JPH11317665A - A/d converting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the indefinitness of a digital value which is caused by the failure of an A/D converting part, in addition to disconnection detection on an analog detection signal side. SOLUTION: An A/D converting part 4 performs conversion at a fixed timing obtained from a timer device 5. An operation and storage device 6 successively stores a digital signal value that is its output signal and also calculates the difference between a digital signal value stored the last time and a digital signal value of this time. A deciding device 8 decides whether the difference of the digital signal values is within the set values stored in a setting device 7 with high accuracy in addition to whether the digital value of an analog signal is within an operation area. Thus, an A/D converting device which is highly safe can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an A / D converter for converting an analog signal into a digital signal.

[0002]

2. Description of the Related Art Conventionally, in order to prevent a Hi failure or an LO failure in an analog signal side circuit, an A / D converter normally uses (power supply voltage-α) when the analog signal side circuit is operating normally. And (ground + β), and safety measures were taken to confirm that the A / D conversion result was between α and β.

FIG. 2 shows the configuration of a conventional A / D converter. Reference numeral 1 denotes an A / D converter, which receives an analog value and outputs it as a digital value to the next stage. 2 is a digital reference voltage device. (Power supply voltage) to (power supply voltage-
α) and a constant region from (ground voltage) to (ground voltage + β) as abnormal regions.
The values obtained by converting the above-described values into digital values in advance are stored, with the range between .alpha. Reference numeral 3 denotes a determination device that compares the output of the A / D converter 1 with the reference value of the digital reference voltage device 2.

When the output value of the A / D converter 1 is in the operating range, the output of the A / D converter 1 is output to the next stage. ing.
As described above, in this A / D converter, the region where the circuit on the analog signal side operates normally and the abnormal region at the time of circuit failure are obtained in advance. Then, the area is stored in the digital reference voltage device 2 as a digital value.
Abnormalities on the analog signal side were detected by comparing the values with the determination device 3 based on the values.

[0005]

However, in the above configuration, the digital value becomes indeterminate due to a failure of the A / D converter 1 or a disconnection between the A / D converter 1 and the judging device 3 connected thereto. If the value falls within the operation area stored in the digital reference voltage device 2, there is a problem that analog signal abnormality cannot be detected in a wide area where an analog signal is to be detected.

[0006]

In order to solve this problem, the present invention provides a digital signal output from an A / D converter at a constant timing obtained by a timer device in addition to a conventional A / D converter. The value is sequentially stored, and the determination device determines whether the calculation result of the calculation / storage device for calculating the difference from the previously stored digital signal value falls within the set value previously stored in the setting device. It is what was constituted.

According to the above invention, it is determined whether or not the change in the analog detection signal is within an expected value.
An indefinite digital value caused by a failure of the D conversion unit, a disconnection between the A / D conversion unit 1 and the determination device 3, and the like can be detected with high accuracy in a region where an analog signal is detected.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, an A / D converter and this A / D converter are operated at set time intervals to convert an analog detection signal into a digital signal. A timer device for giving timing to perform
Each time a digital signal is output from the A / D converter, the value is stored, and the difference between the previously stored digital signal value and the current digital signal value is determined. Connected to this arithmetic and storage device, and stores the difference between the output and the analog detection signal that cannot be changed within the set time of the timer device in advance as a digital value as a set value If the output of the arithmetic and storage device is within the set value, the current digital signal value in the arithmetic and storage device is sent to the next stage.
In addition, a determination device that outputs an abnormal signal to the next stage when the value is larger than the set value is provided.

A digital signal value output from the A / D converter is stored at a constant timing obtained by the timer device, and a difference between the digital signal value and the previous stored digital signal value is calculated. The determination device determines whether or not the calculation result falls within a set value stored in the setting device in advance. As a result, it is determined whether the change in the analog detection signal is within the expected value.
A failure of the A / D converter and an indefinite digital value caused by a disconnection between the A / D converter and the determination device can be detected with high accuracy in a region where an analog signal is detected. Further, by setting the set value in the setting device small, the accuracy is improved.

According to the present invention, the failure of the A / D converter and the disconnection between the A / D converter and the determination device are determined by the determination device receiving the calculation result of the calculation / storage device deviating from the set value. Then, an undefined state of the digital signal can be detected, and the undefined operation can be prevented by stopping the operation of the apparatus.

[0011] The invention described in claim 2 of the present invention provides:
The output of the arithmetic and storage device is compared with the set value in the setting device. If the output of the arithmetic and storage device is within the set value, the current digital value in the arithmetic and storage device is set to the next stage and is larger than the set value. In this case, the previous digital signal value in the arithmetic and storage unit is replaced with the current digital signal value, and the previous digital signal value is output to the next stage. It has a determination device for outputting to a stage.

An abnormality is not determined unless the determination device that has received the output of the arithmetic and storage device repeats the determination larger than the set value in the setting device n times. This makes it possible to ignore superposition of external noise on the analog detection signal and one-time malfunction of each device due to the external noise, and obtain a device that is hardly affected by disturbance.

Further, according to a third aspect of the present invention, a value is selected based on the previous digital signal value of the arithmetic / storage device from the set values in the setting device set in advance in multiple stages, and the determination is made. It has a determination device to be used.

[0014] Even when the change of the analog detection signal greatly differs in a region where the signal value takes, the judging device keeps the setting device based on the previous digital signal value stored in the arithmetic and storage device. Since the set values set in multiple stages are selected and used for the determination, the set values can be determined to be small. This makes it possible to detect digital signal indefiniteness in a region where an analog signal is detected with higher accuracy.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows the configuration of an A / D converter according to the present invention. In FIG. 1, the A / D converter 4 outputs from the A / D converter 4 at a constant timing obtained by the timer device 5. The arithmetic and storage device 6 sequentially stores the digital signal value as the output signal,
Further, the difference between the digital signal value stored last time and the digital signal value this time is obtained. The determination device 8 determines whether the calculation result from the calculation / storage device 6 falls within a set value stored in the setting device 7 in advance.

The operation of the A / D converter configured as described above will be described. The A / D converter 4 performs the same operation as the conventional A / D converter. The A / D converter 4 has a value that is sufficiently short compared to the change in the analog detection signal obtained by the timer device 5 (for example, when the change in room temperature is used as the analog detection signal, about 0.1 second to about 0.1 second). At a fixed timing of (01 seconds), the signal is converted into a digital signal value corresponding to the above-described analog detection signal value and output to the next stage. Each time this signal is received, the arithmetic / storage device 6 stores the signal sequentially.

Further, a difference between the digital signal value stored last time (one time before this time stored) and the digital signal value this time is calculated and obtained. The setting device 7 has a digital value representing the difference between the analog detection signal values that cannot be changed during a certain period of time from the timer device 5 (for example, if the change in room temperature is an analog detection signal, the timer device 5 If the timing is 0.1 to 0.01 seconds, there is always only a change of 1 K or less, taking into account the 1 K with a margin, converting the obtained difference between the analog detection signal values of about 1 to 3 K into a digital value and setting it. Value.

However, the degree of accuracy is determined by the above-mentioned margin, so it is necessary to consider the required accuracy of the analog signal to be detected.) Is stored as a set value. The judging device 8 compares the operation result from the operation / storage device 6 with the set value, and if the operation result is within the set value, the operation
The current digital signal value in the storage device 6 is output to the next stage. If it is not, an error message is output to the next stage. By the way, in the first judgment of the judging device 6, since the previous digital signal value of the arithmetic / storage device 6 is not used as data, a correct operation result cannot be obtained.

As a result, in addition to the conventional failure detection of the analog signal side circuit, the failure of the A / D converter 4 and the A / D conversion
Disconnection between the analog detection signals connected to the conversion unit 4 and A /
Indefinite detection of a digital value caused by a disconnection or the like between the arithmetic / storage device 6 connected to the D conversion unit 4 becomes possible.

[0021]

As described above, according to the present invention, the failure of the A / D converter, the disconnection between the A / D converter and the analog detection signal, the A / D converter and the arithmetic storage device, which could not be detected conventionally, can be obtained. Indefinite detection of digital value caused by disconnection between
At the time of indefinite detection, measures such as stopping the operation of the system can be taken. Therefore, an effective effect of achieving a more secure A / D converter can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an A / D converter according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional A / D converter.

[Explanation of symbols]

 4 A / D conversion unit 5 Timer device 6 Arithmetic / storage device 7 Setting device 8 Judgment device

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuhiro Okada 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] An A / D converter, a timer device for operating the A / D converter for each set time, and providing a timing for converting a detection signal on the analog side into a digital signal;
Each time a digital signal is output from the A / D converter, the value is stored, and the value of the previously stored digital signal is compared with the current digital signal value. A calculation / storage device for obtaining the difference and outputting it to the next stage, and connected to this calculation / storage device, the difference between the output and the analog detection signal which cannot be changed in advance within the set time of the timer device is converted into a digital value. The value is compared with a value stored as a set value, and when the output of the arithmetic / storage device is within the set value, the digital signal value of the current time in the arithmetic / storage device is output to the next stage, and is larger than the set value. A / D equipped with a determination device that outputs an abnormal signal to the next stage
Conversion device. 2. An A / D converter, a timer device for operating the A / D converter for each set time, and providing a timing for converting a detection signal on the analog side into a digital signal.
Each time a digital signal is output from the A / D converter, the value is stored, and the value of the previously stored digital signal is compared with the current digital signal value. A calculation / storage device for obtaining the difference and outputting it to the next stage, and connected to this calculation / storage device, the difference between the output and the analog detection signal which cannot be changed in advance within the set time of the timer device is converted into a digital value. The value is compared with a value stored as a set value, and if the output of the arithmetic / storage device is within the set value, the digital signal value in the arithmetic / memory device is set to the next stage. ,
The previous digital signal value in the arithmetic and storage device is replaced with the current digital signal value, and the previous digital signal value is output to the next stage. An A / D converter having a determination device for outputting to a stage. 3. An A / D converter, a timer device for operating the A / D converter for each set time and providing timing for converting an analog detection signal into a digital signal.
Each time a digital signal is output from the A / D converter, the value is stored, and the value of the previously stored digital signal is compared with the current digital signal value. A calculation / storage device for obtaining the difference and outputting it to the next stage, and connected to this calculation / storage device, the difference between the output and the analog detection signal which cannot be changed in advance within the set time of the timer device is converted into a digital value. The value is compared with one of the values stored as a set value in multiple stages, and if the output of the arithmetic and storage device is within the set value, the current digital signal value in the arithmetic and storage device is output to the next stage. If the set value is larger than the set value, an abnormal signal is output to the next stage, and the set value in the set device which has been set in multiple stages in advance is selected based on the previous digital value of the operation / storage device and used for determination. A / D converter having a constant device.