CN114383758A - Multichannel thermal resistance input module calibration equipment and system - Google Patents
Multichannel thermal resistance input module calibration equipment and system Download PDFInfo
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- CN114383758A CN114383758A CN202011110288.XA CN202011110288A CN114383758A CN 114383758 A CN114383758 A CN 114383758A CN 202011110288 A CN202011110288 A CN 202011110288A CN 114383758 A CN114383758 A CN 114383758A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K15/00—Testing or calibrating of thermometers
- G01K15/005—Calibration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
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Abstract
The invention provides a multichannel thermal resistance input module calibration device and system, comprising: the precision resistor is connected with a channel to be verified of the multi-channel thermal resistor input module and generates a voltage through a constant current source configured on the multi-channel thermal resistor input module; the voltage sampling module is used for collecting sampling voltage on the precision resistor; the micro-processing module is connected with the voltage sampling module and used for acquiring a constant current value of the constant current source based on the sampling voltage and the precision resistor and calculating a voltage value corresponding to the thermal resistor to be output based on the constant current value and the thermal resistor to be output; and the voltage output module is connected with the micro-processing module and used for outputting the voltage value to the multi-channel thermal resistance input module. The multi-channel thermal resistance input module calibration device and the multi-channel thermal resistance input module calibration system realize the calibration of each channel of the thermal resistance input module based on the voltage signal, effectively improve the calibration accuracy and reduce the volume of the calibration device.
Description
Technical Field
The present invention relates to a calibration apparatus, and more particularly, to a calibration apparatus and system for a multi-channel thermal resistance input module.
Background
Thermal resistance (thermal resistor) is the most commonly used temperature detector in the middle and low temperature region, and is used for measuring temperature based on the characteristic that the resistance value of a metal conductor increases along with the increase of temperature, and has the advantages of high measurement precision and stable performance. Therefore, the thermal resistor is not only widely used for industrial temperature measurement, but also made into a standard reference instrument.
Therefore, accurate measurement of thermal resistance is of great significance. The multi-channel thermal resistance input module is a commonly used thermal resistance acquisition device. In the prior art, a mode of switching a precision resistor by a relay is usually adopted to realize the verification of a multi-channel thermal resistor input module. However, the verification method has the following disadvantages:
(1) the device required by calibration is large in size;
(2) the checking precision is not good.
Disclosure of Invention
In view of the above drawbacks of the prior art, an object of the present invention is to provide a multi-channel thermal resistance input module calibration apparatus and system, which implement calibration of each channel of a thermal resistance input module based on a voltage signal, effectively improve calibration accuracy, and reduce the volume of the calibration apparatus.
To achieve the above and other related objects, the present invention provides a multi-channel thermal resistance input module verification apparatus, comprising: the precision resistor is connected with a channel to be verified of the multi-channel thermal resistor input module and generates a voltage through a constant current source configured on the multi-channel thermal resistor input module; the voltage sampling module is used for collecting sampling voltage on the precision resistor; the micro-processing module is connected with the voltage sampling module and used for acquiring a constant current value of the constant current source based on the sampling voltage and the precision resistor and calculating a voltage value corresponding to the thermal resistor to be output based on the constant current value and the thermal resistor to be output; and the voltage output module is connected with the micro-processing module and used for outputting the voltage value to the multi-channel thermal resistance input module.
In an embodiment of the present invention, the constant current source is an ADS1248 chip.
In an embodiment of the present invention, the voltage sampling module employs an ADS1252 chip.
In an embodiment of the present invention, the voltage sampling module includes a filter circuit and a voltage sampling module, and the filter circuit is configured to filter a voltage value obtained by converting a constant current source output by the channel to be verified through the precision resistor; the voltage sampling module is used for sampling the filtered voltage.
In an embodiment of the present invention, the voltage output module includes a digital-to-analog converter, a voltage dividing circuit, a filter circuit, and a voltage follower; the digital-to-analog converter is used for converting the reference digital voltage into a reference analog voltage; the voltage division circuit is used for dividing the reference analog voltage to obtain the voltage value; the filter circuit is used for filtering the voltage value; the voltage follower is used for outputting a filtered voltage value.
In an embodiment of the present invention, the DAC7631 chip is used as the DAC.
In an embodiment of the invention, the reference digital voltage is 0V-2.5V.
In an embodiment of the present invention, the voltage dividing circuit employs two voltage dividing resistors; the resistance values of the divider resistors are 20K omega and 5K omega respectively.
In an embodiment of the invention, the voltage follower employs a negative feedback operational amplifier.
In addition, the invention provides a multi-channel thermal resistance input module calibration system, which comprises a multi-channel thermal resistance input module, an upper computer and the multi-channel thermal resistance input module calibration device;
the upper computer is used for sending a checking instruction to the multichannel thermal resistance input module checking device so as to enable the multichannel thermal resistance input module checking device to be connected with a channel to be checked of the multichannel thermal resistance input module and check a thermal resistance to be output of the channel to be checked;
the multichannel thermal resistance input module is used for storing the voltage value of the channel to be verified under the control of the upper computer.
As described above, the multi-channel thermal resistance input module calibration device and system of the present invention have the following beneficial effects:
(1) the verification of each channel of the thermal resistance input module is realized based on the voltage signal, the realization of a hardware system is facilitated, and a large-size device and a line resistance which is difficult to offset are avoided by switching a precise resistance verification module;
(2) the calibration accuracy of the multi-channel thermal resistance input module is effectively improved;
(3) the delivery qualification rate and the production efficiency of the multi-channel thermal resistance input module are effectively improved, and the equipment cost and the labor cost required by the multi-channel thermal resistance input module are reduced;
(4) data support is provided for digital production and continuous improvement of the multi-channel thermal resistance input module.
Drawings
FIG. 1 is a schematic structural diagram of a multi-channel thermal resistance input module verification apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a conversion circuit for converting a current signal output by a constant current source into a voltage signal according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a filter circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a voltage sampling module according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a voltage output module according to an embodiment of the present invention;
FIG. 6 is a circuit diagram of a multi-channel thermal resistance input module verification system according to an embodiment of the present invention.
Description of the element reference numerals
1 precision resistor
2 voltage sampling module
3 micro-processing module
4 voltage output module
61 multichannel thermal resistance input module
62 upper computer
63 multichannel thermal resistance input module verifying attachment
Detailed Description
The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.
It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
The multichannel thermal resistance input module calibration device and the multichannel thermal resistance input module calibration system realize the calibration of each channel of the thermal resistance input module through the output of the voltage signal, replace the calibration mode of directly adopting the thermal resistance signal, effectively improve the calibration accuracy, reduce the volume of the calibration device and have practicability.
In the invention, the multi-channel thermal resistance input module can realize the thermal resistance input of a plurality of channels. In one embodiment, the parameters of the multi-channel thermal resistance input module are shown in table 1.
TABLE 1 multichannel thermal resistance input Module parameters
According to the technical indexes, the thermal resistance input module selects 18 omega and 320 omega as upper and lower limit standard values of the PT100 division number, selects 40 omega and 80 omega as upper and lower limit standard values of the Cu50 division number, and selects 50 omega and 150 omega as upper and lower limit standard values of the Cu100 division number.
The constant current source of the thermal resistance input module adopts an ADS1248 chip, the ADS1248 chip has a double constant current source output function, the constant current source outputs 1mA, and the resistance value of the input thermal resistance is calculated by a sampling voltage value obtained by the constant current source flowing through the standard thermal resistance. For example, if the index number of a channel is PT100, the high-end verification value is PTH, the low-end verification value is PTL, and the sampling voltage value of the channel is n, the thermal resistance value OM of the channel is calculated as OM ═ n/(PTH-PTL) + 18.
As shown in fig. 1, in an embodiment, the multi-channel thermal resistance input module verification apparatus of the present invention includes a precision resistor 1, a voltage sampling module 2, a micro-processing module 3, and a voltage output module 4.
The precision resistor 1 is connected with a channel to be verified of the multi-channel thermal resistor input module and generates a voltage through a constant current source configured on the multi-channel thermal resistor input module.
Specifically, the constant current source of the configuration of the multi-channel thermal resistance input module itself can supply a constant current to each channel. In an embodiment of the present invention, the constant current source of the thermal resistance input module adopts an ADS1248 chip, which has a dual constant current source output function and outputs a constant current source of 1mA, so as to convert a precise resistance signal accessed by a channel to be verified into a voltage signal, so as to obtain a precise constant current value of the constant current source for calculation, thereby facilitating sampling by a subsequent voltage sampling module.
And the voltage sampling module 2 is connected with the precision resistor 1 and is used for sampling a voltage value which is output by the channel to be verified and obtained by converting the constant current source through the precision resistor.
Specifically, the constant current supplied from the constant current source generates a voltage across the precision resistor 2 via the precision resistor 1. The voltage sampling module 2 samples the voltage to obtain a specific voltage value. As shown in fig. 2, when the precision resistor is set to 1.5K Ω and the constant current source is set to 1mA, a voltage of 1.5V can be converted.
In an embodiment of the present invention, the voltage sampling module 2 includes a filter circuit and a voltage sampling module, and the filter circuit is configured to filter a voltage value obtained by converting the precision resistor connected to the channel to be verified through the constant current source, so as to remove noise interference. Preferably, the filter circuit is as shown in fig. 3. The voltage sampling module is used for sampling the filtered voltage. Preferably, the voltage sampling module adopts an ADS1252 chip, and the circuit connection is as shown in fig. 4. The ADS1252 chip is a high-precision AD converter, has 24-bit effective resolution, and can ensure the sampling precision of the multi-channel thermal resistance input module calibration device.
The micro-processing module 3 is connected with the voltage sampling module 3, and is used for acquiring a constant current value of the constant current source based on the sampling voltage and the precision resistor, and calculating a voltage value corresponding to the thermal resistor to be output based on the constant current value and the thermal resistor to be output.
Specifically, the microprocessor module 3 calculates an accurate constant current value of the constant current source according to the sampling voltage and the precise resistor. And when the thermal resistor to be output is connected to the multi-channel thermal resistor input module, multiplying the thermal resistor to be output by the constant current value to obtain a voltage value corresponding to the thermal resistor to be output.
And the voltage output module 4 is connected with the micro-processing module 3 and is used for outputting the voltage value to the multi-channel thermal resistance input module.
In an embodiment of the present invention, as shown in fig. 5, the voltage output module 4 includes a digital-to-analog converter, a voltage dividing circuit, a filter circuit, and a voltage follower; the digital-to-analog converter is used for converting the reference digital voltage into a reference analog voltage; the voltage division circuit is used for dividing the reference analog voltage to obtain the voltage value; the filter circuit is used for filtering the voltage value; the voltage follower is used for outputting a filtered voltage value. In an embodiment of the invention, the voltage follower employs a negative feedback operational amplifier.
In an embodiment of the present invention, the DAC7631 chip is used as the DAC. Is provided withThe maximum sampling range of the constant-heat resistor is 18.52-390.481 omega, and the converted voltage range is 18.52-390.481 mV. The DAC7631 chip is a 16-bit single-channel output DA converter, an external reference source is set to be 2.5V, and the output voltage formula of the DAC is as follows: vout＝Vref L+N*(Vref H-VrefL)/65536 its output voltage is limited by power supply, and its maximum output voltage is not lower than VrefL is not more than VrefH. Therefore VrefH is 2.5V, VrefL is 0V, the output voltage of the DAC7631 chip is controlled to be 0-2.5V, two resistors of 20K omega and 5K omega are connected in series with an output pin, voltage division output is controlled to be 0-500mV, and therefore the voltage output module 4 outputs a sampled voltage value.
As shown in fig. 6, in an embodiment, the multi-channel thermal resistance input module verification system of the present invention includes a multi-channel thermal resistance input module 61, an upper computer 623, and the multi-channel thermal resistance input module verification device 63.
The upper computer 62 is connected with the multichannel thermal resistance input module calibration device 63 and is used for sending a calibration instruction to the multichannel thermal resistance input module calibration device 61, so that the multichannel thermal resistance input module calibration device is connected with a channel to be calibrated of the multichannel thermal resistance input module, and the input thermal resistance of the channel to be calibrated is calibrated. Preferably, the upper computer 62 and the multichannel thermal resistance input module calibration device 63 communicate through a preset communication device. The communication device may be a wired communication device or a wireless communication device.
The multichannel thermal resistance input module 61 is connected with the multichannel thermal resistance input module calibration device 63 and used for storing the voltage value of the channel to be calibrated under the control of the upper computer 62. Specifically, when the voltage value output by the multichannel thermal resistance input module calibration device 63 is stable, the upper computer 62 enables the multichannel thermal resistance input module 63 to store the voltage value of the channel to be calibrated.
In summary, the multi-channel thermal resistance input module calibration device and system of the invention can realize calibration of each channel of the thermal resistance input module based on the voltage signal, which is more beneficial to realization of a hardware system, and avoids large-volume devices and line resistance which is difficult to offset by switching the precise resistance calibration module; the calibration accuracy of the multi-channel thermal resistance input module is effectively improved; the delivery qualification rate and the production efficiency of the multi-channel thermal resistance input module are effectively improved, and the equipment cost and the labor cost required by the multi-channel thermal resistance input module are reduced; data support is provided for digital production and continuous improvement of the multi-channel thermal resistance input module. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. The utility model provides a multichannel thermal resistance input module calibration equipment which characterized in that: the method comprises the following steps:
the precision resistor is connected with a channel to be verified of the multi-channel thermal resistor input module and generates a voltage through a constant current source configured on the multi-channel thermal resistor input module;
the voltage sampling module is used for collecting sampling voltage on the precision resistor;
the micro-processing module is connected with the voltage sampling module and used for acquiring a constant current value of the constant current source based on the sampling voltage and the precision resistor and calculating a voltage value corresponding to the thermal resistor to be output based on the constant current value and the thermal resistor to be output;
and the voltage output module is connected with the micro-processing module and used for outputting the voltage value to the multi-channel thermal resistance input module.
2. The multi-channel thermal resistive input module verification device of claim 1, wherein: the constant current source adopts an ADS1248 chip.
3. The multi-channel thermal resistive input module verification device of claim 1, wherein: the voltage sampling module adopts an ADS1252 chip.
4. The multi-channel thermal resistive input module verification device of claim 1, wherein: the voltage sampling module comprises a filter circuit and a voltage sampling module, and the filter circuit is used for filtering a voltage value obtained by converting a constant current source output by the channel to be verified through the precision resistor; the voltage sampling module is used for sampling the filtered voltage.
5. The multi-channel thermal resistive input module verification device of claim 1, wherein: the voltage output module comprises a digital-to-analog converter, a voltage division circuit, a filter circuit and a voltage follower; the digital-to-analog converter is used for converting the reference digital voltage into a reference analog voltage; the voltage division circuit is used for dividing the reference analog voltage to obtain the voltage value; the filter circuit is used for filtering the voltage value; the voltage follower is used for outputting a filtered voltage value.
6. The multi-channel thermal resistive input module verification device of claim 5, wherein: the digital-to-analog converter adopts a DAC7631 chip.
7. The multi-channel thermal resistive input module verification device of claim 5, wherein: the reference digital voltage is 0V-2.5V.
8. The multi-channel thermal resistive input module verification device of claim 5, wherein: the voltage division circuit adopts two voltage division resistors; the resistance values of the divider resistors are 20K omega and 5K omega respectively.
9. The multi-channel thermal resistive input module verification device of claim 5, wherein: the voltage follower adopts a negative feedback operational amplifier.
10. A multichannel thermal resistance input module check-up system which characterized in that: the multi-channel thermal resistance input module verifying device comprises a multi-channel thermal resistance input module, an upper computer and the multi-channel thermal resistance input module verifying device as claimed in any one of claims 1 to 9;
the upper computer is used for sending a checking instruction to the multichannel thermal resistance input module checking device so as to enable the multichannel thermal resistance input module checking device to be connected with a channel to be checked of the multichannel thermal resistance input module and check a thermal resistance to be output of the channel to be checked;
the multichannel thermal resistance input module is used for storing the voltage value of the channel to be verified under the control of the upper computer.
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| CN115452179A (en) * | 2022-11-07 | 2022-12-09 | 四川天利科技有限责任公司 | Multi-channel real-time self-calibration thermocouple cold end temperature measurement method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115452179A (en) * | 2022-11-07 | 2022-12-09 | 四川天利科技有限责任公司 | Multi-channel real-time self-calibration thermocouple cold end temperature measurement method |
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