JP2003222544A - Digital panel instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a cost by facilitating inventory control, when manufacturing many kinds of digital panel instruments. <P>SOLUTION: This digital panel instrument is constituted of units classified and divided into a plurality of function units. An EEPROM is provided in a unit including an electronic circuit requiring adjustment of a characteristic value, and a constitution test is performed in the unit step to determine a correction value. The correction value is recorded and set in the EEPROM, and, when measurement is performed by an instrument constituted by integrating the units selectively, correction operation is performed based on the correction value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on a control panel or the like for processing and digitally displaying electric signals indicating various physical quantities such as voltage and current which are electrically detected by a detector. It relates to a digital panel instrument used.

[0002]

2. Description of the Related Art A digital panel instrument is a general-purpose instrument for measuring and displaying the detected physical quantity in combination with a detector (sensor) for detecting various physical quantities. The configuration is adapted to the width of the measurement range, etc. Therefore, in order to apply the digital panel instrument to a wide range, it is necessary to prepare many kinds of instruments. When a large number of types of digital panel instruments are prepared in this way, not only the direct manufacturing cost of the product but also the production management cost such as production process management and product inventory management will increase. It becomes high and is not preferable.

In order to reduce the product cost, conventionally, for each functional unit of a digital panel instrument, for example, a display section for displaying data, a signal processing section for converting a detection signal into a digitally displayable signal, etc. It has been practiced to manufacture functional units by dividing them into two types, prepare each functional unit for each required type, and selectively assemble each functional unit to assemble a meter with required specifications.
According to this method, since many parts are standardized as a unit, mass production is possible and direct manufacturing cost can be reduced.

[0004]

However, in such a digital panel instrument, an error may occur in the measured value due to variations in the characteristic values of the electronic parts constituting the electronic circuit in the signal processing section or the like. . Until now, such an error has been corrected by a calibration test for a product whose assembly has been completed by selectively combining functional units according to required specifications. In order to ship the digital panel instrument from the factory, it is necessary to perform such a calibration test to correct and eliminate various errors.

Therefore, the conventional digital panel instrument, even if it is unitized, is not effective in reducing the cost for inventory control because the completed product which has undergone the calibration test is inventoried. .

In view of the above, according to the present invention, a digital panel instrument is stocked in units of incomplete functional units, and the functional units in stock at the time of shipping are selectively combined so that the product can be assembled and shipped immediately. It is an object of the present invention to reduce the cost of inventory management and to provide a low-cost digital panel instrument.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides an input signal processing configured according to the type of a detection target for performing processing such as level conversion of a detection signal input from at least a detector. A unit and a display processing unit which is coupled to the input signal processing unit and which converts a signal from the input signal processing unit into a digital display signal to display by a digital display and is selected according to required specifications. In a digital panel instrument configured by combining the input signal processing unit and the display processing unit, each unit is provided with a rewritable read-only memory, and the unique data of each unit and each unit are implemented. Record the data to correct the characteristic error obtained by the calibration test, and measure it. Sometimes it is characterized in that to perform the correction operation of the display data based on the correction data.

Further, in the above invention, an external output unit for performing processing for outputting the data displayed on the display processing unit and a signal based on this data to the outside is provided, and this unit is selectively used as the display processing unit. Can be combined with. Of course, this external output unit is equipped with a rewritable read-only memory in which the correction data obtained by the calibration test is recorded in the same way as other units, and the correction calculation of the output data is performed during actual use. Can be

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described with reference to the embodiments shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 to 4 are functional units constituting a digital panel instrument. Reference numeral 1 denotes an input signal processing unit (simply referred to as an input unit, which performs processing such as converting a signal level into a unit according to the type of a detection signal input from a detector (not shown), shaping the waveform, and the like. Sometimes called). Plural types of the input signal processing unit 1 are prepared corresponding to the type of the detection target, the measurement range, and the like. Here, an example of a DC voltage input signal processing unit having four measurement ranges of DC voltage of 1, 10, 100 and 600 V is shown.

The input unit 1 includes four input terminals I1 to I4 to which a DC voltage detection signal is selectively input according to a measurement range, a multiplexer 11 for selecting one of these input terminals, This multiplexer 11
A read-only memory (hereinafter referred to as an EEPROM) 13 that is electrically rewritable is provided with an operational amplifier 12 that performs level conversion of a detection signal applied via.

Reference numeral 2 denotes a display processing unit (which may be simply referred to as a display unit) which converts the signal processed by the input unit 1 into a digital display signal and displays it on a digital display. The display processing unit 2 includes a microcomputer 21 and a digital display 22 programmed to perform calculation and control for overall measurement and display, and setting operation keys 23a to 23d for performing various settings and operations. Is equipped with. Reference numeral 23a is an enter key, 23b is a mode selection key, 23c is a shift key, and 23d is an increment key.

Reference numeral 3 denotes a main unit including a power supply circuit 31, an A / D converter 32 and an EEPROM 33, which supplies power from the power supply circuit 31 to all units, and
When the signal processed by the input unit 1 is an analog signal by the / D converter 32, the analog signal output from the input unit 1 is converted into a digital signal and output to the display unit 2. Since the main unit 3 and the display unit 2 are units commonly prepared for all digital panel instruments, it is possible to combine them into one unit, but here, for convenience of design and manufacture, It is divided into

Reference numeral 4 denotes an external output unit for outputting the data displayed on the display unit 2 to the outside, which is optionally prepared. This external output unit 4
Is a non-contact output circuit 41 composed of an electronic relay circuit for comparing the measured value with a set value and outputting a comparison result (so-called meter relay function), a contact output circuit 42 composed of an electromagnetic relay, and a digital display 22. Digital output signal of the RS-232C format or RS-485 format for outputting the display data of the above to the outside or exchanging the data by connecting to the external computer and the digital signal displayed on the display 22. Analog output circuit 44 and EE for converting the analog signal into an analog signal for output
It has a PROM 45.

In each unit, the terminal with the symbol T is an input or output terminal for signal, and the terminal with P is an input or output terminal for power supply.

EEPR in units 1, 3 and 4
The OM includes operational amplifiers 12 and A, each of which requires a calibration test for correcting an error in a characteristic value after completion.
It is provided to record and set a correction value based on a calibration test of an electronic circuit such as the analog output circuit 44 including the / D converter 32 and a D / A converter (not shown).

These units are manufactured in units of factories at the factory, are in stock, and each unit selected in accordance with the required specifications is combined to be assembled into a desired digital panel instrument and shipped as a product.

When the digital panel instrument having the above-mentioned configuration has a plurality of measurement ranges as in the illustrated embodiment, the measurement range to be applied is set when the actual measurement is used. It can be set by the operation of. When a detection signal from a voltage detector (not shown) is applied to, for example, the input terminal I1 of the selected 1V range of the input unit 1, the multiplexer 11 is activated by a command from the microcomputer 21 based on preset measurement range setting data. The detection signal at the terminal I1 is selected and transmitted to the input of the operational amplifier 12. The signal level-converted by the amplifier 12 is converted into a digital signal by the A / D converter 32 of the main unit 3 and input to the microcomputer 21 of the display unit 2. The microcomputer 21 reads this digital signal, converts it into digital display data, sends it to the digital display 22, and displays it on the digital display 22. If necessary, the display data is added to the external output unit 4 so that a comparison signal from the non-contact output circuit 41, the contact output circuit 42, the digital input / output circuit 43 and the analog output circuit 44 of this unit,
It can be output to the outside as a digital signal or an analog signal.

In the present invention, when each unit is completed, a calibration test is performed for each unit, and a correction value for correcting the error of the characteristic value of the unit obtained there is recorded and set in the EEPROM of each unit. By doing so, it is not necessary to carry out a calibration test after combining each unit into a finished product of a digital panel instrument.

The procedure of the calibration test according to the present invention will be described. (1) Calibration test of main unit (see FIG. 2) The main unit 3 to be tested is replaced with the input signal processing unit 1 and a calibration tester and a display processing unit 2 (not shown) prepared for calibration are combined to perform a calibration test.

After the power is turned on (S1), the check mode is set (S2), the operation setting keys (23a to 23d) or the external output unit 4 is added, and the external computer is connected through the digital input / output circuit 43. Command to indicate the calibration mode of the main unit [MA
IN] is input (S3), and the display 22 of the display unit 2 is input.
"MEMo" indicating that it is a calibration mode is displayed on the screen (S4).

Mode key 23b or command [J]
When (jump) is input (S5), the offset value measurement mode is entered. To show this, the digital display 2
2 indicates whether to blink the decimal point segment of 10 ⁰ digits, or "oFF" (S6).

Here, the input terminal T3 of the main unit 3
When a DC calibration voltage of 0 V is applied to 1 from the calibration tester (S7), the output of the A / D converter 32 of the main unit 3 at that time is read as an offset value (Mg),
It is displayed on the display 22 (S8).

When the shift key 23c for advancing the step or the [N] (next) command is input (S9), the read offset value Mg is compared with the preset calibration judgment value Mgs and whether Mg is in the range of Mgs or not. It is determined whether or not (S10). If Mg is not within the range of Mgs, it is determined that an error has occurred, and the progress to the next step is stopped.
"Err" (error) is displayed on the display 22 (S1)
1). If an error is displayed in this way, it is not possible to proceed with the subsequent operation, so it is necessary to take measures to eliminate the cause, such as by replacing parts, and then start over.

As a result of the comparison, if Mg is within the range of Mgs, the indicator 22 indicates 10 ³ to indicate that it is normal.
The decimal point segment of the digit is displayed in a blinking manner, or "FSC" is displayed on the display 22 and the full scale measurement mode is set (S12). Here, when a DC calibration voltage of 1V is applied from the calibration tester to the input terminal T31 as a full-scale input (S13), the A / D of the main unit 3 is
The digital value of the output of the converter 32 is the full-scale value Mh
Is read, and the value is displayed on the display 22 (S14).

Next, when the mode key 23b or the command [J] is input (S15), the read Mh is compared with the preset calibration judgment value Mhs to judge the correctness of the A / D converter 32 (S16). .

If Mh is outside the range of Mhs, "Er
r ”(error) is displayed, and the process to the next step is stopped. If such an error occurs, a procedure for eliminating the cause of the error in the main unit 3 is performed, and then the process is restarted from the beginning. It must be (S17).

If Mh is within the range of Mhs, that value is taken in as a full-scale value, and internally a calculation for obtaining the correction value ML is performed by the following equation (1). The value Mg value is written in the EEPROM 33 of this unit as correction data (S1
8) Then, "MEMo" is displayed on the display unit 22 to indicate that the calibration mode has ended (S19).

ML = Mj / (Mh−Mg) (1) However, Mj is an arbitrary set value of the value output when a signal of 1 V is applied to the input of the A / D converter 32, for example, It is set to 12000. That is, the A / D converter 32 is designed and adjusted to output a digital value of 12000 when an input of 1V is applied.

The display value Y displayed on the digital display 22 at the time of actual measurement is calculated by the microcomputer 21 using the correction value ML and the offset value Mg thus recorded and set in the EEPROM 33. ) Is obtained by performing an operation such as the formula.

Y = (M−Mg) × ML (2) where M is the output value of the A / D converter 32 at each time. (2) Calibration test of the input signal processing unit (see FIG. 3) The calibration of the input signal unit 1 is performed by combining the main unit 3 and the display processing unit 2 which are calibrated in advance. When controlling using an external computer,
An external output unit 4 is added to this, and an external computer is connected through the digital input / output circuit 43.

When the power is turned on (S31), the check mode is entered, and it is confirmed that "cHk" is displayed on the display 22 (S32), and the command [U-in] for performing the calibration test of the input unit is issued. Operation setting key 23a-
23d or input from an external computer (S3
3). As a result, "U-in" indicating the input unit calibration test mode is displayed on the display 22 (S34).

Mode key 23b or command [J]
When (jump) is input (S35), the first range to be calibrated and tested is displayed on the display 22 for a predetermined time (about 1 second), for example, "r-1" (range 1), and then the offset value is displayed. or digital display 22 is flashing decimal point segment of 10 ⁰ digit is a measurement mode,
Alternatively, "oFF" is displayed (S36). Here, when a DC calibration voltage of 0 V is applied from the calibration tester to the input terminal I1 of the range 1 of the input unit 1 (S37), the output of the A / D converter 32 of the main unit 3 at that time is the offset value g. Is displayed on the display 22 (S38).

When the shift key 23c for advancing the step or the command [N] (next) is input (S39),
The offset value g at this time is the microcomputer 21.
And the read offset value g is compared with a preset calibration determination value gs, and the process proceeds to step (S40) for determining whether or not g is in the range of gs,
If it is not within this range, it is judged as an error, the process to the next step is stopped, and "Err" (error) is displayed on the display 22 (S41). When an error is displayed in this way, it is necessary to replace the part, take measures to eliminate the cause, and then start over from the beginning. As a result of the comparison, if g is within the range of gs, the display unit 22 blinks the decimal point segment of 10 ³ digits or the display unit 22 displays “FSC” to indicate that it is normal. The process moves to the next full-scale value measurement mode (S42).

Here, in the case where the full-scale input value predetermined for the range is input terminal I1, for example, 1 V range, 0.98 from the calibration tester.
When a DC calibrating voltage of V is applied (S43), the digital value of the output of the A / D converter 32 of the main unit 3 is read as the full scale value h, and the value is displayed on the display 22 (S44). Then, when the mode key 23b or the [J] command for advancing to the next step is input (S
45), and compares the full scale value h with a preset calibration determination value hs of the full scale value to determine the operational amplifier 1
The correctness of 2 is determined (S46).

If h is outside the range of hs, "Err"
(Error) is displayed and the process to the next step is stopped. When such an error occurs, the input unit 1
After the action to eliminate the cause of the error is performed, the process must be started again from the beginning (S47).

If h is within the range of hs, the value is taken in as a full scale value and internally calculated based on the following equations (3) and (4) to obtain the correction values a and b. , Write this in the EEPROM 13 of this unit as the correction data of range 1 of this unit,
Set (S48). When this is finished, it is judged whether or not the range being tested is the final range (S4
9) If it is not the final range, return to step S36, shift to the calibration mode for the next range 2, repeat the same procedure thereafter, and complete calibration for all ranges.
"U-in" is displayed on the display unit 22 to indicate that the calibration mode has ended (S50).

A = (j−i) / (h−g) (3) Here, j is a predetermined constant, and for example, in the case of the 1V range, it is determined as a full-scale value for calibration. It is set to 9800 corresponding to 0.98V.
Further, i is a constant of an offset value determined for calibration, and is normally set to 0.

B = i− (g × a) (4) At the time of actual measurement, the display value Y ′ of the digital display 22 corresponding to the detection signal applied to the input terminal I1 is recorded and set in the EEPROM 13 described above. Using the corrected values a and b, the following (5) is performed by the microcomputer 21.
It is obtained by performing an operation like an expression.

Y ′ = a × Y + b (5) where Y is the output value of the A / D converter 32 at the time of measurement.

Main unit 3 constructed as described above
The total correction calculation at the time of measurement when combined with the input unit 1 is performed by using the correction values a, b, ML and Mg recorded and set in the EEPROMs 13 and 33, and (5)
The equation (6) is obtained by substituting the equation (2) into the equation, and the error in assembling each unit is compensated by this.

Y ′ = a × [(M−Mg) × ML] + b (6) As described above, in the present invention, the configuration test is performed for each functional unit, and the correction data obtained at that time are respectively obtained. In the digital panel instrument that is assembled by combining the units by recording and setting it in the EEPROM in advance,
Since the correction calculation of the display value is performed based on the correction data set in the ROM, the calibration test after the product is completed is unnecessary and the product can be shipped immediately after being assembled.

(3) Calibration test of the external output unit The calibration test of the external output unit 4 is combined with the calibration-tested input unit 1, display unit 2 and main unit 3 to perform the calibration test of the above two units. The same procedure is carried out, and the correction value obtained by this test is recorded and set in the EEPROM 45, so a detailed description thereof will be omitted.

EEPROM 1 provided in each unit
In addition to the correction values obtained by the above-mentioned calibration test, data indicating the format and specifications of each unit are recorded in 3, 33, and 45. Therefore, when each unit is coupled to the display unit 2, the type and the correction value of the coupled unit are read by the microcomputer, and automatic adjustment is performed according to the type of each unit, etc. Is not needed at all.

[0046]

According to the present invention, as is apparent from the above description, an input signal processing unit configured according to the type of a detection target for performing processing such as level conversion of a detection signal input from a detector, and an input signal processing unit A display processing unit which is coupled to an input signal processing unit, converts a signal from the input signal processing unit into a digital display signal and displays the digital display signal, and the input selected according to required specifications In a digital panel instrument configured by combining a signal processing unit and a display processing unit, each unit is provided with a rewritable read-only memory, and this memory is provided with unique data of each unit and a calibration test conducted for each unit. Record the data to correct the obtained characteristic error, and Since the correction calculation of the display data is performed based on the correction data of the above, in the case of manufacturing at the factory, it is stocked in functional unit units and assembled by selectively combining the necessary units according to the required specifications. Since the finished product can be shipped immediately without performing a calibration test, the finished product does not need to be in stock, and the effect of significantly reducing the inventory management cost can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a calibration procedure of the main unit according to the present invention.

FIG. 3 is a flowchart showing a calibration procedure of the input signal processing unit according to the present invention.

[Explanation of symbols]

1 Input signal processing unit 11 multiplexer 12 Operational amplifier 13 EEPROM 2 Display processing unit 21 Microcomputer 22 Digital display 23a-23d operation setting key 3 main unit 31 power supply circuit 32 A / D converter 33 EEPROM 4 External output unit 41 Non-contact output circuit 42 contact output circuit 43 Digital I / O circuit 44 analog output circuit 45 EEPROM

Claims (3)

[Claims] 1. An input signal processing unit configured according to a type of a detection target for performing processing such as level conversion of a detection signal input from a detector, and a signal from the input signal processing unit is converted into a digital display signal. And a display processing unit for displaying with a digital display is provided, and in each of the digital panel meters configured by combining the input signal processing unit and the display processing unit selected according to the required specifications, each unit is A rewritable read-only memory is provided, and the data unique to each unit and the data for correcting the characteristic error obtained by the calibration test conducted for each unit are recorded in this memory, and based on this correction data at the time of measurement. Digital panel characterized by performing correction calculation of display data Instrument. 2. The digital panel instrument according to claim 1, further comprising an external output unit for performing processing for outputting data displayed on the display processing unit and a signal based on the data to the outside, and displaying this unit on the display. A digital panel instrument characterized by being selectively connectable to a processing unit. 3. The digital panel instrument according to claim 2, wherein the external output unit is provided with a rewritable read-only memory, and correction data obtained by a calibration test of this unit is recorded for actual use. A digital panel instrument characterized by performing correction calculation of output data based on this correction data.