has occurred in the application unit of the corresponding node. If this bit is on, it means that an abnormality has occurred in the application unit.

The other area 30d stores other management information about the corresponding node.

In addition to the table 30 regarding the management information of all these nodes, a local station information area 33 is provided in the RAM 23, and the management information regarding the local station is stored therein. Like the table 30, the configuration of the own station information area 33 includes a communicable bit 33a, a non-response bit 33b, an application monitoring bit 33c, and another area 33d.

In FIG. 4, the monitoring area 40 provided on the shared RAM 25 in the node is shown as a transmission section a and an application section b.
7 is a flowchart showing a process when the user accesses.

As shown in the figure, the monitoring area 4 provided in the shared RAM 25
0 means that the CPU 21 of the transmission unit a also
It is also accessed from the CPU 26.

The transmission unit a regularly increments the value of the monitoring area 40 (step 401), while the application unit b periodically clears the value of the monitoring area 40 (step 411). As a result, when some error or the like occurs in the application section b or the CPU 26 runs out of control, the value of the monitoring area 40 reaches the constant value determined by the system (Yes at step 402), and the transmission section a is set to the application section b. Will be detected, and the application monitoring bit 33c of the own station information area 33 existing in the work area on the RAM 23 will be set to ON (step 403).

FIG. 5 is a diagram conceptually showing a theoretical ring constructed by polling of the management station 1. In this logical ring, the tokens are delegated in the order of the address of the memory area to which the nodes assigned in the table 30 correspond, the tokens make a round, and when the normal station 5 at the end is reached,
It is shown that the token returns to the head management station 1.

FIG. 6 is a diagram showing a sequence of polling processing performed by the management station 1 in order to grasp the operation status of each normal station.

The management station 1 counts as one round when the token makes one round in the logical ring shown in FIG. 5 and returns, and when the count value reaches a preset value, it is a normal station on the transmission path. Start polling the node. The number of times the polling frame is sent at this time is also set as a system constant.

In the figure, a sequence is shown in the case where 1 is set to the system constant that specifies the number of times a polling frame is transmitted.

First, the management station 1 sends a polling frame to the normal station 2 based on the order of addresses in the table 30. Then, if the normal station 2 that received the polling frame is functioning normally, the data stored in the information area of the own station is transmitted by the polling response frame. Here, when the normal station 2 is not functioning normally, for example, when the power is not turned on or when some trouble occurs in the transmission section a, no response is made.

From the response to the polling obtained in this way, the situation of the normal station 2 is grasped and the information is stored in the memory area of the corresponding address of the table 30 in the management station 1.

Next, when the transmission of the polling frame is completed a predetermined number of times, the updated network management information in the table 30 is broadcast to all the normal stations.

Here, the token passing process shown in FIG. 5 is started again. Note that the next polling frame transmission for grasping the normal station operation will be performed to the next normal station 3.

FIG. 7 is a flowchart showing a process performed by the management station 1 in order to grasp the operating status of the normal station.

In the figure, the token returns to the management station 1, and when the polling process is executed, the polling counter provided in the RAM 23 or the like is cleared (step 701).

Next, the value of the polling number counter is compared with the allowable value of the number of polling preset as a system constant (step 702).

When the value of the polling number counter is less than the allowable number of times (No at Step 702), the partner station to which the polling frame is transmitted is selected (Step 703). The normal station selected here is a node station having an address obtained by adding 1 to the address of the node station to which the polling frame was last sent in the previous polling process.

Next, the management station 1 sends a polling frame to the selected ordinary station (step 704) and waits for a response from the ordinary station (step 705).

When the polling response frame is transmitted, each bit of the corresponding memory area of the table 30 is updated by the received data content (step 706), and then the polling number counter is incremented (step 706).
708) and proceed to step 702.

If no response is obtained to the transmission of the polling frame, ON is set to the no-response bit 30b of the corresponding memory area of the table 30 (step 707), and then the polling number counter is incremented (step 708) and proceed to step 702.

Also, when a frame other than the polling response frame is received, the corresponding process is performed.

After that, the processing is continued until the value of the polling number counter reaches the set value, and when the two match (Yes at Step 702), the updated data of the table 30 is simultaneously broadcast to each normal station as network management information. The notification is given (step 709), the process of grasping the operation status of the normal station is ended, and the process proceeds to the token passing process.

In this polling process, polling was started when the token returned to the management station and the timing for executing the set polling process was reached, but the process is started only when there is extra time for token circulation. It can also be set.

FIG. 8 is a flowchart showing a process for notifying the operating status of a normal station.

In the figure, the normal station receives various frames in an idle state and performs processing such as content identification (step 801).

Next, the type of the received frame is determined (step
802).

If the received frame is a token frame, token reception processing is performed (step 803).

If the received frame is a polling frame, a token response frame carrying the contents of its own station information area is transmitted to the management station (step 804).

If the received frame is a network management information frame, the network management information table 30 is updated based on the data of the received frame (step 80).
Five).

If the received frame is a data frame, data reception processing is performed (step 806).

When these frame reception processes are completed, the process proceeds to step 801 again, and the next frame reception process is performed.

As is apparent from the above processing, according to the present invention, by the regular polling performed by the management station, the failure of only the application section and the failure of the transmission section that have occurred in the normal station are distinguished and recognized by the management station. Furthermore, the collected network management information is broadcast to each normal station. As a result, the management station and each normal station include the failure occurrence point of other station, including the failure occurrence point in the application section or the transmission section. Can be grasped.

According to the present invention, since the failure occurrence point in the failed node is clarified in this way, the failure node can be handled more accurately than before, and the network operation can be performed efficiently. You can

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a bus LAN according to the present invention, and FIG.
FIG. 4 is a block diagram showing the internal configuration of a node, FIG. 3 is a configuration diagram of a network management information table, FIG. 4 is a flow chart showing operations of a transmission unit and an application unit in the node, and FIG. 5 is a conceptual diagram of a logical ring. 6 is a diagram showing the sequence of polling processing in the management station, FIG. 7 is a flowchart showing the operation of the management station, and FIG. 8 is a flowchart showing the operation of the normal station. 1 ... Management station (node) 1a ... Transmission section 1b ... Application section 2 to N ... Normal station (node) 2a to Na ... Transmission section 2b to Nb ... Application section 10 ... Transmission path 18,19 Internal bus 21,26 CPU 22,27 ROM 23,28 RAM 24 Transmission controller 25 Shared RAM 29 I / O interface 30 Network management information table 30a Communication Possible bit 30b …… No response bit 30c …… Application monitoring bit 33 …… Own station information area 40 …… Monitoring area

Claims (1)

(57) [Claims] 1. A bus-type LAN for performing data communication between a plurality of communication nodes including a transmission unit that realizes a communication function and an application unit that performs various application processes using the communication function of the transmission unit, The plurality of communication nodes are divided into a management station that transmits a polling frame for failure information collection and a plurality of normal stations that transmit a polling response frame in response to the polling frame. Detects a failure that occurred in the application section,
When the polling frame is received from the management station, the failure information is placed in the polling response frame and transmitted to the management station, while the management station periodically transmits the polling frame to a predetermined number of normal stations. Then, the polling response frame from the predetermined number of normal stations is received, the failure of the transmission unit in the predetermined number of normal stations is detected based on the presence or absence of the polling response frame, and the polling response frame is detected. Based on the failure information, the failure of the application section in the predetermined number of normal stations is detected, and the failure information of the transmission section and the failure information of the application section in the predetermined number of normal stations are distinguished and notified to all normal stations. A bus-type LAN that is characterized by: