JPS58223929A - System for detecting failure of transmission line of data communication system - Google Patents

Abstract

PURPOSE:To detect surely a failure of transmission line of both transmission and reception, by comparing trasmitted test data with received folding data and discriminating as no failure when both are coincident. CONSTITUTION:A signal is generated repetitively by a signal generator 37 at each section where a value is fluctuated at random for 10msec. The interval of signal generation is varied in this way, preventing test data transmitted from >=2 transceivers from being transmitted at the same time at all times. A data sensing circuit 40 detects that other stations do not perform any transmission, then test data from a data generator 38 is transmitted from a light emitting diode 18. The received test data received at a photodiode 22 is compared with transmitted data by a detecting circuit 41 and it is discriminated for the presence of a failure depending on the dissidence of the both.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a communication system that uses optical space propagation technology to communicate between two stations, such as a master station and a slave station. The present invention relates to a system for detecting failures in optical space transmission lines between remote stations at slave stations.

As shown in FIG. 1, one master station 101 and multiple slave stations 1
In a communication system in which optical transmission lines 105 to 107 are communicated between slave stations 02 to 104 or between slave stations via a master station, for example, the transmission line 107 between slave station 104 and master station 101 is When a failure occurs, from the master station 101 to the slave station 1
While transmitting a signal towards 04, it is detected that the reception level of the signal at slave station 104 has fallen below a certain level, and it is determined that a transmission path failure has occurred.

However, in such a conventional method, a failure in the transmission path is detected only from the signal sent from the master station 101 to the slave station 104, so a failure occurs in the signal transmitted from the slave station 104 to the master station 101. It was not possible to determine whether

Further, since the reception level is judged based on the value of the reception level, it is difficult to overturn the judgment as to whether the level at which it is judged that there is no failure is the level at which the slave station 104 can reliably reproduce data.

Furthermore, failure detection is limited to when the master station 101 is sending a signal to the slave station 104, so if there is no communication between the master station 101 and the slave station 104, the transmission line Even if a failure occurs in the 107, there is a drawback that it cannot be known.

The main object of the present invention is to provide a transmission path failure detection method that can reliably detect failures in transmission paths in both sending and receiving directions, and can guarantee reproduction of received data.

Another object of the present invention is to provide a transmission line failure detection method that can detect failures in the transmission line not only during data transmission but also when data is not being transmitted.

Still another object of the present invention is to provide a fault detection method that can detect faults without affecting communication between other stations.

In order to achieve such an objective, the present invention provides a system in which at least two stations communicate with each other,
One station transmits test data using a frequency different from the normal data frequency, and the other station that received this test data transmits return data. The test data received and the received return data are compared, and when the two match, it is determined that there is no fault, and when the two do not match, it is determined that there is a fault.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows the configuration of an example of a communication system according to the present invention, and is an example in which data communication is performed between devices such as terminals and computers installed in a premises.

In the figure, two rooms 1.2 are connected by a coaxial cable 3, and a reflector 4.5 is provided at a high place in each room for this coaxial cable 3.
It is connected by a T-branch.

In addition, transceivers 6.7 and 8.9 are provided at low places in each of the rooms 1 and 2, facing the reflectors 4 and 5. Alternatively, it is connected to devices 10, 11, 12, and 13 consisting of computers.

And transceiver 6 and devices 10, 7 and 11°8 and 1
2, 9 and 13 each constitute a slave station, and reflectors 4 and 5 each constitute a master station. These slave stations can be moved.

Reflectors 4 and 5 each have a light emitting diode 1.
4 and 15, photodiodes 16 and 17, and the transceivers 6 to 9 are also provided with light emitting diodes 18 to 21° and photodiodes 22 to 2, respectively.
5 is provided.

In such a configuration, the transceivers 6 to 9 receive and receive transmission data from the corresponding devices 10 to 13, intensity modulate the infrared rays emitted by the light emitting diodes 18 to 21, and focus the infrared rays to respond. Freshita 4 and 5
emit toward.

The light emitting diodes 18-21 are designed to emit light only when data is not transmitted from the devices 10-13.

On the other hand, infrared rays emitted from transceivers 6 to 9 are received by photodiodes 16 and 17 of reflectors 4 and 5, converted into electrical signal data, and sent to coaxial cable 3. The data sent to the coaxial cable 3 is transmitted to all the flaps connected to the coaxial cable 3, including the transmitter and the flap.

Receives data from the coaxial cable 3, modulates the intensity of the infrared light S emitted by the light emitting diodes 14 and 15 at the flapers 4 and 5, and transmits the infrared light to cover all the transceivers 6 to 9 in the room. Diffusion and release toward the target. After receiving the infrared rays emitted from the reflectors 4 and 5 by the photodiodes 22 to 25 of the transceivers 6 to 9 and converting them into electrical signal data,
It is sent to devices 10-13.

Therefore, when sending data from a device such as a terminal in one room, that data is sent to the other room's device.
Not only will it be received by all terminals and other devices in the same room, but it will also be received by other terminals and other devices in the same room.

The reflectors 4 and 5 are configured to diffuse and emit infrared rays in a range that can be received simultaneously by terminals installed in all locations in each room, and the transceivers 6 to 9 What is necessary is to emit focused infrared rays so that the corresponding beams 4 and 5 can receive the light.

FIG. 3 shows the configuration of an example of the transceiver on the slave station side of FIG. 2, which includes a device for implementing the failure detection method according to the present invention.

In the figure, 37 is a signal generator that generates a transmission request signal for fault detection data (hereinafter test data), 38 is a data generator that generates test data, 39 is a clock generator that generates a clock signal, and 40 is another a data sense circuit that determines whether the transceiver is transmitting test data; 41 a detection circuit that detects a mismatch between transmitted test data and received test data; 42 to 44;
is Fritub Flora 7', 45-47 is and gate, 4
9 is a light emitting diode constituting a failure detection lamp; 52 is a signal line for transmitting data; 53 is a signal line for receiving data; 54 is a signal line for transmitting clock; 60 is a signal line for transmitting data at the first frequency. 61 is a modulator that modulates the transmitted test data to a second frequency f2; 62 is a mixer that mixes the two frequencies f1 and f2; and 63 is a modulator that modulates the two frequencies f1 from the signal received from the reflector. A branching filter 64 for separating f2i is a 1-tone device that reproduces test data rather than data from the received signal of the divided frequency f1.

In FIG. 3, data transmission and reception between the device 10 and the transceiver 6 will be explained first.

When the device 10 transmits data, the signal line 52 is
Transmission data (a series of pids 1" and 0") synchronized with the clock signal on the signal line 54 is sent out. In the transceiver 6, this transmission data is input to a modulator 60, and the carrier signal of frequency f1 is modulated. The modulated carrier signal passes through mixer 62 to drive light emitting diode 18 . Further, after receiving the received carrier signal from the reflector 4 at the photodiode 22, it is passed through the demultiplexer 63 to the 1-device 64.
, take out the received data, put it on the signal line 53,
It is sent to the device 10 side.

When a fault occurs in the optical transmission path between the transceiver 6 and the reflector 4, the operation of warning the transceiver 6 of the fault according to the present invention will be explained with reference to the waveform diagrams of FIGS. 4 and 5. .

The signal generator 37 has an average value of 10Qm9130. ±1
A test data transmission request signal shown in FIG. 4(a) is generated, which is repeated in each section in which the value fluctuates from a random number trap within 0 m%. The purpose of varying the signal generation intervals in this manner is to prevent test data transmitted by two or more transceivers from always being transmitted simultaneously. Fourth
The transmission request signal as shown in the enlarged view of FIG. 4(b) is synchronized with the clock signal shown in the clock signal of FIG. 4(c) and has a length of 16 bits.

Furthermore, as shown in FIG. 5<8), the data generator 38 generates 8-bit continuous "'1" data and 8-bit continuous Mo data in synchronization with the clock signal of FIG. #Generate test data that alternately repeats data. The data from the data generator 38 is passed through the AND gate 47, the modulator 61 and the mixer 62 to the light emitting diode 18.
is applied.

When the test data transmission request signal from the signal generator 37 is on, the data sense circuit 40 determines whether or not another station is transmitting test data, and the data sense circuit 40 determines whether the other station is transmitting test data. When the output of the AND gate 45 is detected, the output of the AND gate 45 is turned on, and the flip-flop 42 is set when the output of the Asahi AND gate 45 is turned on, turning on the output of the AND gate 46, and opening the AND gate 47. Thereby, the data generator 3
8 and gate 47% modulator 61
and the mixer 62 to apply an optical signal corresponding to the data to the light emitting diode 18.
Send from 8.

The photodiode 22 receives the return data from the beam shifter 4 as the master station, and after extracting a signal containing test data using the duplexer 63 (the test data is demodulated by the modulator 65 and input to the detection circuit 41).

The detection circuit 41 compares the transmitted test data and the received test data, turns on the output when a mismatch is detected, and turns off the output when no mismatch is detected.

Therefore, when a failure occurs in the transmission path and data corresponding to the transmitted test data is not received, the output of the detection circuit 41 is turned on and the flip-flop 43 is set. As a result, AND gate 46 is closed and its output is turned off. When the output of the AND gate 46 turns off, the AND gate 47 is closed and the transmission of test data is stopped, and at the timing when the output of the AND gate 46 changes from on to off, the flip-flop 44 changes the output of the flip-flop 43. The data is taken in as new data, and then the output of the flip-flop 44 is turned on and the fault detection lamp 49 is lit. In this way, if the fault detection lamp 49 is lit, it can be determined that the fault has not been removed.

If the fault is removed and the transmitted data is received as received data as is, the output of the detection circuit 41 remains off and the flip 70 knob 43 is not set. At this time, the test data transmission continues while the test data transmission request signal is on, but when it is turned off, the flip 70 knob 42 is reset, the output of the AND gate 46 is turned off, and the AND gate 47 is closed and stops transmitting test data. Further, the flip 70 knob 44 is latched at the timing when the output of the AND gate 46 changes from on to off, and the output turns off the indicator lamp consisting of the light emitting diode 49 to indicate that the fault has been removed. The flip-flop 44 outputs the current state of the flip-flop 43 at the timing when the output of the AND gate 46 changes from on to off. Since the flip-flop 43 is in the reset state unless there is a failure, the flip-flop 44 is in the reset state. The output remains off, and the failure detection lamp 49 continues to be turned off, so that it can be determined that no failure has occurred.

While the transceiver 6 of one slave station is transmitting test data, the data sense circuit 40 of the transceiver of another slave station is
detects that test data is being sent, does not issue a transmission request signal, and enters a waiting state, so there will be no collision between the test data of the own station and the test data being sent by another station. . Furthermore, it goes without saying that if a certain slave station is not transmitting test data, another slave station can transmit the test data.

When the data sense circuit 40 detects that another slave station is transmitting test data, even if the test data transmission request signal is turned on, the AND gate 45
Since the output of the AND gate 46 is not turned on and the flip-flop 42 is not set, the output of the AND gate 46 is not turned on and no test data is transmitted. In this case, since there is no point where the output of the AND gate 46 changes from on to off,
No new data is sampled at flip 70 tube 44 either. Therefore, a slave station will not transmit test data until the next time the transmission request signal is turned on and the data sense circuit 4o detects that the other station is not transmitting test data. It enters a waiting state, during which no test data is sent.

FIG. 6 shows an example of a specific configuration of each of the shifters 4 and 5 that constitute the main station in FIG. 2, and shows an example of the shifter 4.

As shown in the figure, after the photodiode 16 receives the light emitted from the opposing transceiver 6 or 7 and converts it into an electrical signal, the electrical signal is amplified by the amplifier 60 and sent to the coaxial cable 3 via the coupling transformer 61. Send to. On the other hand, the signal on the coaxial cable 3 is taken into the amplifier 63 via the coupling transformer 62, where the signal is amplified, and then converted into light by the light emitting diode 14, which is transmitted to the opposite transceiver 6.
Send to C and 7.

In short, the reflector 4 receives transmission data from an opposing transceiver, sends the data to another reflector, and also sends back data to the transceiver that sent the transmission data. .

FIG. 7 shows an example of a specific configuration of the detection circuit 41 of FIG. 3, in which 70 and 71 are seven lip-flops, 72 is an oscillator that generates a reception clock, and 73 is an exclusive OR circuit. And flip flop 70.71
Transmission data is input to the D terminal, a transmission clock signal is input to the CK terminal, and reception data is input to the exclusive OR circuit 73 and the oscillator 72. The oscillator 72 starts from the point where the received data bit changes from ``0'' to 1''.
A receive sampling clock pulse is generated at the midpoint of a bit of received data.

Transmission data is sampled by the transmission clock signal and held by the D-type flip-flop 7o for l bit time. An exclusive OR of the output of this flip-flop 70 and the received data is taken by a circuit 73,
The value tD type flip-flop 71 samples the received clock from the oscillator 72, so that when the transmitted and received data do not match, the output of the flip-flop 71 is turned on.

In addition, although the embodiment shown in FIG. 2 described above shows an example in which communication is performed between the reflector and the transceiver using infrared rays, the communication is not limited to this, and may be realized using other optical spatial propagation means. It's okay.

Further, the number of transceivers facing each reflector is not limited to the example shown in the figure, but may be any number as long as it is one or more.

Furthermore, in the above embodiment, an example was shown in which two rooms are connected using a coaxial cable, but different locations within the same room may be connected using a coaxial cable, and an optical signal may be used instead of a coaxial cable. A transmission line such as an optical fiber that transmits the signal as is may be used.

Furthermore, two or more receivers may not be connected through a transmission path such as a coaxial cable, but a single lever may be used to perform data communication between devices such as terminals under their control.

According to the embodiment of the present invention described above, while the test data transmitted from the slave station is being transmitted back from the master station to the slave station, the master station simultaneously receives the looped data and transmits the transmitted test data. and the received test data are compared bit by bit.

This has the advantage of being able to confirm whether the received data is reliable, and to detect faults in transmission paths in both directions, transmission and reception, at the same time.

In addition, test data is transmitted and received using a different frequency from that of normal data, so it can be transmitted without interfering with normal data transmission or reception, and even when normal data is not being sent or received. This has the effect of being able to detect road obstacles.

Also, since the test data is sent to the master station after confirming that other stations are not transmitting test data, two or more stations can transmit test data at the same time, and the result is This has the effect that the transmitted test data and the received test data at the slave station do not become inconsistent and are not determined to be faulty.

Furthermore, since the test data is transmitted for a certain period of time at intervals varied by random numbers, the master station and slave stations do not need to constantly transmit test data, which is effective in saving energy.

In the embodiment of the present invention described above, the system has one master station and a plurality of slave stations, and communication is performed between the master station and the slave stations, or between the slave stations via one parent station. However, it goes without saying that the present invention is applicable to cases where there is one master station and one slave station and communication is carried out between them, or where communication is carried out between two slave stations. stomach.

As described above, according to the present invention, not only can faults in the transmission paths in the transmitting and receiving directions be detected simultaneously, but also it can be determined whether the transmitted and received data are reliable.

i), E F Ofij'I'f''Nkai Figure 1 is a system configuration diagram for explaining a conventional transmission path failure detection method, and Figure 2 is a configuration diagram of an embodiment of a communication system according to the present invention. , FIG. 3 is a circuit diagram of an embodiment of a transceiver portion realizing the transmission line fault detection method according to the present invention, FIGS. 4 and 5 are signal waveform diagrams for explaining the operation of the circuit of FIG. 3, FIG. 6 is a circuit diagram of an embodiment of a shifter portion that implements the transmission path failure detection system of the present invention, and FIG. 7 is a circuit diagram showing an example of a specific configuration of the detection circuit of FIG. 3.

4.5...Reflector, 6-9...Transceiver,
14.15.18-21...Light emitting diode, 16°17.22-25...Photodiode, 37...
Test data transmission request signal generator, 38...Test Figure 3 Figure 47 ¥15 Figure, 52

Claims (1)

[Claims] 1. In a data communication system in which at least two stations communicate with each other using a light beam, test data is transmitted from one station at a frequency different from that of normal data. The other station that received the test data sends return data, and the one station compares the transmitted test data and the received return data, and if the two do not match, it is determined that there is a transmission path failure. A transmission line failure detection method characterized in that it is determined that a failure has occurred. 2. The transmission path failure detection method according to claim 1, wherein the test data is transmitted from the one station at intervals staggered by random numbers. 3. In a data communication system in which a master station and multiple slave stations communicate with each other using light beams, one slave station communicates between another slave station and the master station. The test data is transmitted to the master station on a frequency different from the frequency of normal data, and the master station that received the test data transmits return data, and the one slave station A transmission line failure detection method characterized in that the transmitted test data and the return data are compared, and when the two do not match, it is determined that a transmission line failure has occurred. 4. The transmission path failure detection method according to claim 3, wherein the test data is transmitted from one of the slave stations at intervals determined by a random number.