JPS6226927A - Error check system of analog-digital conversion circuit - Google Patents

Abstract

PURPOSE:To decide surely the normality of the titled circuit by applying a reference voltage to an A/D conversion circuit inputting an analog signal from each sensor, comparing the reference voltage with a pre-stored data so as to discriminate a fault of the circuit. CONSTITUTION:Whether or not a check circuit is connected is judged and when not connected, an input value, a minimum value and a maximum value of each sensor at normal state are set to detect the fault of a sensor, and if sensor 1 is faulty, an alarm display output informing the fault is outputted to a display device 13 from a control section 12. When the check circuit is connected, the input value, maximum value and minimum value of the reference voltage at check are set and a reference signal given from a voltage Vcc via an analog IC1A is converted by an A/D conversion circuit 11. Whether or not an output from the circuit 11 is within a permissible range stored in the control section 12 is decided and when the output is at the outside of the range, alarm display is applied, and when within the range, it is discriminated as OK and the output from the next analog IC is checked. The operation above is repeated similarly.

Description

[Detailed description of the invention] (Technical field to which the invention pertains) This invention relates to an A for inputting analog values from a sensor.
This invention relates to an error checking method for a /D conversion circuit.

[Prior art and its problems]

FIG. 8 shows the abnormality detection circuit of each general sensor. ~． N is each sensor that detects an abnormality in the device, 1
1 is an A/D conversion circuit that inputs analog signals from each sensor and converts them into digital signals; 12 is a control section using a microcomputer; and the output of the A/D conversion circuit is input to this control section 12. 18 is a display device. In addition, 14
is a printed board on which an A/T) conversion circuit 11 and a control section 12 are attached.

In this configuration, sensors 1.2. ~． When there is an abnormal output from N, an analog signal is input to the A/D conversion circuit 11,
The control unit 12 converts this analog signal into a digital signal.
The control unit 12 outputs the data to the display device 18 depending on the content of the abnormality.

However, in the above-mentioned circuit, it is necessary to check the normality of the A/D conversion circuit, and conventionally, the input voltage and output value were compared manually to check for circuit abnormalities, which was difficult to do. It was inefficient and also lacked reliability.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a checking method for an analog input circuit that can reliably determine the normality of a circuit that inputs analog signals from each sensor. do.

[Key points of the invention]

This invention is an A
The normality of the circuit can be reliably determined by applying a reference voltage to the /D conversion circuit and comparing this reference m-pressure with pre-stored data to determine the abnormality of the circuit. It is.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, and the same reference numerals as in FIG. 8 indicate the same or similar parts.

A voltage VCC is applied to the input terminal of the circuit via a resistor 21. Also, the reference voltage for output and 17 is A, / I)
Output to the conversion circuit. Reference numeral 22 denotes a buffer, and based on the signal from this buffer 16, the control section 12 determines whether the A/D conversion circuit 11 is being checked or is in normal operation. In addition, the control unit 12 compares the reference voltage value with a voltage value preset in the control unit 12, and outputs an alarm if it is abnormal.

In this configuration, the operation will be explained in flowchart 1 of FIG.
・Explain while referring to.

In step 5iot, it is determined whether the check circuit is connected, and if it is not connected, the process advances to step 8202. In step 5202, the input value, minimum value, and maximum value of each sensor under normal conditions are set, and the process advances to step 8108. In step 810B, an abnormality in the sensor is detected, and if there is an abnormality in sensor l, the process advances to step 8808.
In this step 5808, the control unit 12 outputs an alarm display output to notify the abnormality to the display device 18.

After this, the same process as for sensor 1 is performed for each sensor, and when sensor N is completed in step ION, ill goes to the next step.

Next, in step 5101, it is determined whether the check circuit is connected, and if the check circuit is connected, the process advances to step 5102. In step 8102, the reference value signal given as the input value and maximum value of the reference voltage at the time of checking is converted by the A/D conversion circuit, and the output from this conversion circuit is stored in the control unit 12. It is determined whether it is within the range, and if it is outside the range 4f, the process proceeds to step 820B, where an alarm is displayed, and if it is within the range, it is determined as OK and the process proceeds to the next step, where the output from the next analog IC is checked.

Thereafter, the same operations as described above are repeated to check for abnormalities in the A/D conversion circuit 11.

〔Effect of the invention〕

According to this invention, a reference voltage is applied separately from each sensor to an A/D conversion circuit that inputs an analog signal from each sensor and converts it into a digital signal, and the output from the circuit and pre-stored data are By comparison, it is possible to determine the abnormality of the circuit, so it is possible to accurately determine the abnormality of the circuit.
Reliability can also be improved.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of the invention, FIG. 2 is a flowchart explaining the operation of the invention, and FIG. 8 is a block circuit diagram showing the normal operation of the invention. 1.2. ~． N...Sensor, 11...A/D conversion circuit, 12...Control unit. Figure 2 = 193-

Claims (1)

[Claims] 1) In a device equipped with an A/D conversion circuit that inputs the output of each sensor and outputs a signal to the control unit, a reference voltage is applied to the A/D conversion circuit, and the output from the A/D conversion circuit is Provide a means for comparing with pre-stored data,
An error check method for an A/D converter circuit that determines an abnormality in the A/D converter circuit based on the result of the comparison means.