JPS60229104A - Data reading device - Google Patents

Abstract

PURPOSE:To read process data after deleting the superposed noises out of the data by comparing the input data given at every sampling cycle with data preceding by one and two sampling cycles respectively and reading the data having its changing width set within an allowable range. CONSTITUTION:The process value given from a control subject 1 is converted into electric signals by a sensor 2 and sent to a CPU6 of a control part 5 via an amplifier 4 and an A/D converter 4 which is started by the signal sent from the CPU6 and in a fixed sampling cycle. The data obtained at every sampling cycle is compared with the data preceding by one and two sampling cycles stored in a RAM8 respectively. If the changing widths of the compared data are set within K and 2K compared with the allowable changing range K stored in the RAM8 via an allowable range setting part 11, these data are decided to be correct and read into the RAM8. The subject 1 is controlled by the control amount corresponding to said data via an output operation part 9. Thus it is possible to read the process data after deleting the superposed noises.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data reading device that is used in a control device that performs feedback control, etc., and reads data at every sampling period.

Conventional technology and its problems Feedback control devices are widely used in control devices for temperature, pressure, etc., in which a sensor is installed in the controlled object, the manipulated variable is determined based on the process amount obtained from the sensor, and the controlled object is operated. ing.

In such a control device, since the sensor output is minute, the process amount is amplified by an amplifier with a high amplification factor, converted to a digital device using an A/D converter, and read into the control device. There are many. However, when the sensor output is small, the influence of external noise is large, so a low-pass filter or the like is inserted into the amplifier, or a digital filter is used after reading digital data to reduce the influence of noise. However, it is extremely difficult to completely eliminate the influence of noise with such a filter, so in order to reduce the influence of noise, it is necessary to perform operation by reducing the differential operation amount below the theoretical value in PID control. there were. If such a correction is made, there is a problem in that control cannot be performed with the correct amount of operation, and the controlled object cannot be appropriately controlled.

OBJECTS OF THE INVENTION The present invention has been made in view of the problems of conventional data reading devices, and provides a data reading device that can read process data with noise superimposed thereon while removing the noise. This is what we provide.

Structure and Effects of the Invention The present invention provides a data reading device for reading continuously changing input data at a predetermined sampling period, and the device includes a setting means for setting an allowable change width of input data for one sampling period, and a setting means for setting an allowable change range of input data for one sampling period, a storage means having an area for storing a predetermined number of input data read in each time and an allowable width set by the setting means; a comparison means for comparing a given sampling value with input data already read; The present invention is characterized by comprising a control means for reading sampled input data when a comparison value obtained by the means is within an allowable range corresponding to a sampling period.

According to the present invention having such characteristics, even if data exceeding the change tolerance range stored between each sampling data is input, this data is held and the input of the next sampling period is awaited.

Therefore, even if noise is added and abnormal data is sampled at a certain moment, that data will not be read, and only data within a permissible change range determined according to the sampling period will be read. Therefore, when noise exceeding the permissible change range is superimposed, it is possible to remove the influence. Also PI
Also in the DlljJ control device, there is no need to reduce the differential operation amount, and appropriate feedback control can be performed.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a block diagram showing an example of a control device including an analog data reading device according to the present invention.

In this figure, a sensor 2 is connected to a controlled object 1, and process values of the controlled object, such as temperature and pressure, are converted into electrical signals. The output thereof is amplified by an amplifier 3 and given to an A/D converter 4.

The A/D converter 4 converts a process value, which is an analog quantity, amplified according to an A/D conversion signal given at a predetermined period into digital data, and its output is sent to the central processing unit ( (hereinafter referred to as CPU) 6.

In addition to the CPU 6, the control unit 5 includes a random access memory (hereinafter referred to as RAM) 8, which stores the arithmetic processing procedures, and a random access memory (hereinafter referred to as RAM) 7, which temporarily stores data used when reading process values and input signals. A storage means consisting of the following is connected, and the controlled object is controlled according to a predetermined procedure. The control section 5 is connected to an output operation section 9 which is composed of a heater, a motor, etc. and directly controls a controlled object as an output means, and is also connected to a display 10 which displays set values and current values. Furthermore, in the present invention, the CPU 6 is provided with an allowable range setting section 11 for setting an allowable range of change in the input process value.

FIG. 2 is a memory map showing the contents stored in the RAM 8. In this figure, the RAM 8 includes an input buffer area Buf that temporarily holds input values, a read value area Dn, Dn-1+Dn-2, which sequentially stores three read data in the order of reception.
Input difference areas Sl and S2 that store input differences, an input reception data area Da that holds input data to be accepted and transmitted to the CPU 6 among the values obtained in the power buffer, and changes input from the allowable width setting unit 11. A change permissible width area for storing the permissible width K is provided.

FIG. 3 is a diagram showing a front panel of an automatic control device using the data input device of the present invention. rP at the top of the panel surface
VJ is a display section that displays the current value.

rSVJ is a display section that displays set values and has a display that indicates units according to the process amount. Also, the r at the bottom
The RUN/5TOPJ switch is an output operation switch, rAuTo/MANUAL, that switches between normal operation mode and stop mode, which stops time progression and stops control output.
The J switch is a switch that switches between automatic feed bank control and manual output setting, and the "↑", "↓", and "→" switches are numerical control switches that increase, decrease, and digits of the parameter values, respectively. rWRITE/NEXTJ The switch is a switch for setting display data and storing it in the RAM 8. Then, a numerical value is set in the above-mentioned allowable change range using the numerical control switch, and is input to the control device by pressing the rWRITEJ key.

Next, the operation of this embodiment will be explained with reference to flowcharts and waveform diagrams. FIG. 4 is a flowchart showing the overall operation of this automatic control device, FIG. 5 is a flowchart showing processing for reading input process values, and FIG. 6 is a graph showing an example of changes in process values. In these flowcharts, the numbers indicated using leader lines are CPU6.
These are the operating steps. First, when the operation starts, initial processing is performed in routine 12 in FIG. In this initial processing, the permissible width K of change is set by the permissible width setting section 11 based on conditions such as the heat capacity of the controlled object 1. This allowable change range indicates the maximum amount of input change of the amplifier 3 that changes every predetermined sampling period T, and only changes smaller than this are accepted as changes in the process value, and if the allowable range is exceeded, In this method, noise is processed as if it were superimposed on the process signal. When this initial processing is completed, the program moves to the main routine, and in step 13, an A/D conversion signal is transmitted to start up the A/D converter 4.

Then, in step 14, the end of the A/D conversion is awaited, and when the A/D conversion is completed, input data is accepted in routine 15, and the flow proceeds to routine 16, where the control amount by PID control is determined. Then, in routine 17, the manipulated variable is output from the output operation unit 9, and the process advances to step 18, where it waits for the end of the sampling period T. When the sampling is completed, the process returns to step 13 and the same process is repeated every sampling period thereafter. Then, the process value is A/D converted at every predetermined sampling period T and held in the input buffer Buf of the RAM 8, and reception processing is performed.

Now, the process value obtained at the current side t1 is stored in RAM8.
It is assumed that the data is stored in the large power buffer Buf. When the input process value reading process of routine 15 is started, the already stored digital process values are sequentially shifted in the flowchart shown in FIG. That is, Dn
Move the process value stored in the area to the Dn-1 area,
The data in the Dn-1 area is transferred to the Dn-2 area (step 21). Then, the latest A/D converted digital data is transferred from the input sofa Buf to the Dn area (step 22).

Then, as shown in FIG. 6, the data DI at time t1 is in the Dn area, and the data from the past two times are in the Dn-1 area.

D Stored in the n-2 area. The process then proceeds to step 23, where the difference between Dn and Dn-1 is calculated and stored in the input difference area Sl, and the process proceeds to step 24, where the absolute value of sl is compared with the allowable width. Here, if the absolute value of the input difference s1 is smaller than K as at time 11 in FIG. (step 26). If the input difference Sl is larger than the allowable input width, the process advances to step 27 and Dn and Dr
The difference between +=2 is calculated and stored in the long difference s2 area.

Then, it is checked whether this S2 is twice the input permissible width of one sampling period T, that is, whether it is 2 or more (
Step 28). If this is within 2, it is considered to be within the permissible range within twice the sampling period, so proceed to step 29 and convert the DnO value to the received data Da.
At the same time, the digital value Dn is also stored in the Dn-1 area, Dn and Dn-1 are made equal, and the process proceeds to step 26 to perform data transmission.

However, if the absolute value of 82 is greater than or equal to 2 in step 28, noise continues to be superimposed on the process data. It is transmitted to the CPU 6 as is.

For example, in the case of the process value change pattern shown in FIG. 6, all process values up to time t3 are within the allowable change range, so A/D conversion is performed from step 21 to step 24.25. The obtained data is directly transmitted to the CPU 6 as reception data. However, time t4
Since the data D4 obtained at the time exceeds the permissible change range K, in step 27, the data at time t4 is compared with the data D2 at time t2, which is two sampling periods earlier. In the case of FIG. 6, the human power] S2 is greater than or equal to 2, so at time t4, the reception data D3 at time t3 is held as is in the reception data area Da, and the reception data D4 at time t4 is
It is transmitted to the CPU 6 as Then, at time t5 when reading after the next sampling period, the immediately preceding process data D
4 is large and the input difference S1 is large, so step 24
This would exceed the allowable range of change. However, time t5
Difference S2 with read data D3 two sampling periods earlier than
is within the permissible change width 2 of 2 sampling periods. Therefore, proceeding from step 27.28 to step 29, the input data Dn (i.e., D5) at that time is set as the received data Da, and the value of Dn (D5) is also written to the Dn-1 area, resulting in the data obtained at time t4. After removing D4, the process proceeds to step 26 to perform data transmission. Also, at time t7, the input data D7 obtained from the A/D converter 4 exceeds the permissible change range K, but the data DB obtained at time t8 has a permissible range of 2 with respect to the read data D6 two sampling periods earlier.
within. Therefore, at time t7, the true process value is D
For example, it is considered to be D7r as shown in the figure, so it is accepted as normal data and the process is controlled as input data as shown in the figure.

In this way, the present invention sets an input permissible range in one sampling period and accepts input within that range as correct data based on that, so it is possible to prevent abnormal process data from occurring during a certain sampling period due to noise from the sensor. Even if the data is given, no operation is performed based on that data, making it possible to perform error-free ILJ control.

In this embodiment, the read data up to two sampling cycles ago is stored and the allowable input width between two sampling cycles is checked, but the input data is also accepted using the allowable input range up to the previous sampling cycle. You can also do it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a feedback control device including a data reading device according to the present invention, FIG. 2 is a memory map showing the storage contents of RAM 8 used in the data reading device, and FIG. 3 is a diagram showing its front panel. , FIG. 4 is a flowchart showing the overall operation of this automatic control device, FIG. 5 is a flowchart showing the operation when reading data,
FIG. 6 is a graph showing an example of changes in input process values and received data. ! Controlled object 2 - sensor + 3 = amplifier 4・--
---A/D converter 5-----Control unit 6--
------CPU 7-----ROM 8-----
--RAM9-・-Output operation section to---------
Display device 11--Tolerance width setting section Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Yoshiki Okamoto (and one other person) Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (2)

[Claims] (1) A data reading device that reads continuously changing input data at a predetermined sampling period, including a setting means for setting an allowable change width of the input data for one sampling period, and a predetermined number of input data read for each sampling period. storage means having an area for storing the input data of and the tolerance and range set by the setting means; a comparison means for comparing the given sampling value with input data already read; A data reading device comprising: control means for reading sampled input data when a comparison value is within a tolerance range corresponding to a sampling period. (2) The comparison means includes a first comparison means that compares the given input data with input data read one sampling period ago, and a first comparison means that compares the given input data with input data read two sampling periods ago. , and the control means reads the input data when the input data is within a tolerance range corresponding to one of the sampling periods. The data reading device according to item 1.