JPH09247192A - Real time communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To place priority onto data transmission with high emergency, to compensate a loss of transmission time and to allow other terminal equipment to use immediately communication when the emergency transmission is finished by providing each means of network occupancy, abort of occupancy right and explicit flag denoting presence of occupancy. SOLUTION: In the case of transmission of emergency data from a host A being a sender of the emergency data to a host D, a network driver 103 receives transmission data designating emergency data communication from a host communication program. The network driver 103 stores an address 107b of the sender host A for emergency data communication and an address 107c of the destination host D to a network use right request packet to generate a network use right request packet 107. Then the packet is broadcast to all terminal equipments connected to the network. The occupancy of the network is discriminated by a reply ACK denoting the reception of the network use right request packet sent by the host D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a real-time communication system between a plurality of terminal devices connected to a local area network.

[0002]

2. Description of the Related Art Conventionally, as a method of performing emergency data communication on a local area network, Japanese Patent Laid-Open No. 7-18
There was something like that shown in 3901. According to this method, a terminal device that performs emergency data communication transmits a network usage right request packet to occupy the network,
On the other hand, when the other terminal device receives this packet, it stops transmission for a certain period of time to secure the communication path. Furthermore, each terminal device connected to the network is given a priority, and when the transmission request is generated by the terminal device with a higher priority while the terminal device itself is stopping transmission, the data transmission stop state is released. There was a method of transmitting a network usage right request packet. 25 to 27 show the configuration of a local area network for performing such emergency data communication in the conventional method. In FIG. 25, host A (2501) to host D (2504) are terminal devices. When it is necessary to perform emergency data communication from the host A (2501) to the host D (2504) when the network is congested in the state where normal communication is being performed, the host A (2501) transmits to the network. , Broadcast the network usage right request packet P. In FIG. 26, the host A (2501),
A terminal device other than the host D (2504) receives the network usage right request packet, and the host B (250
2) The host C (2503) suspends data transmission to the network for a predetermined time and releases the network for the host A and the host D. As a result, the host A and the host D can occupy the network for a certain period of time, and the emergency data can be transferred quickly. In FIG. 27, host A (2501)
And host D (2504) occupy the network and perform emergency data communication, host A (25
01), it is assumed that host B, which has a higher priority for the terminal device than host D (2504), has stopped transmission. In this situation, as shown in FIG. 27, when the host B (2502) having a higher priority needs to transmit the emergency data to the host C (2503), the host B is in the transmission stop state. To release the network usage right request packet.

[0003]

Since the conventional local area network communication system is configured as described above, the network occupation time can be set only to a fixed value, and the time setting method can also set only the expected value. Therefore, the emergency data communication is not completed within a specific time, and the other terminal device restarts the transmission, which hinders the emergency data communication.
Alternatively, there has been a problem that other terminal devices cannot perform transmission for a certain period of time, even though the emergency data communication is completed early enough and the network is available. In addition, the priority must be set uniquely for all terminal devices connected to the network, and when changing the partner of emergency data communication to be performed between terminals, each terminal is changed. There was a problem that the priority of the device had to be adjusted. Furthermore, in each terminal device, generally, transmission data with high urgency and transmission data with low urgency are mixed, and when transmitting data on the network, the emergency data is hindered by general data. was there.

The present invention has been made in order to solve the above problems, and in a network to which a plurality of terminal devices are connected, data of high urgency is preferentially transmitted, and the time until the transmission is completed is completed. It is an object of the present invention to provide a real-time communication method that guarantees and opens a network and enables the use of other terminal devices when emergency data communication ends early. Further, even when data having different urgency levels are mixed in each terminal device, by transmitting data on the network based on the urgency level, high priority data can be communicated without being obstructed by low data. The purpose is to provide a real-time communication method.

[0005]

In a real-time communication system according to the first invention, in a local area network in which a plurality of terminal devices are connected, each terminal device broadcasts a network usage right request packet to occupy the network. Means for allocating a packet for abandoning the network usage right after using the occupied network, and waiving the network occupancy right, and a flag indicating whether or not the network is occupied by another terminal device. It is intended to guarantee data communication during the period occupied by the device.

In a real-time communication system according to the second invention, in a local area network in which a plurality of terminal devices are connected, each terminal device broadcasts a network usage right request packet storing priority and occupies the network. Means, a means for broadcasting a packet of network usage right abandonment after the occupied network is used, for giving up the network ownership right, and a management table for recording the received network usage right request information. If the transmission data has a higher priority than that registered in the management table, the device broadcasts a network usage right request packet and registers it in the registration table, and if the priority is low, registers it in the registration table. Update the registration table when a subsequent network usage right abandonment packet is received , In which so as to resume the communication that has been suspended until then.

In a third aspect of the present invention, in the real-time communication system according to the first or second aspect, each terminal device provides a plurality of transmission queues according to the priority of a higher-level process with which the communication protocol and the network driver are connected. An intervening communication protocol stores transmission data from a higher-level process in a transmission queue corresponding to a priority, and a network driver sequentially performs transmission processing from a transmission queue having a higher priority.

According to a fourth aspect of the present invention, in the real-time communication system according to the first or second aspect, each terminal device provides a plurality of receive queues according to the priority of a higher-level process with which it communicates with a network driver and a communication protocol. In between, the network driver stores the received data in the corresponding reception queue based on the priority of the received data, and the communication protocol performs the reception process sequentially from the reception queue with the higher priority.

In a fifth aspect of the present invention, in the real-time communication system according to the third aspect of the invention, the transmission queue is provided with a last transmission time storage means and a time counter, and the number of collisions on the network occurring within a certain period in the past has a constant value. When the time exceeds, the transmission time interval from the transmission queue with a low priority is set to be long so as to suppress the traffic on the network and guarantee the transmission processing from the transmission queue with a high priority.

In a sixth aspect of the present invention, in the real-time communication system according to the third aspect of the invention, the transmission queue has an upper limit on the storable data length, and when the transmission queue overflows, old data on the low priority queue is replaced with lost data. It is intended to suppress the load on the network by deleting the data and suppressing the data transmission to the network.

In a seventh aspect of the present invention, in the real-time communication system according to the first or second aspect of the invention, memory resources used for data transmission / reception are secured for each process priority, and low-priority memory resources are exhausted. , High priority transmission / reception processing is not affected.

According to an eighth aspect of the present invention, in the real-time communication system according to the seventh aspect, when the memory resources for the high-priority communication process become insufficient, the memory resources are allocated from the memory resources allocated for the low-priority communication process. To avoid memory exhaustion.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. FIG. 1 shows a first embodiment of the present invention.
It will be described with reference to FIG. FIG. 1 shows one terminal device connected to a local area network. In the figure, 101 is a communication process for communication, 102 is a protocol layer in TCP / UDP / IP, etc., 103 is a network driver, 104 is a LAN
The controller 106 is a network usage right request packet reception flag, which is set by the network driver when the network usage right request packet 107 is received from another terminal device connected to the network.
A network usage right request packet 107 includes a packet header 107a, a source address 107b of a host who wants to occupy the network, a destination address 107c of a partner host who occupies the network for communication,
This packet includes a usage right request bit 107d indicating that this packet is a network usage right request packet. Also,
Reference numeral 108 denotes a network usage right abandonment packet, which includes a packet header 108a, a source address 108b of the host that initiated the network usage right request packet, a destination address 108c of the other party host that has occupied the network for communication, and Right to use bit 10 to indicate that the packet is a network right to use packet
It consists of 8d.

In FIG. 2, a plurality of terminal devices having the configuration of FIG. 1 are connected to a local area network, and host A (2
01) to host D (204) are communicating with each other.

Next, in the state where the load on the network is high, the host A (201)
4) will be described with reference to FIGS. 3 and 4. FIG. 3 is a flowchart showing the operation of the host A (201) that is the transmission source of the emergency data. The network driver 103, which has received the transmission data specifying that the emergency data communication is to be performed from the higher-level communication program, sends the address 107b of the transmission source host A and the destination host which perform the emergency data communication to the network usage right request packet in step 301. After the address 107c of D is stored and the network usage right request packet 107 is generated, it is broadcast to all terminal devices connected to the network in step 302. Next, it waits for a reply (ACK signal) indicating that the network usage right request packet has been received from the host D (step 303), and when the ACK signal is received, it is determined that the network can be occupied. After occupying the network, urgent data transmission / reception processing is executed with the host D (step 304) until a packet indicating the end of transmission / reception is received (step 305). After the transmission / reception of the urgent data is completed, the network use right abandonment packet 108 is generated (step 306) and broadcast to all terminal devices connected to the network (step 307).

Next, the operation of the host D that performs emergency data communication with the host A will be described with reference to FIG. When the host D receives the network usage right request packet (step 401), it confirms whether or not the destination host is itself (step 406) and sends an ACK signal to the host A indicating that the network usage right request packet has been received. It is returned (step 407). Host D considers that it has occupied the network when it returns the ACK signal,
A packet indicating the end of transmission / reception is received (step 40).
Up to 9), transmission / reception processing of emergency data with the host A is performed (step 408).

Here, FIG. 4 is used for transmission / reception processing when another host B connected to the network receives a network usage right request packet while the host A and the host D are executing the processing for occupying the network. Explain. When the host B receives the network usage right request packet (step 401), it confirms whether the destination host is itself (step 406). As a result of the confirmation, since the destination host is not itself, the network usage right request packet reception flag 106 is set (step 410).
In the transmission process of the host B, the flag 106 is checked before transmission as in (step 501) of FIG. 5, and if the flag is set, it is determined that the network is occupied by other terminal devices. , Does not send data on the network. In this way, Host A and Host D
Can occupy the network and send and receive data.

Next, the operation of the other host B when the emergency data communication between the host A and the host D is completed will be described with reference to FIG.
This will be described with reference to FIGS. The host B can execute the reception process even when the network usage right request packet reception flag 106 is set. Therefore, when the host A transmits the network use right abandonment packet in step 307 (FIG. 3), it is received by the host B in step 403 (FIG. 4), and the network use right request packet reception flag 106 is initialized in step 405. Then
Since the flag has been initialized, the transmission process of the host B can be restarted as shown in FIG. 5, and the communication state of the network is restored to the normal state before the host A and the host D occupied it.

Embodiment 2. A second embodiment of the present invention will be described based on FIGS. 6 to 9. FIG.
The block diagram of the terminal device in the second embodiment is shown, and a network usage right request packet management table 602 is provided in place of the network usage right request packet reception flag 106 of FIG. The network usage right request packet management table 602 includes items of source host address information 602a, destination host address information 602b, and packet priority 602c. Network usage right request packet reception flag 1
Although 06 is not certified by the host occupying the network, the network usage right request packet management table 6
02 is different in that it is set even by the host occupying the network. In the figure, the same numbers indicate the same components.

Next, as shown in FIG. 2, when the host A and the host D have already occupied the network and are performing the emergency data communication, the host B needs to perform the emergency data communication with a higher priority. The operation of each host will be described later by taking as an example the case where the host B occupies the network and performs communication when it occurs.

The operation of the host A is shown in FIG. Host A
Creates a network usage right request packet 601 when the need for emergency data communication with the host D arises (step 301). The network driver 103 of the host A embeds the priority of the communication received from the upper-layer protocol in the packet creation in the data portion 601e of the packet, and stores the content of the generated network usage right request packet in the network usage right request packet management table 602.
After registration (step 701), broadcast (step 302). Then, through steps 303 and 304, the network is occupied between the host A and the host D to perform emergency data communication. Step 7
In 02, when the network usage right request packet from the host B, which needs to communicate at a higher priority during the emergency data communication, is received, the host A receives the contents of the network usage right request packet management table 602.
(Step 703), the transmission process is stopped, and the network is released for the communication of the host B. Host A
After that, when the network usage right abandonment packet from the host B is received in step 704, the network usage right request packet management table 602 is followed by the previous step 7
The item set in 03 is deleted, and the emergency data communication is restarted (step 705).

Next, the operation of the host D will be described with reference to FIG. When the host D receives the network usage right request packet from the host A (step 801), the host D registers it in the network usage right request packet management table 602 (step 802), and steps 803 and 80.
It occupies the network through 5 and performs emergency data communication with the host A. Here, when a network usage right request packet is received from the host B that needs to communicate with a higher priority (step 804), the content is registered in the network usage right request packet management table 602 in step 806. , Stops the transmission process of host D and releases the network for communication of host B. When the host D subsequently receives the network usage right abandonment packet from the host B (step 807), it deletes the item set in step 806 from the network usage right request packet management table 602 in step 808,
Resume emergency data communication.

Next, the operation of the host B when the hosts A and D occupy the network will be described with reference to FIG. In step 901, it is checked whether there is an item already registered in the network usage right request packet management table 602. Since the hosts A and D occupy the network, if the priority of the emergency data to be transmitted is higher than any item in the management table (step 902), a network usage right request packet is generated (step 903). ). The content of the network usage right request packet to be transmitted from now on is registered in the network usage right request packet management table 602 (step 904),
Broadcast (step 905). Step 9
When the ACK signal is received from the host C, which is the destination of the emergency data transmission, in 06, it is assumed that the network has been occupied and the emergency data communication is performed in steps 907 and 908.
After the emergency data communication is completed, a network usage right abandonment packet is generated (step 909), the item registered in the network usage right request packet management table is deleted (step 910), and the packet generated in step 909 is broadcast (step 909). 911). On the other hand, in step 902, if the priority of the urgent data to be transmitted by the host B is lower than the entry in the management table that has already been set, the content of the network usage right request packet is changed to the network usage right request packet in step 912. Register in the management table 602. Step 91
When the network usage right abandonment packet is received in step 3, the corresponding item in the network usage right request packet management table 602 is deleted (step 914), and then the process returns to step 902 and the priority is given to the entry registered in the management table. This process is repeated until it becomes higher.

As described above, in the state where the hosts A and D occupy the network, the host B, which needs to transmit the emergency data with higher priority, intercepts the network and occupies the network. can do.

In the second embodiment, the two-step preemption for preempting the already occupied network has been described, but the N-step preemption can be realized in the same manner.

Embodiment 3 FIG. A third embodiment of the present invention will be described based on FIGS. 10 to 12.
FIG. 10 is a configuration diagram of a terminal device according to the third embodiment. In the figure, 1001 is a transmission queue provided between the protocol layer 102 and the network driver 103, and the transmission queue is prioritized by the upper communication process 101. It is provided for each degree or the number of priorities divided into several levels. Reference numeral 1002 denotes a packet to be sent to the network, and the protocol header portion 1002b stores the priority corresponding to the transmission queue. In the drawings, the same numbers indicate the same components.

Next, the flow of the transmission process from the upper communication process to the network driver when the transmission queue is provided will be described with reference to FIG. In step 1101, the communication process specifies the destination and passes the transmission data to the protocol layer. In the protocol layer, the transmission data is copied to the memory reserved for communication, the protocol header is added, the priority of the upper communication process is acquired (step 1102), and the priority is transmitted inside the protocol header or copied. Store at the beginning of the data (step 1
103), after storing the transmission data in the transmission queue corresponding to the priority (step 1104), the network driver is activated (step 1105).

Next, the operation of the activated network driver will be described with reference to FIG. Step 110
The network driver started in step 5 stores the highest priority of the transmission queue in i (step 1201), goes through steps 1202, 1203 and 1204, and determines whether or not there is data in the transmission queue in descending order of priority. To find out. When the transmission data is confirmed in the transmission queue (step 1203), the transmission data is extracted from the transmission queue (step 1205), the transmission data is passed to the LAN controller (step 1206), and the data is sent out on the network. By the above processing, the transmission process of the communication process having a high priority can be executed with priority over the transmission process of the communication process having a low priority.

Embodiment 4 A fourth embodiment of the present invention will be described based on FIGS. 13 to 15. FIG.
Is a block diagram of the terminal device in the fourth embodiment, and in the figure, 1301 is a reception queue provided between the network driver 103 and the protocol layer 102.
The reception queue is provided for each priority of the higher-level communication process 101 or for the number of priority divided into several levels. In the drawings, the same numbers indicate the same components.

Next, the flow of the reception process from the network driver to the upper layer protocol when the priority-based reception queue is provided will be described with reference to FIG. When the LAN controller receives data via the network, an interrupt is generated to the network driver. When an interrupt occurs, the network driver acquires the received data from the LAN controller (step 1401)
Then, the priority embedded in the beginning of the protocol header or the data part of the received data is acquired (step 140).
2). The reception data is stored in the reception queue corresponding to the priority acquired in step 1403, and the reception of the data is notified to the upper layer protocol (step 1404).

Next, the operation of the protocol layer which has received the reception notification will be described with reference to FIG. Step 140
The protocol layer which received the reception notification in step 4 stores the highest priority of the reception queue in i (step 1501), and through steps 1502, 1503 and 1504, there is data in the reception queue in descending order of priority. Check whether or not. When the reception data is confirmed in the reception queue in step 1503, the reception data is extracted from the reception queue (step 1505), the protocol header is removed from the reception data (step 1506), and the data stored in the communication memory is transferred to the upper communication. Copy and pass to the memory area of the protocol. Then, the process returns to step 1501, the reception queue is checked again, and the remaining received data is processed. By the above processing, the receiving process of the communication process having a high priority can be prioritized over the receiving process of the communication process having a low priority.

Embodiment 5 A fifth embodiment of the present invention will be described based on FIGS. 16 to 18. FIG.
FIG. 9 shows a block diagram of a terminal device in the fifth embodiment. In the figure, reference numeral 1601 denotes a transmission queue provided between the network driver 103 and the protocol layer 102. Each transmission queue has a previous transmission time 1601.
a and a clock counter 1601b are provided. In the drawings, the same numbers indicate the same components.

Next, the setting operation of the time counter by the network driver at the time of collision detection will be described with reference to FIG. Upon receiving the transmission completion interrupt from the LAN controller, the network driver acquires the number of collision occurrences from the register of the LAN controller (step 1701). Next, the difference between the number of collisions this time and the number of collisions last time is calculated, the elapsed time from the time of confirmation of the number of collisions last time is calculated, and the number of collisions per unit time is calculated and stored in i (step 1702). If the value of i (the number of collisions per unit time) exceeds a certain value in step 1703, the value of the clock counter 1601b of the transmission queue of each priority is increased (step 1704). At this time, the increment of the clock counter value is set such that the lower the priority, the larger the increment.

Next, the flow of the transmission process after the network driver operates the clock counter will be described with reference to FIG. The communication process is step 1101,
Step 1102, Step 1103, Step 110
After 4, the transmission data is stored in the transmission queue. next,
The previous transmission time (Tp) is acquired from the transmission queue (1601a) (step 1801), and the value of the clock counter (K) is acquired from the transmission queue (1601b). In step 1802, the current time (Tn) is acquired, and Tn> Tp +
Only when K is satisfied (step 1803), the network driver is activated to perform the transmission process (step 1804). By the above operation, the rate of satisfying the condition (Tn> Tp + K) of step 1803 decreases in a transmission queue with a lower priority. Therefore, when the network is congested, the transmission frequency of the low priority communication process is reduced to reduce the network load. By doing so, communication can be performed without reducing the transmission frequency of the high-priority communication process.

Sixth Embodiment A sixth embodiment of the present invention will be described based on FIGS. 19 and 20. FIG.
FIG. 19 is a configuration diagram of a terminal device showing a sixth embodiment. In the figure, 1901 is a transmission queue provided between the network driver 103 and the protocol layer 102, and the transmission queue length increases as the priority decreases. An upper limit is set for the queue length so that In the drawings, the same numbers indicate the same components.

The flow of the transmission process when the upper limit is set in the transmission queue according to the priority will be described with reference to FIG. The communication process is step 1101, step 110
2, through step 1103 and step 1104, the transmission data is stored in the transmission queue. When the priority of the stored queue is low, it is checked in step 2001 whether or not the length of the transmission queue exceeds the upper limit value, and if it does not exceed the upper limit value, the network driver is activated (step 2002) and transmission processing is executed. On the other hand, when the upper limit is exceeded, the head data of the transmission queue is extracted from the queue (step 2
003), it is determined that the transmission process for the data has failed, and an error is returned to the upper protocol (step 2004), and the data is not transmitted to the network. With the above operation, it is possible to avoid an increase in network load due to low-priority transmission processing.

Embodiment 7 A seventh embodiment of the present invention will be described based on FIGS. 21 and 22. FIG.
It is a block diagram of the terminal device in 7th Embodiment, Comprising: The memory for communication is prepared according to the priority, or the priority divided into several steps. In the figure, 2101 is a high-priority communication process memory, 2102 is a medium-priority communication process memory, 2103 is a low-priority communication process memory, and even if the communication memory for a low-priority communication process is exhausted, The memory of the high-priority communication process is not exhausted so that the transmission / reception processing of the high-priority communication process is not hindered. In the figure, the same numbers indicate the same components.

The transmission data from the communication process is once copied to the area obtained from the communication memory in the protocol layer, the protocol header is further obtained from the communication memory, added to the transmission data and passed to the network driver. Next, the transmission operation when the communication memory is divided will be described with reference to FIG. First, the communication process passes the transmission data to the protocol layer (step 22).
01). At the protocol layer, the process priority is acquired (step 2202), and after confirming that the priority is high priority (step 2203), the memory is acquired from the high priority communication memory (step 2204), and the network is acquired. Generate send data to pass to the driver. If the priority is not high in step 2203, it is checked in step 2205 whether the priority is medium priority (step 2206), the memory is acquired from the medium priority communication memory, and the result is passed to the network driver. Generate send data. On the other hand, if the priority is low, step 22
At 07, the memory is acquired from the low-priority communication memory and transmission data to be passed to the network driver is generated. The transmission data to the network driver generated using the communication memory corresponding to each priority is stored in the transmission queue (step 2208), and the network driver is activated and transmitted (step 2209).

In the present embodiment, the case of three priorities of high, medium and low has been described, but the number of priorities may be n, and the processing of steps 2203 and 2205 should be increased. Needless to say, can be dealt with.

Embodiment 8 FIG. An eighth embodiment of the present invention will be described based on FIGS. 23 and 24. FIG. 23 is a block diagram of the terminal device in the eighth embodiment, in which the communication memory is prepared according to the priority of the higher-level communication process, and when the high-priority communication memory is exhausted, it is lower than that. It is possible to supplement the memory from the communication memory of the priority and give priority to the communication process of the high priority. In the drawings, the same numbers indicate the same components.

Next, the communication operation when the high-priority communication memory is exhausted and the transmission operation will be described with reference to FIG. As already described with reference to FIG. 22, when steps 2201, 2202, 2203 and 2204 attempt to acquire the high-priority communication memory, the high-priority memory is exhausted and the memory is acquired. Upon confirming the failure (step 2401), in step 2206, acquisition is performed from the medium priority communication memory.
Next, in step 2402, it is confirmed whether or not the memory acquisition is successful, and if it is successful, the data is transmitted to the network driver through steps 2208 and 2209.
On the other hand, in the case of failure, the memory is acquired from the communication memory of lower priority (step 2207), and if the memory acquisition is confirmed (step 2403), step 220 is executed.
8. The network driver is made to transmit through step 2209. If memory acquisition fails in step 2403, it is determined that transmission data to the network driver could not be generated, and an error is returned (step 2404). In this way, the memory acquisition of the high priority process can be prioritized.

In the present embodiment, the case of three priorities of high, medium and low has been described, but the number of priorities may be n, and the steps of (2203) and (2205) are increased. Needless to say, it can be dealt with.

[0043]

As described above, according to the first aspect of the invention, the terminal device transmitting the emergency data broadcasts the network usage right request packet to occupy the network and sends the network usage right abandonment packet after transmitting the emergency data. Since the network is broadcast to open the network, it is possible to flexibly and surely occupy the network without depending on the time required for emergency data transfer.

According to the second aspect of the invention, the communication status of the emergency data is recorded in the network usage right request packet management table. Therefore, even when the other terminal device occupies the network, the emergency data If the priority is higher than any emergency data recorded in the table, there is an effect that the right to use the network can be intercepted and the emergency data communication can be performed.

Further, according to the third invention, since the transmission queue corresponding to the priority of the transmission data is provided and the transmission process is performed from the transmission queue of high priority, the transmission of the communication process of high priority is performed. Processing can be prioritized.

Further, according to the fourth aspect of the invention, the reception queue corresponding to the priority of the reception data is provided, and the reception data is stored in the reception queue corresponding to the priority of the reception data. Since the reception process is performed sequentially, the reception process from a communication process having a high priority can be prioritized.

According to the fifth aspect of the invention, the number of collisions per unit time is obtained, and when the number of collisions exceeds a certain number, the transmission interval is set longer for the transmission queue of lower priority. There is an effect that high priority communication can be preferentially processed while suppressing the load on the network.

According to the sixth aspect of the invention, when the transmission data length exceeds the upper limit value that can be stored in the transmission queue of the corresponding priority, it is determined that the data transmission has failed and the data is not transmitted to the network. , It is possible to suppress the increase in network load due to low priority mass data communication.

Further, according to the seventh invention, since the memory required for communication is divided and managed according to the priority, even if the low priority communication memory is exhausted, the high priority communication is performed. There is an effect that data communication can be performed without hindering the communication memory acquisition process.

In addition, according to the eighth aspect, the memory required for communication is divided and managed according to the priority, and even when the high priority communication memory is exhausted, the low priority communication memory is compensated for. Since the configuration is made possible, it is possible to avoid a situation where high-priority data communication is made to wait due to lack of memory.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a terminal device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a network to which terminal devices are connected.

FIG. 3 is a flowchart showing an emergency data transmission operation of the terminal device according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a data receiving operation of the terminal device according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the terminal device other than during emergency data transmission / reception according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram showing a terminal device according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing an emergency data transmission operation of the terminal device according to the second embodiment of the present invention.

FIG. 8 is a flowchart showing a data receiving operation of the terminal device according to the second embodiment of the present invention.

FIG. 9 is a flowchart showing the operation of the terminal device other than during emergency data transmission / reception according to the second embodiment of the present invention.

FIG. 10 is a configuration diagram showing a terminal device according to a third embodiment of the present invention.

FIG. 11 is a flowchart showing a transmission operation of a communication process according to the third embodiment of the present invention.

FIG. 12 is a flowchart showing a transmission operation of a network driver according to the third embodiment of the present invention.

FIG. 13 is a configuration diagram showing a terminal device according to a fourth embodiment of the present invention.

FIG. 14 is a flowchart showing a receiving operation of the network driver according to the fourth embodiment of the present invention.

FIG. 15 is a flowchart showing a protocol layer reception operation according to the fourth embodiment of the present invention.

FIG. 16 is a configuration diagram showing a terminal device according to a fifth embodiment of the present invention.

FIG. 17 is a flowchart showing the operation of the network driver according to the fifth embodiment of the present invention.

FIG. 18 is a flowchart showing a transmission operation of a communication process according to the fifth embodiment of the present invention.

FIG. 19 is a configuration diagram showing a terminal device according to a sixth embodiment of the present invention.

FIG. 20 is a flowchart showing a transmission operation of a communication process according to the sixth embodiment of the present invention.

FIG. 21 is a configuration diagram showing a terminal device according to a seventh embodiment of the present invention.

FIG. 22 is a flowchart showing a memory acquisition operation of a high priority communication process according to the seventh embodiment of the present invention.

FIG. 23 is a configuration diagram showing a terminal device according to an eighth embodiment of the present invention.

FIG. 24 is a flowchart showing a memory acquisition operation of a high priority communication process according to the eighth embodiment of the present invention.

FIG. 25 is a diagram showing a transmission process of a network usage right request packet according to a conventional technique.

FIG. 26 is a diagram showing a network occupancy state in the related art.

FIG. 27 is a diagram showing cancellation of transmission stop in the conventional technique.

[Explanation of symbols]

101 communication process, 102 protocol layer, 103
Network driver, 104 LAN controller, 105 local area network, 106 network usage right request packet reception flag, 107 network usage right request packet, 107a packet header, 107b source address, 107c destination address, 107d usage right request bit, 108 network usage Waiver packet, 108a packet header,
108b source address, 108c destination address,
108d Usage right abandonment bit, 201 Terminal device according to the present invention (host A), 202 Terminal device according to the present invention (host B), 203 Terminal device according to the present invention (host C), 204 Terminal device according to the present invention (host D), 6
01 network usage right request packet, 601a packet header, 601b source address, 601c destination address, 601d usage right request bit, 601e
Usage right request packet priority, 602 network usage right request packet management table, 602a source host address information, 602b destination host address information,
602c packet priority, 1001 priority assigned transmission queue, 1002 transmission packet including priority in protocol header, 1002a packet header, 100
2b protocol header, 1301 priority-based reception queue, 1302 reception packet including priority in protocol header, 1302a packet header, 130
2b protocol header, 1601 prioritized transmission queue with last transmission time and time counter, 1
601a Last transmission time, 1601b Clock counter, 1901 Transmission queue with upper limit of queue length, 2
101 high-priority communication memory, 2102 medium-priority communication memory, 2103 low-priority communication memory.

Claims (8)

[Claims] 1. In a local area network connecting a plurality of terminal devices, each terminal device broadcasts a network usage right request packet to occupy the network, and a network usage right after the occupied network is used. Provided with means for broadcasting abandonment packets to abandon the network occupancy right and a flag indicating whether or not the other terminal device occupies the network so that data communication is guaranteed during the occupied period by the other terminal device. Real-time communication method characterized by. 2. In a local area network connecting a plurality of terminal devices, each of the terminal devices broadcasts a network usage right request packet storing priority and occupies the network, and a means for occupying the network. A means for waiving the exclusive right to the network by broadcasting a packet of network usage right abandonment after use and a management table for recording the received network usage right request information are provided. If it is higher than the one registered in the management table, a network usage right request packet is broadcast and registered in the registration table. If the priority is low, the network usage right abandonment packet is received after registration in the registration table. The registration table is updated at the point when the Real-time communication system, characterized in that the the like. 3. Each of the terminal devices is provided with a plurality of transmission queues according to the priority of the higher-level process for communication between the communication protocol and the network driver, and the communication protocol is assigned to the transmission queue corresponding to the priority from the higher-level process. 3. The real-time communication system according to claim 1 or 2, wherein the transmission data is stored, and the network driver sequentially performs transmission processing from a transmission queue having a high priority. 4. Each of the terminal devices has a plurality of reception queues between the network driver and the communication protocol according to the priority of the higher-level process with which the communication is performed, and the network driver receives corresponding data based on the priority of the received data. The real-time communication system according to claim 1 or 2, wherein the reception data is stored in a queue, and the communication protocol is such that reception processing is sequentially performed from a reception queue having a high priority. 5. The transmission queue is provided with a storage means for storing the last transmission time and a clock counter, and when the number of collisions on the network that has occurred within a certain period in the past exceeds a certain value, the transmission queue with a low priority is transmitted. 4. The real-time communication method according to claim 3, wherein the transmission time interval is set to be long so that the transmission process from the transmission queue having a high priority is suppressed by suppressing the traffic on the network. 6. The transmission queue has an upper limit on the length of data that can be stored, and when the transmission queue overflows, old data on the low-priority queue is deleted as lost data to prevent data transmission to the network. 4. The real-time communication system according to claim 3, wherein the load of the network is suppressed by the above. 7. A memory resource used for data transmission / reception is secured for each process priority, and even if low-priority memory resources are exhausted, high-priority transmission / reception processing is not affected. The real-time communication system according to claim 1 or 2. 8. When the memory resources for the high-priority communication process are insufficient, memory is allocated from the memory resources allocated for the low-priority communication process to avoid memory depletion. The real-time communication system according to claim 7.