JPH0793627B2 - Transmission control method of token bus network with dedicated reception station - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transmission control system for a token bus network, and more particularly to a control system for a token bus network having a dedicated reception station applied to an optical MAP network. .

[Prior Art] In recent years, the appearance of distributed processing systems has changed dramatically with the development of LANs (local area networks). This is because LAN (1M-10Mbit / sec class) standards have been almost fixed, and products adapted to it have been introduced one after another. Such standards include the international standard IEEE802.4
(Token bus)

Fig. 3 shows an example of the configuration of this international standard IEEE802.4 token bus network. In this figure, bus-type LAN
Is formed by connecting each station (node station) 50 to 53 to a line 100 formed of a coaxial cable.
Although the addresses are set to the stations 50 to 53, for example, the address of the station 50 is "10", the address of the station 51 is "8", the address of the station 52 is "6", and the address of the station 53 is "5". Set to “2”.

Therefore, in the token bus network, the tokens are sequentially circulated as shown by the dotted line in the figure from the larger address to the smaller address uniquely assigned to each station 50 to 53, thereby equalizing the data transmission right.

Reference numeral 54 is a reception-only station, which is connected to the line 100 of the token bus network and is a reception-only station that does not have a token and only receives data from the token holding station. This is a device such as an annunciator (display device) at a production site, which only needs to receive data unilaterally by a so-called non-intelligent terminal device.

Recently, in the token bus network shown in FIG. 4, optical communication is realized by using an optical star coupler and an optical fiber.

In the LAN shown in FIG. 4, an optical star coupler 60 is connected to each of the stations 61 to 64 by optical fiber lines 200 and 201.

The reception-only station 65 is connected to the optical star coupler 60 by the optical fiber line 202. Each station 61,
Addresses are set in 62, 63, and 46 as in the network shown in FIG. 3, and the data are transmitted in the same manner as the dotted line in FIG.

As described above, the token network shown in FIG. 4 is obtained by realizing the configuration of the token network shown in FIG. 3 with the optical token bus.

[Problems to be Solved by the Invention] However, in the token network of FIG. 4, for example, when the optical fiber line 200 on the receiving side of the station 46 is disconnected, the station 46 cannot receive the token from the logical ring. Disconnected, token is station 61 → station 62 → station 63 → station 61
It will be orbited like. Here, this station 46
Since no tokens or data can be received from other stations at all, only the own station remains in the logical ring, it is determined that the other station is not operating, and it becomes dormant until the token is received. In this state, for example, when data to be transmitted to the station 46 is generated, the station 46 becomes a temporary state in which it has a token and transmits the data.

The reason for this is that even if the logical ring is not formed, there is a possibility that the reception-only station 65 exists in the network as described above. Also (the transmitting station is 1
This is because it is configured so that data can be transmitted even at the station.

However, when data is transmitted from each station in which the receiving system (optical fiber, connector, and receiving circuit) is in a failure state in this way, noise is generated in the fiber transmission line,
As a result, the reliability of the system is extremely deteriorated, resulting in an unfavorable state.

Here, an object of the present invention is to provide a transmission control method for a token bus network in which a new exclusive reception station exists that enables highly reliable data transmission.

[Means for Solving the Problems] As a means for solving the above problems, according to the present invention, each station for transmitting and receiving and a dedicated reception station are connected in a transmission path so as to form a bus type configuration, and each station is sequentially connected to a logical ring. In a token bus network that can transmit data only when it has a token, when it is determined that each station that can form the logical link has only one station, the data is transmitted to another station. It is not permitted, and transmission is possible only when the logical ring is formed by two or more stations excluding the own station. In a preferred mode, the station that can form the logical ring is the own station 1. When it is judged that only the station remains, when the address of the succeeding station is not known, when the token lap count is not updated, and when all the stations are solicited by the succeeding station, responses are sent. It's time to go. In addition, each station that performs transmission / reception and a dedicated reception station configures a bus type network by a transmission optical fiber and an optical star coupler, and each station sequentially configures a logical ring and transmits data when a token is held. In the network, each station that can form the logical ring determines whether or not the data transmitted by itself is sent back to the receiving side through the transmitting side optical fiber, the optical star coupler, and the receiving side optical fiber in sequence. Equipped with a function to detect
When the data transmitted by the own station is not returned to the receiving side, the transmission is disabled. As a preferable mode, the data transmitted by the own station indicates that the transmission is being displayed. When there is no signal in the time zone, the transmission permission signal is set to a state in which transmission is not permitted regardless of the state of the display signal during transmission.

[Operation] When it is determined that the logical ring is not formed including the own station and only the own station remains as a transmittable station, control is performed so as not to transmit even if data occurs in the own station.

Therefore, when there is a receive-only station in the system and the number of stations that can join the logical ring becomes one, data cannot be transmitted, but it is possible to prevent the entire system from going down due to a failure of one station. Will be possible.

In this preferred mode, when it is judged that only one station that can form a logical ring remains, the address of the succeeding station is not known, the wraparound count of the token is not updated, and the succession to all stations is succeeded. There are times when there is no response after soliciting a station.

In addition, each transmittable station has a function to detect whether or not the transmission data of its own station is returned to the receiving side, and if the transmission data of its own station is not returned, even if the data that you want to transmit occurs in your own station Even in this case, however, it is configured so that the failure of the receiving system is not propagated to the entire system by controlling not to transmit.

Also, when the signal of that system disappears due to the failure of the receiving system, it is monitored so as not to mistakenly judge that only the own station and the dedicated reception station exist in the system, and the transmission data of the failed station can be used to It is possible to prevent the system from going down.

In a preferred embodiment, the transmission data of the own station is
When there is no signal in the time zone indicating that the transmission is being displayed, there is a method in which the transmission permission signal is not transmitted regardless of the state of the during-transmission display signal.

[Embodiment] Next, an embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic configuration diagram showing an embodiment of a communication control device to which the system of the present invention is applied.

The optical LAN shown in this figure is configured by connecting an optical star coupler to each station by an optical fiber line for transmission and reception. The optical coupler 1 is an optical fiber line 300 for transmission and reception,
Each station is connected to each of the stations 2 to 5 via 301, and a reception-only station (not shown) is also connected. Here, for example, as shown in FIG. 1, when the receiving system of the station 3 (the optical fiber line 300, a connector and a receiving circuit not shown) is out of order, the normal station 3 fails in its own receiving system. It is impossible to determine whether the subscriber station has left the logical ring or has left the logical ring (for example, the power has been cut off). Therefore, the station 3 does not notice the abnormal state and considers that the other station has left the logical ring. Here, in the station 3, when data to be transmitted to another station occurs, the data is transmitted as in the above-described conventional technique. At that time, if data in the other station flows on the transmission path, the data is disturbed. Will be lost.

Therefore, when the station 3 determines that only its own station remains in the logical ring, it prohibits data transmission. This allows
This will prevent the above situation.

Here, several methods can be considered as means for determining that only the own station remains in the logical ring. It is shown below.

There are methods such as determining that the address of the succeeding station is unknown, determining that the wraparound count of the token is not updated, and soliciting the succeeding station from all stations to determine that there is no response.

Therefore, whether each station is in one of the above states,
Whether or not there is transmission data is controlled so that no data is transmitted in such a state.

Each station has the configuration shown in FIG. In this figure, reference numeral 10 is a photoelectric converter that converts an optical signal received through the receiving optical fiber line 300 into an electric signal.

One of the received data converted into an electric signal by the photoelectric converter 10 is modulated and demodulated by the modem 11, but the other is received signal monitoring unit.
Monitored at 12. The reception signal monitoring unit 12 has the following functions.

When the transmission-in-progress signal T from the modem 11 at the start of operation indicates that the transmission is in progress, the transmission permission signal TE is set to the permission state.

Monitor the received signal RD and confirm that the data that you have output is indeed returned during transmission. Here, the time zone (however, the transmission display signal T indicates that the transmission is being displayed)
The signal is present in the received signal RD during the propagation time later). If no signal is present during this period, the transmission permission signal TE is not transmitted regardless of the state of the during-transmission display signal T.

Further, the reception signal monitoring unit 12 informs the data generation processing unit 13 by the RM signal that the transmission is not permitted.

The modem 11 sends a signal obtained by modulating and demodulating the received data to the token bus control unit 14, but the token bus control unit 14 sends a bus line based on the sent signal.
Control 400. The transmission / reception buffer 15 stores temporary reception data according to a bus control signal (not shown) from the token bus control unit 14. The received data stored in the transmission / reception buffer 15 is the photoelectric converter 10, the modem 11, and the token bus control unit.
This is so-called processed reception data that has gone through 14. The processed reception data stored in the transmission / reception buffer 15 is called to the data generation processing unit 13 by a bus control signal from the token bus control unit 14, and is input via the bus line 400. The data generation processing unit 13 performs processing such as data generation based on the RM signal transmitted from the reception signal monitoring unit 12 and the processed reception data transmitted from the transmission / reception buffer 15. The signal that has undergone processing such as generation in the data generation processing unit 13 is again returned to the bus line based on the control signal from the token bus control unit 14.
400 is controlled and stored in the transmission / reception buffer 15. At this time, the data stored in the transmission / reception buffer 15 is so-called processed transmission data after the data generation processing unit 13 has performed the data generation processing. Then, after a lapse of a certain time, a control signal is sent from the token bus control unit 14 to the transmission / reception buffer 15, the modified transmission data is called, and the modified transmission data is input to the modem 11 via the transmission / reception buffer 15 and the token bus control unit 14. To do. At this time, the modem 11 sends the display signal T being transmitted to the reception signal monitoring unit 12. Then, when the reception signal monitoring unit 12 indicates that the transmission is in progress, the transmission permission signal TE indicating the transmission permission is transmitted to the transmission control gate 16 to set the transmission permission signal TE, and the optical / electrical converter 17 transmits the light. The signal is transmitted to its own station or each other station through the transmission fiber line 301.

Further, the reception signal monitoring unit 12 monitors the reception signal RD transmitted from the photoelectric converter 10, and the modem 11 receives the reception signal monitoring unit.
It is monitored whether or not a signal is present in the reception signal RD in the time zone in which the during-transmission display signal T sent to 12 indicates the during-transmission display. If there is no signal during this period, the transmission permission signal TE is not sent to the transmission permission gate 16 and the transmission is not permitted regardless of the state of the during-transmission display signal T. At this time, the reception signal monitoring unit 12 transmits the RM signal indicating that the transmission is not permitted to the data generation processing unit 13
To stop the processing of the data generation processing unit 13.

As described above, according to the present device, when there is a dedicated reception station in the system and only one station can join the logical ring, data cannot be transmitted, but the failure of one station causes the entire system to fail. Prevent being disturbed by downs.

In addition, this device monitors the transmission data transmitted from the faulty station even if it mistakenly determines that only the own station and the reception-only station exist in the system when the reception system signal disappears due to the failure of the reception system. By doing so, it is possible to prevent the entire system from going down.

Although the embodiment of the present invention has described the case of the optical token bus in which such a state often occurs, the same measure can occur even if the coaxial cable is used if the receiving circuit fails, so an effective countermeasure. Becomes

[Effect of the Invention] As described above, according to the present invention, when there is a receiving-only station in the system and the number of stations that can join the logical ring becomes one, data cannot be sent, but one station fails. This makes it possible to prevent the entire system from being disturbed.
Further, in the present invention, when the signal of the receiving system disappears due to the failure of the receiving system, even if it is erroneously determined that only the own station and the dedicated reception station exist in the system, the transmission data transmitted from the failed station is monitored. By doing so, it is possible to prevent the entire system from going down.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a communication control device to which the system of the present invention is applied, FIG. 2 is a block diagram showing the configuration of the main part thereof, and FIGS. 3 and 4 are conventional token bus networks. FIG. In the figure, 1 is an optical star coupler, 2 to 5 are stations (node stations), 300 and 301 are optical fiber lines, and 12 is a received signal monitoring unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 60-246145 (JP, A) JP 60-246147 (JP, A) JP 61-240738 (JP, A) JP 62- 193339 (JP, A)

Claims (4)

[Claims] 1. A token which is connected to a station for transmission / reception and a station for exclusive use of reception on a transmission line so as to form a bus type structure, and each station sequentially forms a logical ring and can transmit data only when it has a token. In the bus network, when it is determined that each station capable of forming the logical ring remains only one station of its own station, transmission of data to another station is prohibited,
A transmission control method for a token bus network in which a dedicated reception station exists, wherein transmission is possible only when the logical ring is formed by two or more stations excluding the own station. 2. When it is judged that only one station which can form the logical ring remains, one station does not know the address of the succeeding station, the wraparound count of the token is not updated, and all stations 2. The transmission control method of the token bus network according to claim 1, wherein it is when there is no response after soliciting a subsequent station. 3. A station for transmitting and receiving and a station for exclusive use of reception form a bus type network by a transmission line optical fiber and an optical star coupler, and each station sequentially forms a logical ring and stores data when a token is held. In the token bus network for transmitting, each station that can form the logical ring is such that the data transmitted by itself is an optical fiber on the transmitting side,
An optical star coupler and an optical fiber on the receiving side
The existence of a dedicated reception station, which is equipped with a function to detect whether or not the data has been returned to the receiving side, and which disables transmission when the data transmitted by the local station is not returned to the receiving side. Token bus network transmission control method. 4. The data transmitted by the local station is in a state in which the transmission permission signal is not permitted to be transmitted regardless of the state of the transmission display signal when no signal is present in the time zone indicating that the transmission is being displayed. The transmission control method of a token bus network according to claim 3, wherein the dedicated reception station exists.