JPH06216921A - Optical multi-way communication system - Google Patents

Abstract

PURPOSE:To eliminate a need to make the transmission signal from a master station to a slave station dual in time series. CONSTITUTION:A master station 1 and slave stations 21, 2n-1, and 2n are connected like a loop by dual optical transmission lines 31 and 33, and transmission and reception signals are transmitted in opposite directions. When optical transmitters and optical transmission lines are normal, a signal A0 is transmitted to slave stations through an optical transmitter 42 and the optical transmission line 31 by one system, and response signals from slave stations are received as a signal B2 by an optical receiver 45; and if the response from slave stations to transmission of the signal A0 is not returned within a certain time, the system is switched to transmit a signal Ae to slave stations through an optical transmitter 44 and an optical transmission line 32. In the case of disconnection of both systems at a point A or B, signals are transmitted and received by transmission and reception in inverse directions on optical transmission lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transmits / receives data between a master station communication device and a plurality of slave station communication devices using a duplex optical transmission line having a loop structure, and each slave station uses an optical branching / combining device to perform optical transmission / reception. The present invention relates to an optical multi-branch communication system for branching and merging signals.

[0002]

2. Description of the Related Art A system configuration of an optical multi-branch communication system is shown in FIG.
Shown in. A master station communication device (hereinafter abbreviated as a master station) 1 and n slave station communication devices 2 ₁ , ... 2 _n-1 , 2 _n are coupled by an optical transmission line 3 ₁ , 3 ₂ having a duplicated loop configuration. It The transmission / reception processing between the master station 1 and the slave stations 2 ₁ to 2 _n will be described below.

(1) When transmitting from a master station to a slave station.

[0004] outputs the signal A _O from the processing circuit 4 _first master station 1, the signal A _O is sent to the optical transmitter 4 ₄ through the optical transmitter 4 ₂ and the delay circuit 4 _3, converted into an optical signal Signal A ₁ ,
Is output as A ₂ optical transmission line 3 _1, 3 _2.

The signals A ₁ and A ₂ are transmitted through the optical transmission lines 3 ₁ and 3 ₂ in opposite directions, and arrive at the slave stations 2 ₁ to 2 _n . These two optical signals A ₁ and A ₂ are transmitted to the X-branch multiplexers 5 ₁ and 5 _{2 in the} slave station.
At the optical receiver 5 _{4 and} is merged by the Y-branch multiplexer 5 ₃ to arrive at the optical receiver 5 ₄ as a signal A ₃ composed of the signals E and F having a time-series difference, and the optical receiver 5 ₄ Is taken out as a signal A ₄ converted into an electric signal by.

The processing circuit 5 ₅ in each of the slave stations 2 _{1 to} 2 _n discards the signal F when receiving the signal E of the signals A ₄ and starts the internal processing when the signal E is received. Create a response signal to.

Here, the signals A ₁ and A ₂ are transmitted to all the slave stations 2 ₁
To 2 _n , and the slave stations other than the slave station receive the signal by the internal processing circuit 5 ₅ , but discard it by internal processing.

(2) When transmitting from the child station to the parent station.

Upon receiving the signal from the master station, the slave station (referred to as slave station 2 ₁ ) transmits a signal to the master station after the signal transmission state of the master station is completed.

Child station 2₁Processing circuit 5_FiveIs the transmission signal B_OThe light
Transmitter 5₆Output to this optical transmitter 5 ₆Converted to optical signal with
Signal B₁Optical branching and converging device 5₇By
Two signals B₂, B₃Branch to.

These signals B ₂ and B ₃ are respectively sent to the X-branch combiner 5
₁ , 5 ₂ and is transmitted in the reverse direction to the master station 1 via the optical transmission lines 3 ₁ , 3 ₂ .

In the master station 1, the optical receivers 4 ₅ and 4 ₆ receive the signals B ₂ and B ₃ transmitted from the two optical transmission lines 3 ₁ and 3 ₂ , respectively. The optical receiver 4 ₅ receives the optical signal B ₂ and converts it into an electric signal, which is given to the processing circuit 4 ₁ as a signal B ₄ . Optical receiver 4 ₆ is converted into an electric signal by receiving the optical signal B _3, the signal B ₅
To the processing circuit 4 ₁ .

The processing circuit 4 ₁ receives the signals B ₄ and B ₅ , performs predetermined processing, edits them into one signal, and performs internal processing.

(3) In case of one-line transmission / reception error of the master station.

(3-1) When the signal A _O output from the processing circuit 4 _{1 of the} master station cannot be transmitted due to an abnormality in the optical transmitter 4 ₂ and the optical receiver 4 ₅ , the signal A _O is transmitted to the optical transmitter 4 ₄ From the optical transmission line.

The signal A ₂ output from the optical transmitter 4 ₄ is transmitted to the child station by optical cable 3 ₂ (a slave station 2 _1), through the X branching device 5 ₂ and Y branching device 5 ₃ The signal A ₃ is taken in and converted into an electric signal by the optical receiver 5 ₄ . In this case, the signal A ₃ is the signal A ₂ itself which is one of the two signals A ₁ and A ₂ .

The processing circuit 5 ₅ of the slave station 2 ₁ receives the signal A ₄ obtained by converting the signal A ₃ and performs normal processing. That is, the internal processing is performed exactly as in the case where the master station is normal, and the response signal is created.

[0018] (3-2) signal B _O processing circuit 5 ₅ outputs the slave station is converted by the optical transmitter 5 ₆ signals B _1, Y
The signals are transmitted from the optical transmission lines 3 ₁ , 3 ₂ to the master station 1 via the branching / combining unit 5 ₇ and the X-branching / combining units 5 ₁ , 5 ₂ .

At the master station, the transmitter 4 ₅ is abnormal,
Of the two transmitted signals, only the signal B ₃ is received by the optical receiver 4 ₆ and becomes a signal B ₅ by photoelectric conversion.
The processing circuit 4 ₁ receives the signal B ₅ and performs internal processing. However, although the signal B ₄ has not been received, the level of signal transmission / reception between the master station and the slave station indicates that one of them is correctly received, and therefore there is no difference from the case where the master station is normal.

(4) When the optical transmission line is broken.

(4-1) Optical transmission line 3 between slave stations 2 ₁ and 2 _n-1
When both ₁ and 3 ₂ are disconnected and transmission / reception processing is performed between the master station 1 and the slave station 2 ₁ , the transmission signal from the master station 1 is the _two signals A ₁ and A _{2 and} the optical transmission lines 3 ₁ and 3 2. Output to ₂ .

The signal A ₁ is normally transmitted to the slave station 2 ₁ by the optical transmission line 3 ₁ . Signal A ₂ can not receive the signal A ₂ in the child station 2 ₁ for disconnection in the preceding stage of the optical transmission line 3 2 ₂ but is transmitted slave station ₁ occurs.

However, the signal A ₁ on the optical transmission line 3 ₁ side is transmitted to the slave station 2 ₁
Since the incoming call has arrived, the processing circuit of the slave station 2 ₁ performs the internal processing as normal and creates a response signal.

(4-2) The processing circuit 5 ₅ of the slave station 2 ₁ outputs the signal B
Output _O. This signal is converted into a signal B ₁ in the optical transmitter 5 _6, Y branching device 5 ₇ and X branching device 5 _1, 5 ₂ through the optical transmission line 3 _1, 3 ₂ in each signal B _2, B ₃ Output as.

The signal B ₂ is not transmitted to the master station because the optical transmission line is broken. The master station 1 receives only the signal B ₃ transmitted from the slave station 2 ₁ .

The master station 1 receives the signal B ₃ by the optical receiver 4 ₆ and takes it in the processing circuit 4 ₁ as the signal B ₅ . Processing circuit 4 ₁
Receives the signal B ₅ and performs internal processing. However, although the signal B ₄ has not been received yet, the signal transmission / reception level between the master station and the slave station indicates that one of the signals has been correctly received, and therefore the signal is processed in the same way as when the optical transmission line is normal. ..

[0027]

[Problems to be Solved by the Invention] Master station 1 to each slave station 2 ₁
Since the signal transmission to to 2 _n is to ensure the transmission and reception processing function at the time of abnormality occurrence, the sequence directly transmitting signals A _O, the streams to be transmitted by delaying the signal A _O by the delay circuit 4 ₃ provided, The signal A _O is duplicated in time series, the optical transmission line is duplicated, and the signal transmission directions are opposite to each other.

Therefore, for signal transmission from the master station 1 to each of the slave stations 2 ₁ to 2 _n , as shown in FIG. 6, in contrast to the signal A _O , at the slave station, the signal A ₄ is converted into the signal E and the delay circuit is added thereto. 4 ₃ receives as a signal F having a delay time Td by, twice as long compared to the signal a _O as the transmission and reception is required for transmission and reception of signals a _O.

In particular, when the number n of slave stations increases, there is a problem that a delay in signal transmission / reception time between master stations increases the overall signal processing time.

Further, in the conventional system complicates the delay circuit 4 ₃ parent station configuration in the master station, it is necessary to increase the delay circuit number as particular network of optical multi-branched in the master station is increased, increasing the circuit scale There was a problem that caused it.

An object of the present invention is to provide a communication system that does not require time-series duplexing for signal transmission from a master station to a slave station.

[0032]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, one master station and a plurality of slave stations are loop-coupled by a dual optical transmission line of 1-system and 2-system, Outputs the transmission signal to the slave station to the optical transmission lines of the 1st and 2nd systems via the two optical transmitters, and the optical transmission lines of the 1st and 2nd systems transmit signals to the slave station in opposite directions. Each slave station splits and receives the optical signals from the optical transmission lines of the 1st and 2nd systems by a pair of X-branch mergers, and merges the branch outputs of both X-branch mergers by the first Y-branch merger. , This signal is photoelectrically converted by the optical receiver and taken into the processing circuit in the slave station, and the response signal from the processing circuit in the slave station to the master station is photoelectrically converted by the optical transmitter, and this optical signal is converted into the second signal.
1 through the pair of X-branch mergers
In the optical multi-branching communication system, the master station outputs to the two-system and two-system optical transmission paths, and the master station received from this optical transmission path is incorporated into an internal processing circuit via a pair of optical receivers. When the transmission system is normal, one system is used to transmit to the slave station, and transmission / reception processing is performed to receive a response signal from the slave station in response to the transmission, and the master station transmits to the slave station via the one system. When the response signal from the slave station does not arrive within a certain time for transmission to the other station, it switches to the optical transmission line of the other system and transmits again to the slave station, and receives and sends the response signal from the slave station to this transmission and reception It is characterized by performing processing.

[0033]

[Operation] When the optical transmitter and the optical transmission line are normal, the transmission from the master station to the slave station is performed by transmitting from the master station to the slave station using one transmission system, thereby duplicating the transmission signals in time series. The transmission time is halved as compared with the conventional method described above, and a delay circuit for time-sequential duplication of the transmission signal is unnecessary.

When an abnormality occurs in the transmission system, it is determined by the time management on the side of the parent station that there is no response from the slave station within a fixed time for the transmission using one transmission system. A response from the slave station is obtained by switching to the system and retransmitting the transmission signal.

With respect to the disconnection of both systems of the transmission line, the response from the slave station is obtained both when the transmission system is normal and when the transmission system is abnormal due to the loop transmission line configuration.

[0036]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention. 5 is different from FIG. 5 in that the delay circuit 4 ₃ in the master station 1 is deleted, and the master station 1 normally operates from the slave stations 2 ₁ to
The signal transmission to 2 _n is one-series transmission in which only the optical transmitter 4 ₂ transmits, and the transmission from the optical transmitter 4 ₄ is performed only when the 1-system transmission is abnormal.

That is, when an error occurs in the 1-system transmitter such as an error in the optical transmitter 4 ₂ and there is no response from the slave station, the signal transmission system is switched to the slave side from the 2 system side of the optical transmitter 4 _4. Send to the station. In this case, transmission from the 1-system on the optical transmitter 4 ₂ side to the slave station is not performed.

When an abnormality occurs in the optical transmission lines 3 ₁ and 3 ₂ , the master station transmits a signal to the same slave station twice. In this case, the system for transmitting the signal is switched to the 1-series side for the first time and switched to the 2-series side for the second time to transmit the signal.

The transmission / reception processing in this embodiment will be described below. However, since the basic processing part is the same as the conventional one, the description will focus on the changed part from the conventional one.

(1) When the signal is normally transmitted from the master station 1 to the slave stations 2 ₁ to 2 _n .

As shown in FIG. 2, and outputs a signal A _O from the processing circuit 4 _first master station 1. This signal A _O is immediately converted into an optical signal by the optical transmitter 4 ₂ and transmitted to the slave station as the signal A ₁ .

The processing on the receiving side in the slave station is performed by, for example, the slave station 2 ₁
Then, the signal A _{1 taken} in from the optical transmission line 3 ₁ by the X-branch combiner 5 ₁ is obtained as the signal A ₃ by the Y-branch combiner 5 ₃ .

A series of these processing timings are shown in FIG. 2, and the time T ₁ in the figure is the propagation delay time received when the signal A ₁ propagates through the optical transmission line 3 ₁ , and the signal A ₃ , A ₄ is delayed by time T ₁ .

Signal transmission from the slave station to the master station is the same as in the conventional case, and the times T ₃ and T ₄ are propagation delay times received when the signal B ₁ propagates through the optical transmission lines 3 ₁ and 3 _2. is there.

(2) When an abnormality occurs in the optical transmitter 4 ₂ or the optical transmission line 3 ₁ of the master station ₁ , the signal transmitted from the master station does not reach the slave station, and there is no response from the slave station.

As shown in FIG. 3, the master station 1 activates a slave station response waiting timer by an internal software timer when transmitting the signal A _O. The signal A _O output from the processing circuit 4 ₁ of the master station is transmitted from the optical transmitter 4 _2, but the signal A _O is not transmitted to the slave station due to the 1-system transmission error, and a response is returned from the slave station. Don't come

Therefore, in the master station 1, the timer times out when the time Ta has passed, and it is determined that there is a transmission abnormality in one master station at this time up, and the system that transmits the signal changes from system 1 to system 2.
Switch to the system and send the signal to the slave station again.

In this case, the processing circuit 4 ₁ does not output the signal A _O to the optical transmitter 4 ₂ but outputs the signal Ae having the same content as the signal A _O to the optical transmitter 4 ₄ . This signal Ae is transmitted to the slave station 2 ₁ through the optical transmission line 3 ₂ of the 2 system via the optical transmitter 4 ₄ .

The child station sends back a response in response to the signal from the parent station. Since the signal transmitted from the slave station is normal in the optical transmission line 3 ₂ and the optical receivers 4 ₅ and 4 _{6 of the} master station 1, the master station can finally receive the signals B ₄ and B ₅ .

(3) In the case of disconnection of both systems of the optical transmission lines 3 ₁ and 3 ₂ .

For example, if a disconnection occurs in both systems at point A or point B in FIG. 1, the response from the slave station is signal B as shown in FIG.
It is received by either ₄ or B ₅ .

[0052] That is, signal A _O was transmitted to the optical transmission line 3 _1, signal B _O is the optical transmitter 5 ₆ from the slave station 2 ₁ from the master station 1 at point A disconnection shown in FIG. 4 (a) And a signal B ₃ is transmitted to the X-branch combiner 5 ₂ via the Y-branch combiner 5 ₇ , and this signal B ₃ propagates through the optical transmission line 3 ₂ and the signal B _{5 is} received by the optical receiver 4 ₆ of the master station. Is taken into the processing circuit 4 ₁ .

In the broken line B shown in FIG. 4B, the response from the slave station cannot be obtained for the transmission of the signal A _O , so that the master station 1 increases the timer and the signal Ae optical transmitter 4 ₄ output, this output is sent as a signal a ₂ through the optical transmission line 3 ₂ to the slave station 2 _1. Response from the slave station 2 ₁ for the transmission converts the signal B _O in the optical transmitter 5 ₆ signals B _1, the optical transmission path 3 ₁ through Y branching device 5 ₇ and X branching device 5 ₁
Is output to the processing circuit 4 ₁ as the signal B ₄ at the optical receiver 4 ₅ of the master station 1.

In the figure, times T ₂ , T ₃ , and T ₄ are propagation delay times depending on the transmission direction of the optical transmission lines 3 ₁ and 3 ₂ .

[0055]

As described above, according to the present invention, the transmission from the master station to the slave station uses one system when the transmission system is normal,
Performs transmission / reception processing to receive the response signal from the slave station, and when there is no response from the slave station within a certain time in response to the transmission from the master station, it switches to another system as a transmission system error and transmits and receives. As a result, the transmission time to the slave station is reduced by half as compared with the conventional time-series duplex transmission method, and the delay circuit on the master station side is unnecessary.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

FIG. 2 is a processing timing in the embodiment.

FIG. 3 is a processing timing in the embodiment.

FIG. 4 is a processing timing in the embodiment.

FIG. 5 is a conventional system configuration diagram.

FIG. 6 is a conventional processing timing.

[Explanation of symbols]

1 ... master station 2 _1, 2 _n ... slave station 3 _1, 3 ₂ ... optical transmission path 4 _1, 5 ₅ ... processing circuit 4 _{2, 4} 4, 5 ₆ ... optical transmitter 4 _5, 4 _6, 5 ₄ ... Optical receiver 5 ₁ , 5 ₂ ... X-branch merger 5 ₃ , 5 ₇ ... Y-branch merger

Claims (1)

[Claims] 1. A master station and a plurality of slave stations are loop-coupled by a dual optical transmission line of a 1-system and a 2-system, and the master station transmits a transmission signal to the slave station via two optical transmitters. Output to the optical transmission lines of the 1st and 2nd systems, and the optical transmission lines of the 1st and 2nd systems transmit signals to the slave stations in opposite directions. The optical signal from the optical transmission line is received by branching, the branched outputs of both X branching and joining devices are joined by the first Y branching and joining device, and this signal is photoelectrically converted by the optical receiver to be processed in the slave station. And the response signal from the processing circuit in the slave station to the master station is photoelectrically converted by the optical transmitter, and this optical signal is converted into the second signal.
1 through the pair of X-branch mergers
In the optical multi-branch communication system, the master station outputs to the two-system and two-system optical transmission paths, and the master station received from this optical transmission path is incorporated into an internal processing circuit via a pair of optical receivers. When the transmission system is normal, one system is used to transmit to the slave station, and transmission / reception processing is performed to receive a response signal from the slave station for this transmission, and the master station is the slave station via the one system. When the response signal from the slave station does not arrive within a certain time for transmission to the other station, it switches to the optical transmission line of the other system and transmits again to the slave station, and receives and sends the response signal from the slave station to this transmission and reception An optical multi-branch communication method characterized by performing processing.