JPS6363923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a conversion device that converts an analog input signal into a digital signal, such as a digital temperature control device. This makes it possible to stabilize the system and also to notify of input abnormalities.

[Conventional technology]

Conventionally, this type of conversion device sends a signal to a CPU 9 (microcomputer), which is a processing device, through an A/D converter 1 that simply converts an analog signal into a digital signal, as shown in Figure 2. It was hot.

[Problem that the invention seeks to solve]

However, in the conventional method described above, noise components that are naturally included in the input signal are converted into digital signals and sent to the CPU, so there is a possibility of malfunction, and the noise components may cause the signal to be distorted. When the data suddenly changes, for example, the display changes suddenly and flickers, making it very difficult to read, which can cause problems, and furthermore, it is expected that such a state will continue for a certain period of time, causing an abnormality in the input. Sometimes they had no means of reporting.

The above problems can be processed by the CPU, which is a processing device, but even if the complexity of creating a program for the CPU to execute is tolerable, the CPU processing A large portion of the CPU's capacity is used, causing the problem of insufficient capacity that prevents the original processing, and other problems such as slow execution speed due to sequential execution processing, which is a characteristic of the CPU. It was hot.

[Means for solving problems]

The present invention provides an A/D converter for converting an analog input signal into a digital signal, a level switch for setting a noise level, and a noise level switch set in the level switch as a specific means for solving the above-mentioned conventional problems. a noise judger that makes a judgment based on the noise level, a noise counter that measures the duration of time that the noise judger judges noise and outputs an input abnormality alarm signal or an input abnormality recovery signal, and data held up to the previous time. a data determiner that compares the current data value with a data value, a data adder that increments the retained data value based on the result of the data determiner, a data subtracter that decrements the retained data value, and data that retains the retained data value and outputs it. To solve the above-mentioned problems by removing noise components and preventing sudden changes in signals by providing a signal stabilizing device characterized by being equipped with a retainer, and also to notify abnormalities in input signals. This made it possible.

〔Example〕

Next, the present invention will be explained in detail based on an embodiment shown in the drawings. In order to facilitate understanding, the same parts as in the conventional example will be described with the same reference numerals.

The reference numeral 1 in FIG. 1 is an A/D converter similar to the conventional example, which converts an analog signal from a signal line a into a digital signal and outputs it to a signal line b. As explained in the conventional example, the analog signal from the signal line a naturally includes a noise component, and this noise component is transmitted to the A/D converter 1.
It is also included in the digital signal output to signal line b after conversion.

However, in almost all cases, such as when the analog signal is a thermistor output for temperature measurement, it is possible to set the normal range of the output value, and when an output outside that range occurs, it is due to noise components. A certain judgment is possible. A particularly extreme example is shown in the case of the thermistor output described above. When the thermistor circuit is disconnected or short-circuited, an output outside the normal range is connected.

The level switch 2 sets the above-mentioned normal range, and by using a digital switch, for example, it is possible to set the upper limit value, the lower limit value, or both as digital values. The noise determiner 3, which is obtained by using, for example, a digital comparator, operates according to the value set on the level switch 2, and its operation is based on the signal line b.
If the value of the digital signal input via the level switch 2 is within the range of the value set in the level switch 2, the digital signal on the signal line b is passed through as is and outputted to the signal line c, and the normal signal is sent to the signal line d. If it is outside the range, the output on signal line c is stopped and an abnormal signal is output on signal line e.

For example, in the noise counter 4 obtained using a retrigger timer, the signal line d, which outputs the above-mentioned normal signal, is connected to the retrigger terminal, and the abnormal signal is input by connecting the signal line e, which is the abnormal signal, to the count start terminal. Then, the noise counter 4 counts up until it reaches a preset time, and when it reaches the time, it outputs an input abnormality alarm signal to the signal line g. Since the count is reset to zero when the signal is output to the signal line g, the input abnormality alarm signal will not be output to the signal line g unless the abnormality signal continues for more than the preset time in the noise counter 4. The input abnormality recovery signal is output to the signal line h when there is no signal output to the signal line g.

For example, a data determiner 5 obtained using a digital comparator inputs an input signal inputted through a signal line c converted into a digital value by the A/D converter 1 via the noise determiner 3 and a data holder 6. The data held up to the previous time is compared, and when both signals are the same, it is output to signal line j, and when the input signal > held data, it is output to signal line k.
When input signal<retained data, each is output to signal line l. At the same time, a signal line f branched off from the signal line e that outputs the abnormal signal of the noise judger 3 is input to the data determiner 5, and if there is an output on the signal line f, the comparison function is stopped. This stops the operation of the data determiner 5 when the noise determiner 3, which has no output on the signal line c, determines that it is abnormal, thereby preventing abnormal data from becoming a comparison target.

For example, the data holder 6 obtained using a register has an input/output function and a storage function, and the data adder 7, which also uses a register etc., has an input/output function and an increment function (adds 1 to the contents of the register). Data subtractor 8 obtained in the same way
has an input/output function and a decrement function (subtracts 1 from the contents of the register) and exchanges contents with each other.As a result, the comparison by the data determiner 5 explained above will result in input signal>retention. In the case of data, 1 is added to the contents of the data holder 6 in one operation, in the opposite case, 1 is subtracted from the contents of the data holder 6, and in the case of the same, the contents of the data holder 6 are changed. CPU via signal line p without
Output to 9.

Note that the signal lines m and n are bidirectional signal lines through which the data holder 6, data adder 7, and data subtracter 8 exchange data, respectively. Furthermore, the input/output functions of the data holder 6, data adder 7, and data subtracter 8 described above can of course be implemented by a single register having increment and decrement functions.

〔Effect of the invention〕

As explained above, by providing a level switch that sets the noise level and a noise judger that makes a judgment based on the noise level set to the level switch, signals outside the set range can be detected by the noise judgement. Since the device does not transfer the signal to the next stage, the data judger, it is possible to process only the signals within the range that has been set as valid, and accurate results can be obtained. In addition, the setting values are flexible and highly practical. By providing a noise counter, when a signal outside the set range continues for a certain period of time, an input abnormality alarm signal is generated, thereby preventing disconnection of the input device.
A function is added to notify an abnormality such as a short circuit, and when the abnormality is recovered, the operation can be resumed immediately using the input abnormality recovery signal and the previous data stored in the data holder. Furthermore, by combining a data judge, a data adder, a data subtracter, and a data holder, the data increases or decreases by one unit in one operation, which prevents sudden data changes and, for example, surge voltage. It has an extremely high practical effect in compressing noise components caused by noise, and by freeing the CPU, which is a processing device, from such processing, it enables even faster processing and expansion of functions. It is also effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a signal stabilizing device according to the present invention, and FIG. 2 is a block diagram showing a conventional example. 1... A/D converter, 2... Level switch, 3... Nozzle judge, 4... Noise counter, 5... Data judge, 6... Data holder,
7...Data adder, 8...Data subtracter, 9...
...CPU, a~p...signal lines.

Claims (1)

[Claims] 1. An A/D converter that converts an analog input signal into a digital signal, a level switch that sets a noise level, a noise determiner that makes a determination based on the noise level set in the level switch, and the noise determiner a noise counter that measures the duration of noise and outputs an input abnormality alarm signal or an input abnormality recovery signal; a data determiner that compares the data value held up to the previous time with the current data value; and the data determiner. A signal stabilizing device comprising: a data adder that increments the held data value; a data subtracter that decrements the held data value; and a data holder that holds and outputs the held data value.