Electromagnetic flowmeter transmitter with temperature measurement

Abstract

The utility model relates to electromagnetic flowmeter technical field, the utility model discloses a kind of electromagnetic flowmeter transmitter with temperature measurement, including through power supply circuit and signal isolation circuit connection control circuit and signal processing circuit, the signal processing circuit includes the wiring terminal J8 of realizing multiple wiring mode;Based on the selective connection temperature sensor of wiring terminal J8, temperature signal is connected to the input end of operational amplifier UT1A by analog switch U18 output, based on the input end of analog-digital converter U19 connected to the output end of operational amplifier UT1A;The control pin of analog-digital converter U19 is connected to control circuit, for controlling the collection and transmission of data, the utility model is through integrated multifunction and flexible measurement mode, high precision, high flexibility, low cost, high reliability and strong anti-interference ability are realized, the efficiency and performance of industrial measurement system are significantly improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of electromagnetic flowmeter, more specifically, the utility model relates to a kind of electromagnetic flowmeter transmitter with temperature measurement. BACKGROUND

[0002] Electromagnetic water meter meets actual demand by integrating multiple functions and flexible measurement mode in different industrial scenarios, may need to monitor the flow and temperature of fluid simultaneously, to ensure the accurate control of reaction condition;But field wiring is limited by space, needs to support multiple wiring modes to adapt to different installation conditions, under multiple wiring modes, it also needs to consider how to transmit the data obtained under multiple wiring, on this basis, it needs to consider communication mode;In addition, if there is strong electromagnetic interference in corresponding application scenario, it also needs to have good anti-interference ability.

[0003] Therefore, the utility model provides a kind of electromagnetic flowmeter transmitter with temperature measurement. UTILITY MODEL CONTENT

[0004] In order to overcome the problems in the prior art, the utility model provides a kind of electromagnetic flowmeter transmitter with temperature measurement, supports multiple temperature sensors, supports multiple wiring modes, and simultaneously increases multiple outputs. Greatly improve the flexibility of instrument, expand the use range.

[0005] According to one aspect of the utility model, a kind of electromagnetic flowmeter transmitter with temperature measurement is provided, including the control circuit of PT100 / PT1000 measurement circuit by power supply circuit and signal isolation circuit connection, signal processing circuit, excitation circuit, PT100 / PT1000 measurement circuit, NTC measurement circuit, flow 4-20mA output circuit, temperature 4-20mA output circuit, flow frequency signal output circuit, temperature frequency signal output circuit, RS485 output circuit, flow alarm output circuit and temperature alarm output circuit, wherein;

[0006] The signal processing circuit includes wiring terminal J8 for realizing multiple wiring modes;Temperature sensor is selectively connected based on wiring terminal J8, NTC temperature signal is output connected to the input end of operational amplifier UT1A through analog switch U18, the input end (AIN2) of analog-digital converter U19 is connected based on the output end of operational amplifier UT1A;PT100 / PT1000 temperature signal is connected to the input end (AIN0, AIN1) of analog-digital converter U19 through analog switch U18;The control pin (SCLK, DI N, DOUT, CS) of analog-digital converter U19 is connected to control circuit, for controlling the acquisition and transmission of data.

[0007] As a preferred technical scheme of the utility model, the analog switch U18 is a double-channel single-pole double-throw analog switch, different measurement paths are selected through the analog switch, and analog signals are converted into digital signals through the ADC channel.

[0008] As a preferred technical scheme of the utility model, the analog switch U18 includes a switch S1A, a switch S1B, a switch S2A and a switch S2B, when the common end is connected to the switch S1A and the switch S2A, the wiring terminal is connected to the RC filter circuit to the PT100 / PT1000 measurement circuit connection end AIN0 and the PT100 / PT1000 measurement circuit connection end AIN1 at this time;

[0009] When the common end is connected to the switch S1B and the switch S2B, the wiring terminal is connected to the 10K precision resistor to the follower and is connected to the NTC measurement circuit wiring end AIN2 at this time, and the signal for the NTC temperature sensor is used.

[0010] As a preferred technical scheme of the utility model, the utility model also includes the resistance that sets up the working parameter of the analog-digital converter U19 and the capacitor that filters and decouples the circuit.

[0011] As a preferred technical scheme of the utility model, the analog switch U18 is also provided with two diodes at the input end, and the diodes are connected in reverse parallel between the power supply and the ground.

[0012] As a preferred technical scheme of the utility model, the wiring terminal J8 is a 4-core wiring terminal, and the input end of the 4-core wiring terminal is used to connect external sensors and equipment.

[0013] As a preferred technical scheme of the utility model, the wiring terminal J8 is a PT100 / PT1000 two-wire system connection method, the PT100 / PT1000 is connected to the wiring terminal 2 and the wiring terminal 3, the wiring terminal 4 is short-circuited with the wiring terminal 3, and the wiring terminal 1 is short-circuited with the wiring terminal 2.

[0014] As a preferred technical scheme of the utility model, the wiring terminal J8 is a PT100 / PT1000 three-wire system connection method, when the three-wire system connection method, the PT100 / PT1000 measurement line is connected to the wiring terminal 2 and the wiring terminal 3, the compensation line is connected to the wiring terminal 1, and the wiring terminal 4 is short-circuited with the wiring terminal 3.

[0015] As a preferred technical scheme of the utility model, the wiring terminal J8 is a PT100 / PT1000 four-wire system connection method, when the four-wire system connection method, the PT100 / PT1000 measurement line is connected to the wiring terminal 2 and the wiring terminal 3, and the two compensation lines are connected to the wiring terminal 1 and the wiring terminal 4.

[0016] As a preferred technical scheme of the utility model, the wiring terminal J8 is NTC resistance connection method; when measuring NTC resistance, the NTC resistance measuring line is connected to the wiring terminal 2 and the wiring terminal 3, and the analog switch is switched to the switch S1B and the switch S2B.

[0017] The technical effect and advantages of the electromagnetic flowmeter transmitter with temperature measurement of the utility model are as follows:

[0018] The utility model discloses a high-precision, high flexibility, low cost, high reliability and strong anti-interference ability are realized through the integrated multifunctional and flexible measurement mode, and the efficiency and performance of industrial measurement system are obviously improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The system block diagram of the electromagnetic flowmeter transmitter with temperature measurement in the embodiment of the utility model is shown in the figure.

[0020] Figure 2 The circuit connection diagram of the electromagnetic flowmeter transmitter with temperature measurement in the embodiment of the utility model is shown in the figure.

[0021] Figure 3 The circuit diagram of the PT100 / PT1000 two-wire system connection method in the embodiment of the utility model is shown in the figure.

[0022] Figure 4 The circuit diagram of the PT100 / PT1000 three-wire system connection method in the embodiment of the utility model is shown in the figure.

[0023] Figure 5 The circuit diagram of the PT100 / PT1000 four-wire system connection method in the embodiment of the utility model is shown in the figure.

[0024] Figure 6 The circuit diagram of the NTC resistance connection method in the embodiment of the utility model is shown in the figure. DETAILED DESCRIPTION

[0025] The technical scheme in the embodiment of the utility model will be described clearly and completely in combination with the drawings in the embodiment of the utility model, and obviously, the described embodiment is only a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.

[0026] Embodiment 1

[0027] Please refer to Figure 1As shown, the electromagnetic flowmeter transmitter with temperature measurement described in this embodiment includes a control circuit, a signal processing circuit, an excitation circuit, a PT100 / PT1000 measurement circuit, an NTC measurement circuit, a flow 4-20mA output circuit, a temperature 4-20mA output circuit, a flow frequency signal output circuit, a temperature frequency signal output circuit, an RS485 output circuit, a flow alarm output circuit, and a temperature alarm output circuit connected through a power supply circuit and a signal isolation circuit, forming a complete electromagnetic flowmeter transmitter system.

[0028] Power supply circuit: provides the required power for the entire system.

[0029] Control circuit: responsible for the control logic and operation of the entire system.

[0030] Signal processing circuit: processes and analyzes the collected signals.

[0031] Signal isolation circuit: used to isolate different circuit parts to prevent mutual interference.

[0032] Excitation circuit: provides excitation current for the electromagnetic flowmeter.

[0033] PT100 / PT1000 measurement circuit: used to measure the signal of PT100 or PT1000 temperature sensor.

[0034] NTC measurement circuit: used to measure the signal of NTC temperature sensor.

[0035] Flow 4-20mA output circuit: converts flow signal to 4-20mA current signal output.

[0036] Temperature 4-20mA output circuit: converts temperature signal to 4-20mA current signal output.

[0037] Flow frequency signal output circuit: converts flow signal to frequency signal output.

[0038] Temperature frequency signal output circuit: converts temperature signal to frequency signal output.

[0039] RS485 output circuit: used to output data through RS485 communication interface.

[0040] Flow alarm output circuit: outputs alarm signal when flow exceeds preset range.

[0041] Temperature alarm output circuit: outputs alarm signal when temperature exceeds preset range.

[0042] Specifically, the application is adaptive to select PT100, PT1000 and NTC three kinds of temperature sensors to realize signal processing on a converter through three wiring modes of two-wire, three-wire and four-wire, reduces the production cost and improves the flexibility. The temperature 4-20MA output, temperature frequency output and temperature alarm output are added, which greatly improves the flexibility of the instrument and expands the use range.

[0043] The signal processing circuit comprises a wiring terminal J8 for realizing multiple wiring modes; the temperature sensor is selectively connected based on the wiring terminal J8, the NTC temperature signal is output through an analog switch U18 and connected to the input end of an operational amplifier UT1A, the output end of the operational amplifier UT1A is connected to the input end (AIN0, AIN1, AIN2) of an analog-to-digital converter U19 based on the operational amplifier UT1A; the PT100 / PT1000 temperature signal is connected to the input end (AIN0, AIN1) of the analog-to-digital converter U19 through the analog switch U18; and the control pin (SCLK, DIN, DOUT, CS) of the analog-to-digital converter U19 is connected to a control circuit for controlling the collection and transmission of data.

[0044] As shown in Figure 2 The analog switch U18 is of the model TMUX4827, the control end (SEL, RT_Select) of the analog switch is connected to the control circuit for selecting different measurement modes (such as PT100 / PT1000 or NTC measurement), and different input signal paths are selected to measure different sensor signals; the TMUX4827 is a double-channel single-pole double-throw analog switch, different measurement paths are selected through the analog switch, and the analog signal is converted into a digital signal through the ADC channel; when the common end is connected to the switch S1A and the switch S2A, the wiring terminal is connected to the RC filter circuit to the PT100 / PT1000 measurement circuit connection end AIN0 and the PT100 / PT1000 measurement circuit connection end AIN1 at this time, which is used for measuring the signal of the PT100 or PT1000 temperature sensor. When the common end is connected to the switch S1B and the switch S2B, the wiring terminal is connected to a 10K precision resistor to a follower and then connected to the NTC measurement circuit wiring terminal AIN2 at this time, which is used for the signal of the NTC temperature sensor.

[0045] The operational amplifier UT1A is of the model TLV2333 IDR, which is used for amplifying and conditioning the input signal to facilitate subsequent analog-to-digital conversion, and the gain of the operational amplifier is set through external resistors (R1, R2) to adapt to different input signal ranges.

[0046] The model of the analog-to-digital converter U19 is ADS1148, which converts analog signals into digital signals for further processing by the control circuit. Different input channels and operating modes are selected through control signals. ADS1148 is a 16-bit analog-to-digital converter integrated with an IDAC current source. The built-in IDAC current source can feed external reference precision resistors. By configuring differently, it can measure thermal resistors in different wiring methods.

[0047] Further explanation, precision resistors (R3, R4, R8) are used to set the reference voltage and gain of the analog-to-digital converter; capacitors (C1, C2, C3, C4, C5, C6) are used for filtering and decoupling to reduce power supply noise and signal interference, and to set the working parameters and filtering of the analog-to-digital converter U19, to ensure the accuracy and stability of the signal.

[0048] Further explanation, the analog switch U18 is also provided with two diodes (D1, D2) at the input end. Diodes are used to protect the circuit from reverse voltage damage. Diodes are connected in reverse parallel between the power supply and ground. When the reverse voltage exceeds a certain value, the diode conducts and clamps the reverse voltage to a safe range.

[0049] Further explanation, the terminal J8 is a 4-core terminal. The input end of the 4-core terminal is used to connect external sensors and equipment. The output end of the 4-core terminal is connected to the input of the analog switch U18, which is used to receive signals from the sensor. The analog switch selects different input signal paths according to the control signal and switches the signal to the operational amplifier UT1A. The operational amplifier UT1A amplifies and conditions the input signal to facilitate subsequent analog-to-digital conversion U19. The analog-to-digital converter U19 converts the amplified analog signal into a digital signal and communicates with the control circuit through the control pin, realizing the measurement of flow and temperature.

[0050] Through the above circuit design, this embodiment flexibly selects different sensor signals for measurement and converts analog signals into digital signals through analog-to-digital conversion for subsequent signal processing and analysis. This design not only improves the flexibility and accuracy of measurement, but also enhances the stability and reliability of the system.

[0051] As shown in Figure 3 , the terminal J8 is a PT100 / PT1000 two-wire connection method. When using the two-wire connection method, the PT100 / PT1000 is connected to the terminal 2 and the terminal 3, and the terminal 4 is shorted with the terminal 3, and the terminal 1 is shorted with the terminal 2.

[0052] At this time, the internal constant current source of the analog-to-digital converter ADS1148 outputs current, which passes through the terminal 4 to the terminal 3, through a wire to the PT100 / PT1000 temperature sensor, and then returns to the terminal 2 through a wire, and then passes through the terminal 2 to the terminal 1, and then passes through the 2K precision resistor to the ground;

[0053] The terminal 2 and the terminal 3 pass through the analog switch TMUX4827, and then pass through a filter circuit to the ADC channel 0 and the ADC channel 1. The voltage on the 2K precision resistor can be obtained by ADC sampling as the ADC reference voltage. Since the thermal resistor is in series with the 2K precision resistor, the temperature drift of the constant current source and the error have no effect on the sampling result, and the precision is relatively high. The two-wire connection method cannot eliminate the influence of the wire resistance, and thus is suitable for occasions with short wires.

[0054] As shown in Figure 4 the terminal J8 is the PT100 / PT1000 three-wire connection method; in the three-wire connection method, the PT100 / PT1000 measurement line is connected to the terminal 2 and the terminal 3, the compensation line is connected to the terminal 1, and the terminal 4 is short-circuited with the terminal 3. At this time, the internal constant current source of the analog-to-digital converter ADS1148 outputs two currents, the first current passes through the terminal 4 to the terminal 3, through a wire to the PT100 / PT1000 temperature sensor, and then returns to the terminal 1 through a wire; the second current passes through the terminal 2, through a wire to the PT100 / PT1000 temperature sensor, and then returns to the terminal 1 through a wire. The two currents are combined and then pass through the 2K precision resistor to the ground. The terminal 2 and the terminal 3 pass through the analog switch TMUX4827, and then pass through a filter circuit to the ADC channel 0 and the ADC channel 1. The voltage on the 2K precision resistor can be obtained by ADC sampling as the ADC reference voltage. It can be seen that the current flows through both wires of the thermal resistor, and since the wire lengths are almost the same, the resistance is the same, the current size is the same, and thus the voltage drop on the two wires is also the same, which compensates for the influence of the wire resistance on the measurement result, and a relatively high precision is obtained.

[0055] As shown in Figure 5As shown, the terminal J8 is PT100 / PT1000 four-wire connection; when four-wire connection, PT100 / PT1000 measurement line is connected to terminal 2 and terminal 3, two compensation lines are connected to terminal 1 and terminal 4. At this time, the internal constant current source of the analog-to-digital converter ADS1148 will output a current, the current passes through terminal 4, through the wire to the PT100 / PT1000 temperature sensor, and then returns to terminal 1 through the wire; and then passes through a 2K precision resistor to the ground. Terminal 2 and terminal 3 pass through the analog switch TMUX4827 and then pass through the filter circuit to the ADC channel 0 and the ADC channel 1. It can be seen that the current does not flow through the measurement line, but is fed through the compensation line to the thermal resistance. In this way, there is no voltage drop on the measurement line, and the wire impedance has no effect on the measurement result, so a relatively high precision can be obtained.

[0056] As shown in the figure, Figure 6 As shown, the terminal J8 is NTC resistance connection; when measuring NTC resistance, the NTC resistance measurement line is connected to terminal 2 and terminal 3, and the analog switch is switched to switch S1B and switch S2B. At this time, the NTC will be divided with a 10K precision resistor, and the divided signal will enter the ADC channel 2 after passing through the filter follower. The NTC resistance is suitable for occasions where the precision requirement is not high.

[0057] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0058] Finally: the above is only a preferred embodiment of the present application and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An electromagnetic flowmeter transmitter with temperature measurement, characterized by, The control circuit, signal processing circuit, excitation circuit, PT100 / PT1000 measurement circuit, NTC measurement circuit, flow 4-20mA output circuit, temperature 4-20mA output circuit, flow frequency signal output circuit, temperature frequency signal output circuit, RS485 output circuit, flow alarm output circuit and temperature alarm output circuit are connected by the power supply circuit and the signal isolation circuit. The signal processing circuit includes a wiring terminal J8 for realizing multiple wiring modes; a temperature sensor is selectively connected based on the wiring terminal J8, and an NTC temperature signal is output through an analog switch U18 and connected to an input end of an operational amplifier UT1A, and the output end of the operational amplifier UT1A is connected to input ends AIN0 interface, AIN1 interface and AIN2 interface of an analog-to-digital converter U19; a PT100 / PT1000 temperature signal is connected to the input ends AIN0 interface and AIN1 interface of the analog-to-digital converter U19 through the analog switch U18. Control pins SCLK interface, DIN interface, DOUT interface and CS interface of the analog-to-digital converter U19 are connected to the control circuit, for controlling data acquisition and transmission.

2. A flowmeter transmitter with temperature measurement according to claim 1, characterized in that The analog switch U18 is a double-channel single-pole double-throw analog switch, which selects different measurement paths through the analog switch and converts analog signals into digital signals through an ADC channel.

3. A flowmeter transmitter with temperature measurement according to claim 2, wherein, The analog switch U18 includes switches S1A, S1B, S2A and S2B; when the common end is connected to the switches S1A and S2A, the wiring terminal is connected to an RC filter circuit to a PT100 / PT1000 measurement circuit connection end AIN0 and a PT100 / PT1000 measurement circuit connection end AIN1; When the common end is connected to the switches S1B and S2B, the wiring terminal is connected to a 10K precision resistor to a follower and connected to an NTC measurement circuit connection end AIN2, which is used for the signal of the NTC temperature sensor.

4. A flowmeter transmitter with temperature measurement according to claim 1, wherein, Resistors for setting working parameters of the analog-to-digital converter U19 and capacitors for filtering and decoupling the circuit are further included.

5. A temperature-measuring electromagnetic flowmeter transmitter according to claim 1, wherein, Two diodes are further provided at the input end of the analog switch U18 and connected in reverse parallel between the power supply and the ground.

6. A temperature-measuring electromagnetic flowmeter transmitter according to claim 1, wherein, The wiring terminal J8 is a 4-core wiring terminal, and the input end of the 4-core wiring terminal is used for connecting external sensors and devices.

7. A temperature-measuring electromagnetic flowmeter transmitter according to claim 1, wherein, The wiring terminal J8 is a PT100 / PT1000 two-wire connection method, the PT100 / PT1000 is connected to the wiring terminal 2 and the wiring terminal 3, and the wiring terminal 4 is short-circuited with the wiring terminal 3, and the wiring terminal 1 is short-circuited with the wiring terminal 2.

8. A temperature-measuring electromagnetic flowmeter transmitter according to claim 1, wherein, The wiring terminal J8 is a PT100 / PT1000 three-wire connection method; in the three-wire connection method, the PT100 / PT1000 measurement line is connected to the wiring terminal 2 and the wiring terminal 3, the compensation line is connected to the wiring terminal 1, and the wiring terminal 4 is short-circuited with the wiring terminal 3.

9. A temperature-measuring electromagnetic flowmeter transmitter according to claim 1 wherein, The wiring terminal J8 is a PT100 / PT1000 four-wire connection method; when the four-wire connection method is used, the PT100 / PT1000 measurement line is connected to the wiring terminal 2 and the wiring terminal 3, and the two compensation lines are connected to the wiring terminal 1 and the wiring terminal 4.

10. A temperature-measuring electromagnetic flowmeter transmitter according to claim 1, wherein, The wiring terminal J8 is an NTC resistance connection method; when the NTC resistance is measured, the NTC resistance measurement line is connected to the wiring terminal 2 and the wiring terminal 3, and the analog switch is switched to the switch S1B and the switch S2B.

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