JPH0479007B2 - - Google Patents

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 determined as an integral multiple of the power supply period.

Conventional technology and its problems In control devices for temperature, pressure, etc., a sensor is installed inside the controlled object, and the manipulated variable is determined based on the process amount obtained by the sensor at each predetermined sampling period, and the controlled object is operated. Feedback control devices are widely used. In such a control device, since the sensor output is minute, the process quantity is amplified by an amplifier with a high amplification factor, converted to a digital quantity using an A/D converter, and read out to the control device. It is often crowded. However, when the sensor output is small, the influence of external noise is large, so the influence of noise has been reduced by inserting a low-pass filter into the amplifier, or by using a digital filter after reading digital data. 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, the differential operation amount is lowered than the theoretical value in PID control. Something happened. If such correction is performed, there is a problem in that control cannot be performed with the correct amount of operation, and the controlled object cannot be appropriately controlled.

Purpose of the Invention The present invention has been made in view of the problems of the conventional data reading device. The present invention provides a data reading device that can read processed process data with noise removed.

Structure and Effects of the Invention The present invention is a data reading device that reads continuously changing input data at a predetermined sampling period having a time that is an integral multiple of the power supply period. a setting means for setting, a predetermined number of input data read in each corner sampling period, a storage means having an area for storing the allowable width set by the setting means, and input data having already read the given sampling value. and a control means that reads the sampled input data and changes the sampling phase by a minute time when the comparison value obtained from the comparison means is within a tolerance range corresponding to the sampling period. It is characterized by:

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 waits for the input of the next sampling period, and the sampling The phase is changed by a minute amount of time. By doing so, when phase control is performed and noise is added at a predetermined phase of the power cycle, the influence of such noise can be removed, and data can be read at a phase with less noise. Even if noise is added and abnormal data is sampled at a certain moment, that data will not be read, but 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 its influence. Also, in the PID 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. And its output is amplifier 3
The signal is amplified by the A/D converter 4 and provided to the 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 5. It is given to the device (hereinafter referred to as CPU) 6. Control unit 5 is a CPU
In addition to 6, storage means consisting of a read-only memory (hereinafter referred to as ROM) 7 that stores the arithmetic processing procedure and a random access memory (hereinafter referred to as RAM) 8 that temporarily stores data used when reading process values and input signals is connected. The control target is controlled according to a predetermined procedure.
The control unit 5 is connected to an output operation unit 9 which is composed of a heater, a motor, etc. as an output means and which directly controls the controlled object, and a display 10 which displays set values and current values.
is connected. 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 input process values.

FIG. 2 is a memory map showing the memory contents of the RAM 8. In this figure, RAM 8 includes an input area Buf that temporarily holds input values, and read value areas Dn and Dn- that sequentially store three pieces of read data in the order of reception.
1, Dn-2, input difference areas S1 and S2 for storing input differences, further input reception data area Da for holding input data to be accepted and transmitted to the CPU 6 from among the values obtained in the input buffer, and further for setting the allowable width. A permissible change width area for storing the permissible change width K input from the section 11, an area for a sampling change request flag and a sampling change time ΔT that are set when changing the sampling phase are provided.

FIG. 3 is a diagram showing a front panel of an automatic control device using the data input device of the present invention. "PV" at the top of the panel is the display section that displays the current value.
"SV" is a display section that displays set values, and has a display that indicates units according to the process amount. The "RUN/STOP" switch at the bottom is an output operation switch that switches between normal operation mode and stop mode that stops time progression and control output, and the "AUTO/MANUAL" switch allows automatic feedback control and manual output setting. The "↑", "↓", and "→" switches are numerical control switches that increase, decrease, and digits of the parameter values, respectively, and the "WRITE/NEXT" switch sets display data and stores it in RAM8. let me,
This is a switch that moves the setting operation to the next step.
The above-mentioned permissible change range K is input to the control device by setting a numerical value using a numerical control switch and pressing the "WRITE" key.

Next, the operation of this embodiment will be explained with reference to a flowchart and waveform diagram. FIG. 4 is a flowchart showing the overall operation of the automatic control device of this embodiment, FIG. 5 is a flowchart showing A/D conversion processing, and FIG. 6 is a flowchart showing input process value reading processing.
FIG. 7 is a graph showing an example of changes in process values. In these flowcharts, the numbers indicated using leader lines indicate the operation steps of the CPU 6.
First, when the operation starts, initial processing is performed in routine 12 in FIG. 4. In this initial processing, first, 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 width K indicates the maximum amount of input variation of the amplifier 3 that changes every predetermined sampling period T, which is selected as an integral multiple of the power supply period in order to reduce the influence of noise. Only the amount of change in the process value is accepted as the amount of change in the process value, and if it exceeds the allowable range, it is treated as noise being superimposed on the process signal. When this initial processing is completed, the main routine is started, and in routine 13 the A/D
A conversion signal is given to perform A/D conversion processing. When the A/D conversion is completed, the input data is accepted in routine 14, and the process proceeds to routine 15.
Determine the control amount by PID control. Then, in routine 16, the manipulated variable is output from the output operation unit 9, and the process advances to step 17, where it waits for the end of the sampling period T. When the sampling is completed, the process returns to routine 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 A/D conversion process shown in FIG. 5 is performed every predetermined sampling period T. When this routine is entered, first in step 21 it is determined whether the sampling period change flag is set. If this flag is set, the process advances from step 22 to step 23 to wait for processing for the sampling change time ΔT, and then advances to step 24 to reset the sampling change request flag. Then, in step 25, the A/D converter circuit 4 is activated and the A/D conversion circuit 4 is activated.
Execute D conversion. If the sampling change request flag is not set in step 22, the A/D conversion circuit 4 is activated immediately in step 25 without performing steps 23 and 24. Then, the A/D conversion circuit 4 provides the A/D conversion circuit 4.
The D-converted data is stored in the input buffer Buf (step 26), and this process ends.

Now, the process value obtained at the current time t1 is
Assume that it is stored in the input buffer Buf of RAM8. When the input process value reading process is started, the already stored digital process values are sequentially shifted in the flowchart shown in FIG. In other words, the process value stored in the Dn area is moved to the Dn-1 area, and the data in the Dn-1 area is transferred to the Dn-1 area.
-2 area (step 31). And A/D
Input the latest converted digital data into the buffer
Transfer from Buf to Dn area (step 32). Then, as shown in FIG. 7, the data D1 at time t1 becomes
In the Dn area, the past two data are Dn-1 and Dn respectively.
- Stored in area 2. Then, proceeding to step 33, the difference between Dn and Dn-1 is calculated and the input difference area S1 is calculated.
Then, the process proceeds to step 34, where the absolute value of S1 and the allowable width K are compared. Here, time t in FIG.
If the absolute value of the input difference S1 is smaller than K as at time 1, the process proceeds to step 35 and the current process value is
The data of Dn is stored in the Da area as reception data, and the data is further transmitted to the CPU 6 (step 36). However, if the input difference S1 is larger than the input permissible width K, the process advances to step 37 and a sampling conversion request flag is set. And step 3
8, calculate the difference between Dn and Dn-2 and calculate the input difference
Store in S2 area. Then, it is checked whether this S2 is twice the allowable input width K for one sampling period T, that is, 2K or more (step 3).
9). If this is within 2K, it is considered to be within the input permissible width within twice the sampling period, so proceed to step 40, set the value of Dn as the received data Da, and set the process value Dn to the Dn-1 area. is also stored, Dn and Dn-1 are made equal, and the process proceeds to step 36 to perform data transmission. However, if the absolute value of S2 is 2K or more in step 39, noise is continuously superimposed on the process data, so in step 36, the acceptance data Da held in RAM 8 is sent to the reader one sampling period before. Transmit it as is to CPU6.
In this case, the sampling conversion request flag is set, so in the next A/D conversion cycle, the fifth
As shown in the figure, even when the A/D conversion routine is executed, A/D conversion is not performed immediately, but is performed after a delay of sampling change time ΔT, and at this time, the sampling change request flag is reset. Therefore, from now on, A/D conversion will be performed at the same sampling period T.

In addition, in the case of the process value change pattern shown in FIG. 7, all the process values up to time t3 are within the allowable change range K, so they are obtained by A/D conversion from step 31 through steps 34 and 35. The received data is directly transmitted to the CPU 6 as reception data. However, the data obtained at time t4
D4 exceeds the allowable change range K, so step 3
At step 7, the sampling change request flag is set, and the process proceeds to step 38, where the data at time t4 is compared with the data D2 at time t2, two sampling periods earlier. In the case of Figure 7, the input difference S2 is
Since it is 2K or more, at time t4, the reception data D3 at time t3 is held as is in the reception data area Da, and transmitted to the CPU 6 as the reception data at time t4. Thereafter, as described above, the sampling phase is delayed by ΔT, and at time t5 of reading after the next sampling cycle, the change in the immediately preceding process data D4 is large and the input difference S1 is large, so at step 34, the change exceeds the allowable range. I end up. However, the difference S2 from the read-over data D3 two sampling periods before time t5 is within the allowable change width 2K of two sampling periods. Therefore, proceeding from step 39 to step 40, the input data Dn (i.e., D5) at that time is set as the reception data Da, and
After writing the value of Dn (D5) into the Dn-1 area and removing data D4 obtained at time t4, the process advances to step 36 and data transmission is performed. Also, at time t7, the input data D7 obtained from the A/D converter 4 exceeds the permissible change range K, but the data D8 obtained at time t8 has a permissible range of 2K with respect to the read data D6 two sampling periods earlier. Within Therefore, time t
7, the true process value is between D6 and D7;
For example, as shown in the figure, it is considered to be D7r, 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 at a certain sampling point due to noise from the sensor. Even when data is given, no operation is performed based on that data, making it possible to perform error-free control.

Note that this embodiment stores the read data up to two sampling cycles ago and checks the input permissible width for two sampling weeks, but it is also possible to accept input data using the input permissible 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, Fig. 3 is a diagram showing its front panel, Fig. 4 is a flowchart showing the overall operation of this automatic control device, and Fig. 5 is a A flowchart showing the A/D conversion process, FIG. 6 is a flowchart showing the operation when reading data, and FIG. 7 is a flowchart showing the operation when reading data.
The figure is a graph showing an example of changes in input process values and received data. 1...Controlled object, 2...Sensor, 3...Amplifier, 4...A/D converter, 5...Control unit, 6...
CPU, 7...ROM, 8...RAM, 9...Output operation unit, 10...Display unit, 11...Permissible width setting unit.

Claims (1)

[Scope of Claims] 1. In a data reading device that reads continuously changing input data at a predetermined sampling period having a time that is an integral multiple of the power supply period, a setting that sets an allowable change range of input data for one sampling period. means, a storage means having an area for storing a predetermined number of input data read in each sampling period and an allowable width set by the setting means, and comparing the given sampling value with the already read input data. and a control means that reads sampled input data and changes the sampling phase by a minute time when the comparison value obtained from the comparison means is within a tolerance range corresponding to a sampling period. A data reading device characterized by: 2 The comparison means converts the given input data into 1
a first comparing means for comparing input data read in from a sampling period before; and a second comparing means for comparing the given input data with input data read two sampling periods ago; 2. The data reading device according to claim 1, wherein the input data is read when the input data is within a tolerance range corresponding to any sampling period.