JPH1146204A - Network system for system providing plural tokens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a network system adopting the system which provides plural tokens in which tokens are given to stations with many transmission opportunities to the utmost, so as to allow the stations to make communication not via a central station in the case that stations with many transmission opportunities and stations with small transmission opportunities are in existence on a same network. SOLUTION: In this network system, a master station (a) has a token provision function and sends a transmission permission frame having destinations of plural slave stations (b), (c), (d) to each slave station. In the case that the slave station(b), (c) or (d) receiving the transmission permission frame has transmission data, the slave station (b), (c) or (d) sends the transmission permission frame without deleting an address of its own station. Upon the receipt of the circulated transmission permission frame, in the case that the transmission permission frame indicates the slave station (b), (c) or (d) with transmission data, the master station (a) retransmits the transmission permission frame to a transmission line, without rewriting at all the address of at least a destination address part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting a plurality of stations by giving a transmission right to a station having a large number of transmission opportunities as much as possible when a station having a large number of transmission opportunities and a station having a small number of transmission opportunities are present in the same network. The present invention relates to a right-granting network system.

[0002]

2. Description of the Related Art Generally, a local network (hereinafter referred to as L)
A token passing method is widely known as a method for arbitrating the transmission right of a communication frame to the communication network (hereinafter referred to as AN).

[0003] In the form of the network of the token passing system, each station (a, b, c, d) is connected in a ring shape by a transmission line.

In such a token passing system in a network, a control packet generally called a token is circulated on a transmission line, and when a token arrives at a station having a transmission request, the token is captured and only that station transmits the token. (Hereinafter, referred to as transmission in this description).

[0005] The right to transmit is granted one per token capture in order to give each station an equal opportunity to transmit.
Packet transmissions are allowed. After transmitting the packet, the station returns the token to the transmission path. Further, when the token that has transmitted the token makes a round, the token is newly generated and transmitted to the transmission path.

That is, in the token passing method, a control packet called a token is circulated through a network so that each station is given a transmission right in order and transfers data.

On the other hand, in the local area network management system disclosed in Japanese Unexamined Patent Application Publication No. 5-95361, one central device and a plurality of terminal devices are connected to one central network in a ring by a transmission line. Only the apparatus is given the right to use the transmission path, and this central apparatus sequentially communicates with each terminal apparatus and instructs only the terminal requesting communication to start communication, thereby preventing data collision on the transmission path.

[0008] When the terminal devices communicate with each other, the communication is realized via a central device.

[0009]

However, in the above-mentioned conventional token passing method, the right to transmit is given to each station in order by circulating a control packet called a token in a network, and the station that has acquired the right to transmit is transmitted once. One data transmission is transmitted when the transmission right is acquired.

[0010] That is, since the transmission right is always equally transmitted to each station, the transmission right of each of the stations having a large number of transmission opportunities and that of the station having a small number of transmissions is limited to only once each time the token makes one round.

For this reason, a station having a large number of transmission opportunities, after performing data transmission once, waits until the next token circulates even though there is no data to be transmitted by another station and no transmission path is used. have to wait.

For example, if the slave station transmits the transmission data to the transmission line in accordance with the order of generation of the transmission data every time the token circulates, and when the emergency transmission data occurs later, the emergency transmission The data is sent to the transmission line at the next round of the token.

That is, in the conventional token passing system, when a station having a large number of transmission opportunities and a station having a small number of transmission opportunities are arranged on a network, the transmission path cannot be used efficiently. Emergency transmission data cannot be sent quickly.

In the local area network management system disclosed in Japanese Patent Application Laid-Open No. 5-95361, since each terminal device always communicates via the central device when performing communication, the data transfer speed is increased. Decrease.

Therefore, when a station having a large number of transmission opportunities and a station having a small number of transmission opportunities are present in the same network, it is possible to give a transmission right to a station having a large number of transmission opportunities as much as possible without passing through a central office. desirable.

[0016]

According to the present invention, a plurality of stations are connected by a transmission line, and among these stations, any one of the first stations is connected to a plurality of other second stations connected to the transmission line. This is a network system that performs communication with a function of granting a transmission right to a station.

When the first station grants the transmission right from the own station to the plurality of second stations, the transmission permit frame in which the plurality of second stations are written in the destination address portion is transmitted to the transmission path. When transmitting and receiving a transmission permission frame, if predetermined information remains in the header of the transmission permission frame, the received transmission permission frame is transmitted to the transmission path as it is.

The second station receives the transmission permission frame,
When there is transmission data, the transmission data is transmitted. When there is further transmission data, predetermined information indicating that transmission data exists in the own station is written in a predetermined area of a header portion of the transmission permission frame. When the transmission frame is transmitted to the transmission path, and when there is no transmission data or when there is no further transmission data, the transmission permission frame obtained by removing predetermined information related to the own station from the header portion of the received transmission permission frame is transmitted to the transmission path. The gist is to transmit to.

According to the present invention, in a network system including a first station as a master station and a plurality of second stations as slave stations, the second station transmits a transmission permission frame from the first station. Upon receipt, if there is data to be transmitted next time, the second station writes predetermined information indicating that there is data to be transmitted next time in a predetermined area of the header portion of the transmission permission frame and transmits the frame.

The first station receives the transmission permission frame from the second station, and if the header of the frame indicates that there is a second station having data to be transmitted, the first station receives the frame. The transmission permission frame for the second station is transmitted.

According to the second aspect, when a plurality of transmission permission frames generated by the first station and transmitted to the second stations are transmitted to the transmission path, the transmission permission frames are received by the second station. .

When there is data to be transmitted, the second station transmits the transmission data. When there is further transmission data, the second station keeps its own address in the destination address portion of the transmission permission frame. The transmission permission frame is transmitted to the transmission path, and if there is no further transmission data, and if there is no transmission data, the transmission permission frame in which the destination of the own station is deleted from the received transmission permission frame is transmitted to the transmission path. .

For this reason, the first station, which is the master station to which the transmission right is assigned, receives the transmission permission frame in which the destination address of the second station having the data to be transmitted is written. When there is no data to be sent to any of the stations, a transmission permission frame in which the destination address of the second station is deleted is received.

Therefore, the first station, which is the master station, sets the destination address of the transmission permission frame to the second station in which data to be transmitted exists.
Since the transmission is made to the transmission path with the destination address of the first station, only the second station can obtain the transmission right.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiment of the present invention, addresses A, B, C and D are assigned to a master station a and slave stations b, c and d, respectively.
An embodiment in which the present invention is applied to a network in which these stations are connected in a ring by a transmission line will be described.

FIG. 1 is a schematic configuration diagram of a network system using a multiple transmission right grant method. In the network system shown in FIG. 1, the master station a has a transmission right grant function, transmits a transmission permission frame having a plurality of destinations of the slave stations b, c, and d to each of the slave stations. The received slave station b, c, or d transmits the transmission data to the corresponding station.

At this time, when there are a plurality of transmission data, the slave stations b, c, and d transmit the transmission data having the highest priority level first, and the transmission permission frame transmitted to the transmission path still has the transmission data. Write it and send it.

When receiving the transmission permission frame, the main station a does not rewrite any data when the transmission permission frame indicates that there is a slave station b, c or d having transmission data. Instead, it is retransmitted to the transmission path.

For this reason, as shown in FIG. 1, the master station a has at least the transmission right granting means 1 for granting the transmission right to the slave stations b, c and d, and the received transmission permission frame has transmission data. A transmission data existence station determining means for determining whether or not there is a slave station;

The above-mentioned transmission right granting means 1 transmits a transmission permission frame having destinations of a plurality of slave stations b, c and d to each slave station (hereinafter referred to as broadcast communication).

In transmitting the transmission permission frame, the address of the slave station b, c or d from the transmission data existence station determining means 2 is written in the destination address portion of the transmission permission frame. The configuration of the transmission permission frame will be described later with reference to the drawings.

The transmission data existence station judging means 2 judges the slave station having the transmission data from the address of the slave station written in the received transmission permission frame, and notifies the transmission right granting means 1.

On the other hand, the slave stations b, c and d are provided with at least the slave station communication processing means 3 for enabling communication between the slave stations, and the transmission with the highest priority when a plurality of transmission data exist. A priority data determining means for determining data and setting the data in the communication processing means between slave stations;

When there is no transmission data in response to the reception of the transmission permission frame, the inter-station communication processing means 3 deletes its own address in the destination address portion of the transmission permission frame described later and transmits the frame to the transmission path. .

If there is transmission data, the inter-station communication processing means 3 transmits the transmission data in which the source address and the destination address are written to the transmission path.

When there are a plurality of transmission data, the priority data determination means 4 determines the type of each transmission data, and determines the priority according to the type. Then, the transmission data having the highest priority is set in the inter-station communication processing means 3.

Next, the transmission permission frame will be described with reference to FIG. The transmission permission frame is, as shown in FIG.
A total destination section 8 in which the total destination number n is written, a reception counter section 9 in which the reception counter value cn is written, a destination address section 10 in which the destination address of each slave station is written, and a source address section in which the source address is written 11 and
Transmission permission command section 1 in which a transmission permission command is written
And 2. The above-mentioned total destination section 8, reception counter section 9, destination address section 10, and source address section 11 are collectively called a header section.

<Detailed Configuration of Master Station and Slave Station> FIG.
FIG. 4 is a specific configuration diagram of slave stations b, c, and d (collectively called stations). As shown in FIG. 3, the station receives a transmission permission frame or transmission data from a transmission path and performs a predetermined conversion. The reception I / F 15 decodes the address of the data from the reception I / F 15 and stores it therein. An address decoder 16 to be fetched, a reception buffer 17 in which received data fetched by the address decoder 16 is stored, a functional device I / F unit 18 for receiving data from each device, a data processing unit 19 described later, A transmission buffer 20, a transmission frame generation unit 21 for generating and transmitting transmission data of a frame of a predetermined format, a transmission I / F 22,
A counter management unit 23 for subtracting or adding the total number n of the transmission data generated by the transmission frame generation unit 21 and the reception count value Cn; a destination address management unit 24 for deleting or adding the destination address of the transmission data; A transmission permitting frame buffer 25 for storing frames.

The data processing unit 19 includes, in the master station a, at least the transmission right granting means 1 for granting the transmission right to the slave stations b, c, d, and the slave having the transmission data in the received transmission permission frame. A transmission data existence station determining means 2 for determining whether or not there is a station is provided.

On the other hand, the data processing units 19 of the slave stations b, c, d
In the above, at least the inter-station communication processing means 3 which enables communication between the sub-stations, and when there are a plurality of transmission data, the transmission data having the highest priority is determined and the inter-station communication processing means 3 for setting priority data.

<Explanation of Operation> The operation of the network system using the multiple transmission right grant system configured as described above will be described. In the description of the operation, only the slave station b has two transmission data (command data 1 to the slave station d and command data 2 to the slave station c), and when the station a acquires the transmission right for the second time,
Description will be made on the assumption that one transmission data is generated.

FIG. 4 is a flowchart for explaining the operation of the master station a. FIG. 5 is a flowchart for explaining the operation of the slave station. FIG. 6 is an explanatory diagram illustrating a transmission procedure of a transmission permission frame and transmission data (hereinafter, referred to as data) in the master station a and the slave stations b, c, and d.

As shown in FIG. 4, the master station a first initializes the system (S1). After the system initialization, the master station a generates a new transmission permission frame F shown by p1 in FIG. 6 and transmits it to the slave stations b, c, and d by broadcast communication (S2).
The transmission permission frame in this step S2 is p
As shown in FIG. 1, the transmission permission frame F1 in which the total number of destinations n is 3, the reception counter Cn is 0, and the destination addresses are the address B of the slave station b, the address C of the slave station c, and the address D of the slave station d is written. is there.

That is, the transmission right granting means 1 of the data processing unit 19 of the main station a uses the address management unit 24 to change the destination address to the address B of the slave station b, the address C of the slave station c, and the address of the slave station d. D to the transmission frame generation unit 21 in the order of D, and using the counter management unit 23, the reception counter value Cn
Is set to “0”, and the transmission permission command of the transmission permission frame buffer 25 is transmitted to the transmission frame generation unit 21.
The transmission frame generation unit 21 generates a transmission permission frame F1 of p1 shown in FIG. 6 and transmits the transmission permission frame F1 to the transmission path via the transmission I / F 22.

On the other hand, as shown in FIG. 5, the slave station b monitors whether or not the transmission permission frame F has been received (S2).
0). If it is determined in step S20 that the slave station b has received the transmission permission frame F, the transmission permission frame F1 transmitted by the master station a in step S2 of FIG. 4 is stored in the transmission permission frame buffer 25 (S21). It is determined whether or not there is data in 20 (S22).

More specifically, the processing of step S21 is performed when the address decoder 16 of the slave station b writes the address B into the destination address section 10 of the transmission permission frame F1 and transmits the transmission permission frame F1 to the transmission permission frame buffer 25. To be stored.

When it is determined in step S22 that the slave station b has data, the priority data determination processing means 4 of the slave station b determines which of the command data 1 and the command data 2 in the transmission buffer 20 is urgent. It is determined whether the data is data (S23). The priority data is determined, for example, by providing a table (not shown) in which priority levels are stored in advance for each type of data in the data processing unit 19 and comparing the priority level of this table with the data in the transmission buffer 20. I do.

Then, the data K1 (transmission command data 1) determined in step S23 is transmitted to the transmission frame generation section 21 to be transmitted (S24). The data K1 from the slave station b to the slave station d is represented by P2 in FIG.
The total number n of destinations in the total destination section 8 is “1”, and the reception counter section 9
, The destination address section 10 is set to the address “D”, and the transmission source address section 11 is set to the address “B”.

That is, the destination address management unit 24 uses the counter management unit 23 to set the total number of destinations n to “1” and set the reception counter Cn to “0”, and send them to the transmission frame generation unit 21. The destination address management unit 24 sets the destination address to the address “D” and sets the source address to “B”.

By this processing, the transmission frame generation unit 2
No. 1 generates data K1 shown in P2 of FIG. 6 and sends it out via a transmission line.

That is, when there is data, the inter-slave communication processing means 3 of the data processing unit 19 of the slave station b determines the address of the slave station as the destination of the data and the slave station b as the transmission source.
The provision of the function of writing the address of (own station) enables communication between slave stations without the intervention of the master station a.

Then, after transmitting this data K1,
It is determined whether there is more data to send (S2
5). Since the slave station b has further data 2, step S
At 25, it is determined that there is more data to be transmitted in the transmission buffer 20.

If it is determined in step S25 that there is more data to be transmitted, the transmission permission frame F1 is not processed and the transmission is permitted (transmission permission frame F2) as shown at p2 in FIG. 6 (S26). ), And the process returns to step S20. Since the transmission permission frame F2 has data 2 to be transmitted to the child station c in the transmission buffer 20 of the child station b, the total number of destinations n of the transmission permission frame F2 is n.
Is set to "3", the reception count value Cn is set to "0", the destination address section 10 is set to the address "B, C, D", and the source address is set to "A".

That is, when there is other data to be transmitted in the slave station b, the data processing unit 1 of the slave station b transmits the address B which is its own address without deleting it.
The inter-slave station communication processing means 3 is configured to give the transmission right to the slave station b next time.

Further, the slave station c which has received this data has no data in the transmission buffer 20, so that the slave station c performs step S2.
0, it is determined through step S21 that there is no data in the transmission buffer 20 in step S22, and the process proceeds to step S27. In step S27, the address C, which is the self address of the destination address section 10 of the transmission permission frame F2, is deleted (S27).

Then, the total number n of destinations is decremented by 1 and the reception counter is incremented by 1 (S2
8) The transmission permit frame F3 is transmitted to the next station (S2).
9).

That is, the slave station c deletes the address C of the destination address section 10 of the transmission permission frame F2 received from the slave station b and sets the total number of destinations n to “2”, as indicated by p3 in FIG. The transmission permission frame F3 in which the reception counter value Cn is set to "1" is transmitted.

A description will be given with reference to the configuration diagram of FIG.
The data processing unit 19 uses the counter management unit 23 to
The total number of destinations n is set to “2” and the reception counter Cn is set to “1”, and the transmission frame generation unit 21 transmits the transmission permission frame F3.

On the other hand, the slave station d transmits the response data R1 after receiving the transmission permission frame F3, and there is no more data to be sent in its own transmission buffer at that time, so that steps S25, S27 and S28 are performed. , 29, the transmission permission frame F4 is transmitted to the transmission path.

More specifically, the slave station d receives the above-mentioned transmission command data K1, is stored in the reception buffer 17 by the address decoder 16 of the slave station d, and, as shown at p4 in FIG. Is the address B, the source address section 11 is the address D, and the response data R1 in which the response 1 is written is transmitted. This transmission is performed by the transmission buffer 20, the transmission frame generation unit 21, the destination address management unit 2
4 is performed.

Further, when the slave station d receives the transmission permission frame F3, there is no data to be sent to the master station a in this example, so that the above-mentioned steps S22 and S2 shown in FIG.
The address D, which is its own address, is deleted by the processes of 7, 28, and 29, and the transmission permission frame F4 in which the total number of destinations n is set to "1" and the reception counter value Cn is set to "2" is transmitted to the transmission path.

That is, as shown at p4 in FIG. 6, the transmission permission frame F4 from the slave station d has the address B of the slave station b.
Is left as it is.

On the other hand, when the total number of destinations n is other than "0" and the transmission permission frame F4 is the first round, the master station a which has received the transmission permission frame F4 transmits the transmission permission frame F4 as shown at p6 in FIG. The content of the permission frame F4 is transmitted to the transmission path as the transmission permission frame F5 without rewriting.

The processing up to the transmission of the transmission permission frame F5 will be described with reference to the flowchart of FIG.

Steps S1 and S2 shown in FIG.
After transmitting the transmission permission frame F1 of the broadcast communication to all the slave stations, the main station a monitors whether or not the transmission permission frame F transmitted by the main station a to the transmission path is received (by the processing of (1)). S3).

If it is determined in step S3 that the main station a has received the transmission permission frame F transmitted in step S2, the received transmission permission frame F is transmitted to the main station a.
Of the transmission permitting frame buffer 2
5 (S4). This received transmission frame F
As shown at p4 in FIG. 6, the total number n of destinations is “1”, the reception counter value Cn is “2”, the destination address of the destination address unit 10 is “B”, This is the transmission permission frame F4 in which the transmission source address is set to “A”.

Next, the transmission data existence station judging means 2 of the data processing section 19 of the main station a receives the transmission permission frame F
It is determined whether or not the total number n of destinations of “4” is “0” (S5).
That is, it is determined whether or not there is any of the slave stations b, c, and d that has not been able to transmit all the data in the transmission buffer when the previous transmission right was acquired.

If it is determined in step S5 that the total number of destinations n is not "0", the transmission permission frame F4
Determines whether or not it is the first cycle (S9). When it is determined in step S9 that the transmission permission frame F4 is the first round, it is determined whether or not there is data to be transmitted to the transmission buffer 20 by the transmission right granting unit 1 of the data processing unit 19 of the master station a (S10). In this example, it is determined that there is no data to be transmitted in the transmission buffer 20 of the main station a.

If it is determined in step S10 that there is data to be transmitted to the transmission buffer 20, the transmission right granting means 1 transmits the data as shown at p7 in FIG. 6 (S11), and the process proceeds to step S12. Proceed to

In FIG. 3, the total number of destinations n is set to “3” and the reception counter value Cn is set to “0” using the counter management unit 23.
In addition, the address of the destination address management unit 24 is set to B, C, and D using the destination address unit 10, and the source address is set to the address A.

This processing is performed when n = 0 in step S5.
Alternatively, it is performed in the second round in step S9.

If it is determined in step S10 that there is no data to be transmitted, the transmission permit frame F
(F4) is transmitted without rewriting (transmission permission frame F5) (S12), and the process returns to step S3.

That is, the master station a transmits the transmission permission frame F of the broadcast to the transmission line, and then transmits the transmission permission frame F
Is returned, if the total number n of destinations of the transmission permission frame is equal to or greater than "0" (not including 0), the master station a does not set the transmission right and the master station b obtains the transmission right. To
It is sent to the transmission line as it is. In FIG. 3, the total number of destinations n is set to “1” and the reception counter value Cn is set to “2” using the counter management unit 23, and the address of the destination address unit 10 is changed to only B using the destination address management unit 24. Then, the transmission permission frame F5 in which the source address is set to the address A is transmitted.

On the other hand, the slave station b receives the transmission permission frame F5 transmitted from the master station a. That is, when transmitting the next transmission permission frame F, the main station a transmits the transmission permission frame F to the slave station b having data to be transmitted next time.

Next, the slave station b that has received the transmission permission frame F5 transmits data k3 addressed to the slave station c that could not be transmitted previously, as indicated by p6 in FIG. This data k3
As shown at p6 in FIG. 6, the total number of destinations n is “1”, the reception counter value Cn is “0”, the destination address of the destination address section 10 is “C”, the source address is “B”, and the transmission path is Sent to.

The slave station b receives data 2 (command 2).
Since there is no further data to be transmitted after the transmission, the total number of destinations n is set to "0", the reception counter value Cn is set to "3", and the transmission source address is set to "A" as shown at p6 in FIG. The permission frame F6 is transmitted to the transmission path.

That is, when there is no more data to be transmitted, the slave station b deletes the address B of the slave station b and transmits.

Since no address is written in the destination address section 10 of the transmission permission frame F6, the slave stations c and d transmit the transmission permission frame F6 to the next station without rewriting. I do.

The master station a that has received the transmission permission frame F6 deletes the received transmission permission frame F6 because the total number of destinations n is “0”.

Since one transmission data is generated when the master station a acquires the transmission right for the second time, the broadcast data 3 (command 3) addressed to all the slave stations is written as shown at p7 in FIG. The data k4 is transmitted. Then, a new transmission permission frame F7 is created and transmitted to the transmission path.

The processing of the main station a until the transmission permission frame F7 is transmitted will be described with reference to FIG.

When the main station a receives the transmission permission frame F6 via steps S3 and S4, it determines in step S5 that the total number n of destinations of the transmission permission frame F6 is "0".

If it is determined in step S5 that the total number n of destinations is "0", it is determined whether there is data to be transmitted to the transmission buffer (S6). In this example, data 3 (command 3)
It is determined that there is.

If it is determined in step S6 that there is data to be sent, a data frame for broadcast communication is generated and transmitted (S7).

Then, as shown in step S8, the total number of destinations n is "3", the reception counter value Cn is "0", the addresses of the destination address section 10 are B, C, and D, and the source address 11 is A. Broadcast transmission permission frame F7
Send

<Second Embodiment> FIG. 7 is a schematic configuration diagram of a second embodiment. In the second embodiment, the master station a includes a transmission right granting unit 1, a next transmission data existence station determining unit 2,
And a slave station transmission frequency determining means 30.

The slave station transmission frequency determining means 30 of the master station a
, Statistically investigates the frequency of the source address of the transmission permission frame F that has cycled through each of the slave stations, and grants a transmission right to the station whose transmission number is extremely small every few times.

When the number of transmissions of the slave station c is extremely small, the transmission permitting frame F including only the addresses B and D obtained by removing the address C from the destination address section 10 is transmitted to the transmission line every several times. I do.

Accordingly, since the useless grant of the transmission right is minimized, the use efficiency of the transmission path is improved.

In the first and second embodiments, the connection type is described as a ring type. However, the connection type is not limited to this and may be, for example, a bus type.

Although the function of granting the transmission right is set as the main station,
The information may be provided not only to the master station but also to the slave station.

Further, although the number of data that can be transmitted when each slave station obtains one transmission right has been described as one, a plurality of data may be transmitted without being limited to one.

Further, in the above-described embodiment, the transmission permission frame that the master station has circulated is forcibly deleted after two rounds. However, when there is a child station to which data is transmitted, the child station transmits the data. May be deleted when the number of times of transmission is reached.

[0094]

As described above, according to the present invention, in a network system including a first station as a master station and a plurality of second stations as slave stations, the second station is a first station. When the transmission permission frame is received from the station, if there is data to be transmitted next time, predetermined information indicating that there is data to be transmitted next time by the second station is written in a predetermined area of the header portion of the transmission permission frame. To send.

The first station receives the transmission permission frame from the second station, and if the header of the frame indicates that there is a second station having data to be transmitted, the first station receives the frame. The transmission permission frame for the second station is transmitted.

That is, the effect is obtained that only the second station having the data to be transmitted preferentially obtains the transmission right. Therefore, a station having many transmission opportunities is given priority in transmission without waiting for the next broadcast transmission permission frame to circulate and without passing through the first station which is the master station. As a result, the path can be used efficiently, and the collision of transmission data does not occur.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a network system using a multiple transmission right grant method.

FIG. 2 is an explanatory diagram illustrating a configuration of a transmission permission frame.

FIG. 3 is a specific configuration diagram showing a hardware configuration of a station.

FIG. 4 is a flowchart illustrating an operation of a master station a.

FIG. 5 is a flowchart illustrating an operation of a slave station.

FIG. 6 is an explanatory diagram for explaining a transmission procedure of transmission data in a main station a and a slave station.

FIG. 7 is a schematic configuration diagram of a second embodiment.

[Explanation of symbols]

 a master station b slave station c slave station d slave station 1 transmission right grant means 2 transmission data existence station determination means 3 inter-slave station communication processing means 4 priority data determination means 8 destination total number section 9 reception counter section 10 destination address section 11 transmission Original address section 16 Address decoder 19 Data processing section 20 Transmission buffer 23 Counter management section 24 Destination address management section 25 Transmission permitted frame buffer

Claims (8)

[Claims] 1. A plurality of stations are connected by a transmission line, and a first station among these stations is provided with a transmission right grant function to a plurality of other second stations connected to the transmission line. A communication system comprising: a first station that, when granting a transmission right from the own station to the plurality of second stations, transmits the plurality of second stations to the plurality of second stations; The transmission permission frame written in the address portion is transmitted to the transmission path. When the transmission permission frame is received, and when predetermined information remains in a header portion of the transmission permission frame, the transmission permission frame is transmitted. The second station receives the transmission permission frame, transmits the transmission data if there is transmission data, and transmits the transmission data if there is further transmission data. Of the header part of the transmission permission frame The constant of the area,
A transmission permission frame in which predetermined information indicating that there is transmission data in the own station is transmitted to the transmission path.If there is no transmission data and there is no further transmission data, the transmission permission frame of the received transmission permission frame is transmitted. A transmission right granting network system, wherein a transmission permission frame excluding predetermined information relating to the own station from a header portion is transmitted to the transmission path. 2. The first station, when granting a transmission right from the own station to the plurality of second stations, writes the plurality of second stations in a destination address section and permits transmission. A frame is transmitted to the transmission path. When the transmission permission frame is received, if the destination of the second station remains in the destination address portion of the transmission permission frame, the received transmission permission frame is left as it is. The second station receives the transmission permission frame, transmits the transmission data if there is transmission data, and further transmits the transmission permission frame if there is transmission data. A transmission permission frame in which the address of the own station in the destination address section is left as it is is transmitted to the transmission path, and if there is no further transmission data, and if there is no transmission data, the received transmission permission frame is transmitted. Network systems in different transmission right grant scheme of claim 1, wherein the transmitting a transmission permission frame deleting the destination of its own station from frame to said transmission path. 3. The first station, when receiving a transmission permission frame from the second station, when no destination of the second station remains in a destination address portion of the transmission permission frame. 3. The network system according to claim 1, wherein a transmission permission frame for the plurality of second stations is newly generated and transmitted to the transmission path. 4. The second station, when receiving the transmission permission frame from the first station, when there are a plurality of data to be transmitted, determines a priority of those data, and determines a data having a higher priority. 4. The network system according to claim 1, wherein the transmission is sequentially performed from the transmission right. 5. The first station, when granting a transmission right to the plurality of second stations,
Transmission right granting means for generating the transmission permission frame including a header section including a destination total number section, a reception counter value section, a destination address section and a transmission source address section, and a transmission permission command data section, and transmitting the transmission permission frame to the transmission path. When the transmission permission frame is received, the total number of destinations of the transmission permission frame is checked, and if the total number of destinations does not exist in the total number of destinations, a new transmission permission frame is generated by the transmission right granting means. When the total number of destinations exists, the received transmission permission frame is transmitted to the transmission path as it is, and the second station, when receiving the transmission permission frame from the first station, If not, or if there is no more data to send after data transmission, update the total number of destinations and the reception counter value of the transmission-permitted frame, and A transmission permission frame from which the transmission permission frame is deleted, and if there is further data to be transmitted after the data transmission, the slave station communication processing means transmits the transmission permission frame to the transmission path without rewriting the contents of the transmission permission frame. 5. The network system according to claim 1, wherein the transmission right grant system comprises: 6. The second station, each time the transmission permission frame is received, when there are a plurality of the transmission data, determines the priority of each of the transmission data, and determines the priority of the child station in descending order of the priority. 6. The network system according to claim 5, further comprising priority data determination means set in the inter-communication processing means. 7. The slave-station communication processing means of the second station, when transmitting the data, updates the total number of destinations and sets the destination address to the first or second one for transmitting the data.
7. The network system according to claim 6, wherein the transmission is performed in a format in which the address of the first station is set and the source address is set to the address of the own station. 8. Each time the first station receives the transmission permission frame, the first station determines whether or not the address of the second station remains in the destination address section.
A sub-station transmission frequency determining means for determining a transmission frequency of the second station and transmitting a transmission permission frame to the plurality of second stations at a predetermined rate once for a second station having a low transmission frequency. 5. The network system according to claim 4, further comprising: