JPH01113802A - Abnormality processing method for analog/digital conversion - Google Patents

Abstract

PURPOSE:To prevent the troubles of A/D conversion by controlling the time required for A/D conversion via a timer so as to avoid such a case where the A/D conversion needs much time or an end flag of the A/D conversion could not be set. CONSTITUTION:The process may sometimes never proceed to a control part 14 even when a prescribed time needed for conversion owing to such a fact that the A/D conversion needs much time or an end flag of the A/D conversion could not be set. A timer interruption part 13 which started a time counting action concurrently with start of the A/D conversion records the value of abnormality at a recording part 12 in terms of the A/D conversion with generation of the timer interruption caused by the overflow of a set time. At the same time, the part 13 shifts the process to the part 14. The part 14 performs the control based on the A/D conversion value recorded at the part 12. In this case, however, the abnormality is processed since the A/D conversion value is not normal. Thus it is possible to prevent the troubles of A/D conversion by stopping the energization of a faulty display heater or switching off the power supply of the relevant device itself.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses a microprocessor to
The present invention relates to a method for handling abnormalities in A/D conversion in equipment that performs digital conversion (hereinafter abbreviated as A/D conversion) and performs various controls.

BACKGROUND ART A conventional A/D conversion abnormality handling method of this type involves recording an A/D converter 1 and an A/D converted value by the A/D converter 1, as shown in FIG. If the values of the recording unit 2 and the recording unit 2 are within a predetermined range, the device motor is turned on or off, or the heater is turned on as normal processing.
, OFF, and if the value of the recording section 2 is outside a predetermined range, the control section 3 turns off the motor or heater as abnormality processing.

For example, a simple temperature control circuit is shown in FIG. 3 as an example of a circuit that performs control using A/D conversion.

4 is a negative characteristic thermistor, 5 is a resistor, 6 is a microprocessor, 17 is a relay, 8 is a heater, 9 is a commercial power supply, 1
0 is the power supply, and the microprocessor has an A/
It has a D conversion section 1, a recording section 2, and a control section 3. The relationship between the voltage and temperature at the connection point between the negative characteristic thermistor 4 and the resistor 5, and the temperature control range in the control section 3 are shown in FIG.

The A/D converter 1 detects the voltage at the connection point A by A/D conversion and records it in the A/D conversion recorder 2.

The control section 3 calculates the temperature from the value of the recording section 2, and when this temperature is within the temperature control range (that is, within a predetermined range) shown in FIG. IJ,
OFF is not performed, and -1-8 energization control is performed. On the other hand, if the temperature is out of this range, relay 7 is turned off.
Abnormal processing such as turning off the heater 8 and stopping the power supply to the heater 8 will be performed. Here, if the negative characteristic boomister 4 has a disconnection failure, the voltage at the connection point A will be OV
Therefore, the temperature determined from the A/D conversion value at this time becomes the maximum temperature. However, since the maximum temperature is outside the temperature control range as shown in FIG. 4, the control unit 3 determines that there is an abnormality and turns off the relay to stop energizing the heater 80. Conversely, if the negative characteristic thermistor 4 has a short-circuit failure, the voltage at the connection point A becomes equal to the power supply voltage, so the temperature determined from the A/D conversion value at this time becomes the lowest temperature. However, since the lowest temperature is outside the temperature control range according to FIG.
1, the relay is turned off, and the heater 80 is de-energized.

As described above, when the thermistor 4 is disconnected or short-circuited, power to the heater is stopped as abnormality processing to prevent accidents.

Problems to be Solved by the Invention However, with the above configuration, it is possible to perform abnormality processing for disconnection failures and short circuit failures of the thermistor 4, but the control unit 3 simply records the A/D conversion value. Since only the current state of the recording unit 2 was checked, it was not possible to detect any abnormality due to a hardware failure in the A/D conversion unit of the microprocessor itself.

The control unit 3 is configured to control the A/D recorded in the recording unit 2.
Even if the converted value is not a regular value, if the temperature obtained from this temperature is within the temperature control range, the relay 7 is turned ON/OFF to control the energization of the heater 8, regardless of the actual temperature. It's funny.

That is, in a temperature control circuit as shown in FIG.
If the A/D conversion value cannot take the actual correct value due to a hardware failure in the A/D conversion section of the microprocessor itself, the A/D conversion value is the value that will energize the heater 8 for the control section 3. If there is, relay 7 will be turned on. If the above-mentioned condition were to continue for a long time, there was a risk of abnormal overheating of the heater 8, resulting in accidents such as personal burns or fire.

In addition, an end flag indicating the end of A/D conversion is set in hardware, and in a microprocessor that needs to detect this end flag, if the end flag cannot be set due to a hardware failure, the end flag is set. The flag cannot be detected, and the end flag detection part ends up in an infinite loop, or the previous A
/D conversion remains in the conversion recording section 2, and the control section 3
A problem occurred in that control was performed using the previous A/D conversion value. If the above-mentioned failure occurs in the temperature control circuit shown in Fig. 3 while the heater 8 is turned on, there is a risk of abnormal overheating of the heater 8, resulting in personal burns or a fire. there were.

The present invention solves the above problems and provides an A/D conversion abnormality processing method that can detect hardware failures in the A/D conversion section of a microprocessor and prevent accidents. It is.

Means for Solving the Problems In order to solve the above problems, the A/D conversion abnormality processing method of the present invention includes an A/D conversion unit and an A/D conversion record by the A/D conversion unit. a timer interrupt unit having a set time longer than the maximum time required for A/D conversion; If the value of the recording section is outside a predetermined range (abnormal value), the timer interrupt section starts measuring time at the same time as the start of A/D conversion, and the set time If a timer interrupt occurs due to overflow, perform abnormal processing or
The abnormal value is recorded in the recording section as a D-converted value and transferred to the control section.

Operation By managing the time required for A/D conversion with the above configuration, node-like failures in the A/D converter of the microprocessor, that is, taking more time than necessary for A/D conversion, can be avoided. It is possible to prevent accidents by detecting failures such as failures or inability to set the end flag of A/D conversion.

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

In FIG. 1, 11 is an A/D converter, 12 is the A/D converter, and 12 is the A/D converter.
A recording section 13 records the A/D conversion value by the D conversion section 11, a timer interrupt section 13 having a set time longer than the maximum time required for A/D conversion, and 14 a recording section for recording the A/D conversion value within a predetermined range. 1ii (If the A/D conversion value is normal 1ii, it performs normal processing, and if the A/D conversion value is outside the predetermined range (abnormal value), it is a control unit that performs abnormal processing. Timer interrupt unit 13 starts timing at the same time as the start of A/D conversion, and if the set time exceeds 70- and a timer interrupt occurs, either perform abnormal processing or record the abnormal value at the A/D conversion station. At the same time, the data is transferred to the control unit 14.

In the above configuration, a hardware failure occurs in the A/D conversion section of the microprocessor, such as A/D conversion taking longer than necessary or failure to set the A/D conversion completion flag. If the process does not proceed to the control unit 14 even after the predetermined time required for A/D conversion has passed, the timer interrupt unit 13, which started timing at the same time as the start of A/D conversion, interrupts the timer interrupt due to an overflow of the set time. When an error occurs, an abnormal value is recorded in the recording section 12 as an A/D conversion row, and the process is transferred to the control section 14.

Next, the control unit 14 performs control using the A/D conversion value recorded in the recording unit 12, but since the A/D conversion value is an abnormal value, it decides to perform abnormality processing. Become. In this abnormality processing, it is possible to prevent accidents by performing processing such as stopping the power supply to the failure display heater or turning off the power to the device itself.

Of course, it is also possible to configure the timer interrupt section 13 to directly handle the abnormality.

As is clear from the description of the embodiments above, the effects of the invention are as follows:
The D conversion error handling method uses a timer to manage the time required for A/D conversion, so the microprocessor's A/D
Detects a hardware failure in the converter, such as A/D conversion taking longer than necessary, or failure to set the A/D conversion end 7 lag,
This makes it possible to prevent accidents.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an A/D conversion abnormality processing method according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional A/D conversion abnormality processing method, and FIG. 3 is a block diagram of an A/D conversion abnormality processing method according to an embodiment of the present invention. FIG. 4 is a circuit diagram showing a temperature control circuit using the same circuit, and FIG. 4 is a characteristic diagram showing the temperature control range of the circuit. 11...A/D conversion unit, 12...Recording unit, 13...Timer interrupt unit, 14...
・Control unit. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 3 Figure 4, Heng A @ Jiang

Claims (1)

[Claims] (1) An analog-to-digital conversion section (hereinafter abbreviated as A/D conversion section) and a recording section that records the A/D conversion value by the A/D conversion section, which takes longer than the maximum time required for A/D conversion. If the values of the timer interrupt section having a set time and the recording section are within a predetermined range (normal value), normal processing is performed;
The controller includes a control unit that performs abnormality processing if the value of the recording unit is outside a predetermined range (abnormal value), and the timer interrupt unit starts timing at the same time as the start of A/D conversion, and If the time overflows and a timer interrupt occurs,
A method for handling an abnormality in A/D conversion, which performs abnormality processing or records an abnormal value as an A/D conversion value in the recording section and transfers the processing to the control section.