JPH0219481B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a triplex signal transmission circuit configured to improve reliability of signal transmission.

As shown in Figure 1, conventional triplex transmission operates three circuits in parallel, A signal transmission circuit 10, B signal transmission circuit 20, and C signal transmission circuit 30, each having the same function, and attenuates the output of each circuit. Vessel 11,2
After attenuating to 1/3 by 1 and 31, the adder 2 adds the signal and transmits it to the equipment as the final output signal 3. In this method, if one of the three circuits fails, the final output signal 3 is attenuated. The impact is 1/3, which reduces the impact of the failure, but it cannot eliminate the impact.

The present invention secures the transmission circuit output that is always operating normally without affecting the final output 3 as the final output even if one of the triplex transmission circuits fails, and furthermore, the final output 3 An object of the present invention is to provide a triplex transmission circuit in which a faulty circuit can be repaired without causing any adverse effects.

The present invention focuses on the fact that even if a failure occurs among the three circuits that have the same transmission function, the remaining two circuits remain intact. Always select the highest and lowest values for the outputs a, b, and c, which are a combination of two signals added with a gain of 1/2, so that one of the three signals A, B, and C is on the output high side. By transmitting the minimum value when a failure occurs, and transmitting the maximum value when a failure occurs on the low output side, the final output will not be affected by a failure in one system of the triplex system, and normal signal transmission can be maintained. Furthermore, it is possible to repair a faulty part without affecting the final output while continuing to transmit a normal signal.

FIG. 2 is an embodiment of the present invention.

When transmitting the signal from the detector 1 to the equipment as the output signal 3, a triple system transmission circuit was used to improve the reliability of the transmission circuit, and the output of the A signal transmission circuit 10 was multiplied by 1/2 by the attenuator 11. Let the signal be A, and similarly B,
C signal is output from each transmission circuit, and each signal A, B,
C is combined and added by adders 12, 22, and 32 to calculate a=C+A b=A+B c=B+C.

The a, b, and c signals are input to a high value selection circuit 51 and a low value selection circuit 52.

On the other hand, the deviation detector 53 calculates δ ₁ =2c−a−b, and the deviation detector 56 calculates δ ₂ =a−b.

When each transmission circuit has no failure and is operating normally, A=B=C and a=b=c. A=
B=C1/2a=1/2b=1/2c and a, b, c
Any one of these signals can be used as the final output signal 3 and is a normal output signal.

For example, if the B signal transmission circuit 20 or the attenuator 21 fails, the signal B becomes the normal signal A ₀ , C ₀ (However, A ₀ = C ₀ )
When outputting higher signal B _H , signal b, signal c
Both are higher than the normal output a ₀ where a ₀ = C ₀ + A ₀ ,
Abnormal outputs b _H and c H are output such that b _H = A ₀ + B _H , c _H = B _{H +} C ₀ . If a failure occurs in the direction of outputting a signal B _L lower than the normal signals A ₀ and C ₀ (A ₀ = C ₀ ), the signals b and c will become lower than the normal output a ₀ where a ₀ = C ₀ + A ₀ . b _L = A ₀ + B _L , c _L = B _L + C ₀ output b _L ,
c Output _L.

At this time, the output a of the adder 12 is not affected by the failure signal B and outputs a normal signal _a0 .

When a failure occurs on the B _H side, the signal of δ ₁ becomes the H side output, and the polarity discriminator 54 outputs the signal to the signal switch 55.
turns on. Incidentally, the polarity discriminator 54 calculates that δ ₁ =2c−
When a-b is positive, an ON command is generated, and when negative, an OFF command is generated. Further, the signal of δ ₂ becomes an output on the L side, and the signal switchers 58 and 59 are turned on by the equivalence discriminator 57. Note that the equivalence discriminator 56 determines whether δ ₁ =a−b is within a tolerance value or not, and if it is outside the tolerance value, it issues an ON command, and if it is within the tolerance value, it issues an OFF command. The tolerance value is a standard value for determining whether or not a=b is actually recognized, and if it is within the tolerance value, a and b are considered to be equivalent.

By selecting signals in this manner, when a failure occurs on the _BH side, the output of the low value selector 52 is transmitted as the output signal 3. Low value selector 52 at this time
Outputs a0, which is the lowest value among the three signals _a0 , _bH , and _cH , and transmits the normal signal _a0 , _{where a0} = _C0 + _A0 , as output signal 3. be.

Similarly, when a failure occurs on the B _L side, the signal switch 55 is turned OFF, the signal switch 58 and 59 are turned ON, and the output a ₀ of the high value selector 51 is output as the output signal 3. .

Even in the case of a failure in the C signal transmission circuit, the signal switch operates in the same way as in the case of the B signal transmission circuit, and always outputs a normal signal.

In the case of a failure in the A signal transmission circuit, if there is a failure on the A _H side, the signal switch 55 is turned off, the signal switchers 58 and 59 are turned off, and the output c ₀ of the low value selection circuit 52 is output as the output signal 3. transmitted. similarly
When there is a failure on the A _L side, the signal switch 55 is turned ON and the output c ₀ of the high value selection circuit 51 is transmitted as the output signal 3.

The polarity discriminator 54 turns on the signal switch 55 if the input signal δ ₁ is δ ₀ >0, and turns it off if δ ₁ <0. The equivalence discriminator 57 receives the input signal δ ₂
If δ ₂ >0 or δ ₂ <0, the signal switch 58,
59 is turned on and turned off when δ ₂ =0.
Incidentally, in reality, a permissible value for δ ₂ is taken into consideration. Second
See figures and their explanations. The same applies to δ ₁ .

Note that the equivalence discriminator 54 and the polarity discriminator 57
In order to prevent chattering near zero input signal, a hysteresis or dead zone shall be provided within a range that does not cause any system problems.

The alarm detector 60 turns on when δ ₁ >0 or δ ₁ <0,
It sends out an alarm, and when a failure occurs in any one of the triplex transmission circuits, it sends out an alarm without affecting the transmission signal.

The alarm allows the faulty circuit to be investigated and the faulty part to be repaired without stopping the output signal 3, thereby improving the reliability of the system.

Figure 3 shows the signal states of the adder outputs a, b, and c and the deviation detector outputs δ ₁ and δ ₂ in response to a fault state in each transmission circuit, and the output signal 3 at the time of a fault. 2 is a diagram showing whether the signal to be transmitted as a high value selector output (HVG) or a low value selector output (LVG) is a signal to be transmitted as a high value selector output (HVG) or a low value selector output (LVG). In the figure, A _H = Output when signal A fails to high (H) side A _L = Signal A goes to low (L) side B _H = Signal B goes to high (H) side B _L = Signal B is on the low (L) side 〃 C _H = Signal C is on the high (H) side 〃 C _L = Signal C is on the low (L) side 〃 a ₀ , b ₀ , c ₀ = Normal signals .

For convenience of explanation, the above explanation is based on the signal switching device 5.
Although the explanation has been made using three switchers 5, 58, and 59, the digital outputs of the discriminators 54 and 57 are logically operated,
Use only one signal switch. Alternatively, it is also within the scope of the present invention to switch the signal using an analog switch.

The present invention can also be applied to a system using three detectors 1 to form an independent triplex system.

According to the present invention, in the triplex transmission circuit,
Even if a failure occurs in one of the transmission circuits, the signal from the failed transmission circuit is removed and the output from the remaining two healthy transmission circuits is averaged and output, so a more normal signal can always be transmitted to the system. Furthermore, a failure in the transmission circuit can be repaired without stopping the system, and highly reliable transmission can be realized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional triplex transmission circuit, FIG. 2 is a configuration diagram of a triplex transmission circuit showing an embodiment of the present invention, and FIG. 3 is an operation explanatory diagram showing the operational logic of the present invention. be. 1...Detector, 3...Output signal, 10...A signal transmission circuit, 20...B signal transmission circuit, 30...
C signal transmission circuit, 11, 21, 31...attenuator,
12, 22, 32... Adder, 13, 23, 33
...Amplifier, 51...High value selector, 52...Low value selector, 53, 56...Difference detector, 54...Polarity discriminator, 57...Equivalence discriminator, 55, 58,
59... Signal switch, 60... Alarm detector.

Claims (1)

[Claims] 1. In order to improve the reliability of a signal transmission circuit that calculates and transmits signals, three signal transmission circuits having the same function are always operated in parallel, and one of the outputs of the three signal transmission circuits is In a triplex signal transmission circuit that outputs the final output of a healthy circuit, signals A, B, and C are obtained by multiplying the three signals that are the output of each transmission circuit by 1/2.
, an adder group that adds two signals among the signals A, B, and C in each combination, and a high value selection circuit that selects the maximum signal among the signals a, b, and c that are outputs of the adder group. a low value selection circuit that selects the minimum value among the signals a, b, and c that are the outputs of the adder group; and a first deviation detector that obtains an output δ ₂ by subtracting the signal b from the signal a. , an equivalence discriminator that determines the equivalence of the signal a and the signal b based on whether the output δ ₂ is an allowable value near zero, and an output obtained by subtracting the signal a and the signal b from a signal twice as large as the signal c. a second deviation detector that obtains δ ₁ ; a polarity discriminator that determines the positive or negative polarity of the output δ ₁ ; and a polarity discriminator that determines whether the output δ ₁ is positive or negative; Generates the output of the high value selection circuit, generates the output of the low value selection circuit from the second output terminal, and selects the low value from the first output terminal if the output δ ₂ of the equivalence discriminator is within the tolerance value. a first selection means that generates an output of the circuit and an output of the high value selection circuit from a second output terminal; and if the output δ ₁ of the polarity discriminator is positive including the tolerance value, the first Select the signal on the second output terminal of the selection means, and if the output δ ₁ of the polarity discriminator is negative including the tolerance value, select the signal on the first output terminal of the first selection means. a triplex transmission circuit comprising: second selection means for selecting; 2. The triplex transmission circuit according to claim 1, which issues a failure warning or display when the signal δ ₂ exceeds a permissible value.