JP2724572B2 - Token passing LAN device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a token passing type local area network (hereinafter referred to as LAN) device, and more particularly to a LAN device having a blackboard-type memory used for exchanging information between devices. It is about.

[Conventional technology]

2. Description of the Related Art Conventionally, in the field of factory automation and the like, a plurality of control devices are arranged in a distributed manner, and these control devices are connected by a bus or a communication path to operate a production line. A LAN device having a so-called blackboard type memory for coordinating between such control devices is known (Japanese Patent Laid-Open No. 62-254545). The blackboard-type memory is a memory provided in each control device and having a region for holding information output from all the control devices connected to the bus, and stores information sent from each control device in this memory. By holding the information in the area corresponding to each device, any control device can obtain necessary information of all the control devices when necessary. Thus, in a bus-connected LAN device having a blackboard type memory, each control device sequentially transmits its own information in the form of a broadcast, and the other control devices receive this and store it in the memory. The above operation is sequentially performed, and the time when all the control devices end the simultaneous broadcast is defined as one cycle. By repeating this cycle, the blackboard type memory of each device is refreshed. In each control device, it is necessary to detect the end point in order to perform various controls using the data in the blackboard type memory after the refresh. In a conventional LAN device, the end point of the simultaneous broadcast of the last control unit is detected, and each control unit determines whether or not the refresh of the blackboard type memory has ended.

[Problems to be solved by the invention]

However, a LAN with such a conventional blackboard type memory
In the device, each control device individually detects the end point of the memory refresh. Therefore, each control device requires a circuit and software for judging the end of one cycle, and has a drawback that the structure becomes complicated and the load on the CPU increases. There is also a drawback that if noise is present in the simultaneous broadcast of the last control device, there may be a control device which cannot determine the end of the refresh cycle.

The present invention relates to a LAN using such a conventional blackboard type memory.
It is a technical problem to be solved in view of the problem of the device and to solve the problem associated with determining the end point of the refresh cycle by managing the end of the refresh cycle by a specific device.

[Means for solving the problem]

The present invention is a token-passing type LAN device in which a plurality of control devices 1 and a management device 2 are connected to a bus 3, and as shown in FIG. It corresponds to a blackboard type memory 4 having an area for holding data transmitted from the device, and another control device connected to the bus after receiving a token from the preceding device of the token logic ring. Data transmitting means 5 for transmitting data and transmitting a token to a subsequent control device, token receiving means 6 for receiving a token provided from another control device, and receiving data provided from another control device. Data receiving means 7 for writing data to a corresponding area of the blackboard-type memory, and a memory 8 for holding data of the blackboard-type memory when a cycle end is transmitted from the data receiving means. The management device includes a cycle end monitoring unit 9 for monitoring the end of the refresh cycle based on the token reception, and a cycle end transmission unit for transmitting the end of the refresh cycle to the connected control device after detecting the end of the cycle. It is characterized by having.

[Action]

According to the present invention having such a feature, the refreshing of the blackboard type memory of each control device connected to the LAN device is started by sending a token by the management device, and the memory is refreshed when the token returns. An end signal is sent from the cycle end transmission means to each control device in a simultaneous broadcast assuming that the refresh has ended. In this way, each control device takes in the data of the blackboard type memory into another memory within a certain period of time so as to perform each control using the data after the refresh is completed.

〔The invention's effect〕

Therefore, according to the present invention, it is not necessary for each control device to determine that the refresh cycle of the blackboard type memory has been completed, and a circuit therefor is not required. Also, there is no need to detect the end of refreshing by software, so that the load on software is reduced and the capability of the original control function can be improved. Further, since the end of one cycle is determined by one management device, the risk of erroneously determining the end of one cycle in each control device is reduced, and a stable constant periodicity is obtained in all control devices. Will be obtained. In addition, since the data of the blackboard type memory is taken into another memory after the refresh is completed, it is easy to create an application program for each control device, and it is possible to prevent malfunctions in each control device. .

[Explanation of Example]

FIG. 2 is a block diagram showing a configuration of a control device and a management device, and FIG. 3 is a diagram showing a logical ring of a token passing LAN device according to an embodiment of the present invention. In these figures, the control devices 11 to 17 and the management device 18 are commonly connected to the bus 3. Since the control devices 11 to 17 and the area device 18 have the same configuration, the structure of the control device 11 will be described in more detail. In FIG. 2, the control device 11
Has a driver / receiver 21 and a protocol handler 22 for checking the validity of a given transmission frame and controlling a communication protocol. The protocol handler 22 is connected to an internal bus line 23. Each control unit has a central processing unit (hereinafter referred to as CPU) 24, and the above-described blackboard type memory 4 and direct memory access (hereinafter referred to as DMA) 25 are connected to a bus line 23. The user memory 7 is connected. The blackboard-type memory 4 is a blackboard-type memory having an area for holding information obtained from the own device and other control devices connected to the LAN as described above, and a portion indicated by hatching is sent from the own device. Indicates information. Each controller transfers the contents of the blackboard memory 4 to the user memory 7 by the DMA 25 when the refresh of the blackboard memory 4 is completed. Each control device executes various applications based on data in the user memory 7.

The control devices 11 to 17 and the management device 18 are commonly connected to the bus 3 as shown in FIG. 1, but the transmission order of the tokens is determined as shown in FIG. Figure 3 shows the management device
FIG. 8 is a diagram of a logical ring showing a state in which tokens sent from 18 are sequentially given to control devices 11 to 17 and tokens are returned from control device 17 to management device 18. The control devices 11 to 17 and the management device 18 hold the addresses of the preceding device to which the token is given and the address of the succeeding device that sends the token.

Next, the operation of this embodiment will be described with reference to the flowcharts of FIGS. 4 and 5 and the time chart of FIG.
First, to start the operation from the management device 18 at time t ₁ for transmitting data from the own apparatus (step 31). Then, the token rotation timer is started, and the token is transferred to the next control device, that is, the control device 11 (steps 32 and 3).
3). Then, in steps 34 to 36, it is checked whether the token has returned, whether the token rotation timer has expired, and whether simultaneous broadcast has been obtained from another device.

On the other hand, in a normal control device, the steps shown in FIG.
At 41 to 43, it is checked whether the token has been received or whether there has been a simultaneous broadcast from another control device other than the management device 18 or the management device 18. For example, when the control device 11 receives the token, the process proceeds to step 44 as shown in FIG. 6 (b) to send the data held in the blackboard type memory 4 of the own station onto the bus 3 and Transmit to all other stations. Then, the process proceeds to step 45, where the token is sent to the next device, in this embodiment, the control device 12 (time t ₃ ). If there is a simultaneous broadcast of data from another control device, the process proceeds from step 42 to step 46, where the data sent to the area of the blackboard type memory corresponding to the station is transferred to the loop of steps 41 to 43. Return. In this way, as shown in FIGS. 6 (a) to 6 (d), the tokens are sequentially received, and the data of the own device are simultaneously broadcast to all the other control devices and management devices. It will be refreshed. Now the control unit 17 at time t ₆ is sent to the token management device 18 finishes the broadcast management device 18 receives the token at step 34. And broadcast the completion of one cycle as shown at time t ₇ ~t ₈ of FIG. 6 (a) proceeds to step 38. Then, data is instantaneously transferred from the blackboard type memory 4 to the user memory 7 by DMA (step 3).
9). During this time period t ₉ ~t ₁₀ access the user memory 7 is inhibited from an application program created by the user as shown in Figure No. 6 (e). At this time, new data may be simultaneously written in the area corresponding to the next station in the blackboard type memory 4. Here the management device 18
In the steps 32 to 35, the function of the cycle end monitoring means 8 for detecting the end of the cycle is achieved.
The function of the cycle end transmitting means 9 for transmitting the end of the cycle is achieved. In step 40, the process waits for the timer to expire, and returns to step 31 again in the next cycle to transmit data from the own station.

Also, if there is a simultaneous broadcast from the management device 18 in each of the control devices 11 to 17, the process proceeds from step 43 to step 47 and the DM
A transfers from the blackboard type memory 4 to the user memory 7 by A. Then, the process returns to the loop of steps 41 to 43 and repeats the same processing.

In this embodiment, the management device 18 itself also has a blackboard type memory,
The management device is also configured to execute a specific application program, but the management device sends a token, detects only the end of memory refresh, and sends the end to other control devices in a broadcast. You can also. In this embodiment, each control unit has a blackboard type memory and a user memory for executing an application. By doing so, the user memory can be freely accessed from the user program at all other times except for a certain time immediately after the end of the refresh cycle.

[Brief description of the drawings]

FIG. 1 is a diagram showing the overall configuration of a token passing LAN device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a management device and each control device, and FIG. FIG. 4 is a diagram showing a logic ring of a token of the device, FIG. 4 is a flowchart showing an operation of the management device, FIG. 5 is a flowchart showing an operation of another control device, and FIG. 6 is a time chart showing the operation. 1, 11-17: control device, 2, 18: management device, 3: bus, 4: blackboard type memory, 5: data transmission means, 6
... Token receiving means, 7 ... Data receiving means, 8 ... Memory, 9 ... Cycle end monitoring means, 10 ... Cycle end transmission means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshiro Tasaka, Inventor Tachiishi Electric Co., Ltd. (10) Hanazono Todocho, Ukyo-ku, Kyoto, Kyoto Prefecture (56) References JP-A-63-310242 (JP, A) JP-A-61-150436 (JP, A) JP-A-60-246147 (JP, A) JP-A-2-60340 (JP, A A) JP-A-62-254545 (JP, A) JP-A-58-18740 (JP, A) JP-A-59-161953 (JP, A) JP-A-59-33953 (JP, A) 98045 (JP, A) SYSMAC LINK Development System, Tetsuo Kato et al., OMRON TECH HNICS Vol. 30, No. 1, PP. 26 −32

Claims (1)

(57) [Claims] 1. A token-passing LAN device in which a plurality of control devices and a management device are connected to a bus, wherein each control device holds data transmitted from all devices connected to the bus. A memory corresponding to the blackboard type memory having a region to be transmitted to the other controller connected to the bus after receiving a token from the preceding device of the token logical ring; Data sending means for sending a token to the device, token receiving means for receiving a token given from another control device,
A data receiving means for receiving data provided from another control device and writing the data in a corresponding area of the blackboard type memory, and a memory for holding the data of the blackboard type memory when a cycle end is transmitted from the data receiving means The management device includes a cycle end monitoring unit that monitors the end of the refresh cycle based on the token reception, and a cycle that transmits the end of the refresh cycle to the control device connected after detecting the end of the cycle. Termination transmission means;
A token-passing LAN device characterized by having: