JPH0442637A - Optical multi-branch communication equipment - Google Patents

Abstract

PURPOSE:To obtain the system reliability equal to or more than that of duplicated system configuration by implementing optical transmission reception between a master station and an optical cable by system, and implementing optical transmission/reception between a slave station and the optical cable depending on combination between an optical demultiplexer and multiplexer and a Y demultiplexer and multiplier in such a way that the transmission reception of optical signals being duplicated is implemented from a couple of optical transmitters and receivers. CONSTITUTION:An optical signal Y demultiplexer and multiplier 111 is provided respec tively to slave stations 61 - 6n, optical demultiplexers and multipliers 7A1, 7B1 multiplex two systems of optical signals demultiplexed to form an optical input signal to an optical receiver 81. Moreover, an optical signal Y demultiplexer and multiplier 121 is provided respectively to the slave stations 61 - 6n, an optical signal from an optical transmitter 91 is demultiplexed into two systems of optical signals, the one optical signal is used for the optical multiplex signal to the optical demultiplexers and multi plier 7A1 and the remaining one optical signal is used for the optical demultiplexers and multiplier 7B1. Since normal communication function is ensured even in the case of a broken optical cable or a fault of one system of the optical receiver of a master station, the reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention performs data communication between a master station communication device and a plurality of slave station communication devices using an optical cable as a transmission path, and an optical branching/merging system provided in the middle of the optical cable. The present invention relates to an optical multi-branching communication device in which optical signals are branched and combined by a device and transmitted and received by a slave communication device.

B0 Summary of the Invention The present invention provides an optical multi-branching communication device in which optical cables have a duplex configuration and optical transmission/reception between a master station communication device and a slave station communication device is duplicated.The slave station communication device is transmitted from a pair of optical cables. The optical signal is superimposed into one signal or made into two time-series signals using a combination of an optical branch/combiner and an By using a combination of an X-branch combiner and an optical branch-combiner to split the signals into two signals and send them on a pair of optical cables, system reliability is equal to or higher than that of a duplex configuration, but the configuration becomes more complex. This was done so that there would be no

C0 Prior Art The basic configuration between a master station communication device (hereinafter referred to as a master station) and a slave station communication device (hereinafter referred to as a slave station) in an optical multi-branch communication system is shown in FIG. When the master station 1 needs to exchange data with the slave station for data processing by the internal processing circuit 2, it sends an optical signal from the optical transmitter 3 to the optical cable 4 under predetermined transmission control, and also transmits it from the slave station through the optical cable 4. The received signal is received by the optical receiver 5 and taken into the processing circuit 2. The optical cable 4 is looped and connected to n slave stations 6, -6. is combined with Each slave station 61 to 6° has an optical branch/combiner 7 which becomes an X branch/combiner for the optical cable 4;
~7. The optical signals carried on the optical cable 4 are branched and received by the optical receivers 81-8, and the optical transmitters 91-9. merging the optical transmission signals from and onto the optical cable. Electrical signals from the optical receiver and optical transmitter are processed by internal processing circuits 101 to 10. The import and acceptance will be done.

In the basic configuration described above, signals are exchanged between the master station 1 and the slave stations 6, . . . , in the following procedure.

First, for transmission from master station 1 to one of slave stations 61 to 61,
A master station 1 sends a signal A to an optical cable 4 using an optical transmitter 3. This signal A is transmitted to each slave station 61-6 through the optical cable 4. Optical branching/merging device 7□~7. to each slave station 6, to 6. and finally received by the optical receiver 5. That is, in the optical multi-branch communication system, all slave stations are coupled to one optical cable 4, and signals transmitted from the master station are transmitted to all slave stations.

Each slave station6. ~63 receives the signal A from the master station through the optical receiver 8, ~
8. The processing circuits 10□ to 10° determine whether or not the signal is addressed to the master station based on the contents of the signal A. If the signal A is not addressed to the master station, the signal A is discarded.

In addition, if it is addressed to the master station, the response signal B to the signal A, -
B. Optical transmitter 9. ~9. and optical branching/merging device 7, ~7.
and put it on the optical cable 4 through the signal B.

~B, is transmitted to the master station 1. In the master station 1, one of the signals B1 to B is received by the optical receiver 5 and taken into the internal processing circuit 2.

Furthermore, the signal A from the master station to the slave station unites the slave stations that are the destination, and the slave station that is the destination transmits the signal B to the master station after the signal transmission state of the master station ends. . That is, the slave station does not transmit a signal to the master station at its own discretion, but always transmits signal B when replying as a response signal after receiving a signal from the master station (polling method).

D1 Problems to be Solved by the Invention Although the above-mentioned optical multi-branch communication system is simple as an optical multi-branch communication system, it is difficult to solve problems such as when an abnormality occurs in the optical transmitter or optical receiver of the master station or when the optical cable is disconnected. If an abnormality occurs, transmission and reception with all slave stations becomes impossible, resulting in system failure.

To solve this problem, there is a duplex optical multi-branch communication system shown in FIG. This figure shows the basic configuration shown in Figure 7, with the weak parts of the system duplicated. The master station 1 is equipped with optical transmitters 3A, 3B and optical receivers 5A, 5B, and optical cables are connected to the paired optical transmitters/receivers, respectively. 4A and 4B are combined, and slave stations 6, to 6. Then, for the optical cables 4A and 4B, the optical branching and combining devices 7A, ~7A, 7B 1~7B are installed.
, and pair optical receivers 8A, ~8A, , 8B+~8B, and optical transmitters 9A, ~
9A, 9B, to 9B are provided. Master station 1 and slave station 6゜～
Although the signal transmission and reception between 61 is the same as the basic configuration described above, the signal processing mode of the duplexed portion is different because the signal transmission route is duplexed.

This signal processing is performed in the master station 1 by sending the same signal from the internal processing circuit 2 to the optical transmitter 3A at the same timing.

3B, and connect each slave station 6 through optical cables 4A and 4B.
I~6. are transmitted in parallel up to Each slave station 61-6. Then, the optical receivers 8A r~8A, , 8B+~8B receive the data in parallel, and the internal processing circuit 10. The parallel signals are edited into one signal by ~10° and used for internal processing. Further, transmission from each slave station is carried out by internal processing circuits 101 to 10. The transmission signal from the optical transmitter 9A, ~9A at the same timing
, 9B+ to 9B, and transmit them in parallel from these optical transmitters through optical cables 4A and 4B. At master station 1, the received signals of optical receivers 5A and 5B are edited into one signal, and then the internal Perform processing. In the duplex configuration, the signals carried on the optical cables 4A and 4B are transmitted in opposite directions.

According to such transmission with a duplex configuration, even if a failure occurs in one system of the optical transmitter, optical receiver, and optical cable, the transmission and reception functions of the other system can be ensured, and reliability is also improved. However, compared to the basic configuration, the duplex configuration requires twice as many optical transmitters, optical receivers, and optical branching/combiners for both the master station and the slave stations, and also requires two optical cable systems, making it less economical. remain. In particular, when a large number of slave stations are installed, the cost of the slave stations deteriorates the economic efficiency of the entire system.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical multi-branch communication device that has system reliability equivalent to or higher than that of a duplex configuration and does not have a complicated configuration.

E1 Means and Effects for Solving Problems In order to achieve the above-mentioned object, the present invention performs data communication between a master station communication device and a plurality of slave station communication devices using an optical cable as a transmission path, and a method is provided in the middle of the optical cable. In an optical multiplexing communication device in which optical signals are branched and merged by an optical branching/combining device and transmitted/received by a slave station communication device, the master station communication device has a pair of optical transmitters each converting the same transmission signal into an optical signal, and a pair of optical receivers that respectively convert the same transmission signal into an optical signal. A pair of optical receivers each converting an optical signal into an electrical signal is provided, and the optical cable transmits the optical signals from the pair of optical transmitters in opposite directions, and causes the optical receivers of the pair to receive the optical signals, respectively. The slave station communication device has a duplex configuration, and the slave station communication device has a pair of optical branch/combiners respectively coupled to the optical cables of the duplex configuration, and a Y branch that superimposes the received optical signals from the pair of optical branch/combiners into one optical signal. a combiner, an optical receiver that converts the two optical signals into electrical signals, an optical transmitter that converts the transmitted signal into an optical signal, and an optical signal from the optical transmitter that is split into the pair of optical branches. It is equipped with a Y branch combiner that feeds each combiner, and optical transmission and reception between the master station and the optical cable is performed separately for each system, and optical transmission and reception between the slave station and the optical cable is performed by the optical branch combiner and
In combination with a branch/combiner, each pair of optical transceivers can transmit and receive duplicated optical signals inside the slave station.

The present invention also provides an optical transmitter that directly converts a transmission signal into an optical signal, an optical transmitter that converts the transmission signal delayed for a certain period of time through a delay circuit into an optical signal, and a receiving optical The slave station communication device is equipped with a pair of optical receivers that convert each signal into an electrical signal, and the slave station communication device converts the received optical signals from the pair of optical branching/merging devices into two time-series signals at timings that do not overlap each other due to the delay of the delay circuit. The configuration is such that the signals received through a pair of optical cables are combined into two time-series optical signals at the Y-branch combiner, which is useful for long-distance or high-speed transmission. This eliminates waveform distortion at the time of merging due to a timing shift in the received signals due to the propagation delay time of optical cables transmitting in opposite directions, and eliminates restrictions on the merging of two received signals in long-distance or high-speed transmission. be.

F. Example FIG. 1 is a block diagram showing an embodiment of the present invention.

The differences between this figure and FIG. 8 are as follows.

(1a) The slave stations 61 to 63, as shown by the slave station 61, are optical signal Y-branch combiners 11. is provided, and combines (superimposes) the two systems of optical signals branched by the optical branching/combining devices 7A+ and 7B+, respectively, and sends them to the optical receiver 8. to the optical input signal.

(1b) Child station 6! 61, as shown as a representative of the slave station 6I, is provided with a Y-branch/combiner 12□ for optical signals, which branches the optical signal from the optical transmitter 9 into two optical signals, one of which The optical signal is converted into an optical convergence signal to the optical branching and converging device 7Al,
The remaining one optical signal is made into an optical combining signal to the optical branching/merging device 7B+.

(2) The operation of this embodiment configured as described above will be explained in detail below with reference to the time chart of FIG.

(2a) When transmitting a signal from the master station 1 to the slave stations 61 to 61, the master station 1 first transmits a signal to the slave stations to be transmitted and received. For this transmission, the internal processing circuit 2 gives signals to the optical transmitters 3A and 3B, and the respective optical transmitters 3A and 3B
From 3B, optical signals A,,A.

Convert it to optical cables 4A and 4B. Both signals A,
, A are transmitted through the optical cables 4A and 4B in opposite directions to each slave station 6I to 6. Receive a call. In each slave station, two optical signals A, ,A, are taken into the interior from the optical branch/combiner 7A+, 7Bt, respectively, and taken into the optical receiver (8□) as the combined signal A3 by the Y branch/combiner (llt). The optical receiver 81 converts it into an electrical signal A4 and sends it to the internal processing circuit (
10□), and this signal is sent to the internal processing circuit (101).
Then, internal processing is performed to create a response signal to the master station 1. Note that the optical signals A, , A2 are sent to all slave stations 6. ~6. The signal is transmitted to the destination slave station, and the slave stations other than the destination slave station receive the signal in their internal processing circuits, but discard the signal through internal processing.

(2b) From one of the slave stations 6 to 61 to the master station 1
When the slave station receives the signal from the master station, after the signal transmission state of the master station 1 is completed, the internal processing circuit (6,) transmits the response signal B0 to the optical transmitter (9, ). The optical transmitter (9,) converts this input signal into an optical signal, inputs this signal B1 to the Y-branch/combiner (+2+), and the Y-branch/combiner (121) converts the two optical signals B! +
Branch to BS.

These signals B2. B3 is an optical branching/merging device (7AI).

7B1) and placed on optical cables 4A and 4B,
The signal is transmitted to the master station 1 through the optical cables 4A and 4B.

This transmission is also performed in opposite directions to the master station. In the master station 1, optical signals B, , B3 from optical cables 4A, 4B are received by optical receivers 5A, 5B, respectively, and electrical signals B, , B,
The signal is converted into one signal by the internal processing circuit 2 and used for internal processing.

(3) The operations described above are for when each part is in a normal state, and the signal transmission and reception operations when an abnormality occurs in the master station will be described in detail below.

(3a) When an abnormality occurs in one or both of the optical transmitter 3A and optical receiver 5A, which are one system of the optical transceiver of the master station, the signal A output from the internal processing circuit 2 of the master station is Due to a system abnormality in the optical transmitter 3A, the signal is transmitted only from the optical transmitter 3B to the slave station through the optical cable 4B. Assuming that this signal A2 is transmitted to the destination slave station 61, the signal A3 is sent to the slave station 61 via the optical branch/combiner 7B1 and the Y branch/combiner 11+.
The signal is received by the optical receiver 8□. In this case, signal A
3 is not a superimposed signal of two signals A and A2, but signal A.

That is what it is. The internal processing circuit 10+ of the slave station 61 converts the signal A3 into an electrical signal and imports it as the signal A4, and performs normal internal processing in exactly the same way as when the master station 1 is normal.
Create its response signal.

(3b) Internal processing circuit 10 of the slave station 6□. is the response signal B, and the optical transmitter 9. and the optical transmitter 9 transmits the optical signal B
1, Y branch/merger 12, and optical branch/merger 7A.
Signal Bit to optical cable 4A, 4B through +, 7B+
Put it on as B. At this time, if the optical receiver 5A is abnormal in the master station 1, the signal B is sent.

Only the converted signal B is received by the optical receiver 5B, and only the converted signal B is taken into the internal processing circuit 2 for internal processing. In this internal processing, although the signal B4 is not received, in terms of the level of signal transmission and reception between the master station and the slave station, one side is correctly received, so the same processing as when the master station is normal is performed.

(4) Next, the signal transmission and reception operation when the optical cables 4A and 4B are disconnected will be described in detail below.

(4a) When optical cables 4A and 4B are disconnected at part F in Fig. 1 and transmission and reception are performed between master station 1 and slave station 6, the transmission signal from master station 1 is divided into two signals A, A, and A. It is carried as a signal on the optical cables 4A and 4B. The signal A is normally transmitted to the slave station 6□ by the optical cable 4A, and the signal A2 is transmitted by the optical cable 4B, but because there is a disconnection at the F section, the slave station 61 cannot receive the signal A. At this time, the slave station 61 receives the signal A1 from the optical cable 4A side, and the internal processing circuit 10. Upon receiving normal reception, a response signal B0 is generated.

(4b) The signal B0 from the slave station 6I is sent to the optical transmitter 9. The optical signal B1 is converted into an optical signal B1, and then sent to the Y branch/combiner 121 and the optical branch/combiner ? A. Optical cable 4A through 7BI.

It will be placed on 4B. At this time, the signal B2 is the optical cable 4
Since A is disconnected at the F part, it disappears at that part, but the signal B3 is sent to the optical receiver 5B of the master station 1 through the optical cable 4B.
will be transmitted up to. At master station 1, signal B is converted from signal B3.
, is taken into the internal processing circuit 2 and internally processed.

At this time, the signal B4 side is not received, but when looking at the signal transmission/reception level between the master station and the slave station, one signal is correctly received, so the same processing as when the optical cable is normal is performed.

FIG. 3 is a block diagram showing another embodiment of the present invention. The differences between this figure and FIG. 1 will be explained. Master station 1 is delay circuit 1
3 is provided, and the signal sent to the optical transmitter 3B from the signal A0 output from the internal processing circuit is transmitted through the delay circuit 13.
It is transmitted with a delay of time Ta from O. Each slave station6.
~6. Then, the signal A2 is delayed with respect to the optical reception signal A1 and is sequentially taken into the Y branch/combiner 11+ at a timing when they do not overlap with each other, and the signal A4 which has passed through the optical receiver 81 is
Signal A41 converted from 1 and signal A4 converted from signal A2
2 as internal processing circuit 10. and both signals A
41. The signal that is normally received first among A4□ is treated as the normal received signal.

With the configuration of this embodiment, restrictions on the transmission speed and transmission distance of signals to be transmitted can be eliminated. This will be explained in detail below.

First, in the embodiment shown in FIG. 1 described above, the transmitted optical signals A r and A 2 from the master station 1 are transmitted through the optical cable 4A.

4B to slave stations 61 to 6. and is taken into the slave station by the optical branch/multiplexer 7A+, 7B+. At the slave station, the branch output signals A of the optical branch/combiner 7Al, 7B+ are
A, are combined into one signal by the Y branch/combiner 11 and passed to the optical receiver 81 as the signal A3. Optical receiver 8
1 is passed to the internal processing circuit 101 as a signal A4 obtained by photoelectrically converting the signal A3.

In such signal transmission and reception between a master station and a slave station, if the lengths of the two optical cables 4A and 4B that transmit the optical signal transmitted from the master station to the slave station are the same or the distance is short, There's no problem. However, in the case of long-distance transmission where the optical cable lengths are significantly different, the slave station 6. ~6. Optical signals A, ,A arrive at , respectively.

In the meantime, there will be a difference in arrival time due to the transmission delay of the optical cable.

Now, the optical cable 4A transmitting the signal A1 is connected from the master station 1 to the slave station 6. Similarly, if the distance of the optical cable 4B transmitting the signal A is 12, then the signal A1 and the signal A2
The propagation delay time T, ,T, is expressed by the following formula% T1; Propagation delay time of signal A1 (sec)/+; Distance T2 of optical cable 4A from master station to slave station; Signal A2
Propagation delay time (s e c) I2; Distance α of the optical cable 4B from the master station to the slave station; Delay time per unit distance when an optical signal propagates through the optical cable (s e c
/JIIg) (k irises) (k tom) In the above equations (1) and (2), the distance of the optical cable is 1. , 1. In this case, the optical cables 4A and 4B are connected to each slave station 6. in opposite directions (clockwise and counterclockwise). ~61, so it does not match in most slave stations (1,≠
1□). Therefore, the optical reception signal A at each slave station 61~6°
1, A2 are mutually different propagation delay times T, ”r
2, and this time difference increases in proportion to the length of the optical cable. As a result, the output of the Y branch/combiner 111 which superimposes the two systems of signals A, . . . A2 becomes as shown in FIG. In the figure, an optical signal Ao with a time width T0 propagates through optical cables 4A and 4B, resulting in a propagation delay time T, , T.
The output signal A of the Y branch/combiner 11 arrives at the slave station as a signal A, , A2 having , and superimposes both signals in terms of optical power.
3, a staircase waveform distortion occurs in terms of power, and the signal A4
differs from the original signal A0, and becomes a signal whose time width is wider by (TzT+).

Child stations 61-6. The internal processing circuit 101 receives the signal A and uses it for internal processing, but the error of the signal A4 (T2
Tl) is the time width T of the original signal A0, although it does not affect signal decoding even if it is up to a certain limit. If the time width exceeds a certain value, errors will occur in signal decoding.

The above-mentioned time width error does not have much effect in the case of short transmission distance and low-speed signal transmission, but becomes a constraint in the case of long-distance or high-speed transmission. In high-speed transmission, the time width of the signal itself becomes smaller, but the propagation delay of optical cables is a fixed value determined by the transmission distance, so the signal becomes faster and the time width becomes smaller, making it possible to transmit over long distances. As the propagation delay increases, the time width error based on the propagation delay time occupies a higher proportion of the entire signal, and the signal becomes unreceivable at a certain transmission speed and transmission distance.

To specifically explain the constraints due to the propagation time delay mentioned above,
Suppose that when the slave station 6I is located closest to the master station 1, the propagation delay time of the signal A1 received by propagating through the optical cable 4A is almost zero, and the signal A! received by propagating through the optical cable 4B! The propagation delay time is the cable length L (71111)
is multiplied by the propagation delay time α-5 μs/& iris. For this delay time T, -5×L, the code transmission rate N(1/
If the allowable code distortion for transmission of bit) is 0.3 (30%), then from 1 bit time X 0.3 > Tg-5XL, upper・(3
) becomes a constraint condition. This is done on the condition that NXL is below a certain value, and as shown in FIG. 5 for cases of 30% and 50% distortion, the transmission speed N becomes more restricted as the cable length increases.

In order to eliminate the above-mentioned restrictions on transmission speed and distance, in this embodiment, a delay circuit 3 is provided to eliminate the overlap between signals A and A2, and on the slave station side, signals A41 . Obtain a regular received signal from A42. This operation will be explained in detail below.

From the master station 1 to the slave stations 61-6. Upon transmission to the optical branch/combiner 7A1 of the slave station, the signal A1 is immediately placed on the optical cable 4A and transmitted to the optical branch/combiner 7A1 of the slave station. On the other hand, the signal A2 is the delay circuit 1
3, the signal is placed on the optical cable 4B with a delay time Ta and is transmitted to the optical branch/combiner 7B1 of the slave station. The receiving process on the slave station side will be explained using the slave station 61. Signal A1 and signal A! are merged at a Y-branch merger 111. As shown in the time chart of slave station processing in FIG. 6, the signals A and A2 are received at timings that do not overlap each other due to the delay Ta of the delay circuit 13. As a result, the signal A3 is not a superimposed signal of the signals A and A2, but consists of two signals that are the same in content but different in time series. In the figure, the delay time T, , T is the signal AI.

A! indicates the propagation delay time experienced when the signal propagates through the optical cables 4A and 4B, and even if the time T2 becomes zero, the propagation delay time TI is the difference between the signal width T6 and Ta (Tg - Ta
) signals A1 and A if within the range.

overlap can be avoided. That is, the delay time Ta by the delay circuit 13 is set to a time at which the two signals do not overlap based on the transmission speed N, the length of the optical cable, and the propagation time.

The signal A is photoelectrically converted by the optical receiver 81, and the signal A
Get 4. This signal A4 consists of two signals,
Assuming that the first half is a signal E and the second half is a signal F, the internal processing circuit 10. When it correctly receives signal E, it completes the reception process from master station 1, enters internal processing, and discards signal F. Furthermore, if the signal E cannot be received correctly due to a failure of the master station 1 or a break in the optical cable, internal processing is started by correctly receiving the signal F. That is, the slave station treats the signal that is normally received first of both signals E and F as the normal received signal. Also, signal E.

When only one of F is received normally, the slave station uses this to determine and monitor that the transmission system of the abnormal reception is abnormal.

The reception process at the slave station 6I is performed in the same manner as in the previous embodiment. Optical cable 4 is also used for transmission from this slave station to the master station.
A and 4B cause a difference in propagation delay time T3 and T4, but the master station 1 that receives this signal receives it with separate optical receivers 5A and 5B, and does not combine them, so the transmission speed due to distortion is .

No distance restrictions occur, and the processing is similar to that of the previous embodiment.

As described above, in this embodiment, in the configuration in which the slave station combines signals A and A2 into one signal, signals A1 and A!
By preventing them from overlapping, it is possible to eliminate restrictions on transmission speed and transmission distance due to the propagation delay time of the optical cable.

Note that the delay time of the delay circuit 13 is not limited to being fixed;
By making the delay time variable, the processing time for signal transmission and reception between the master station and the slave station can be adjusted, and the number of signal transmission pits can be easily increased or decreased. The delay time Ta in this case is Ta>m+N (4) However, m is made to satisfy the number of transmission bits (bit) of the signal, so that the two signals E and F do not overlap. In addition, the condition for the maximum delay time Ta is such that if an abnormality occurs during transmission from the master station to the slave station and the signal E is lost, the processing time will be delayed by Ta compared to normal times, so the device processing Determined from time.

G0 Effects of the Invention As described above, according to the present invention, in an optical multiplexing communication device having a duplex configuration, a slave station combines received optical signals from a pair of optical cables by a combination of an optical branching combiner and a Y branching combiner. The received optical signal is converted into two optical signals, and the transmitted optical signal is
By combining the branching/merging device and the optical branching/merging device, the signals are split into a pair of optical signals and sent onto a pair of optical cables, resulting in the following effects.

(1) The number of optical transmitters/receivers in the slave station can be halved, and the optical branch/combiner and Y-branch/combiner, which are passive elements, improve reliability and provide an economically superior duplex configuration.

(2) Even though the number of optical transceivers in the slave station is halved, normal communication function can be ensured even if the optical cable is disconnected and one optical transceiver in the master station becomes abnormal.

Further, according to the present invention, when transmitting a pair of optical signals from a master station to a slave station, one of the transmission signals is delayed, and two time-series optical signals that do not overlap each other are transmitted at the Y-branch combiner of the slave station. Since the received optical signals are combined as one received optical signal, it is possible to eliminate restrictions on transmission speed and transmission distance due to distortion during reception due to propagation delay time in optical cables that transmit optical signals in opposite directions.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a time chart of the embodiment, Fig. 3 is a block diagram showing another embodiment of the present invention, and Fig. 4 is a merging time diagram in the embodiment. Fig. 5 is a diagram of constraints on transmission speed and distance, Fig. 6 is a time chart of other embodiments, Fig. 7 is a basic configuration diagram of the optical multi-branch communication system, and Fig. 8 is a conventional duplexing diagram. It is a block diagram of a method. 1... Master station communication device, 2... Internal processing circuit, 3, 3
A, 3B, L... Optical transmitter, 4.4A, 4B... Optical cable, 5.5A, 5B, L... Optical receiver, 61°6,... Slave station communication device, L- 7-17A+, 7B+・
...Light branching/merging device, 10+, 10. ...Internal processing circuit, 11+, 12□...Y branch merger, 13...Delay circuit. Figure 2 Time chart of the embodiment

Claims (2)

[Claims] (1) Data communication is performed between a master station communication device and multiple slave station communication devices using an optical cable as a transmission path, and an optical branch/combiner installed in the middle of the optical cable branches and merges optical signals, which are then transmitted and received by the slave station communication devices. In the optical multi-branch communication device, the master station communication device includes a pair of optical transmitters that each convert the same transmitted signal into an optical signal, and a pair of optical receivers that each converts the same received optical signal into an electrical signal, The optical cable has a duplex configuration in which optical signals from the pair of optical transmitters are transmitted in opposite directions and received by the pair of optical receivers, and the slave station communication devices are respectively coupled to the optical cables with the duplex configuration. a pair of optical branch/combiners; a Y-branch/combiner that superimposes received optical signals from the pair of optical branch/combiners into one optical signal; and an optical receiver that converts the one optical signal into an electrical signal. and an optical transmitter that converts a transmitted signal into an optical signal, and a Y-branch/combiner that branches the optical signal of the optical transmitter and supplies the optical signal to the pair of optical branch/combiners, respectively. Multi-branch communication device. (2) Data communication is performed between the master station communication device and multiple slave station communication devices using an optical cable as a transmission path, and an optical branch/combiner installed in the middle of the optical cable branches and merges optical signals, which are then transmitted and received by the slave station communication devices. In the optical multi-branch communication device, the master station communication device includes an optical transmitter that directly converts a transmission signal into an optical signal, and an optical transmitter that delays the transmission signal for a certain period of time through a delay circuit and converts the signal into an optical signal. and a pair of optical receivers each converting the same received optical signal into an electrical signal, and the optical cable transmits the optical signals from the pair of optical transmitters in opposite directions and to the pair of optical receivers, respectively. The slave station communication device has a duplex configuration in which the optical cables are received, and the slave station communication device has a pair of optical branch/combiners respectively coupled to the optical cables of the duplex configuration, and overlaps the received optical signals from the pair of optical branch/converges with each other by delaying the delay circuit. A Y-branch combiner that converts two optical signals in time series at different timings, an optical receiver that sequentially converts the two optical signals into electrical signals, and the first of the two electrical signals from the optical receiver. An internal processing circuit that handles a normally received signal as a regular received signal, an optical transmitter that converts the transmitted signal from the internal processing circuit into an optical signal, and an optical transmitter that branches the optical signal of the optical transmitter into a pair. What is claimed is: 1. An optical multi-branching communication device comprising: a Y-branching/merging device that supplies signals to each of the optical branching/merging devices.