WO2018179372A1 - Analog input unit and reference voltage stabilizing circuit - Google Patents
Analog input unit and reference voltage stabilizing circuit Download PDFInfo
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- WO2018179372A1 WO2018179372A1 PCT/JP2017/013706 JP2017013706W WO2018179372A1 WO 2018179372 A1 WO2018179372 A1 WO 2018179372A1 JP 2017013706 W JP2017013706 W JP 2017013706W WO 2018179372 A1 WO2018179372 A1 WO 2018179372A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
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- 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
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- the present invention provides an analog input unit that can be connected to a resistance temperature detector, connected to a current output sensor, and connected to a voltage output sensor by a switch, and can be applied to the analog input unit.
- the present invention relates to a reference voltage stabilization circuit.
- the sensor connected to the input terminal of the analog input unit includes a resistance temperature detector that detects temperature, a current output sensor that detects physical quantities such as pressure and flow rate, or a voltage output sensor.
- a resistance temperature detector that detects temperature
- a current output sensor that detects physical quantities such as pressure and flow rate
- a voltage output sensor Conventionally, there is an analog input unit that can connect these sensors and can selectively connect various sensors to input terminals by incorporating a circuit that executes input processing according to the sensor input specifications. (For example, the following patent document 1).
- AD Analog-to-Digital
- Patent Documents 1 and 2 when an input is selected by switching an internal switch according to a connected sensor, a leakage current is generated in a circuit not selected through the switch. It will flow. Due to this leakage current, there is a problem that a current necessary for a circuit that should flow originally is not supplied.
- the reference voltage is generated by passing a current through the reference resistor.
- the current that should originally flow is reduced by the leakage current.
- the reference voltage varies.
- the resolution and accuracy required for AD conversion are reduced. From the above viewpoint, when a sensor that needs to generate a reference voltage is connected to an analog input unit, a mechanism for keeping the reference voltage constant with high accuracy is required.
- the present invention has been made in view of the above, and even when a sensor is connected to an analog input unit that needs to generate a reference voltage, a reference caused by a leak current that can occur when switching the sensor input
- An object of the present invention is to provide a reference voltage stabilization circuit capable of reducing voltage fluctuation.
- an analog input unit includes an input terminal that can input an analog value from an analog sensor, a switch that enables selection or non-selection of the analog sensor, and selection
- An AD converter that converts an analog value from the analog sensor into a digital value, a reference resistor that generates a reference voltage that is referenced by the AD converter, and a reference voltage stabilization circuit that is connected in parallel to the reference resistor.
- FIG. 1 The figure which shows the structure of the input process part in the analog input unit which concerns on embodiment
- the figure which shows the state by which the three-wire type resistance thermometer was connected to the analog input unit shown in FIG. 1 is a circuit diagram showing the internal configuration of the reference voltage stabilization circuit shown in FIGS.
- FIG. 1 is a diagram illustrating a configuration of an input processing unit in the analog input unit according to the embodiment.
- an analog input unit 1 includes input terminals 2, 3, 4, and 5 used for at least one of a three-wire resistance thermometer, a voltage output sensor, and a current output sensor. More specifically, the input terminals 2 and 3 are voltage input terminals for a three-wire resistance thermometer.
- the input terminal 4 is a current input terminal for the three-wire resistance thermometer, and is also used as a voltage input terminal for the voltage output sensor and a current input terminal for the current output sensor.
- the input terminal 5 is a voltage input terminal of the voltage output sensor and a current input terminal of the current output sensor.
- thermometer voltage output sensor
- current output sensor current output sensor
- input terminals 2, 3, 4, and 5 are examples, and any terminals may be used as long as at least one of the voltage value and the current value can be input.
- the analog input unit 1 can select or deselect an AD converter 6 that converts an input analog value into a digital value, a reference resistor 7 that generates a reference voltage referenced by the AD converter 6, and an analog sensor.
- the switches 8 and 9 are further provided. More specifically, the switch 8 selects an input of a current supplied from the three-wire temperature measuring resistor, an applied voltage from the voltage output sensor, or a supply current from the current output sensor.
- the switch 9 selects an input of an applied voltage from the voltage output sensor or a supply current from the current output sensor.
- the analog input unit 1 further includes a reference voltage stabilization circuit 10 that suppresses fluctuations in the reference voltage generated by the reference resistor 7 and a current-voltage conversion resistor 11.
- a reference voltage stabilization circuit 10 that suppresses fluctuations in the reference voltage generated by the reference resistor 7 and a current-voltage conversion resistor 11.
- the resistance value of the reference resistor 7 is R ref
- the resistance value of the current-voltage conversion resistor 11 is R.
- FIG. 2 is a diagram showing a state where the voltage output sensor 12 is connected to the analog input unit 1 shown in FIG. As shown in FIG. 2, the voltage output sensor 12 is connected between the input terminal 4 and the input terminal 5.
- the switch 8 is controlled to be turned off by software inside the analog input unit 1.
- the switch 9 is switched to a side where the voltage applied from the input terminal 4 can be directly input to the AD converter 6 by software inside the analog input unit 1.
- the voltage applied from the input terminal 4 is input to the AD converter 6 via the switch 9, and the AD converter 6 measures the potential difference between the input terminal 4 and the input terminal 5.
- FIG. 3 is a diagram showing a state where the current output sensor 13 is connected to the analog input unit 1 shown in FIG.
- the current output sensor 13 is connected between the input terminal 4 and the input terminal 5.
- the switch 8 is controlled to be turned off by software inside the analog input unit 1.
- the switch 9 is switched to the side where the current supplied from the input terminal 4 flows to the current-voltage conversion resistor 11 by software inside the analog input unit 1.
- the current is converted into a voltage by the current-voltage conversion resistor 11. That is, the current supplied from the input terminal 4 flows to the current-voltage conversion resistor 11 via the switch 9, and the current value is converted into a voltage value in the current-voltage conversion resistor 11.
- the voltage generated at both ends of the current-voltage conversion resistor 11 is measured by the AD converter 6, and the current value of the current supplied from the input terminal 4 is calculated by the AD converter 6.
- FIG. 4 is a diagram showing a state in which a three-wire resistance thermometer 14 is connected to the analog input unit 1 shown in FIG.
- the three-wire resistance thermometer 14 is connected to the input terminals 2, 3, and 4.
- the switch 8 is turned on by software inside the analog input unit 1.
- the switch 9 is controlled to be turned off by software inside the analog input unit 1.
- the input terminals 2 and 3 operate as voltage input terminals and current input terminals.
- a constant current I is supplied from the AD converter 6 toward the three-wire temperature measuring resistor 14.
- the current 2I directed from the input terminals 2 and 3 to the three-wire temperature measuring resistor 14 flows into the reference resistor 7 via the input terminal 4 and the switch 8, and generates the reference voltage R ref ⁇ 2I.
- a part of the current 2I flows to the switch 9 as the leakage current I leak .
- the current 2I flowing into the reference resistor 7 is reduced by the amount of the leakage current I leak .
- the reference voltage decreases by R ref ⁇ I leak .
- the reference voltage stabilization circuit 10 is connected to the reference resistor 7 in parallel. With this connection, the reference voltage stabilization circuit 10 can detect a decrease in the reference voltage.
- the reference voltage stabilizing circuit 10 detects R ref ⁇ I leak that is a reduced voltage component from the voltage of the reference resistor 7, and generates a compensation current I comp that is the same as the leakage current I leak from the detected voltage. Returning the compensation current I comp to the reference resistor 7 cancels out the leakage current I leak which is a decrease of the current 2I.
- FIG. 5 is a circuit diagram showing an internal configuration of the reference voltage stabilizing circuit 10 shown in FIGS.
- a resistor 16 which is a first resistor, is connected between the output terminal of the operational amplifier 15 and a positive terminal (+ side) on the input side of the operational amplifier 15.
- a resistor 17, which is a second resistor is connected between the negative terminal and the negative terminal ( ⁇ ) terminal of the reference voltage stabilizing circuit 10, and the output terminal of the operational amplifier 15 and the input side of the operational amplifier 15.
- a resistor 18, which is a third resistor, is connected between the negative terminal ( ⁇ side) of the terminal.
- the positive side (+ side) terminal of the reference voltage stabilizing circuit 10 is connected to the reference voltage input terminal 20 of the AD converter 6 to which the reference resistor 7 is connected as shown in FIG.
- the voltage of the reference resistor 7 is V ref .
- the resistance value R 2 of the resistor 17 and the resistance R 3 of the resistor 18 is set to the same value, the relational expression is obtained.
- V ref ⁇ R 1 ⁇ I comp (1)
- R 1 is the resistance value of the resistor 16
- the reference voltage stabilizing circuit 10 is given a function of positive current feedback by the resistor and the operational amplifier. By providing the reference voltage stabilization circuit 10 having this function, the current flowing through the reference resistor 7 can be made constant, and the reference voltage V ref can be maintained with high accuracy.
- the resistance value R 2 and the resistance value R 3 may be regarded as the same value.
- the above equation (1) means that the error of the reference voltage V ref can be reduced by selecting the resistance value R 1 of the resistor 16. That is, if the method of the present embodiment is used, the error of the reference voltage V ref can be reduced regardless of the resistance value R ref of the reference resistor 7.
- the reference voltage stabilization circuit 10 can be externally attached to an external terminal of the analog input unit 1. . According to this configuration, the reference voltage stabilization circuit 10 may be retrofitted when needed, and it is not necessary to incorporate the reference voltage stabilization circuit 10, thereby suppressing an increase in cost of the analog input unit 1. Is possible.
- the reference voltage stabilizing circuit 10 is connected to the outside of the AD converter 6, but may be built in the AD converter 6.
- the analog input unit 1 can be downsized by making an IC together with the AD converter 6.
- thermometer a case where a three-wire resistance thermometer is used has been described as an example, but the present invention can also be applied to a two-wire resistance thermometer or a four-wire resistance thermometer.
- 1 analog input unit 2, 3, 4, 5 input terminal, 6 AD converter, 7 reference resistor, 8, 9 switch, 10 reference voltage stabilization circuit, 11 current voltage conversion resistor, 12 voltage output sensor, 13 current output Sensor, 14 3-wire resistance thermometer, 15 operational amplifier, 16, 17, 18 resistance, 20 reference voltage input terminal.
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Abstract
An analog input unit (1) is provided with: input terminals (2, 3, 4, 5) to which analog values from analog sensors can be inputted; switches (8, 9) with which selection or non-selection of the analog sensors can be made; an AD converter (6) which converts an analog value from a selected analog sensor to a digital value; a reference resistor (7) which generates a reference voltage to which the AD converter (6) refers; and a reference voltage stabilizing circuit (10) connected in parallel to the reference resistor (7).
Description
本発明は、測温抵抗体との接続、電流出力センサとの接続、及び電圧出力センサとの接続をスイッチにより選択可能に構成されるアナログ入力ユニット、並びに、当該アナログ入力ユニットに適用可能に構成される基準電圧安定化回路に関する。
The present invention provides an analog input unit that can be connected to a resistance temperature detector, connected to a current output sensor, and connected to a voltage output sensor by a switch, and can be applied to the analog input unit. The present invention relates to a reference voltage stabilization circuit.
アナログ入力ユニットの入力端子に接続されるセンサには、温度を検出する測温抵抗体、圧力及び流量といった物理量を検出する電流出力センサ、又は電圧出力センサがある。従来、これらのセンサを接続できるように構成し、センサの入力仕様に応じた入力処理を実行する回路を内蔵することにより、各種センサを入力端子に選択的に接続可能としたアナログ入力ユニットがある(例えば、下記特許文献1)。
The sensor connected to the input terminal of the analog input unit includes a resistance temperature detector that detects temperature, a current output sensor that detects physical quantities such as pressure and flow rate, or a voltage output sensor. Conventionally, there is an analog input unit that can connect these sensors and can selectively connect various sensors to input terminals by incorporating a circuit that executes input processing according to the sensor input specifications. (For example, the following patent document 1).
また、実際のアナログディジタル(Analog to Digital:以下「AD」と表記)変換による変換値と変動分のないAD変換値とを比較し、演算処理をすることにより変動分を算出し、定電流値を補正するものもある(例えば、下記特許文献2)。
In addition, the conversion value by actual analog digital (Analog-to-Digital: hereinafter referred to as “AD”) conversion is compared with the AD conversion value with no fluctuation, and the fluctuation is calculated by arithmetic processing, and the constant current value There is also one that corrects (for example, Patent Document 2 below).
しかしながら、上記特許文献1,2に代表される従来のアナログ入力ユニットでは、接続されたセンサに応じて内部のスイッチを切り替えて入力を選択する際に、スイッチを通して選択されていない回路にリーク電流が流れてしまう。このリーク電流によって、本来流れるべき回路に必要な電流が供給されないという問題がある。
However, in the conventional analog input units represented by Patent Documents 1 and 2, when an input is selected by switching an internal switch according to a connected sensor, a leakage current is generated in a circuit not selected through the switch. It will flow. Due to this leakage current, there is a problem that a current necessary for a circuit that should flow originally is not supplied.
また、3線式測温抵抗体を接続した場合には、基準電圧を生成する必要がある。基準電圧は、基準抵抗に電流を流すことで生成する。しかしながら、リーク電流により本来流れるべき電流が小さくなる。電流が小さくなると、基準電圧が変動する。基準電圧が変動することにより、AD変換に必要な分解能及び精度が低下してしまう。以上の観点により、基準電圧を生成する必要があるセンサをアナログ入力ユニットに接続する場合には、基準電圧を高精度に一定に保つ仕組みが必要とされる。
Also, when a three-wire RTD is connected, it is necessary to generate a reference voltage. The reference voltage is generated by passing a current through the reference resistor. However, the current that should originally flow is reduced by the leakage current. As the current decreases, the reference voltage varies. As the reference voltage fluctuates, the resolution and accuracy required for AD conversion are reduced. From the above viewpoint, when a sensor that needs to generate a reference voltage is connected to an analog input unit, a mechanism for keeping the reference voltage constant with high accuracy is required.
本発明は、上記に鑑みてなされたものであって、基準電圧を生成する必要があるアナログ入力ユニットにセンサを接続する場合であっても、センサ入力の切替時に生じ得るリーク電流に起因する基準電圧の変動を低減できる基準電圧安定化回路を提供することを目的とする。
The present invention has been made in view of the above, and even when a sensor is connected to an analog input unit that needs to generate a reference voltage, a reference caused by a leak current that can occur when switching the sensor input An object of the present invention is to provide a reference voltage stabilization circuit capable of reducing voltage fluctuation.
上述した課題を解決し、目的を達成するため、本発明に係るアナログ入力ユニットは、アナログセンサからのアナログ値の入力が可能な入力端子、アナログセンサの選択又は非選択を可能とするスイッチ、選択されたアナログセンサからのアナログ値をディジタル値へ変換するADコンバータ、ADコンバータによって参照される基準電圧を生成する基準抵抗、並びに、基準抵抗に並列に接続される基準電圧安定化回路を備える。
In order to solve the above-described problems and achieve the object, an analog input unit according to the present invention includes an input terminal that can input an analog value from an analog sensor, a switch that enables selection or non-selection of the analog sensor, and selection An AD converter that converts an analog value from the analog sensor into a digital value, a reference resistor that generates a reference voltage that is referenced by the AD converter, and a reference voltage stabilization circuit that is connected in parallel to the reference resistor.
本発明によれば、基準電圧を生成する必要があるアナログ入力ユニットにセンサを接続する場合であっても、センサ入力の切替時に生じ得るリーク電流に起因する基準電圧の変動を低減できる、という効果を奏する。
According to the present invention, even when a sensor is connected to an analog input unit that needs to generate a reference voltage, it is possible to reduce fluctuations in the reference voltage caused by a leakage current that may occur when the sensor input is switched. Play.
以下に、本発明の実施の形態に係るアナログ入力ユニット及び基準電圧安定化回路を図面に基づいて詳細に説明する。なお、以下の実施の形態により、本発明が限定されるものではない。
Hereinafter, an analog input unit and a reference voltage stabilization circuit according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments.
実施の形態.
図1は、実施の形態に係るアナログ入力ユニットにおける入力処理部の構成を示す図である。図1において、実施の形態に係るアナログ入力ユニット1は、3線式測温抵抗体、電圧出力センサ及び電流出力センサのうちの少なくとも1つに用いる入力端子2,3,4,5を備える。より詳細に説明すると、入力端子2,3は3線式測温抵抗体の電圧入力用端子である。入力端子4は、3線式測温抵抗体の電流入力用端子であるのと共に、電圧出力センサの電圧入力用端子、及び電流出力センサの電流入力用端子としても用いられる。入力端子5は、電圧出力センサの電圧入力用端子、及び電流出力センサの電流入力用端子である。なお、ここで挙げた3線式測温抵抗体、電圧出力センサ及び電流出力センサは、アナログ値を出力するアナログセンサの例示である。また、入力端子2,3,4,5は一例であり、電圧値又は電流値のうちの少なくとも一つが入力可能な端子であれば、どのような端子であってもよい。 Embodiment.
FIG. 1 is a diagram illustrating a configuration of an input processing unit in the analog input unit according to the embodiment. In FIG. 1, ananalog input unit 1 according to the embodiment includes input terminals 2, 3, 4, and 5 used for at least one of a three-wire resistance thermometer, a voltage output sensor, and a current output sensor. More specifically, the input terminals 2 and 3 are voltage input terminals for a three-wire resistance thermometer. The input terminal 4 is a current input terminal for the three-wire resistance thermometer, and is also used as a voltage input terminal for the voltage output sensor and a current input terminal for the current output sensor. The input terminal 5 is a voltage input terminal of the voltage output sensor and a current input terminal of the current output sensor. Note that the three-wire resistance thermometer, voltage output sensor, and current output sensor mentioned here are examples of analog sensors that output analog values. Further, the input terminals 2, 3, 4, and 5 are examples, and any terminals may be used as long as at least one of the voltage value and the current value can be input.
図1は、実施の形態に係るアナログ入力ユニットにおける入力処理部の構成を示す図である。図1において、実施の形態に係るアナログ入力ユニット1は、3線式測温抵抗体、電圧出力センサ及び電流出力センサのうちの少なくとも1つに用いる入力端子2,3,4,5を備える。より詳細に説明すると、入力端子2,3は3線式測温抵抗体の電圧入力用端子である。入力端子4は、3線式測温抵抗体の電流入力用端子であるのと共に、電圧出力センサの電圧入力用端子、及び電流出力センサの電流入力用端子としても用いられる。入力端子5は、電圧出力センサの電圧入力用端子、及び電流出力センサの電流入力用端子である。なお、ここで挙げた3線式測温抵抗体、電圧出力センサ及び電流出力センサは、アナログ値を出力するアナログセンサの例示である。また、入力端子2,3,4,5は一例であり、電圧値又は電流値のうちの少なくとも一つが入力可能な端子であれば、どのような端子であってもよい。 Embodiment.
FIG. 1 is a diagram illustrating a configuration of an input processing unit in the analog input unit according to the embodiment. In FIG. 1, an
また、アナログ入力ユニット1は、入力されたアナログ値をディジタル値へ変換するADコンバータ6と、ADコンバータ6によって参照される基準電圧を生成する基準抵抗7と、アナログセンサの選択又は非選択を可能とするスイッチ8,9と、を更に備える。より詳細に説明すると、スイッチ8は、3線式測温抵抗体から供給される電流、電圧出力センサからの印加電圧、又は電流出力センサからの供給電流の入力を選択する。また、スイッチ9は、電圧出力センサからの印加電圧、又は電流出力センサからの供給電流の入力を選択する。
In addition, the analog input unit 1 can select or deselect an AD converter 6 that converts an input analog value into a digital value, a reference resistor 7 that generates a reference voltage referenced by the AD converter 6, and an analog sensor. The switches 8 and 9 are further provided. More specifically, the switch 8 selects an input of a current supplied from the three-wire temperature measuring resistor, an applied voltage from the voltage output sensor, or a supply current from the current output sensor. The switch 9 selects an input of an applied voltage from the voltage output sensor or a supply current from the current output sensor.
また、アナログ入力ユニット1は、基準抵抗7で生成された基準電圧の変動を抑制する基準電圧安定化回路10と、電流電圧変換用抵抗11と、を更に備える。ここで、図1にも示すように、基準抵抗7の抵抗値をRrefとし、電流電圧変換用抵抗11の抵抗値をRとする。
The analog input unit 1 further includes a reference voltage stabilization circuit 10 that suppresses fluctuations in the reference voltage generated by the reference resistor 7 and a current-voltage conversion resistor 11. Here, as shown in FIG. 1, the resistance value of the reference resistor 7 is R ref, and the resistance value of the current-voltage conversion resistor 11 is R.
図2は、図1に示すアナログ入力ユニット1に電圧出力センサ12が接続された状態を示す図である。図2に示すように、電圧出力センサ12は、入力端子4と入力端子5との間に接続されている。電圧出力センサ12が入力端子4,5間に接続されると、スイッチ8は、アナログ入力ユニット1の内部のソフトウェアによってオフに制御される。また、スイッチ9は、アナログ入力ユニット1の内部のソフトウェアによって、入力端子4から印加される電圧がADコンバータ6へ直接入力できる側へ切り替えられる。これにより、入力端子4から印加された電圧は、スイッチ9を経由してADコンバータ6に入力され、ADコンバータ6では、入力端子4と入力端子5との間の電位差が測定される。
FIG. 2 is a diagram showing a state where the voltage output sensor 12 is connected to the analog input unit 1 shown in FIG. As shown in FIG. 2, the voltage output sensor 12 is connected between the input terminal 4 and the input terminal 5. When the voltage output sensor 12 is connected between the input terminals 4 and 5, the switch 8 is controlled to be turned off by software inside the analog input unit 1. In addition, the switch 9 is switched to a side where the voltage applied from the input terminal 4 can be directly input to the AD converter 6 by software inside the analog input unit 1. As a result, the voltage applied from the input terminal 4 is input to the AD converter 6 via the switch 9, and the AD converter 6 measures the potential difference between the input terminal 4 and the input terminal 5.
図3は、図1に示すアナログ入力ユニット1に電流出力センサ13が接続された状態を示す図である。電流出力センサ13は、入力端子4と入力端子5との間に接続されている。電流出力センサ13が入力端子4,5間に接続されると、スイッチ8は、アナログ入力ユニット1の内部のソフトウェアによってオフに制御される。また、スイッチ9は、アナログ入力ユニット1の内部のソフトウェアによって、入力端子4から供給される電流が電流電圧変換用抵抗11に流れる側へ切り替えられる。このとき、電流電圧変換用抵抗11によって、電流が電圧へ変換される。すなわち、入力端子4から供給された電流は、スイッチ9を経由して電流電圧変換用抵抗11に流れ、電流電圧変換用抵抗11において電流値が電圧値に変換される。そして、電流電圧変換用抵抗11の両端に生じた電圧がADコンバータ6によって測定され、ADコンバータ6によって入力端子4から供給された電流の電流値が算出される。
FIG. 3 is a diagram showing a state where the current output sensor 13 is connected to the analog input unit 1 shown in FIG. The current output sensor 13 is connected between the input terminal 4 and the input terminal 5. When the current output sensor 13 is connected between the input terminals 4 and 5, the switch 8 is controlled to be turned off by software inside the analog input unit 1. The switch 9 is switched to the side where the current supplied from the input terminal 4 flows to the current-voltage conversion resistor 11 by software inside the analog input unit 1. At this time, the current is converted into a voltage by the current-voltage conversion resistor 11. That is, the current supplied from the input terminal 4 flows to the current-voltage conversion resistor 11 via the switch 9, and the current value is converted into a voltage value in the current-voltage conversion resistor 11. The voltage generated at both ends of the current-voltage conversion resistor 11 is measured by the AD converter 6, and the current value of the current supplied from the input terminal 4 is calculated by the AD converter 6.
図4は、図1に示すアナログ入力ユニット1に3線式測温抵抗体14が接続された状態を示す図である。3線式測温抵抗体14は、入力端子2,3,4に接続されている。3線式測温抵抗体14が入力端子2,3,4に接続されると、スイッチ8は、アナログ入力ユニット1の内部のソフトウェアによってオンに制御される。また、スイッチ9は、アナログ入力ユニット1の内部のソフトウェアによってオフに制御される。
FIG. 4 is a diagram showing a state in which a three-wire resistance thermometer 14 is connected to the analog input unit 1 shown in FIG. The three-wire resistance thermometer 14 is connected to the input terminals 2, 3, and 4. When the three-wire RTD 14 is connected to the input terminals 2, 3, and 4, the switch 8 is turned on by software inside the analog input unit 1. The switch 9 is controlled to be turned off by software inside the analog input unit 1.
3線式測温抵抗体14が入力端子2,3,4に接続されるとき、入力端子2,3は、電圧入力用の端子であると共に、電流入力用の端子としても動作する。具体的には、図4に示されるように、ADコンバータ6から3線式測温抵抗体14に向けて定電流Iが供給される。これにより、入力端子2,3から3線式測温抵抗体14に向かう電流2Iは入力端子4及びスイッチ8を経由して、基準抵抗7に流れ込み、基準電圧Rref・2Iを生成する。ここで、電流2Iのうちの一部がリーク電流Ileakとしてスイッチ9へ流れる。このため、基準抵抗7に流れ込む電流2Iは、リーク電流Ileakの分、電流が小さくなる。その結果、基準電圧は、Rref・Ileakだけ低下する。
When the three-wire resistance thermometer 14 is connected to the input terminals 2, 3, and 4, the input terminals 2 and 3 operate as voltage input terminals and current input terminals. Specifically, as shown in FIG. 4, a constant current I is supplied from the AD converter 6 toward the three-wire temperature measuring resistor 14. As a result, the current 2I directed from the input terminals 2 and 3 to the three-wire temperature measuring resistor 14 flows into the reference resistor 7 via the input terminal 4 and the switch 8, and generates the reference voltage R ref · 2I. Here, a part of the current 2I flows to the switch 9 as the leakage current I leak . For this reason, the current 2I flowing into the reference resistor 7 is reduced by the amount of the leakage current I leak . As a result, the reference voltage decreases by R ref · I leak .
基準電圧安定化回路10は、基準抵抗7に並列に接続されている。この接続により、基準電圧安定化回路10は、基準電圧の低下を検知することができる。基準電圧安定化回路10は、基準抵抗7の電圧から、低下した電圧成分であるRref・Ileakを検知し、検知した電圧からリーク電流Ileakと同じ補償電流Icompを生成し、生成した補償電流Icompを基準抵抗7に戻すことで、電流2Iのうちの減少分であるリーク電流Ileakを相殺する。
The reference voltage stabilization circuit 10 is connected to the reference resistor 7 in parallel. With this connection, the reference voltage stabilization circuit 10 can detect a decrease in the reference voltage. The reference voltage stabilizing circuit 10 detects R ref · I leak that is a reduced voltage component from the voltage of the reference resistor 7, and generates a compensation current I comp that is the same as the leakage current I leak from the detected voltage. Returning the compensation current I comp to the reference resistor 7 cancels out the leakage current I leak which is a decrease of the current 2I.
図5は、図1から図4に示した基準電圧安定化回路10の内部構成を示す回路図である。図示のように、オペアンプ15の出力端とオペアンプ15の入力側における正極側(+側)の端子との間に第1の抵抗である抵抗16が接続され、オペアンプ15の入力側における負極側(-側)の端子と基準電圧安定化回路10における負極側負極側(-側)の端子との間に第2の抵抗である抵抗17が接続され、オペアンプ15の出力端とオペアンプ15の入力側における負極側(-側)の端子との間に第3の抵抗である抵抗18が接続されている。また、基準電圧安定化回路10の正極側(+側)の端子は、図4に示すように基準抵抗7が接続されているADコンバータ6の基準電圧入力端子20に接続されている。
FIG. 5 is a circuit diagram showing an internal configuration of the reference voltage stabilizing circuit 10 shown in FIGS. As shown in the figure, a resistor 16, which is a first resistor, is connected between the output terminal of the operational amplifier 15 and a positive terminal (+ side) on the input side of the operational amplifier 15. A resistor 17, which is a second resistor, is connected between the negative terminal and the negative terminal (−) terminal of the reference voltage stabilizing circuit 10, and the output terminal of the operational amplifier 15 and the input side of the operational amplifier 15. A resistor 18, which is a third resistor, is connected between the negative terminal (− side) of the terminal. Further, the positive side (+ side) terminal of the reference voltage stabilizing circuit 10 is connected to the reference voltage input terminal 20 of the AD converter 6 to which the reference resistor 7 is connected as shown in FIG.
ここで、基準抵抗7の電圧をVrefとする。このとき、補償電流Icompの極性を図示の向きにとり、また、抵抗17の抵抗値R2と、抵抗18の抵抗値R3とを同じ値に設定すると、以下の関係式が得られる。
Here, the voltage of the reference resistor 7 is V ref . At this time, taking the polarity of the compensation current I comp in the drawing direction, also, the resistance value R 2 of the resistor 17 and the resistance R 3 of the resistor 18 is set to the same value, the relational expression is obtained.
Vref=-R1・Icomp …(1)
但し、R1は抵抗16の抵抗値 V ref = −R 1 · I comp (1)
Where R 1 is the resistance value of theresistor 16
但し、R1は抵抗16の抵抗値 V ref = −R 1 · I comp (1)
Where R 1 is the resistance value of the
上記(1)式の右辺には、-の符号が付されており、基準電圧Vrefが増加すれば補償電流Icompが基準電圧安定化回路10の内部に引き込まれ、基準電圧Vrefが低下すれば補償電流Icompが基準電圧安定化回路10から流れ出すことを意味する。よって、リーク電流Ileakが生じると基準電圧Vrefが低下しようとするが、この低下を検知した基準電圧安定化回路10が、補償電流Icompを生成して基準抵抗7に正帰還させる。これにより、リーク電流Ileakが相殺され、基準電圧Vrefの低下が抑制される。
On the right side of the above equation (1), a sign “−” is attached. When the reference voltage V ref increases, the compensation current I comp is drawn into the reference voltage stabilization circuit 10 and the reference voltage V ref decreases. This means that the compensation current I comp flows out of the reference voltage stabilization circuit 10. Therefore, when the leak current I leak occurs, the reference voltage V ref tends to decrease. The reference voltage stabilization circuit 10 that detects this decrease generates the compensation current I comp and positively feeds it back to the reference resistor 7. As a result, the leakage current I leak is canceled out, and the decrease in the reference voltage V ref is suppressed.
以上の説明のように、基準電圧安定化回路10は、抵抗及びオペアンプによって、電流正帰還の機能が付与される。本機能を有する基準電圧安定化回路10を設けることにより、基準抵抗7に流れる電流を一定にでき、基準電圧Vrefを精度よく維持することが可能となる。
As described above, the reference voltage stabilizing circuit 10 is given a function of positive current feedback by the resistor and the operational amplifier. By providing the reference voltage stabilization circuit 10 having this function, the current flowing through the reference resistor 7 can be made constant, and the reference voltage V ref can be maintained with high accuracy.
なお、上記の説明では、抵抗17の抵抗値R2と、抵抗18の抵抗値R3とを同じ値に設定すると説明したが、抵抗値R2と抵抗値R3とが必ずしも同じ値をとらなくてもよい。具体的には、以下の関係が満たされる数値であってもよい。
In the above description, taken with the resistance value R 2 of the resistor 17, although the resistance value R 3 of the resistor 18 has been described as set to the same value, and the resistance value R 2 and the resistance R 3 is necessarily the same value It does not have to be. Specifically, it may be a numerical value satisfying the following relationship.
0.95・R2≦R3≦R2 …(2)
0.95 · R 2 ≦ R 3 ≦ R 2 (2)
すなわち、抵抗値R2と抵抗値R3とが、上記(2)式が満たされる場合に、抵抗値R2と抵抗値R3とが同値であると見なしてもよい。
That is, when the resistance value R 2 and the resistance value R 3 satisfy the above equation (2), the resistance value R 2 and the resistance value R 3 may be regarded as the same value.
また、上記(1)式は、抵抗16の抵抗値R1を選択することで基準電圧Vrefの誤差の低減が可能となることを意味している。すなわち、本実施の形態の手法を用いれば、基準抵抗7の抵抗値Rrefに関わらず、基準電圧Vrefの誤差の低減が可能となる。
Further, the above equation (1) means that the error of the reference voltage V ref can be reduced by selecting the resistance value R 1 of the resistor 16. That is, if the method of the present embodiment is used, the error of the reference voltage V ref can be reduced regardless of the resistance value R ref of the reference resistor 7.
なお、基準抵抗7に相当する素子に並列に接続できる端子をアナログ入力ユニット1が備えている場合、基準電圧安定化回路10は、アナログ入力ユニット1の外部端子に外付けすることも可能である。この構成によれば、必要とされるときに基準電圧安定化回路10を後付けで取り付ければよく、基準電圧安定化回路10を内蔵する必要がないので、アナログ入力ユニット1のコスト増を抑制することが可能となる。
When the analog input unit 1 includes a terminal that can be connected in parallel to an element corresponding to the reference resistor 7, the reference voltage stabilization circuit 10 can be externally attached to an external terminal of the analog input unit 1. . According to this configuration, the reference voltage stabilization circuit 10 may be retrofitted when needed, and it is not necessary to incorporate the reference voltage stabilization circuit 10, thereby suppressing an increase in cost of the analog input unit 1. Is possible.
また、図1~図4の構成では、基準電圧安定化回路10をADコンバータ6の外部に接続しているが、ADコンバータ6の内部に内蔵してもよい。ADコンバータ6がIC化される場合には、ADコンバータ6と共にIC化することで、アナログ入力ユニット1の小型化が可能となる。
1 to 4, the reference voltage stabilizing circuit 10 is connected to the outside of the AD converter 6, but may be built in the AD converter 6. When the AD converter 6 is made into an IC, the analog input unit 1 can be downsized by making an IC together with the AD converter 6.
また、上記では、3線式測温抵抗体を使用した場合を一例として説明したが、2線式測温抵抗体又は4線式測温抵抗体にも適用可能である。
In the above description, a case where a three-wire resistance thermometer is used has been described as an example, but the present invention can also be applied to a two-wire resistance thermometer or a four-wire resistance thermometer.
また、上記では、基準抵抗に電流を流すことで基準電圧を生成する回路構成への適用について説明したが、電流により基準電圧を生成する回路構成への適用も可能であり、基準電圧を精度よく保持できる効果を得ることができる。
In the above description, the application to a circuit configuration in which a reference voltage is generated by flowing a current through a reference resistor has been described. However, application to a circuit configuration in which a reference voltage is generated by a current is also possible, and the reference voltage can be accurately The effect which can be hold | maintained can be acquired.
なお、以上の実施の形態に示した構成は、本発明の内容の一例を示すものであり、別の公知の技術と組み合わせることも可能であるし、本発明の要旨を逸脱しない範囲で、構成の一部を省略、変更することも可能である。
Note that the configurations shown in the above embodiments are examples of the contents of the present invention, and can be combined with other known techniques, and can be combined without departing from the gist of the present invention. It is also possible to omit or change a part of.
1 アナログ入力ユニット、2,3,4,5 入力端子、6 ADコンバータ、7 基準抵抗、8,9 スイッチ、10 基準電圧安定化回路、11 電流電圧変換用抵抗、12 電圧出力センサ、13 電流出力センサ、14 3線式測温抵抗体、15 オペアンプ、16,17,18 抵抗、20 基準電圧入力端子。
1 analog input unit, 2, 3, 4, 5 input terminal, 6 AD converter, 7 reference resistor, 8, 9 switch, 10 reference voltage stabilization circuit, 11 current voltage conversion resistor, 12 voltage output sensor, 13 current output Sensor, 14 3-wire resistance thermometer, 15 operational amplifier, 16, 17, 18 resistance, 20 reference voltage input terminal.
Claims (6)
- アナログセンサからのアナログ値の入力が可能な入力端子と、
前記アナログセンサの選択又は非選択を可能とするスイッチと、
選択された前記アナログセンサからのアナログ値をディジタル値へ変換するADコンバータと、
前記ADコンバータによって参照される基準電圧を生成する基準抵抗と、
前記基準抵抗に並列に接続される基準電圧安定化回路と、
を備えたことを特徴とするアナログ入力ユニット。 An input terminal that can input analog values from analog sensors,
A switch that enables selection or non-selection of the analog sensor;
An AD converter for converting an analog value from the selected analog sensor into a digital value;
A reference resistor that generates a reference voltage referenced by the AD converter;
A reference voltage stabilizing circuit connected in parallel to the reference resistor;
An analog input unit characterized by comprising - 前記基準電圧安定化回路は、抵抗及びオペアンプによって電流正帰還の機能が付与されていることを特徴とする請求項1に記載のアナログ入力ユニット。 2. The analog input unit according to claim 1, wherein the reference voltage stabilizing circuit is provided with a function of positive current feedback by a resistor and an operational amplifier.
- 前記基準電圧安定化回路は、前記ADコンバータの内部に実装されていることを特徴とする請求項1又は2に記載のアナログ入力ユニット。 3. The analog input unit according to claim 1, wherein the reference voltage stabilizing circuit is mounted inside the AD converter.
- 前記基準電圧安定化回路は、前記アナログ入力ユニットの外部又は内部に後付け可能に構成されていることを特徴とする請求項1から3の何れか1項に記載のアナログ入力ユニット。 4. The analog input unit according to claim 1, wherein the reference voltage stabilization circuit is configured to be retrofitted outside or inside the analog input unit. 5.
- アナログセンサからのアナログ値の入力が可能な入力端子と、前記アナログセンサの選択又は非選択を可能とするスイッチと、選択された前記アナログセンサからのアナログ値をディジタル値へ変換するADコンバータと、前記アナログ値をディジタル値へ変換する際に参照される基準電圧を生成する基準抵抗と、を備えたアナログ入力ユニットに適用される基準電圧安定化回路であって、
抵抗及びオペアンプを有し、前記基準抵抗に並列に接続され、前記アナログ入力ユニットの内部にリーク電流が流れるときに、前記リーク電流を補償するための補償電流を前記基準抵抗に流すように動作する
ことを特徴とする基準電圧安定化回路。 An input terminal capable of inputting an analog value from the analog sensor; a switch that enables selection or non-selection of the analog sensor; an AD converter that converts the analog value from the selected analog sensor into a digital value; A reference voltage stabilizing circuit applied to an analog input unit comprising: a reference resistor that generates a reference voltage that is referred to when converting the analog value to a digital value;
A resistor and an operational amplifier, which are connected in parallel to the reference resistor, and operate so that a compensation current for compensating the leakage current flows through the reference resistor when the leakage current flows inside the analog input unit A reference voltage stabilizing circuit. - 前記抵抗は、第1の抵抗、第2の抵抗及び第3の抵抗を含み、
前記オペアンプの出力端と前記オペアンプの入力側における正極側の端子との間に前記第1の抵抗が接続され、前記オペアンプの入力側における負極側の端子と前記基準電圧安定化回路における負極側の端子との間に第2の抵抗が接続され、前記オペアンプの出力端と前記オペアンプの入力側における負極側の端子との間に第3の抵抗が接続されている
ことを特徴とする請求項5に記載の基準電圧安定化回路。 The resistor includes a first resistor, a second resistor, and a third resistor,
The first resistor is connected between an output terminal of the operational amplifier and a positive terminal on the input side of the operational amplifier, and a negative terminal on the input side of the operational amplifier and a negative terminal in the reference voltage stabilizing circuit. The second resistor is connected between the terminal and a third resistor is connected between the output terminal of the operational amplifier and the negative terminal on the input side of the operational amplifier. Reference voltage stabilization circuit described in 1.
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH085675A (en) * | 1994-06-16 | 1996-01-12 | Sony Tektronix Corp | Input circuit for voltage/current measuring instrument |
JPH11134588A (en) * | 1997-10-29 | 1999-05-21 | Hitachi Ltd | Analog input device |
JP2008304203A (en) * | 2007-06-05 | 2008-12-18 | Omron Corp | Analog input module and apparatus |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009217809A (en) * | 2008-02-12 | 2009-09-24 | Seiko Epson Corp | Reference voltage generating circuit, integrated circuit device and signal processing apparatus |
CN201748983U (en) * | 2010-06-21 | 2011-02-16 | 江苏安科瑞电器制造有限公司 | Integrated signal intelligent temperature transmitter |
CN101872193B (en) * | 2010-06-23 | 2012-05-02 | 鞍山永恒自控仪表有限公司 | Multifunctional measurement and control module based on field bus |
CN105547341B (en) * | 2014-10-31 | 2018-07-27 | 南京河海南自水电自动化有限公司 | A kind of device and method measuring five-wire system differential resistance type sensor |
CN205861232U (en) * | 2016-07-26 | 2017-01-04 | 高准有限公司 | Temperature measuring circuit and transmitter |
-
2017
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Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH085675A (en) * | 1994-06-16 | 1996-01-12 | Sony Tektronix Corp | Input circuit for voltage/current measuring instrument |
JPH11134588A (en) * | 1997-10-29 | 1999-05-21 | Hitachi Ltd | Analog input device |
JP2008304203A (en) * | 2007-06-05 | 2008-12-18 | Omron Corp | Analog input module and apparatus |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR102253854B1 (en) * | 2020-12-06 | 2021-05-20 | 주식회사 알에스팀 | Universal IoT Monitoring Method for Security |
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