JPH11153653A - Digital circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a digital circuit provided with a function detecting abnormality, by detecting the abnormality from either one of comparison between an output logical value estimated from input value and the output logical value of result of logic operation or comparison between the values before and after transmitting signals of a first value and a second value. SOLUTION: Signal is inputted in a signal input part 20 and transmitted to a logic circuit 30 and a logic value estimation part 60. The result operated in the logic circuit 30 is transmitted to an amplifying part 40 and judging part 70. Amplified signal is transmitted to a signal output part 50 and output outside. The operation results of a logic circuit 30 is estimated in the logic value estimation part and transmitted to the judgment part 70. In the judging part, the signal from the estimation part 60 is compared with the signal from the logic circuit 30 to inspect and judge abnormality and the results are transmitted to an internal direction information output part 80 and an information acquisition part 100. In parallel, the signal from the amplifier 40 is compared with the signal from the logic circuit 30 in the judgment part 70 to inspect and judge abnormality, which is similarly outputted. The signal transmitted to the acquisition part 100 is logically summed with alarm information from an external alarm input part 90 and transmitted to a collected alarm output part 110.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a first value and a second value.
The present invention relates to a signal value of a digital circuit that transmits information by a binary signal based on the above value, and more particularly to detection of an abnormality in an output value.

[0002]

2. Description of the Related Art A digital circuit transmits information by performing processing using a binary signal having a first value and a second value (0 and 1, or L and H).

As an example, a TTL-IC (hereinafter simply referred to as a digital IC) which is a general digital circuit has a configuration as shown in FIG. 8, and a logic result of a logic circuit based on an input value is obtained. Was amplified and output. In a general digital IC, the waveform of a signal to be transmitted or received is basically configured to be a square pulse wave as shown in FIG.

The output value of the digital signal on the transmitting side is:
Generally, it is determined as a relationship in which a noise margin (noise margin) is considered in addition to a value by which a binary value can be identified on the receiving side.

In general, a digital IC has a digital signal whose shape is equal to or more than a minimum input value (VIH) of logic "1" as shown in FIG. 7A and a maximum input value (VIH) of logic "0". By securing a value equal to or less than (VIL), the receiving side can correctly judge the binary value.

[0006] To ensure the above conditions, a digital IC
Outputs a value equal to or greater than the output minimum value (VOH) of logic "1" and a value equal to or less than the output maximum value (VOL) of logic "0".

If it is impossible to secure a value not less than the input minimum value (VIH) of logic "1" and not more than the input maximum value (VIL) of logic "0", the receiving side cannot correctly judge the binary value. The possibility of transmission errors increases.

[0008]

Generally, an electronic device includes:
It consists of a number of functional parts, which are composed of a plurality of circuits, which are further composed of a plurality of digital ICs,
It consists of C and various parts.

[0009] If the digital IC itself in the electronic device breaks down, the logical operation based on the input signal becomes incorrect and an erroneous operation result is output. The digital circuit receiving the erroneous output signal converts the received signal irrespective of the failure of the digital IC,
The processing of the received digital circuit itself is processed normally and output with a normal signal value.

Similarly, when the element connected to the output of the digital IC is out of order and the input impedance of the element is reduced due to a failure, the output of the logic "1" should be output.
If the output value of the logic "1" falls below the minimum output value (VHL), or if the current connected to the output of the digital IC exceeds the fan-out capacity of the output section due to a failure. Then, a current exceeding the rating of the output section of the digital IC flows to the output section, and the output of the logic "0" should be output, but the output maximum value (VOL) of the logic "0" may be exceeded. It is conceivable that a signal transmission error may occur. This is similar to the occurrence of a signal transmission error, and the problem is more serious.

As described above, even if one digital IC in the digital circuit fails, the next digital IC that receives a signal from the failed digital IC outputs erroneous information with a correct output value. Therefore, in order to find a faulty part, it is necessary to reach a place where the logic is wrong while ticking whether the logical value is correct or not. Therefore, in order to limit the defective portion, there is a problem that the digital circuit cannot be repaired without being familiar with the logic of the entire digital circuit.

Further, when the difficulty level of the logic of the whole digital circuit is more difficult,
It takes more time to find the fault location,
The problem is even more acute with the future trend of technological progress. The present invention has been made in view of the above technical problem, and has as its object to realize a digital circuit having a function of detecting an abnormality in a signal value when a digital signal is transmitted.

[0013]

SUMMARY OF THE INVENTION The present invention is a digital circuit having a function of detecting an abnormal signal value when transmitting a digital signal. The details are described below.

(1) An invention according to claim 1 is a digital circuit for transmitting information by a binary signal having different first and second values, wherein an output is estimated from an input value. Comparing a logical value with an output logical value that is a result of a logical operation, or comparing values before and after transmission when transmitting a binary signal based on the first value and the second value; Detecting means for detecting an abnormality by at least one of the following; an external input means for inputting detection information for detecting and informing whether the other digital circuit is normal or abnormal; information input by the external input means; A digital circuit comprising: a collecting unit that generates collected information together with information; and a notifying unit that notifies the collected information generated by the collecting unit to the outside. In this digital circuit, the detection means
Abnormality is detected by comparing the output logical value estimated from the input value with the actual logical circuit operation result value,
Further, "an abnormality in the signal value is detected by detecting a range in which the first value and the second value cannot be distinguished from each other. Further, in this digital circuit, an abnormality in the signal transmission is detected by the detecting means. It is possible to specify a defective portion by detecting the abnormality and notifying the external abnormality together with the detected internal abnormality and the external abnormality. "The range that cannot be distinguished from the value of 2"
It means between the input maximum value of logic "0" and the input minimum value of logic "1".

(2) The invention according to claim 2 is a digital circuit for transmitting information by a binary signal having different first values and second values, wherein the first value and the second value are transmitted. And a detection means for detecting an abnormality by comparing values before and after transmission when transmitting a binary signal based on the value of the digital signal, and an external input for detecting and informing whether another digital circuit is normal or abnormal. An input unit, a collecting unit that generates collected information in combination with the information input by the external input unit and the information of the detecting unit, and a notifying unit that notifies the collected information generated by the collecting unit to the outside, It is a digital circuit provided. In this digital circuit, the detecting means “detects an indistinguishable range between the first value and the second value,
Detects abnormal signal values. Further, in this digital circuit, the detecting means detects an abnormality at the time of transmitting a signal, and notifies the external together with the internal abnormality detected in this way and the external abnormality, thereby specifying a defective portion. It becomes possible.

According to a third aspect of the present invention, there is provided a digital circuit for transmitting information by a binary signal having different first values and second values, wherein the output is estimated from an input value. Comparing a logical value with an output logical value that is a result of a logical operation, or comparing values before and after transmission when transmitting a binary signal based on the first value and the second value; A digital circuit comprising: detecting means for detecting an abnormality by at least one of the following; and notifying means for notifying the information detected by the detecting means to the outside. In this digital circuit, the detecting means detects an abnormality by comparing the output logical value estimated from the input value with the value of the operation result of the actual logical circuit, and further detects "the first value and the second value". By detecting a range in which the signal value cannot be distinguished from the signal value, an abnormality in the signal value is detected.

According to a fourth aspect of the present invention, there is provided a digital circuit for transmitting information by a binary signal having different first values and second values, wherein the first value and the second value are transmitted. Detecting means for detecting an abnormality by comparing the value before and after the transmission of a binary signal by the value of the detection signal, and a notification means for notifying the information detected by the detection means to the outside, Digital circuit. In this digital circuit, the detecting means detects an abnormality in the signal value by detecting a range in which the first value and the second value cannot be distinguished.

(5) The invention according to claim 5 is to compare an output logical value estimated from an input value with an output logical value as a result of a logical operation, or to compare the first logical value with the second logical value. Comparing the values before and after the transmission of the binary signal by the value of the detection means for detecting an abnormality by at least one of the above, and external input means for inputting an abnormality detection result of another digital circuit, A digital circuit comprising: a collecting unit that generates collected information in accordance with the input information from the external input unit and the information of the detecting unit; and a notifying unit that notifies the collected information generated by the collecting unit to the outside. A digital circuit, wherein a plurality of digital circuits are connected to each other and transmit an abnormality detection result in accordance with the transmission of binary signals based on different first and second values. A. According to the present invention, an abnormal result is transmitted along with the transmission of information by a binary signal between a plurality of digital circuits, thereby easily detecting an abnormal result in a group of circuits that are connected to each other and perform a series of operations. Will be able to

[0019]

Embodiments of the present invention will be described below in detail. <First Embodiment> FIG. 1 is a functional block diagram showing an overall electrical schematic configuration of a digital circuit according to a first embodiment of the present invention. The digital circuit according to the embodiment shown in FIG. 1 includes a signal input section 20, a logic circuit 30,
Signal processing system 10 including amplifying unit 40 and signal output unit 50
A logical value estimating unit 60, a determining unit 70, an internal detection information output unit 80, an external alarm input unit 90, and an alarm collecting unit 10.
0 and a collection alarm output unit 110.

In such a configuration, the signal input unit 20
Is connected to the logic value estimating unit 60 at the same time as the output is connected to the logic circuit 30, and transmits an external input signal to the logic circuit 30 and the logic value estimating unit 60.

The logic circuit 30 is interposed between the signal input unit 20 and the amplifying unit 40 and the discriminating unit 70.
And performs an operation in accordance with the determined logic on the basis of the signal transmitted from the controller 40, and transmits the result to the amplifier 40 and the determination unit 70.

The amplifying section 40 is interposed between the logic circuit 30 and the signal output section 50 and between the logic section 30 and the discriminating section 70.
, And transmits the amplified signal to the signal output unit 50 and the determination unit 70.

The signal output section 50 is connected to the amplification section 40 and outputs a signal transmitted from the amplification section 40 to the outside.
In addition, the above-mentioned input unit 20 to logic circuit 30 to amplification unit 40 to
The output unit 50 constitutes the signal processing system 10 and executes the same signal processing as in the related art.

The logical value estimating unit 60 is interposed between the signal input unit 20 and the discriminating unit 70, and performs an operation according to a predetermined logic based on a signal transmitted from the signal input unit 20, and performs an operation of the logical circuit 30. The result is estimated, and the result is transmitted to the determination unit 70. The operation of the logical value estimating unit 60 may be exactly the same as that of the logical circuit 30, or may be such that only the result is obtained mathematically.

The discriminating section 70 is interposed between the logical value estimating section 60 and the logic circuit 30 and the amplifier circuit 40, and between the internal detection information output section 80 and the alarm collecting section 100.
0 and whether the signal is normal or abnormal based on the information of the logic circuit 30 and the amplifier 40, and as a result (in the case of an abnormality,
Alarm) to the internal detection information output unit 80 and the alarm collection unit 100
And transmitted to.

The internal detection information output section 80 is connected to the output of the discriminating section 70 and outputs the discrimination result transmitted from the discriminating section 70 to the outside.

The external alarm input unit 90 includes an alarm collection unit 100
And receives an alarm signal from the connected external device and transmits it to the alarm collection unit 100.

The alarm collecting unit 100 is interposed between the discriminating unit 70 and the external alarm input unit 90, and the collection alarm output unit 110, and adds signals transmitted from the discriminating unit 70 and the external alarm input unit 90. , Collecting the result, and outputting the alert
Transmit to That is, when an alarm is input from either one, the alarm is collected and transmitted to the collection alarm output unit.

The collection / alarm output section 110 is provided for the alarm collection section 10.
0, and outputs a signal transmitted from the alarm collection unit 100 to an external device.

The processing system of the signal input unit 20, the logic circuit 30, the amplifying unit 40, and the signal output unit 50 is a conventional general digital circuit. Further, here, the logical value estimating unit 60 and the determining unit 70 constitute a detecting unit of the claims. The internal detection information output unit 80
Both or one of the collection alarm output unit 110 constitutes a notification unit.

FIG. 2 is a flowchart showing the operation of the digital circuit constructed as described above.
The details will be described below with reference to FIGS.

An external signal is input to the signal input unit 20 (S11 in FIG. 2) and transmitted to the logic circuit 30 and the logic value estimating unit 60.

An operation is performed according to a predetermined logic based on the signal transmitted to the logic circuit 30 (S1 in FIG. 2).
2), the result is transmitted to the amplification unit 40 and the determination unit 70.

The signal transmitted to the amplifier 40 is amplified (S15 in FIG. 2) and transmitted to the signal output unit 50. And
The signal transmitted to the signal output unit 50 is output to the outside.

The signal transmitted to the logical value estimating unit 60 is subjected to logical value estimation for estimating the operation result of the logical circuit 30 (S13 in FIG. 2), and is transmitted to the determining unit 70. The operation of the logic value estimating unit 60 is exactly the same as that of the logic circuit 30, or is such that only the result is obtained mathematically. The result of the estimation matches the result of the logic circuit 30 in the case of normal operation.

Here, the logical value estimating unit 60 to the discriminating unit 70
The signal transmitted from the logic circuit 30 and the signal transmitted from the logic circuit 30 to the determination unit 70 are compared by the determination unit 70 to check for an abnormality.
A determination is made (S14 in FIG. 2), and the result is transmitted to the internal detection information output unit 80 and the alarm collection unit 100.

In parallel with this, the discriminator 70 compares the output signal of the logic circuit 30 transmitted from the logic circuit 30 to the discriminator 70 with the signal transmitted from the amplifier 40 to the discriminator 70. Inspection and discrimination of abnormalities (S1 in FIG. 2)
6) The result is transmitted to the internal detection information output unit 80 and the alarm collection unit 100. Specifically, when the amplification unit 40 itself is abnormal, the logic circuit 30 which is the input signal of the amplification unit is used.
Is compared with the output signal of the amplifying unit 40, which is the amplified signal, to determine abnormality.

Similarly, when the element connected to the output of the digital IC fails, for example, when the input impedance of the element decreases due to the failure of the element connected to the output of the digital IC, the logic circuit Although the logic 30 outputs a value of logic "1", the output of the amplifying unit 40 has a minimum output value of logic "1" (VH) due to the influence of the failed element connected to the output of the digital IC.
L) and determine that an abnormality is detected.

Similarly, when an element connected to the output of the digital IC fails and a current exceeding the fan-out capacity of the output section flows, the logic circuit 30 outputs a logic "0" value. However, in the output of the amplifier 40, a current exceeding the rating of the output section of the digital IC flows to the output section, and the voltage drop due to the product of the internal resistance of the output section and the current exceeding the rating of the output section is logic "0". It is determined that the output exceeds the maximum output value (VOL), and an abnormality is detected.

Then, the signal transmitted to the internal detection information output section 80 is output to the outside. That is, the determination unit 70
If any abnormality is detected in step (1), internal detection information as an alarm is output to the outside (S17 in FIG. 2). If no abnormality is detected, no alarm is output.

The signal transmitted to the alarm collection unit 100 is logically ORed with external alarm information from the external alarm input unit 90 (S22 in FIG. 2) and transmitted to the collection alarm output unit 110. Then, the signal transmitted to the collection alarm output unit 110 is output to the outside (S23 in FIG. 2). That is, when an abnormality is detected inside or outside, a collection alarm is output to the outside. If no abnormality is detected, no alarm is output.

By the above operation, whether the result of the logical operation based on the input value is normal or abnormal, or the element connected to the output of the digital IC fails and is connected to the output of the digital IC. Therefore, it is possible to detect an abnormality due to the influence and to detect that the digital IC itself breaks down and output an erroneous calculation result, and can issue an alarm.

As a result, even if one digital IC in the digital circuit fails, the failed digital IC
Only by investigating the alarm issued from C, it is possible to find the fault location. Therefore, repair can be performed without being familiar with the logic of the entire digital circuit.

The output form of the alarm (notification form as the notification means) of the internal detection information output section 80 and the collection alarm output section 110 is not limited to an electric signal, but may be light, sound, heat, smoke, color,
It may be smell, mechanical vibration, electromagnetic wave or the like. Therefore, various output means (emission means, buzzer, actuator, oscillation means, etc.) for issuing such various alarms may be provided.

<Second Embodiment> FIG. 3 is a block diagram showing the configuration of a digital circuit according to a second embodiment of the present invention. In the digital circuit of FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.

The difference between the digital circuit of FIG. 3 and the embodiment of FIG. 1 is that the discriminator 70 compares only the values of the input and output of the amplifier 40 and detects an abnormality. is there. That is, at the same time as performing the abnormality determination on the amplified signal, the abnormality determination is performed on the abnormality connected to the output of the digital IC, and the result is transmitted to the internal detection information output unit 80 and the alarm collection unit 100.

The discrimination result transmitted to the internal detection information output section 80 is output to the outside. That is, the determination unit 7
If any abnormality is detected at 0, internal detection information as an alarm is output to the outside. If no abnormality is detected, no alarm is output.

The alarm collection unit 100 adds the signals transmitted from the discrimination unit 70 and the external alarm input unit 90, and transmits the result to the collection alarm output unit 110. That is, when an alarm is input from either one, the alarm is collected and transmitted to the collection alarm output unit. Therefore, according to this embodiment, an abnormality at the time of signal transmission is reliably detected, and a defective portion (in this case, the amplifier 40 and the digital
(The side connected to the output of C).

<Third Embodiment> FIG. 4 is a block diagram showing the configuration of a digital circuit according to a third embodiment of the present invention. In the digital circuit of FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.

The digital circuit of FIG. 4 differs from the embodiment of FIG. 1 in that the digital circuit of FIG. That is, abnormality determination is performed on the logical operation result and the amplified signal, and the result is transmitted to the internal detection information output unit 80.

The determination result transmitted to the internal detection information output unit 80 is output to the outside. That is, the determination unit 7
If any abnormality is detected at 0, internal detection information as an alarm is output to the outside. If no abnormality is detected, no alarm is output. Therefore, according to this embodiment, it is possible to reliably detect an abnormality in a logical operation and an abnormality in signal transmission, and to specify a defective portion.

<Fourth Embodiment> FIG. 5 is a block diagram showing the configuration of a digital circuit according to a fourth embodiment of the present invention. In the digital circuit of FIG. 5, the same components as those of FIG. 1 are denoted by the same reference numerals, and the duplicate description will be omitted.

The difference between the digital circuit of FIG. 5 and the embodiment of FIG. 1 is that the discriminator 70 compares only the values of the input and output of the amplifier 40 and detects an abnormality.
That is, the alarm collection unit 100 is not provided. That is, at the same time as performing abnormality determination on the amplified signal, abnormality determination is performed on the abnormality connected to the output of the digital IC, and the result is transmitted to the internal detection information output unit 80.

Then, the determination result transmitted to the internal detection information output section 80 is output to the outside. That is, the determination unit 7
If any abnormality is detected at 0, internal detection information as an alarm is output to the outside. If no abnormality is detected, no alarm is output. Therefore, according to this embodiment, it is possible to reliably detect an abnormality at the time of signal transmission and specify a defective portion (in this case, the side connected to the amplifier 40 and the output of the digital IC). Become.

<Fifth Embodiment> FIG. 6 is a block diagram showing a configuration of a digital circuit according to a fifth embodiment of the present invention. In the above description, the abnormality of the signal value is determined and detected on the output side. However, the detection location is not limited to the output side, and may be, for example, the input side. FIG. 6 shows an example in which an abnormality is determined and detected on the input side.

Specifically, it can be detected by determining whether the input signal value is in a range where the first value and the second value cannot be distinguished from each other. In other words, even if the value on the output side is in the range of the normal value, the value on the receiving side becomes the first value due to an increase in the contact resistance between the connectors due to aging due to intervening connectors during transmission. Even if the second value and the second value cannot be distinguished, the digital I
Due to the nature of C, the digital circuit to which it is input causes a transmission error and causes a wrong logic, but the input digital circuit outputs a normal signal value. Such an abnormality of the input signal can be detected and an alarm can be output.

<Other Embodiments> In each of the above embodiments, the digital circuit has been described alone, but the present invention can also be applied to a case where a plurality of digital circuits are arranged and connected. In other words, by transmitting an error detection result along with the transmission of information by a binary signal between a plurality of digital circuits, it is possible to easily detect an abnormal result in a group of circuits that are connected to each other and perform a series of operations. Will be able to

Further, if a control signal for switching between the active device and the standby device is used by using the alarm signal, for example, the switching between the active device and the standby device can be controlled by another electric circuit or software. This can be performed automatically only by an alarm signal without performing. However, a switching circuit is required.

As described above, since at least one of the internal detection information output unit 80 and the collection alarm output unit 110 constitutes a notifying means, the function of the present invention is provided if at least one is provided. Can be realized. Therefore, in each of the above embodiments, the configuration may be such that an alarm is output only from the collection alarm output unit 110 without providing the internal detection information output unit 80.

[0060]

As described above in detail with the embodiments, according to the inventions described in this specification, the following effects can be obtained.

The detection of whether the result of the logical operation based on the input value is normal or abnormal can cause the digital IC itself to fail and output an erroneous operation result.
If the element connected to the output of the digital IC breaks down and is connected to the output of the digital IC, it will detect an abnormality due to the effect, detect that the digital IC itself has failed and output an incorrect result, and An alarm such as detection can be issued.

As a result, even if one digital IC in the digital circuit fails, the failed digital IC
It is possible to quickly determine that an abnormality has occurred based on the alarm issued from C and minimize the damage.

Further, it is possible to find a faulty part only by investigating the alarm issued from the digital IC. Therefore, repair can be performed without being familiar with the logic of the entire digital circuit.

Further, for example, if a control signal for switching between an active device and a standby device is used by using an alarm signal, switching between the active device and the standby device can be controlled by another electric circuit or software. This can be performed automatically only by an alarm signal without performing. However, a switching circuit is required.

[0065]

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a configuration example of a digital circuit according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a schematic operation in the embodiment shown in FIG. 1;

FIG. 3 is a functional block diagram illustrating a configuration example of a digital circuit according to a second embodiment of the present invention.

FIG. 4 is a functional block diagram illustrating a configuration example of a digital circuit according to a third embodiment of the present invention.

FIG. 5 is a functional block diagram illustrating a configuration example of a digital circuit according to a fourth embodiment of the present invention.

FIG. 6 is a functional block diagram illustrating a configuration example of a digital circuit according to a fifth embodiment of the present invention.

FIG. 7 is a waveform diagram showing a signal waveform in a digital circuit.

FIG. 8 is a functional block diagram showing a configuration example of a conventional general digital circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Digital circuit (signal processing system) 20 Signal input part 30 Logic circuit 40 Amplification part 50 Signal output part 60 Logic value estimating part 70 Judgment part 80 Internal detection information output part 90 External alarm input part 100 Alarm collection part 110 Collection alarm output part

Claims (5)

[Claims] 1. A digital circuit for transmitting information by a binary signal having different first and second values, wherein the digital circuit is an output logical value estimated from an input value and a result of a logical operation. Detecting an abnormality by comparing at least one of an output logic value and a value before and after transmission when transmitting a binary signal based on the first value and the second value. Means, and external input means for inputting detection information for detecting and informing whether the other digital circuit is normal or abnormal, and collecting information is generated by combining the information input by the external input means with the information of the detection means. A digital circuit comprising: a collecting unit; and a notifying unit for notifying the collected information generated by the collecting unit to the outside. 2. A digital circuit for transmitting information by means of a binary signal having different first and second values, wherein the digital signal has a binary signal based on the first value and the second value. Detection means for detecting an abnormality by comparing values before and after transmission during transmission, external input means for detecting and informing whether or not another digital circuit is normal or abnormal; inputting detection information to the external input means; A digital circuit comprising: a collecting unit that generates collected information by combining the input information and the information of the detecting unit; and a notifying unit that notifies the collected information generated by the collecting unit to the outside. 3. A digital circuit for transmitting information by a binary signal having different first and second values, wherein the digital circuit is an output logical value estimated from an input value and a result of a logical operation. Detecting an abnormality by comparing at least one of an output logic value and a value before and after transmission of a binary signal based on the first value and the second value. And a notifying means for notifying the information detected by the detecting means to the outside. 4. A digital circuit for transmitting information by means of a binary signal having different first and second values, wherein a binary signal having said first value and second value is transmitted. A digital circuit comprising: detecting means for detecting an abnormality by comparing values before and after transmission when transmitting; and notifying means for notifying externally information detected by the detecting means. 5. A method for comparing an output logical value inferred from an input value with an output logical value that is a result of a logical operation, or converting a binary signal based on the first value and the second value. Comparing values before and after transmission when transmitting, detecting means for detecting an abnormality by at least one of the above, external input means for inputting an abnormality detection result of another digital circuit, and input information from the external input means. A plurality of digital circuits each including a collecting means for generating collected information in combination with the information of the detecting means, and a notifying means for notifying the collected information generated by the collecting means to the outside are connected, and the plurality of digital circuits are connected. A digital circuit for transmitting an abnormality detection result in accordance with the transmission of information by a binary signal including a first value and a second value that are different between the two.