CN111912470A - NAMUR switch instrument transmitter and control method - Google Patents

NAMUR switch instrument transmitter and control method Download PDF

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Publication number
CN111912470A
CN111912470A CN202010892251.0A CN202010892251A CN111912470A CN 111912470 A CN111912470 A CN 111912470A CN 202010892251 A CN202010892251 A CN 202010892251A CN 111912470 A CN111912470 A CN 111912470A
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China
Prior art keywords
resistor
control circuit
switch
current control
circuit
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CN202010892251.0A
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Chinese (zh)
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CN111912470B (en
Inventor
李亚朋
王晓峰
王洪生
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Beijing Miaosite Instrument Co ltd
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Beijing Miaosite Instrument Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
    • G01F15/06—Indicating or recording devices
    • G01F15/068—Indicating or recording devices with electrical means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • G01F23/261—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields for discrete levels
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
    • G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
    • G05B19/0423—Input/output

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Power Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)

Abstract

The application discloses NAMUR switch instrument changer and a control method, relates to the technical field of changers, and comprises an MCU (microprogrammed control unit), a sensor connected with the input end of the MCU, a key unit connected with the input end of the MCU and a switch current control circuit connected with the output end of the MCU. This application has the effect of being convenient for adjust the alarm point according to on-the-spot demand.

Description

NAMUR switch instrument transmitter and control method
Technical Field
The application relates to the field of transmitters, in particular to a NAMUR switch instrument transmitter and a control method.
Background
In the industrial preparation process, a plurality of places related to flow and liquid level need to monitor the state parameters of the flow or the liquid level in real time so as to ensure the smooth operation of the procedures such as industrial preparation and the like.
The Chinese patent with the publication number of CN202403709U discloses an NAMUR signal alarm device, which comprises a mounting seat, a metal sheet, a groove type NAMUR proximity switch, a wiring terminal and a wiring support plate, wherein the mounting seat is mounted on a shell of an indicator through a long strut and a short strut, the metal sheet is in a fan shape with central symmetry, the symmetry center is mounted on an indicator pointer shaft, the upper part and the lower part of the mounting seat are provided with a groove with the indicator as a circle center, the groove type NAMUR proximity switch is connected with the connection support plate, the connection support plate is fixedly mounted on the pointer shaft and is positioned in two arc grooves through two screws, and the wiring terminal is mounted at the upper end of the mounting seat and is connected with the groove type NAMUR proximity switch through a wire. Through the scheme, signal alarming is realized by adopting pointer swinging. However, the alarm device is a mechanical alarm device, the structure is complex, the alarm point is rough to set, the operation is inconvenient, and the complex mechanical structure needs to be changed if the alarm point needs to be adjusted.
With respect to the related art described above, the inventors consider that there is a drawback that it is inconvenient to set an alarm point on the spot.
Disclosure of Invention
To facilitate setting alarm points in the field, the present application provides a NAMUR switch meter transmitter.
In a first aspect, the application provides a NAMUR switch instrument transmitter, which adopts the following technical scheme:
a NAMUR switch instrument transmitter comprises an MCU microprocessor, a sensor connected with the input end of the MCU microprocessor, a key unit connected with the input end of the MCU microprocessor and a switch current control circuit connected with the output end of the MCU microprocessor.
By adopting the technical scheme, the flow alarm threshold value can be set on site through the key assembly, the sensor sends the collected flow data to the MCU microprocessor for processing, the MCU judges and processes the flow data collected by the sensor and the set alarm threshold value, when the collected flow data reaches the alarm condition, the corresponding switch current control circuit outputs a corresponding current value, and the current value output by the switch current control circuit judges whether the current flow is in the alarm numerical range so as to achieve the flow alarm effect.
Preferably, the output end of the MCU microprocessor is connected with a constant current excitation for supplying power to the sensor, and the constant current excitation is electrically connected with a joint of the sensor; and the MCU microprocessor is used for controlling the constant current excitation to be switched on and off.
By adopting the technical scheme, the on-off state of the constant-current excitation is controlled by the MCU microprocessor, when the constant-current excitation is switched on, the sensor is powered by the MCU microprocessor, when the constant-current excitation is switched off, the sensor is powered off, and the switch of the constant-current excitation is controlled by the MCU microprocessor, so that the average current of the NAMUR switch instrument transmitter during operation is reduced, and the normal operation of the NAMUR switch instrument transmitter is ensured.
Preferably, the switch current control circuit comprises a first switch current control circuit, the first switch current control circuit is electrically connected with the output end of the MCU microprocessor, and the first switch current control circuit is connected with a DC/DC power supply and a connection terminal SW 1.
By adopting the technical scheme, an external power supply is connected through the connecting terminal SW1, and the power supply subjected to voltage stabilization and filtering processing through the voltage stabilizing diode and the capacitor in the first switch current control circuit is transmitted to the DC/DC power supply, so that the stability of the transmitter is improved.
Preferably, the switch current control circuit further comprises a second switch current control circuit, the second switch current control circuit is connected with a wiring terminal SW2, and a low-power isolation element is connected between the second switch current control circuit and the output end of the MCU microprocessor.
By adopting the technical scheme, the MCU microprocessor and the second switch current control circuit are isolated by using the low-power isolation element, so that the MCU microprocessor is prevented from being subjected to external interference introduced by the wiring terminal SW2, and the stable operation of the system is ensured.
Preferably, the first switch current control circuit and the second switch current control circuit each include a power supply processing circuit and an operational amplifier, the power supply processing circuit includes a power supply circuit, a triode state adjustment circuit and a resistor R1 connected between the negative electrode of the connection terminal SW1 and the ground, and the operational amplifier includes an operational amplification unit a and an operational amplification unit B;
the power supply circuit comprises a resistor R3, a resistor R3 is connected with the anode of a connecting terminal SW1, the emitter of a triode Q1 and a resistor R4, the other end of the resistor R4 is connected with the base of a triode Q1, the other end of a resistor R3 is connected with the cathode of a diode D5, a regulated power supply LDO, the collector of the triode Q1, the cathode of a diode D2 and a DC/DC power supply, and the anode of a diode D2 and the anode of a diode D5 are respectively grounded;
the triode state adjusting circuit comprises a resistor R7, a triode Q2 and a resistor R6, wherein the resistor R7 is connected with a pin OUTA of the operational amplification unit A, the other end of the resistor R7 is connected with a base electrode of a triode Q2, an emitting electrode of a triode Q2 is grounded, a collector electrode of the triode Q2 is connected with the resistor R6, and the other end of the resistor R6 is connected with a base electrode B of the triode Q1.
By adopting the technical scheme, in the power-on initial state, the triode Q1 and the triode Q2 are in the cut-off state, the current can only flow through the resistor R3 and the stabilized voltage supply LDO, the stabilized voltage supply LDO supplies power to the operational amplifier and then enters a current loop adjustment state, the current flowing in from the positive electrode of the wiring terminal SW1 flows to the ground through a device in the power supply processing circuit and then flows back to the negative electrode of the power supply through the resistor R1, a closed loop negative feedback circuit is formed, and the stability of the switch current control circuit is improved.
Preferably, the first switching current control circuit and the second switching current control circuit each further preferably include a current output control circuit, and the current output control circuit includes a first voltage dividing circuit, a second voltage dividing circuit, and a current output circuit;
the first voltage division circuit comprises a resistor R9 and a resistor R10, the resistor R9 is connected with the resistor R10 in series, the other end of the resistor R9 is connected with the MCU microprocessor, the other end of the resistor R10 is grounded, and a pin INB + of the operational amplification unit B is connected with a connection point of the resistor R9 and the resistor R10;
the second voltage division circuit comprises a resistor R11 and a resistor R12, the resistor R11 is connected with the resistor R12 in series, the other end of the resistor R12 is connected with the regulated power supply LDO, the other end of the resistor R11 is grounded, and a pin INB-of the operational amplification unit B is connected with a connection point of the resistor R11 and the resistor R12;
the current output circuit comprises a resistor R2, a resistor R5 and a resistor R8, wherein the resistor R2 is connected with the resistor R5 in series, the other end of the resistor R2 is connected with the negative electrode of a wiring terminal SW1, the other end of the resistor R5 is connected with the regulated power supply LDO, the resistor R8 is connected with the connection point of the resistor R2 and the resistor R5, and the other end of the resistor R8 is connected with a pin OUTB of the operational amplification unit B.
By adopting the technical scheme, the MCU microprocessor outputs high and low levels to change the input voltage of the pin INB + of the operational amplification unit B, after the input voltage of the pin INB + is compared with the voltage of the pin INB-, the output end OUTB of the operational amplification unit B outputs high level or low level which is converted into current value through the resistor R5 and is superposed with the current flowing through the resistor R8, and then the current output circuit outputs the current value which is in accordance with NAMUR standard.
Preferably, the power supply circuit is provided with a diode D1, a diode D4 and a capacitor C1, and the diode D1 is connected in series between the anode of the connecting terminal SW1 and the resistor R3; the diode D4 is connected in series between the cathode of the diode D5 and the regulated power supply LDO; the capacitor C1 is connected in parallel with the diode D2.
By adopting the technical scheme, the reliability of the power supply circuit is improved, the diode D1 and the diode D4 are arranged to play a role in unidirectional cut-off, and the situation that current flows backwards is prevented; the capacitor C1 is used for energy storage and filtering in the circuit, and filtering out low-frequency interference in the power supply input to the DC/DC power supply.
Preferably, the MCU microprocessor is also connected with a ROM memory and an LCD display screen respectively.
By adopting the technical scheme, the LCD display screen can display the flow value in real time, and the ROM memory can store the set alarm threshold value, so that the transmitter does not need to be reset after power failure, and the functionality of the transmitter is increased.
In a second aspect, the application provides a control method for a transmitter of a NAMUR switch instrument, which adopts the following technical scheme:
the control method of the NAMUR switch instrument transmitter comprises the following steps:
step S100, controlling the constant current excitation and the AD converter to be simultaneously opened, and enabling the constant current excitation to supply power for the sensor;
step S200, the AD converter processes data input by a plurality of times of sensors and stores the data in a ROM;
step S300, closing the constant current excitation and AD converter, and opening an LCD display screen;
step S400, the data input by the sensor processed by the AD converter for a plurality of times in the step S300 is processed and then is transmitted to an LCD display screen for display;
by adopting the technical scheme, the average current of the NAMUR switch instrument transmitter does not exceed the available current of the power supply, and the normal operation of the NAMUR switch instrument transmitter is ensured.
Preferably, the processing the data input by the sensor processed by the AD converter for several times and then transmitting the processed data to the LCD display screen includes:
step S401, comparing data input by the sensor processed by the AD converter for a plurality of times with a set alarm threshold value, and outputting a current value on a switch current control circuit according to a comparison result to indicate alarm or not to alarm;
s402, displaying the flow data collected by the sensor in a delayed manner by an LCD display screen;
by adopting the technical scheme, the average current of the NAMUR switch instrument transmitter does not exceed the available current of the power supply, and the normal operation of the NAMUR switch instrument transmitter is ensured.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the flow alarm device has the advantages that the flow alarm threshold value can be set on site through the key assembly, the sensor sends collected flow data to the MCU microprocessor for processing, the MCU microprocessor compares the flow data collected by the sensor with the set alarm threshold value for judging and processing, when the collected flow data reach the alarm condition, the corresponding switch current control circuit outputs a corresponding current value, and whether the current flow is in the alarm value range or not is judged through the current value output by the switch current control circuit so as to achieve the flow alarm effect;
2. the MCU microprocessor is isolated from the second switch current control circuit by using a low-power-consumption isolation element, so that the MCU microprocessor is prevented from being subjected to external interference introduced by the wiring terminal SW2, and the stable operation of the system is ensured;
3. in the power-on initial state, the triode Q1 and the triode Q2 are in a cut-off state, current can only flow through the resistor R3 and the stabilized voltage supply LDO, the stabilized voltage supply LDO enters a current loop adjustment state after supplying power to the operational amplifier, the current flowing in from the positive pole of the wiring terminal SW1 flows to the ground through a device in the power supply processing circuit, and then flows back to the negative pole of the power supply through the resistor R1 to form a closed loop negative feedback circuit, so that the stability of the switching current control circuit is improved;
4. the average current of the NAMUR switch instrument transmitter does not exceed the available current of the power supply, and the normal operation of the NAMUR switch instrument transmitter is ensured.
Drawings
Fig. 1 is a schematic circuit diagram of a NAMUR switch meter transmitter according to an embodiment of the present disclosure.
Fig. 2 is a schematic circuit diagram of a first switch current control circuit or a second switch current control circuit in a NAMUR switch meter transmitter according to an embodiment of the present disclosure.
Fig. 3 is a schematic flowchart of a control method of a NAMUR switch meter transmitter according to an embodiment of the present application.
Fig. 4 is a schematic flow chart of a control method of a transmitter of a NAMUR switch meter according to a second embodiment of the present application.
Description of reference numerals: 1. an MCU microprocessor; 2. a sensor; 3. a key unit; 4. an LCD display screen; 5. constant current excitation; 6. a first switching current control circuit; 60. a power supply processing circuit; 61. a power supply circuit; 62. a triode state adjustment circuit; 7. a second switching current control circuit; 70. a current output control circuit; 71. a first voltage dividing circuit; 72. a second voltage dividing circuit; 73. a current output circuit; 8. a high efficiency DC/DC power supply; 80. an operational amplifier; 9. a low power consumption isolation element; 10. a ROM memory.
Detailed Description
The present application is described in further detail below with reference to figures 1-4.
The embodiment of the application discloses NAMUR switch instrument changer. Referring to fig. 1, the NAMUR switch instrument transmitter includes an MCU microprocessor 1, a sensor 2 connected to an input terminal of the MCU microprocessor 1, a key unit 3 connected to an input terminal of the MCU microprocessor 1, and a switch current control circuit connected to an output terminal of the MCU microprocessor 1.
The sensor 2 is used for collecting analog electric signals of the industrial liquid flow or the liquid level in real time, and the MCU microprocessor 1 is used for receiving and processing the analog electric signals of the industrial liquid flow or the liquid level input by the sensor 2. Wherein, the sensor 2 may be one of a bridge resistance type sensor, a hall sensor, a capacitance type sensor or an inductance type sensor.
The MCU microprocessor 1 adopts a low-power MSP430F4270 chip internally integrating a preamplifier and an AD converter. When the NAMUR switch instrument transmitter operates, the sensor 2 is connected with the MCU microprocessor 1 through a joint of the sensor, and a preamplifier and an AD converter in the MCU microprocessor 1 respectively amplify and AD convert an analog electric signal input by the sensor 2 into a digital signal.
Further, the MCU microprocessor 1 internally integrates a ROM for data reading or is electrically connected with a ROM memory 10.
The key component 3 is used for setting a flow or liquid level alarm threshold, the MCU microprocessor 1 compares the flow or liquid level alarm threshold set by the key component 3 with a flow value or a liquid level value which is received and processed by the MCU microprocessor 1 and is acquired and input by the sensor 2, and judges whether an alarm signal needs to be output or not.
The output end of the MCU microprocessor 1 is also respectively connected with an LCD display unit 4 for displaying the flow value in real time and a constant current excitation 5 for supplying power to the sensor 2.
The constant current excitation 5 is electrically connected with a connector of the sensor 2, the MCU microprocessor 1 controls the constant current excitation 5 to be switched on and off by changing the high and low levels of the output end of the MCU microprocessor, when the constant current excitation 5 is switched on, the MCU microprocessor supplies power to the sensor 2, and when the constant current excitation 5 is switched off, the MCU microprocessor stops supplying power to the sensor 2.
Further, the switch current control circuit comprises a first switch current control circuit 6 and a second switch current control circuit 7, and the first switch current control circuit 6 and the second switch current control circuit 7 are respectively electrically connected with the output end of the MCU microprocessor 1. The first switch current control circuit 6 is electrically connected with a DC/DC power supply 8 for supplying power to the MCU microprocessor 1 and a connection terminal SW1, and the connection terminal SW1 is connected with an external power supply. An external power supply is connected to the first switch current control circuit 6 through a wiring terminal SW1, one part supplies power to the first switch current control circuit 6, and the other part supplies power input for the DC/DC power supply 8 after voltage stabilization and filtering processing of the first switch current control circuit 6. The circuit of the MCU microprocessor 1 connected to the first switching power supply control circuit 6 is defined as a SW1 control line, the MCU microprocessor 1 controls the current value output by the first switching current control circuit 6 by controlling the high/low level state on the SW1 control line, and the current value output by the first switching current control circuit 6 is reflected on the negative electrode of the connection terminal SW 1.
Further, the DC/DC power supply 8 is used to power the key unit 3, the LCD display unit 4 and the ROM memory 10, in addition to the MCU microprocessor 1.
A low-power-consumption isolation element 9 is further connected between the MCU microprocessor 1 and the second switch current control circuit 7, and the second switch current control circuit 7 is further connected with an independent power supply through a wiring terminal SW 2. The low power consumption isolation element 9 isolates the MCU microprocessor 1 from the second switch current control circuit 7 by using an optocoupler, so as to prevent the MCU microprocessor 1 from external interference introduced through the connection terminal SW 2. The independent power supply is connected to the second switching current control circuit 7 via a connection terminal SW2 to supply power to the second switching current control circuit 7. The circuit of the MCU microprocessor 1 connected with the low power consumption isolation element 9 is defined as a SW2 control line, the MCU microprocessor 1 indirectly controls the output current value of the second switch current control circuit 7 after being photoelectrically isolated by the low power consumption isolation element 9 by controlling the high and low level state on the SW2 control line, and the output current value of the second switch current control circuit 7 is reflected on the negative electrode of the connection terminal SW 2.
Referring to fig. 2, fig. 2 is a schematic circuit structure diagram of a first switch current control circuit or a second switch current control circuit in a transmitter of a NAMUR switch meter according to an embodiment of the present application. The first switching current control circuit 6 and the second switching current control circuit 7 have the same circuit configuration. The first switching current control circuit 6 will be specifically described below as an example. The first switch current control circuit 6 includes a power supply processing circuit 60 and a current output control circuit 70.
The power supply processing circuit 60 includes a power supply circuit 61 and a transistor state adjustment circuit 62. The power supply circuit 61 comprises a resistor R3, the resistor R3 is connected with the anode of the connecting terminal SW1, the emitter E of the transistor Q1 and a resistor R4, the other end of the resistor R4 is connected with the base B of the transistor Q1, and the resistor R4 is used for shunting to reduce the current flowing into the emitter E of the transistor Q1. The other end of the resistor R3 is connected with the cathode of the voltage stabilizing diode D5, the anode of the voltage stabilizing diode D5 is grounded, and the resistor R3 is used for preventing the voltage stabilizing diode D5 from being broken down by an external power supply. The cathode of the voltage stabilizing diode D5 is also connected with the input end of the voltage stabilizing power LDO, the collector C of the triode Q1, the cathode of the voltage stabilizing diode D2 and the input end of the DC/DC power supply 8. The output end of the LDO of the regulated power supply outputs 3.3V direct-current voltage for supplying power to the triode state adjusting circuit 62, the voltage stabilizing diode D5 is used for stabilizing the voltage of the LDO regulated power supply, and the DC/DC power supply 8 is used for supplying power to the MCU microprocessor 1. The anode of the zener diode D2 is grounded, and the zener diode D2 is used to stabilize the voltage input to the DC/DC power supply 8.
Further, a diode D1 may be connected in series between the positive electrode of the connection terminal SW1 and the resistor R3, the positive electrode of the diode D1 is connected to the positive electrode of SW1, and the negative electrode of the diode D1 is connected to the resistor R3; a diode D4 is connected between the negative electrode of the voltage stabilizing diode D5 and the input end of the regulated power supply LDO in series, the positive electrode of the diode D4 is connected with the negative electrode of a voltage stabilizing tube D5, the negative electrode of the diode D4 is connected with the input end of the regulated power supply LDO, and the diode D1 and the diode D4 play a role in unidirectional cut-off and prevent current from flowing backwards.
Furthermore, a capacitor C1 is connected in parallel to the voltage regulator tube D2, the anode of the capacitor C1 is connected with the cathode of the voltage regulator diode D2, the cathode of the capacitor C1 is grounded, and the capacitor C1 mainly functions in storing energy and filtering low-frequency interference in the power supply.
The base B of transistor Q1 is connected to transistor state adjustment circuit 62, which controls the state of transistor Q1. External current enters through terminal SW1, flows through resistor R3 and flows to regulated power LDO and DC/DC power supply. When the transistor Q1 is controlled by the transistor state adjusting circuit 62, the transistor Q1 is switched from the cut-off state to the linear state or the saturation state, and the current flows to the regulated power supply LDO and the DC/DC power supply through the transistor Q1.
Further, the power processing circuit 60 further includes a resistor R1 connected between the negative electrode of the connection terminal SW1 and the ground, in the power-on initial state, the transistor Q1 and the transistor Q2 are in the cut-off state, the current can only flow through the resistor R3 and the regulated voltage supply LDO, the regulated voltage supply LDO enters the current loop adjustment state after supplying power to the operational amplifier, the current flowing from the positive electrode of the connection terminal SW1 flows to the ground through the device in the power processing circuit, and then flows back to the negative electrode of the power supply through the resistor R1, so as to form a closed-loop negative feedback circuit.
The first switching current control circuit 6 further comprises an operational amplifier 80, wherein the operational amplifier in this embodiment has a model of MAX 9913. The operational amplifier 80 includes two parts, an operational amplification unit a and an operational amplification unit B. The power input pin Vdd of the operational amplifier 80 is connected to the 3.3V output terminal of the regulated power supply LDO, the pin Vss is grounded, and the pin SHDNA and the pin SHDNB are connected to the 3.3V output terminal of the regulated power supply LDO, which function to turn on the operational amplification units a and B of the operational amplifier 80.
The triode state adjusting circuit 62 comprises a resistor R7, a triode Q2 and a resistor R6, an output pin OUTA of the operational amplification unit A is connected with the resistor R7, the other end of the resistor R7 is connected with a base B of the triode Q2, an emitter E of the triode Q2 is grounded, a collector C of the triode Q2 is connected with the resistor R6, and the other end of the resistor R6 is connected with a base B of the triode Q1. When the pin OUTA of the operational amplifier unit a continuously outputs a high level, the high level of the pin OUTA makes the transistor Q2 in a linear state or a saturation state, thereby controlling the transistor Q1 to switch from an off state to a linear state or a saturation state.
The current output control circuit 70 further includes a first voltage dividing circuit 71, a second voltage dividing circuit 72, and a current output circuit 73.
The first voltage division circuit 71 comprises a resistor R9 and a resistor R10, the resistor R9 is connected with the resistor R10 in series, the other end of the resistor R9 is connected with the output end of the MCU microprocessor 1 through a SW1 control line, the other end of the resistor R10 is grounded, and a pin INB + of a non-inverting input end of the operational amplification unit B is connected with a connection point of the resistor R9 and the resistor R10. When the MCU microprocessor outputs a high level, the resistor R10 plays a role in voltage division; when the MCU microprocessor outputs a low level, the resistor R10 keeps the pin INB + in a stable low state.
The second voltage division circuit 72 comprises a resistor R11 and a resistor R12, the resistor R11 is connected in series with the resistor R12, the other end of the resistor R12 is connected with the output end of the regulated power supply LDO, the other end of the resistor R11 is grounded, and the inverting input terminal pin INB-of the operational amplification unit B is connected with the connection point of the resistor R11 and the resistor R12. The regulated LDO provides 3.3V DC voltage for the voltage divider circuit 72, and the resistor R11 performs voltage division to provide reference voltage for the pin INB-.
The current output circuit 73 comprises a resistor R2, a resistor R5 and a resistor R8, the resistor R2 is connected with the resistor R5 in series, the other end of the resistor R2 is connected with the negative electrode of a connecting terminal SW1, the other end of the resistor R5 is connected with the 3.3V output end of the regulated power supply LDO, the resistor R8 is connected with the connecting point of the resistor R2 and the resistor R5, and the other end of the resistor R8 is connected with an output OUTPUT pin B of the operational amplification unit B. The output voltage of the pin OUTB is defined as Voutb, the Voutb and the resistors R5 and R8 determine the output current of the switch current control circuit, the output current of the switch current control circuit is defined as Iout, Iout =3.3/R5+ Voutb/R8, and the resistance values of the resistors R5 and R8 are adjusted to set the output current value meeting NAMUR standard.
Furthermore, a pin INA + of a non-inverting input end of the operational amplification unit A is connected with resistors R8, R5 and R2, the other end of the resistor R2 is further connected with a resistor R1, the other end of the resistor R1 is grounded, a pin INA-of an inverting input end of the operational amplification unit A is grounded, the other end of the resistor R5 is connected with a 3.3V output end of the LDO, and the resistor R5 is used for pulling up the level of the pin INA + of the non-inverting input end of the operational amplification unit A.
Operational amplifier 80 acts as a comparator with pin INA + in a high state and INA-at ground, so pin OUTA continues to output a high level. The high level on pin OUTA places transistor Q2 in a linear state or a saturated state, thereby controlling transistor Q1 to transition from an off state to a linear state or a saturated state.
The working principle of the embodiment is as follows:
the MCU microprocessor 1 controls the output voltage Voutb at the output terminal pin OUTB of the operational amplifier unit B by controlling the level on the SW1 control line. Since the operational amplifier 80 is of rail-to-rail type, when the operational amplifier 80 is used in a comparator, the low level output is 0 and the high level output is 3.3V. When the MCU microprocessor 1 outputs a low level, the input voltage of the pin INB + is smaller than that of the pin INB-, the output terminal pin OUTB of the operational amplification unit B outputs a low level, and the output current Iout is approximately equal to 1.16mA when R5=2.8k Ω and is calculated by a formula Iout =3.3/R5+ Voutb/R8; when the MCU microprocessor 1 outputs a high level, the input voltage of the pin INB + is greater than the input voltage of the pin INB ", the output terminal pin OUTB of the operational amplifier unit B outputs a high level, the resistance of the resistor R5 is known to be 2.8k Ω, the output current Iout ≈ 2.56mA when R8=2.4k Ω is calculated by the formula Iout =3.3/R5+ Voutb/R8, and the MCU microprocessor 1 controls the first switch current control circuit 6 and the second switch current control circuit 7 to output the two current values by outputting high and low levels.
The standard flow safety alarm range required by an industrial field is input through the key unit 3 and is specifically divided into four alarm values of flow upper limit alarm, lower limit alarm and lower limit alarm, the MCU microprocessor 1 compares the actual flow value measured by the sensor 2 with the alarm threshold value input through the key unit 3, and then the MCU microprocessor 1 controls the first switch current control circuit 6 and the second switch current control circuit 7 to output the two current values by outputting high and low levels.
For example, the first switch current control circuit 6 is set as a lower flow limit alarm circuit, the second switch current control circuit 7 is set as a lower flow limit alarm circuit, a lower flow limit alarm threshold is set as 30 cubic meters per hour, the lower flow limit alarm threshold is set as 20 cubic meters per hour, and when the actual flow value measured by the sensor 2 is greater than the lower flow limit alarm threshold, the two switch current control circuits can output current less than or equal to 1.2 mA; when the actual flow measured by the sensor 3 is between the lower limit alarm threshold and the lower limit alarm threshold, the first switch current control circuit 6 can output a current larger than or equal to 2.1mA, the second switch current control circuit can output a current smaller than or equal to 1.2mA, and when the actual current measured by the sensor 2 is smaller than the lower limit alarm threshold, the two switch current control circuits can both output a current larger than or equal to 2.1 mA.
Furthermore, a switch current control circuit A and a switch current control circuit B can be added, the switch current control circuit A is set as an upper flow limit alarm circuit, the switch current control circuit B is set as an upper flow limit alarm circuit, an upper flow limit alarm threshold is set to be 60 cubic meters per hour, an upper flow limit alarm threshold is set to be 80 cubic meters per hour, and when the actual flow value measured by the sensor 2 is smaller than the upper flow limit alarm threshold, the two switch current control circuits can output current less than or equal to 1.2 mA; when the actual flow measured by the sensor 2 is between the upper limit alarm threshold and the upper limit alarm threshold, the switch current control circuit A can output the current larger than or equal to 2.1mA, the switch current control circuit B can output the current smaller than or equal to 1.2mA, and when the actual flow measured by the sensor 2 is larger than the upper limit alarm threshold, the switch current control circuits can output the current larger than or equal to 2.1 mA.
Referring to fig. 3, fig. 3 is a schematic flowchart of a control method of a NAMUR switch meter transmitter according to an embodiment of the present application. When the program starts to run, the MCU microprocessor is initialized firstly, the execution delay program is initialized, the LDO stabilized voltage supply and the DC/DC power supply 8 in the switch current control circuit are ensured to be kept in a stable state, the MCU microprocessor is self-checked after the power supply is stabilized, and the execution time-sharing control main program is executed after the self-checking is completed.
Step S100, controlling the constant current excitation and the AD converter to be simultaneously opened, and enabling the constant current excitation to supply power for the sensor;
specifically, the MCU microprocessor outputs a high level to control the constant current excitation to be turned on, so that the constant current excitation supplies power to the sensor, and meanwhile, the AD converter is turned on; and the LCD display screen is forbidden to run, and the MCU microprocessor enters a low power consumption state.
Step S200, the AD converter processes data input by a plurality of times of sensors and stores the data in a ROM;
specifically, the AD converter in the MCU microprocessor executes an AD acquisition function, acquires a certain amount of analog quantity data returned by the sensor according to a set value, amplifies and AD converts the acquired analog quantity data into a digital signal and stores the digital signal into the ROM.
Step S300, closing the constant current excitation and AD converter, and opening an LCD display screen;
specifically, the MCU microprocessor outputs a low level to control the constant current excitation to be closed, so that the constant current excitation stops supplying power to the sensor, and the sensor stops collecting data; simultaneously, the AD converter is closed, and the acquisition function is stopped; the LCD display screen is brought into a state of receiving a display instruction.
Step S400, the data input by the sensor processed by the AD converter for a plurality of times in the step S300 is processed and then is transmitted to an LCD display screen for display;
specifically, the MCU microprocessor performs judgment and operation processing on the data sent back by the sensor, sends the data to the LCD screen for display, and returns to step S100 after execution is completed.
Further, please refer to fig. 4, fig. 4 is a schematic flow chart illustrating a control method of a transmitter of a NAMUR switch instrument according to a second embodiment of the present application.
Step S100, controlling the constant current excitation and the AD converter to be simultaneously opened, and enabling the constant current excitation to supply power for the sensor;
specifically, the MCU microprocessor outputs a high level to control the constant current excitation to be turned on, so that the constant current excitation supplies power to the sensor, and meanwhile, the AD converter is turned on; and the LCD display screen is forbidden to run, and the MCU microprocessor enters a low power consumption state.
Step S200, the AD converter processes data input by a plurality of times of sensors and stores the data into a ROM;
specifically, the AD converter in the MCU microprocessor executes an AD acquisition function, acquires a certain amount of analog quantity data returned by the sensor according to a set value, amplifies and AD converts the acquired analog quantity data into a digital signal and stores the digital signal into the ROM.
Step S300, closing the constant current excitation and the AD converter, and enabling the LCD display screen;
specifically, the MCU microprocessor outputs a low level to control the constant current excitation to be closed, so that the constant current excitation stops supplying power to the sensor, and the sensor stops collecting data; simultaneously, the AD converter is closed, and the acquisition function is stopped; the LCD display screen is brought into a state of receiving a display instruction.
Step S400, the data input by the sensor after being processed for a plurality of times by the AD converter is transmitted to an LCD display screen for displaying, which comprises the following steps:
step S401, comparing data input by the sensor processed by the AD converter for a plurality of times with a set alarm threshold value, and outputting a current value on a switch current control circuit according to a comparison result to indicate alarm or not to alarm;
s402, displaying the flow data collected by the sensor in a delayed manner by an LCD display screen;
firstly, delaying for a plurality of seconds, and sending the flow value to an LCD display screen for displaying after the delay is finished;
specifically, the MCU microprocessor can control the LCD display screen to delay 2s and then display the flow numerical value.
Specifically, the AD converter collects and processes data input by the sensor for a plurality of times, then the data are compared with an alarm threshold value of a set value, when an alarm condition is met, the current value is output by the switch current control circuit to reflect an alarm state and display the current flow value on an LCD display screen, wherein a plurality of switch current control circuits can be arranged according to needs, and each switch current control circuit can correspond to an alarm range.
For example, the first switch current control circuit is set as a lower flow limit alarm circuit, the second switch current control circuit is set as a lower flow limit alarm circuit, a lower flow limit alarm threshold is set as 30 cubic meters per hour, the lower flow limit alarm threshold is set as 20 cubic meters per hour, and when the actual flow value measured by the sensor is greater than the lower flow limit alarm threshold, the two switch current control circuits can output current less than or equal to 1.2 mA; when the actual flow measured by the sensor is between the lower limit alarm threshold and the lower limit alarm threshold, the first switch current control circuit outputs a current larger than or equal to 2.1mA, the second switch current control circuit outputs a current smaller than or equal to 1.2mA, and when the actual current measured by the sensor 2 is smaller than the lower limit alarm threshold, the two switch current control circuits output a current larger than or equal to 2.1 mA.
The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims (10)

1. The utility model provides a NAMUR switch instrument changer which characterized in that: the device comprises an MCU (microprogrammed control unit) microprocessor (1), a sensor (2) connected with the input end of the MCU microprocessor (1), a key unit (3) connected with the input end of the MCU microprocessor (1) and a switch current control circuit connected with the output end of the MCU microprocessor (1).
2. The NAMUR switch meter transmitter of claim 1, wherein: the output end of the MCU microprocessor (1) is connected with a constant current excitation (5) for supplying power to the sensor (2), and the constant current excitation (5) is electrically connected with a joint of the sensor (2); the MCU microprocessor (1) is used for controlling the constant current excitation (5) to be switched on and off.
3. The NAMUR switch meter transmitter of claim 1 or 2, wherein: the switch current control circuit comprises a first switch current control circuit (6), the first switch current control circuit (6) is electrically connected with the output end of the MCU microprocessor (1), and the first switch current control circuit (6) is connected with a DC/DC power supply (8) and a wiring terminal SW 1.
4. The NAMUR switch meter transmitter of claim 3, wherein: the switch current control circuit further comprises a second switch current control circuit (7), the second switch current control circuit (7) is connected with a wiring terminal SW2, and a low-power isolation element (9) is connected between the second switch current control circuit (7) and the output end of the MCU microprocessor (1).
5. The NAMUR switch meter transmitter of claim 4, wherein: the first switch current control circuit (6) and the second switch current control circuit (7) each include a power supply processing circuit (60) and an operational amplifier (80), the power supply processing circuit (60) includes a power supply circuit (61), a triode state adjustment circuit (62), and a resistor R1 connected between a connection terminal SW1 and ground, and the operational amplifier (80) includes an operational amplification unit A and an operational amplification unit B;
the power supply circuit (61) comprises a resistor R3, the resistor R3 is connected with the anode of a connecting terminal SW1, the emitter of a triode Q1 and a resistor R4, the other end of the resistor R4 is connected with the base of a triode Q1, the other end of the resistor R3 is connected with the cathode of a diode D5, a regulated power supply LDO, the collector of a triode Q1, the cathode of a diode D2 and a DC/DC power supply, and the anode of a diode D2 and the anode of a diode D5 are respectively grounded;
the triode state adjusting circuit (62) comprises a resistor R7, a triode Q2 and a resistor R6, wherein the resistor R7 is connected with a pin OUTA of the operational amplification unit A, the other end of the resistor R7 is connected with a base electrode of the triode Q2, an emitting electrode of the triode Q2 is grounded, a collector electrode of the triode Q2 is connected with the resistor R6, and the other end of the resistor R6 is connected with a base electrode B of the triode Q1.
6. The NAMUR switch meter transmitter of claim 5, wherein: the first switching current control circuit (6) and the second switching current control circuit (7) each further include a current output control circuit (70), and the current output control circuit (70) includes a first voltage dividing circuit (71), a second voltage dividing circuit (72), and a current output circuit (73);
the first voltage division circuit (71) comprises a resistor R9 and a resistor R10, the resistor R9 is connected with the resistor R10 in series, the other end of the resistor R9 is connected with the MCU microprocessor (1), the other end of the resistor R10 is grounded, and a pin INB + of the operational amplification unit B is connected with a connection point of the resistor R9 and the resistor R10;
the second voltage division circuit (72) comprises a resistor R11 and a resistor R12, the resistor R11 is connected with the resistor R12 in series, the other end of the resistor R12 is connected with the regulated power supply LDO, the other end of the resistor R11 is grounded, and a pin INB-of the operational amplification unit B is connected with a connection point of the resistor R11 and the resistor R12;
the current output circuit (73) comprises a resistor R2, a resistor R5 and a resistor R8, the resistor R2 is connected with the resistor R5 in series, the other end of the resistor R2 is connected with the negative electrode of a connecting terminal SW1, the other end of the resistor R5 is connected with the regulated power supply LDO, the resistor R8 is connected with the connecting point of the resistor R2 and the resistor R5, and the other end of the resistor R8 is connected with a pin OUTB of the operational amplification unit B.
7. The NAMUR switch meter transmitter of claim 5 or 6, wherein: the power supply circuit (61) is provided with a diode D1, a diode D4 and a capacitor C1, and the diode D1 is connected between the anode of a connecting terminal SW1 and a resistor R3 in series; the diode D4 is connected in series between the cathode of the diode D5 and the regulated power supply LDO; the capacitor C1 is connected in parallel with the diode D2.
8. The NAMUR switch meter transmitter of claim 1, wherein: the MCU microprocessor (1) is also respectively connected with a ROM (read only memory) memory (10) and an LCD display screen (4).
9. A method of controlling a NAMUR switch meter transmitter according to any of the claims 2 to 8, comprising:
controlling the constant-current excitation and the AD converter to be simultaneously opened, so that the constant-current excitation supplies power to the sensor;
the AD converter processes data input by the sensor for a plurality of times and stores the data in a ROM;
closing the constant current excitation and AD converter, and opening an LCD display screen;
and carrying out operation processing on data input by the sensor after the AD converter processes a plurality of times, and then transmitting the data to an LCD display screen for display.
10. The method of controlling a NAMUR switch meter transmitter of claim 9, wherein: the data input by the sensors after being processed by the AD converter for a plurality of times are transmitted to the LCD display screen after being processed by operation comprises the following steps:
comparing data input by the sensors processed by the AD converter for a plurality of times with a set alarm threshold value, and outputting a current value on a switch current control circuit according to a comparison result to indicate that the alarm is given or not given;
and the LCD display screen displays the flow data acquired by the sensor in a delayed manner.
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Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070096823A1 (en) * 2005-10-17 2007-05-03 Wj Communications, Inc. Bias circuit for BJT amplifier
CN203520551U (en) * 2013-11-01 2014-04-02 浙江爱德电子有限公司 Fire alarm control system
CN104410405A (en) * 2014-09-29 2015-03-11 中国航天科技集团公司第九研究院第七七一研究所 Implementation method of programmable general digital quantity I/O signal conditioning
US20150137859A1 (en) * 2013-11-18 2015-05-21 Fairchild Korea Semiconductor Ltd. Input current control method, switch control circuit and power supply including the switch control circuit
CN104956592A (en) * 2012-12-21 2015-09-30 恩德斯+豪斯流量技术股份有限公司 Transformer circuit with a current interface and measuring instrument with such a transformer circuit
CN208076083U (en) * 2018-05-15 2018-11-09 四川海天仪表电器开发有限公司 A kind of band temperature calibration output configurable type intelligent pressure sensor
CN109164731A (en) * 2018-08-18 2019-01-08 中国海洋大学 A kind of high accuracy in-situ seawater pH sensory-control system and control method
CN208937939U (en) * 2018-02-05 2019-06-04 无锡物博新仪电子科技有限公司 A kind of TVOC gas transmitter based on analog output
CN209419952U (en) * 2018-11-23 2019-09-20 常州市武进区半导体照明应用技术研究院 A kind of constant-current dimming driving circuit based on PWM
CN209881672U (en) * 2019-04-15 2019-12-31 苏州沙丘电子科技有限公司 Switching power supply circuit
CN212206218U (en) * 2020-08-31 2020-12-22 北京妙思特仪表有限公司 NAMUR switch instrument transmitter
CN113252233A (en) * 2021-05-26 2021-08-13 西安微电子技术研究所 Digital piezoresistive pressure sensor circuit and digital piezoresistive pressure sensor
CN215222375U (en) * 2021-07-02 2021-12-17 沈阳中科奥维科技股份有限公司 Low-power consumption intrinsically safe Namur wireless adapter

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070096823A1 (en) * 2005-10-17 2007-05-03 Wj Communications, Inc. Bias circuit for BJT amplifier
CN104956592A (en) * 2012-12-21 2015-09-30 恩德斯+豪斯流量技术股份有限公司 Transformer circuit with a current interface and measuring instrument with such a transformer circuit
CN203520551U (en) * 2013-11-01 2014-04-02 浙江爱德电子有限公司 Fire alarm control system
US20150137859A1 (en) * 2013-11-18 2015-05-21 Fairchild Korea Semiconductor Ltd. Input current control method, switch control circuit and power supply including the switch control circuit
CN104410405A (en) * 2014-09-29 2015-03-11 中国航天科技集团公司第九研究院第七七一研究所 Implementation method of programmable general digital quantity I/O signal conditioning
CN208937939U (en) * 2018-02-05 2019-06-04 无锡物博新仪电子科技有限公司 A kind of TVOC gas transmitter based on analog output
CN208076083U (en) * 2018-05-15 2018-11-09 四川海天仪表电器开发有限公司 A kind of band temperature calibration output configurable type intelligent pressure sensor
CN109164731A (en) * 2018-08-18 2019-01-08 中国海洋大学 A kind of high accuracy in-situ seawater pH sensory-control system and control method
CN209419952U (en) * 2018-11-23 2019-09-20 常州市武进区半导体照明应用技术研究院 A kind of constant-current dimming driving circuit based on PWM
CN209881672U (en) * 2019-04-15 2019-12-31 苏州沙丘电子科技有限公司 Switching power supply circuit
CN212206218U (en) * 2020-08-31 2020-12-22 北京妙思特仪表有限公司 NAMUR switch instrument transmitter
CN113252233A (en) * 2021-05-26 2021-08-13 西安微电子技术研究所 Digital piezoresistive pressure sensor circuit and digital piezoresistive pressure sensor
CN215222375U (en) * 2021-07-02 2021-12-17 沈阳中科奥维科技股份有限公司 Low-power consumption intrinsically safe Namur wireless adapter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
张守福;刘洪超;: "NAMUR型速度传感器信号采集电路的设计", 工矿自动化, no. 08, 10 August 2011 (2011-08-10) *

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