JPS62231301A - Temperature input correcting device - Google Patents

Abstract

PURPOSE:To widely execute a temperature input correction without increasing a memory capacity by calculating temperature-output voltage coordinates based on the rate occupied by the upper and lower values of a new temperature scope. CONSTITUTION:When the upper and lower values TRH and TRL of a new applicable temperature scope are set through a keyboard, these data are stored into a RAM 4. A CDV 1 selects broken line data which come to be the reference from a ROM 3 based on the temperature scope. When the broken line data are coincident with the broken line used earlier, the data are used as they are, and at the time of dissidence, for the storing data of the RAM 4, the refer ence broken line data of the ROM 3 and X coordinate data, the calculation of coordinates Xi by a formula I is executed based on an Xi, applicable tempera ture scopes TNH and TNL, a broken line converting program, etc. Coordinates Yi are also calculated, temperature -output voltage coordinates corresponding to the set limit value are determined, and without increasing the memory capac ity of the ROM, a wide temperature input correction can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a temperature input correction device, and is particularly used in a digital process control device.

(Prior Art) Many control devices used for process control etc. perform control based on temperature. In this case, the detected humidity signal is generally generated by a temperature sensor such as a resistance thermometer or a thermocouple.

However, in these temperature sensors, the relationship between temperature and output signal is not necessarily linear, and it is necessary to correct the sensor signal using a temperature input correction device before inputting it to the control device.

Since the relationship between the temperature and the output signal is a known standard table such as JIS, it is approximated by an n-th degree polynomial or a broken line, and the broken line is particularly often used.

Such a broken line is switched depending on the temperature range to be used, and the coordinates of the broken line are determined by dividing the applicable temperature range.

Therefore, if the temperature range is different, calculations will have to be redone based on the applicable temperature range and specification table in order to change the broken line.

For this purpose, the data from the specification table or the broken line data for each applicable temperature range is stored in the storage device of the control device.
It can be taken out and used as needed. Note that such data is not the value of the temperature itself, but the lower limit of the temperature range TNL, for example, 0% at 20°C, and the lower upper limit Nt (for example, when 80°C is 100%, the temperature range is O%). Lower limit value VNL of the corresponding output voltage, e.g. 1V
For numerical processing of the control device, it is common practice to use dimensionless percentage data in which the upper limit value VNH of the output voltage corresponding to a temperature range of 100%, for example, 5V, is 100%.

However, in order to hold standard table data or broken line data, it is necessary to have a large capacity, and it is difficult to have a built-in storage capacity.

(Problems to be Solved by the Invention) As described above, the conventional temperature input correction device cannot hold sufficient data for temperature correction, so the correction range and the types of temperature sensors that can be corrected are limited. There is a problem.

The present invention has been made to solve such problems, and provides a temperature input correction device that can create correction data even when the temperature range actually used by the control device and the applicable temperature range of the sensor are different. The purpose is to

[Structure of the invention]

(Means for Solving the Problems) The temperature input correction device according to the present invention calculates the ratio of the upper and lower limits of the new applicable temperature range to the original applicable temperature range, and uses this to The coordinate data (xi, yi) representing the temperature-output voltage relationship within the range is used to calculate coordinate data (Xi, Yi) in a new temperature range.

(Function) The principle of temperature input correction in the present invention will be explained with reference to FIGS. 2 and 4.

As shown in Figure 4, a normal correction curve is plotted on the X-axis with the lower limit value TNL of a certain temperature range set at 0% and the upper limit value TNH set at 100%, and the output voltage values VNL and VNH for these are set at 0%, respectively. , 100% are applied to form the polygonal line data. Here, TNL and TNH are °C
, below, °, etc., and VNL, VNH are V, rr+V
It is called an industrial unit (EU) such as
As mentioned above, % data is used for internal processing.

In this situation, the new applicable temperature range TRL-T
When using RH, the original applicable humidity range TNL to TNH
The coordinates (xi, y
Coordinates (Xi, Yi) in the new applicable temperature range from N
The main purpose of the present invention is to know.

First, the relationship between coordinates is as follows.Similarly, PLN represents a polygonal line approximation calculation, and PLN-1 represents a reverse polygonal line approximation calculation.

Next, as shown in FIG. 2, a new temperature range TRL-TRH is considered within the temperature range TNL-TNH. Corresponding to these, a new output voltage range VNL to VNH is provided within the original output voltage range VNL to VNH. Set the lower limit of this new temperature range and output voltage range to 0.
%, the coordinates that fall within the original range with the upper limit as 100% (Xl
.

yi) to a new range (Xi, yi).

According to Fig. 2, the positions TRL' and TRI-1' in the original temperature range of TRL and TR+-1 can be expressed as percentage values, that is, the proportion of the new turbidity range in the mouth temperature range can be calculated. .

Therefore, the coordinate values of xi in the new temperature range are...
(4) Similarly, the new coordinate value Yi is the ratio of the output voltage in the new humidity range, so the new coordinate value Yi is (6).

Here, if we use the polygonal line approximation calculation, x in equation (1)
i = PLN'' (V i ) ヲ用i、1/− Also, yi=PLN (x 1) f7) II ､ｲｲ Therefore, when only the temperature range is known, equations (4) and (8) When the output voltages at the upper and lower limits within the new temperature range are known, temperature input correction is possible by using equations (7) and (6).

In addition, since the change in the percentage value of temperature and voltage is approximately a straight line with a slope of 1, using this, equations (7) and (6) become... (
10) Therefore, voltage-to-temperature conversion is possible by inputting only the temperature range.

(Embodiment) An embodiment of the temperature input correction device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a temperature input correction device according to the present invention, which is constructed as a part of a digital control device.

According to the figure, the CPU that controls the entire system includes the A [
) Converter 2, ROM 3 that stores the control program, line conversion program, reference line data, etc., R A that stores data in the middle of calculation or humidity range to be corrected, etc.
M 4 is provided with an output interface 5 for outputting correction value data obtained by calculation to an external device.

Next, the operation of the temperature input correction device having such a configuration will be explained with reference to the flowchart shown in FIG.

First, when a new upper limit value TRH and lower limit value TRL of the applicable temperature range are input from a keyboard (not shown) or the like (step 11), the data are stored in the RAM 4 (step 12).

Based on this temperature range data, the CPU 1 selects reference line data from the ROM 3 (step 13). The previous reference fold line is used as is for the lift platform whose fold line data obtained at this time matches the previously used fold line (step 14). (Step 15) When the obtained fold line does not match the previous fold line First, read the new temperature range data stored in RAM 4 (Step 16), for example, use equation (4) and (
8) Calculate new coordinates (Xi, Yi) using the formula (
Step 17).

That is, the CPU 1 reads out the original standard polygonal line data, two or more coordinate points, the applicable temperature range, and the polygonal line conversion program from the ROM 3, and uses the new temperature range data that is previously extracted as described above, for example. Taku10) and (11)
) to create data for a new polyline coordinate point.

The temperature data calculated in this way is outputted from the output interface 5, and control is performed based on this value.

In the above embodiments, linear approximation is used as the broken line approximation, but the approximation is not limited to this, and polynomial approximations such as quadratic and cubic can also be used.

Further, although an example of interpolation is shown in the embodiment, extrapolation is also possible.

〔Effect of the invention〕 .

As described above, according to the present invention, when performing a polygonal line approximation calculation, the temperature-output voltage coordinate in a new temperature range is determined based on the ratio of the upper limit value and lower limit value of the new temperature range to the applicable temperature range. Therefore, it is possible to provide a temperature input correction device that does not need to contain a large amount of data or line data, and is not limited by memory capacity.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the temperature input correction device of the present invention, FIG. 2 is a graph showing the principle of correction, FIG. 3 is a flowchart showing the operation of the device of the present invention, and FIG. It is a graph showing broken line data. 1...CPU, 2...A/D converter, 3...RO
M. 4...RAM, 5...Output interface.

Claims (1)

[Scope of Claims] 1. A storage device that stores one or more functions representing a relationship between a temperature in a predetermined range and an output voltage from a temperature sensor;
In the temperature input correction device including an arithmetic device that calculates the function to obtain a corrected temperature, the predetermined temperature range (TNL to
New temperature range (TRL to TRH) different from TNH)
The storage device includes a storage unit that stores the values of A temperature input correction device that calculates a temperature coordinate Xi and an output voltage coordinate Yi in a new temperature range from coordinate data (xi, yi) representing a temperature-output voltage relationship in a predetermined temperature range. 2. The temperature input correction device according to claim 1, wherein the function is a linear function. 3. The temperature input correction device according to claim 1, wherein each coordinate data is given as percentage data.