JPS6156906B2 - - Google Patents

Description

Detailed Description of the Invention The present invention connects a plurality of terminal devices to a central device via a common transmission line, and transmits information from each terminal device to the central device using a carrier wave having a frequency common to each terminal device. The present invention relates to an information transmission device that transmits information.

As shown in FIG. 1, this type of information transmission device has transmission lines 2A and 2B led from a central device 1.
On the other hand, coupler 3 such as a hybrid coil
It has a configuration in which a plurality of terminal devices 4A, 4B are connected via A ₁ , 3A ₂ , 3B ₁ , 3B ₂ , and the central device 1 connects each terminal device 4A, 4B to each terminal device 4A, 4B. The address signal and transmission command signal assigned to the address signal are transmitted in a time-division manner. When the terminal devices 4A and 4B receive the address signal assigned to themselves, they generate a carrier wave and enter a transmission state. The transmission signals are taken into the transmission line 2B from the couplers 3B ₁ and 3B ₂ and transmitted to the central device 1. Therefore, as long as the terminal devices 4A, 4B are operating normally, the carrier waves transmitted from each terminal device 4A, 4B will not overlap in time.

However, if either of the terminal devices 4A, 4B fails and the carrier waves of the terminal devices 4A, 4B are simultaneously output to the common transmission line 2B, the normal time division system is impaired and information transmission becomes impossible. I get used to it.

There are two types of failures that can lead to such an abnormal situation: a failure in which the carrier wave control signal is continuously output, and a failure in which the carrier wave is continuously output due to a failure in the carrier wave output section.
Possible forms are possible. Conventionally, for the former type of failure, a method was used to detect the failure by monitoring the time periods during which the control signal was output and when it was not output, but for the latter type of failure, I had no means of countering it. For this reason,
Conventional information transmission devices have a serious drawback in that information transmission becomes impossible if the carrier wave output section fails.

Furthermore, in the past, the burden of detecting failures through the above-mentioned time element monitoring and detecting failures in which carrier waves are not output due to failures in the address detection circuit, etc., was mainly placed on the central unit 1. Another drawback was that it was not possible to quickly take corrective measures, such as disconnecting a malfunctioning terminal device.

The present invention eliminates the above-mentioned drawbacks, and when a failure occurs in any of the terminal devices, the failure is quickly detected in the terminal device, preventing system disturbance, and at the same time, smoothing the countermeasures after the failure is detected. It is an object of the present invention to provide an information transmission device that can perform the transmission quickly.

In order to achieve the above object, the present invention connects a plurality of terminal devices to a central device through a common transmission line, and transmits an address signal assigned to each terminal device from the central device to each terminal device. from each terminal device to the central device in response to a transmission command signal generated by the address signal.
In an information transmission device that transmits a modulated wave information signal using a carrier wave with a frequency common to each terminal device,
Each of the terminal devices detects the presence or absence of its own carrier wave output and determines a failure after a certain period of time in which the carrier wave input from the carrier wave generation circuit to the modulation circuit reaches a stable level in response to the transmission command signal. The present invention is characterized in that it includes a failure detection circuit that performs the following steps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically explained in detail below with reference to the accompanying drawings, which are examples. FIG. 2 shows a concrete block diagram of an information transmission apparatus according to the present invention. Similar to FIG. 1, this embodiment shows an apparatus equipped with two single-type terminal devices. Further, the same reference numerals as in FIG. 1 represent the same constituent parts.

The terminal devices 4A and 4B each include a demodulation circuit 5, a reception circuit 6, an address detection circuit 7, a transmission circuit 8, a modulation circuit 9, a carrier generation circuit 10, an AND gate 11, and a failure detection circuit 12. .

FIG. 3 is a time chart of waveforms of various parts in the above-mentioned information transmission device.

As shown in FIG. 3 a ₁ , signals fA ₁ and fB ₁ including an address signal and a transmission command signal are sent from the central device 1 to the terminals in a time-division manner with a time interval T ₁ between them.

Now, looking at the signal fA ₁ , the signal fA ₁ is sent to the terminal devices 4A and 4B by the couplers 3A ₁ and 3A _2.
The signals are branched and input to the respective signals, and are received (signal fA ₂ in FIG. 3 a ₂ ). This received signal fA ₂ is demodulated by a demodulation circuit 5 and guided to an address detection circuit 7 via a reception circuit 6. The address detection circuit 7 compares the address signal inputted from the reception circuit 6 with the address previously assigned to itself, and if the two addresses match, it is a transmission command for itself, so as shown in FIG. ₃ , a set signal _fA3 of the carrier wave control signal TB is output. When this set signal _fA3 is output, AND gate 1
1. If the carrier wave generation circuit 10 and the modulation circuit 9 are normal, the AND gate 11 is turned on and the carrier wave is inputted from the carrier wave generation circuit 10 to the modulation circuit 9. When the level of the carrier wave input to the modulation circuit 9 reaches a certain stable level, a level detection signal _fA4 as shown in Fig. _3A4 is input from the modulation circuit 9 to the transmission circuit 8, and the transmission circuit Transmission data is input from 8 to modulation circuit 9 . Transmission data is sent to the modulation circuit 9 using a carrier wave as shown in Figure _3a5 .
fA ₅ and transmitted through the coupler 3B ₂ to the transmission line 2.
B and transmitted to the central device 1.

As long as the circuit is normal, the above transmission operation is ensured, but in the case of a circuit failure,
Failure detection circuit 12 operates. The failure detection circuit 1
2 operates as a circuit that detects the presence or absence of its own carrier wave output within a predetermined period of time based on a carrier wave control signal fA ₃ given as a transmission command signal.

In this embodiment, the terminal devices 4A, 4B include monostable multivibrators 12A ₁ , 12B ₁ , inverters 12A ₂ , 12A ₃ , 12B ₂ , 12B ₃ , AND gates 12A ₄ , 12B ₄ , an OR gate 12C, and a relay 12D. It is configured as follows. 12D ₁
is a contact point of the relay 12D.

The monostable multivibrator _12A1 is used to generate a timing pulse for detecting whether or not there is a carrier wave output after a certain period of time has elapsed from the start of a transmission command, and generates a carrier wave control signal TB which is a transmission command signal. It is triggered by the set signal fA ₃ of FIG _{. 3, and outputs a timing pulse fA 6 with} a time width t ₁ as shown in FIG.

Furthermore, the monostable multivibrator 12B ₁ is used to create a timing pulse for detecting whether or not there is a carrier wave output of its own after a certain period of time has elapsed from the end of the transmission command, and is used to generate a carrier wave control signal.
Triggered by the TB reset signal, Figure 3
A timing pulse of time width t ₂ as shown in ₇
Create fA ₇ .

The transmission command signal that determines when to start or end transmission in each terminal device 4A, 4B is the set signal _fA3 of the carrier wave control signal TB of the address detection circuit 7, but the actual timing to start and end transmission of the carrier wave is Due to the rise or fall time, the third
As can be understood from Figures a ₃ and a ₅ , the carrier signal fA ₅
is delayed by time Td ₁ from the input of set signal fA ₃ , and delayed by time Td ₂ from the end of set signal fA ₃ .
only to be delayed.

The aforementioned monostable multivibrator 12A _1,1
2B ₁ is provided to perform failure detection by covering the delay times Td ₁ and Td ₂ , and the time widths t ₁ and t ₂ of the timing pulses fA ₆ and fA ₇ are at least as long as the delay time Td _{1 .} , Td ₂ is selected.

Next, the operation of the above-mentioned failure detection circuit 12 will be explained.

First, when the carrier wave output sections 9, 10, and 11 are operating normally, they operate according to the time chart shown in FIG. That is, the level detection signal fA ₄ shown in FIG. 3 a ₃ is outputted from the modulation circuit 9 in response to the set signal fA 3 _shown in FIG. 3 a ₃ . If the states of the set signal fA ₃ and the level detection signal fA ₄ at this time are logic 1, then the AND gates 12A ₄ and 12B ₄
Since the input logic of includes (1, 0) or (0, 1), the AND gates 12A ₄ , 12B ₄
and the output of OR gate 12C become logic 0. Therefore, since the relay 12D is in a non-energized state and the contact 12D ₁ is closed, the carrier wave output of the modulation circuit 9 is guided to the coupler 3B ₂ through the contact 12D ₁ and taken into the transmission line 2B. It will be done.

On the other hand, in the case of a failure in which the carrier wave output is not output even after a certain period of time has passed since the transmission command was started, Fig. 4 a ₁ , a ₂
As shown in FIG. 3, even after a certain period of time has elapsed since the set signal fA ₁ serving as the transmission command becomes logic 1, the level detection signal fA ₄ remains at logic 0. Logic 1 obtained by negating the logic 1 set signal fA ₃ and the logic 0 level detection signal fA ₄ by the inverter 12A ₂ .
The signal is input to the AND gate _12A4 .
On the other hand, at the same time that the set signal _fA3 becomes logic 1, the monostable multivibrator _12A1 is triggered,
A timing pulse fA ₆ shown in FIG. 4 a ₃ is created. This timing pulse fA ₆ becomes logic 0 at the moment when time t ₁ has elapsed, is converted to logic 1 by inverter 12A ₃ , and is converted to logic 1 by AND gate 12A ₄ .
is input. As a result, at the trailing edge of the pulse where the timing pulse fA ₆ becomes logic 0, the AND gate 12
Since the input logic of _A4 is (1, 1, 1), its output is also logic 1, and the output of OR gate 12C is logic 1. Since the relay 12D is excited and self-held by this OR gate output of logic 1, its contact 12D ₁ becomes open circuit, and the terminal device 4
B is disconnected from the transmission line 2B.

Next, if a failure occurs in which the carrier wave output continues to be output even after a certain period of time has passed after the transmission command is completed, the set signal fA ₃ will be activated as shown in Figure 5 a ₁ and a ₂ . Even though it has become a logic 0, the level detection signal _fA4 has become a logic 1. Set signal fA ₃
At the same time that is reset to logic 0, the monostable multivibrator 12B ₁ is triggered via the inverter 12B ₂ to generate a timing pulse fA ₇ of time width t ₂ (FIG. 5a ₃ ). At the moment when the timing pulse _fA7 is reset after time _t2 , the input condition of the AND gate _12B4 becomes logic (1, 1, 1), so its output becomes logic 1, and the output of the OR gate 12C also becomes logic 1. The logic becomes 1.
As a result, relay 12D is energized and held,
The contact _12D1 becomes open, and the terminal device 4B is disconnected from the transmission line 2B. Therefore, if the carrier wave output units 9, 10, and 11 fail, continuous output of the carrier wave can be prevented and the information transmission system can be maintained in a normal state.

In the embodiment, the failure detection signal is used as a signal to separate the failed terminal device from the transmission line, but the usage is not limited to this, and it can also be used as a failure indication or alarm signal, for example. After the failure is recovered, the system can be reset by pressing the confirmation push button T or the like.

In addition, as shown in FIG. 6, multiple terminal devices 4
A ₁ and 4A ₂ , and at the same time disconnect the failed terminal device 4A ₁ from the line, disconnect the other normal terminal device 4
It is also possible to configure A ₂ to be connected to a line.

As explained in detail above, the present invention connects a plurality of terminal devices to a central device via a common transmission line,
An address signal assigned to each terminal device is transmitted from the central device to each terminal device in a time-division manner, and in response to a transmission command signal generated by the address signal, each terminal device transmits an address signal to the central device. In an information transmission device that transmits a modulated wave information signal using a carrier wave having a frequency common to terminal devices, each of the terminal devices transmits a carrier wave input from a carrier wave generation circuit to a modulation circuit in response to the transmission command signal. Since the device includes a failure detection circuit that detects the presence or absence of its own carrier wave output after a certain period of time has elapsed to reach a stable level and makes a failure determination, the following effects can be obtained.

(b) The failure detection circuit of each terminal device responds to the transmission command signal generated by the address signal given from the central device to each terminal device as a signal that determines when to start or end transmission, from the carrier wave generation circuit. After a certain period of time has elapsed for the carrier wave input to the modulation circuit to reach a stable level, the system detects the presence or absence of its own carrier wave output and makes a failure determination. It is possible to detect whether or not the system is operating normally when it should be terminated. Therefore, the reliability of failure detection is higher than that in which failure detection is performed during an idle period that is not related to data transmission.

(b) Detect circuit failures in which the carrier wave is not output even though there is a transmission command signal, and circuit failures in which the carrier wave is continuously output even though the transmission command signal has disappeared, and the transmission system is disrupted by the incorrect carrier wave output. can be prevented from occurring.

(c) Since failure detection is performed in the terminal device itself, countermeasures after the failure, such as disconnection and switching of a failed terminal device, can be easily realized using a simple and economical circuit.

(d) After a certain period of time has elapsed for the carrier wave input from the carrier wave generation circuit to the modulation circuit to reach a stable level in response to a transmission command signal, the circuit detects the presence or absence of its own carrier wave output to determine a failure;
Since failure detection can be performed when the signal is stable, reliability is high.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the general configuration of an information transmission device, FIG. 2 is a block diagram of an information transmission device according to the present invention, and FIGS. 3 a ₁ to a ₇ are time charts during normal operation. Figure 4 _a1 to _a3 are time charts for failures, Figures _a1 to _a3 are time charts for other failure types, and Figure 6 is a block diagram of another embodiment of the information transmission device according to the present invention. It is. 1...Central device, 2A, 2B...Transmission line, 3
A ₁ , 3A ₂ , 3B ₁ , 3B ₂ ...Coupler, 4A, 4B
...Terminal device, 12...Failure detection circuit.

Claims (1)

[Claims] 1. A plurality of terminal devices are connected to a central device through a common transmission line, and an address signal assigned to each terminal device is transmitted from the central device to each terminal device in a time-sharing manner. , an information transmission device that transmits a modulated wave information signal from each terminal device to a central device using a carrier wave having a frequency common to each terminal device in response to a transmission command signal generated by the address signal, the terminal device Each of the devices detects the presence or absence of its own carrier wave output after a certain period of time in which the carrier wave input from the carrier wave generation circuit to the modulation circuit reaches a stable level in response to the transmission command signal, and determines the failure. An information transmission device comprising a detection circuit. 2. The failure detection circuit is a circuit that detects the presence or absence of its own carrier wave output after a certain period of time has elapsed for the carrier wave to rise to a stable level from the start of the transmission command signal. The information transmission device described in Section 1. 3. Claims characterized in that the failure detection circuit is a circuit that detects the presence or absence of its own carrier wave output after a certain period of time has elapsed since the end of the transmission command signal and the level of the carrier wave has decreased to a stable level. The information transmission device according to item 1 or 2.