JP2807507B2 - U-shaped optical bus network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding an optical bus network capable of transmitting an optical signal in a U-shape via an optical repeater, a reception test can be performed in an all-optical transceiver, and an erroneous connection of the optical bus An optical transceiver for generating a predetermined alternating light pattern in accordance with the Manchester code at the time of a reception test, and receiving this light pattern to turn on an indicator light with the object of realizing a U-shaped optical bus network capable of detecting , An optical repeater including a Manchester decoder and a Manchester encoder, which passes or folds the optical pattern, and an optical coupler that connects the optical repeater and the optical transceiver via optical fibers arranged in a bus. Configure.

[Industrial applications]

The present invention relates to an optical bus network, and more particularly to an optical bus network capable of transmitting an optical signal in a U-shape by way of an optical repeater.

In recent years, with the development of an optical bus network that transmits an optical signal in a U-shape via an optical repeater, the failure of the optical bus at the time of initial introduction is increasing, and a method for easily detecting such an optical bus failure. Is required.

[Conventional technology]

FIG. 5 shows a configuration example of a conventional U-shaped optical bus network, in which optical transceivers 1a, 1b, and 1c for transmitting and receiving by connecting a terminal device (not shown) and the like include an optical coupler (optical outlet). ) Connected to 3a, 3b, 3c by optical cable 4,
The optical repeaters 2a and 2b are connected to optical couplers 3b and 3c via a cable 4. Then, the optical repeater 2b is set to the return mode and forms a U-shaped optical bus network.

FIG. 6 (a) shows a specific configuration of the optical transceiver shown in FIG. 5, where "11" changes "0" in data from the terminal device to "1,0". Is a Manchester encoder that converts to “0,1”, 12 is a changeover switch that switches between a communication mode and a test mode, and 13 is an E / E that converts an electric signal of the Manchester code from the changeover switch 12 into an optical signal and sends it out.
O converter, 14 is an O / E that converts the input optical signal into an electrical signal
A conversion unit 15 is a Manchester decoder for decoding a Manchester code included in the electric signal from the O / E conversion unit 14, and a test unit 16 is for performing a light level test.

FIG. 2B shows the configuration of the optical repeater. The difference from FIG. 2A is that the line IV is connected to the lines I and III or the line II is connected to the lines I and III in the loopback mode. Line switching units that make up a U-shaped bus network
21 and 22 are further provided, and decoders 17 and 19 for decoding the input Manchester code and Manchester encoders 18 and 20 for shaping and sending out the decoded signal are provided. Is a point. Note that an E / O converter 13 and an O / E converter 14 are provided between the line switching units 21 and 22 and the optical transmission lines.

In such a conventional U-shaped optical bus network, when the optical transceiver 1a outputs the Manchester code signal from the Manchester encoder 11 during normal operation, the optical signal path in the optical cable 4, the optical coupler 3
a, the optical signal path, the optical coupler 3b, and reaches the optical repeater 2a via the optical signal path, the signal passes through the Manchester decoder 17 and the encoder 18 of the optical repeater 2a, the optical signal path, the optical coupler 3c And reaches the optical repeater 2b.

Since the optical repeater 2b is in the repetition mode, the signal is looped back here and sent to the receiving line, received by the optical transceiver 1c via the optical coupler 3c, decoded by the decoder 15, and sent to the terminal device.

Then, the signal is similarly received by the optical transceivers 1b and 1a via the decoder 19 and the encoder 20 of the optical repeater 2b, respectively, decoded by the decoder 15, and sent to the terminal device.

Next, when an optical level measurement test of each optical transceiver is performed, the changeover switch 11 of the optical transceiver 1c is switched to a test mode indicated by a dotted line, and when a DC optical signal for optical level measurement is transmitted from the test unit 16, this DC optical By receiving DC light in the repeater 2b and detecting the level of the signal, it is possible to test whether there is no level fluctuation on the optical transmission line.

Further, by switching from the repeater 2b to the test mode, a DC optical signal for optical level measurement is detected from the test unit 16, and the level can be measured by the optical transceiver 1c.

[Problems to be solved by the invention]

However, in FIG. 5, for example, when a DC optical signal is output from the optical transceiver 1a, it comes to the optical repeater 2a via the optical couplers 3a and 3b. Therefore, a DC optical signal cannot be sent to the optical coupler 3c following the optical repeater 2a.
A reception test for checking whether the optical signal from 1a has been correctly received cannot be performed.

As described above, the DC optical output of the test section of the conventional optical transceiver is for measuring the optical reception level on the receiving side, and therefore cannot pass through the optical repeater. First, an optical coupler as an optical outlet is used for branching / inserting an optical signal. However, since this is directional and cannot be made omnidirectional, an erroneous connection of an optical bus is detected. There was a problem that it was not possible.

Accordingly, an object of the present invention is to realize a U-shaped optical bus network capable of performing a reception test in an all-optical transceiver and detecting an erroneous connection of an optical bus.

[Means for solving the problem]

As shown in FIG. 1, the U-shaped optical bus network according to the present invention for achieving the above object generates a predetermined alternating light pattern in accordance with a mantester code during a reception test, and Transceiver 1 that receives the signal and turns on the indicator light 5, and the Manchester decoder 1
7 and 19 and Manchester encoders 18 and 20 through the optical repeater 2 that passes or folds the optical pattern, and the optical repeater 2 and the optical transceiver 1 through the optical fiber 4 arranged in a bus shape. And an optical coupler 3 connected thereto.

[Action]

In FIG. 1, a certain optical transceiver 1 outputs a predetermined alternating light pattern during a reception test. Then, this alternating light pattern is input to the optical repeater 2 via the optical fiber 4 and the optical coupler 3 arranged in a bus shape.

Since the input optical pattern conforms to the Manchester code in the optical repeater 2, the waveform is shaped by the Manchester decoder 17 and the Manchester encoder 18 as shown in FIG. U
It is folded back into a letter shape and again passes through the Manchester decoder 19 and Manchester encoder 20 of the optical coupler 3 and the optical repeater 2.

At this time, the optical pattern is given to the optical transceiver 1 connected to each optical coupler 3 via the optical fiber 4 arranged in a bus shape. When each optical transceiver 1 receives this optical pattern, the indicator light 5 is turned on.

Thereby, the optical pattern can be transmitted from one optical transceiver to all optical transceivers, and since this optical pattern is an alternating signal, the average value is constant, and thus the optical pattern is connected to each optical transceiver or optical transceiver. A test of the reception level can be performed in a terminal device or the like.

In addition, since the optical pattern can be sent to all the optical transceivers, if the lighting of the indicator lamp 5 of each optical transceiver 1 is confirmed, it is possible to detect an erroneously connected portion of the optical fibers 4 arranged in a bus shape. it can.

〔Example〕

2 (a) and 2 (b) show an embodiment of the optical transceiver 1 and the optical repeater 2 used in the U-shaped optical bus network according to the present invention. Alternating pattern generator 30 that generates a continuous alternating pattern
FIG. 6 differs from the conventional example of FIG. 6 in that an indicator light 40 which is turned on when an alternation pattern is generated and an indicator light 5 connected to the Manchester decoder 15 are provided. The continuous alternation pattern of "1,0" is in accordance with the above-mentioned Manchester code, and is used at the time of a reception test as shown in FIG. It is inserted into the frame header that is used for synchronization during communication. The indicator lamps 40 and 5 may be provided in the Manchester decoders 17 and 19 when test reception is performed not only by the optical transceiver 1 but also by the optical repeater 2 itself.

Now, when the changeover switch 12 of the optical transceiver 1a is set to the test mode in FIG. 2 (a), the optical output signal becomes an alternating pattern of "1,0" and starts continuous transmission.

When this optical pattern signal is input to the optical repeater 2 via the optical fiber 4 and the optical coupler 3 arranged in a bus shape as shown and described in FIG. 1, the optical repeater 2 converts this optical pattern. The waveforms are shaped by Manchester decoders 17 and 19 and Manchester encoders 18 and 20, and output.

Then, the optical pattern is further input to the optical repeater 2 set in the return mode via the optical coupler 3 and is returned there. The optical pattern is received by the optical transceivers 1 via the optical coupler 3 on the receiving optical bus 4. Is done.

In each optical transceiver 1, the clock is extracted and “1,
The indicator "5" is turned on by reproducing the "0" pattern, and the average value (-3dB) of the "1,0" pattern can be measured in the transceiver or in the terminal device.

Therefore, it can be confirmed that the signal has been received by turning on the indicator lamp 5, and since both the transmission display 40 and the reception display 5 are lit on the optical transceiver 1, transmission and reception can be confirmed.

Here, when connecting the two-core optical bus cable as described above, the input and output signals are reversed by connecting the one end incorrectly or by mounting the half mirror of the optical coupler in the reverse direction. Therefore, a failure in which transmission and reception cannot be performed may occur.

That is, the optical buses 4b and 4d shown in FIG.
When the half mirror of 3b is inverted, the optical transceiver 1a is illuminated for both transmission and reception, but after the incorrect connection, the optical pattern signal is not transmitted correctly, and the indicator lights of the optical transceivers 1b and 1c thereafter. Does not light.

Therefore, by first checking the optical bus 4a, then checking the optical coupler 3b and its optical bus 4d, and checking the optical bus 4b, it is possible to identify and process an erroneously connected portion by a simple procedure. .

Incidentally, even if an optical repeater is interposed between these optical couplers, it is possible to detect an erroneous connection in exactly the same manner.

〔The invention's effect〕

As described above, according to the U-shaped optical bus network according to the present invention, each optical transceiver generates a predetermined alternating light pattern in accordance with the Manchester code during a reception test, and receives and displays this light pattern. Since the light is configured to be turned on, even if an optical repeater of the same Manchester code is interposed, the optical pattern can be sent to each optical transceiver without blocking, and the optical level measurement can be performed as the average value of the optical pattern. In addition, since an optical pattern can be passed through the all-optical transceiver, erroneous connection of the optical bus can be easily detected.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a U-shaped optical bus network according to the present invention, FIG. 2 is a block diagram of an embodiment of an optical transceiver and an optical repeater used in the present invention, and FIG. FIG. 4 is a diagram illustrating a frame format of optical transmission used, FIG. 4 is an explanatory diagram when a misconnected network is applied to the present invention, FIG. 5 is a block diagram of a conventional U-shaped optical bus network, FIG. FIG. 2 is a block diagram illustrating a configuration example of a conventional optical transceiver and an optical repeater. In FIG. 1, 1 ... an optical transceiver, 2 ... an optical repeater, 3 ... an optical coupler, 4 ... an optical fiber arranged in a bus shape, 5 ... an indicator light, 17, 19 ... a Manchester decoder, 18, 20: Manchester encoder, 30: Alternating pattern generator. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] An optical transceiver (1) for generating a predetermined alternating light pattern in accordance with a Manchester code at the time of a reception test, receiving the light pattern and lighting an indicator (5), and a Manchester decoder (17). (19) and an optical repeater (2) including the Manchester encoders (18) and (20) and passing or folding the optical pattern; and a bus-shaped optical repeater (2) and the optical transceiver (1). An optical coupler (3) connected via an optical fiber (4) disposed in the U-shaped bus network.