Three-wire system transmitter

Abstract

The utility model relates to a three-wire system transmitter, which comprises a digital conditioning circuit and a signal output circuit, the digital conditioning circuit is integrated with a microprocessor, a signal input port module, a filtering module, a preposed PGA amplifier and an ADC analog-to-digital conversion module which are sequentially connected to the preceding stage of the microprocessor, and a DAC digital-to-analog conversion module connected to the backward stage of the microprocessor, the programming interface is connected to the microprocessor in series; the signal output circuit comprises a voltage follower circuit and a voltage-current conversion circuit which are sequentially connected to the rear stage of the DAC digital-to-analog conversion module, and the control end of the microprocessor is connected with the preposed PGA amplifier. According to the three-wire system transmitter, the ADC is adopted to convert analog signals into digital quantity, then the digital quantity is subjected to processing, digital-to-analog conversion and voltage-current conversion, finally efficient and stable signal output is achieved, the process signal conversion and output adjustment process do not depend on physical adjustable devices, and the problem that parameters of adjustable elements drift for a long time is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of transmitter structure, in particular to a three-wire transmitter. Background Art

[0002] In a narrow sense, a transmitter is a device that converts the physical quantity, chemical quantity and other information sensed by the sensor into a standardized signal that is easy to measure and transmit according to certain rules. Traditional transmitters generally use operational amplifiers to directly process analog signals. Due to the simple and reliable principle, this type of transmitter is still widely used. In order to adapt to the signals of different sensors, multiple adjustable elements (such as adjustable resistors) need to be configured in the transmitter to achieve the purpose of outputting a unified standardized signal by adjusting the zero point, amplification factor, range and other parameters. After long-term use, the adjustable parameters of the adjustable element will change due to temperature, vibration, impact, aging or other environmental factors, which will affect the accuracy of the transmitter output signal. Utility Model Content

[0003] The technical problem to be solved by the utility model is: to overcome the defects of traditional analog output transmitters in terms of dependence on adjustable distance and long-term parameter drift of adjustable components, and to provide a three-wire transmitter with stable operation and accurate output. An ADC is used to convert analog signals into digital quantities, and then the digital quantities are processed, digital-to-analog converted, and pressure-to-current converted, so as to finally achieve efficient and stable signal output. The process signal conversion and output adjustment process do not rely on physical adjustable components, and the problem of long-term parameter drift of adjustable components is avoided.

[0004] The three-wire transmitter includes a digital conditioning circuit for performing analog-to-digital and digital-to-analog processing on the front-end sensor signal, and a signal output circuit for data connection with the back-end instrument equipment, wherein the signal output circuit is connected to the rear stage of the digital conditioning circuit, wherein the digital conditioning circuit integrates a microprocessor, a signal input port module, a filtering module, a pre-PGA amplifier, an ADC analog-to-digital conversion module connected in sequence to the front stage of the microprocessor, a DAC digital-to-analog conversion module connected to the rear stage of the microprocessor, and a programming interface connected in series to the microprocessor; the signal output circuit includes a voltage follower circuit and a voltage-to-current conversion circuit connected in sequence to the rear stage of the DAC digital-to-analog conversion module, and the control end of the microprocessor is connected to the pre-PGA amplifier.

[0005] Furthermore, the signal output circuit adopts an integrated dual operational amplifier circuit, the first stage operational amplifier constitutes the voltage follower circuit, and the second stage operational amplifier constitutes a voltage-to-current conversion circuit that converts a voltage signal into a current signal.

[0006] Specifically, the ADC analog-to-digital conversion module adopts a 14-bits ADC, and the DAC digital-to-analog conversion module adopts a 12-bits DAC.

[0007] Specifically, the digital conditioning circuit adopts the JHM1102 processor.

[0008] The utility model discloses a three-wire transmitter, which overcomes the defects of traditional analog output transmitters in terms of dependence on adjustable distance and long-term parameter drift of adjustable components. It has stable operation and accurate output. It uses ADC to convert analog signals into digital quantities, and then processes the digital quantities, performs digital-to-analog conversion, and voltage-to-current conversion, ultimately achieving efficient and stable signal output. The process of process signal conversion and output adjustment does not rely on physical adjustable components, and avoids the problem of long-term parameter drift of adjustable components. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following is a further description of a three-wire transmitter of the utility model in conjunction with the accompanying drawings:

[0010] Figure 1 This is the logic structure and connection principle wireframe diagram of implementation mode 1 of the three-wire transmitter;

[0011] Figure 2 This is a circuit diagram of implementation mode 2 of the three-wire transmitter.

[0012] In the figure:

[0013] 1-digital conditioning circuit; 11-microprocessor, 12-signal input port module, 13-filter module, 14-pre-PGA amplifier, 15-ADC analog-to-digital conversion module, 16-DAC digital-to-analog conversion module, 17-programming interface; 2-signal output circuit; 21-voltage follower circuit, 22-voltage-to-current conversion circuit. DETAILED DESCRIPTION

[0014] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0015] In the description of the present invention, it should be understood that the terms "left", "right", "front", "back", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0016] The technical solution of the utility model is further described below with specific embodiments, but the protection scope of the utility model is not limited to the following embodiments.

[0017] Implementation method 1: Figure 1 As shown, the three-wire transmitter includes a digital conditioning circuit 1 for processing analog-to-digital and digital-to-analog signals of the front-end sensor, and a signal output circuit 2 for data connection with the back-end instrument equipment, wherein the signal output circuit 2 is connected to the rear stage of the digital conditioning circuit 1, wherein the digital conditioning circuit 1 integrates a microprocessor 11, a signal input port module 12, a filter module 13, a pre-PGA amplifier 14, an ADC analog-to-digital conversion module 15 connected in sequence to the front stage of the microprocessor 11, a DAC digital-to-analog conversion module 16 connected to the rear stage of the microprocessor 11, and a programming interface 17 connected in series to the microprocessor 11; the signal output circuit 2 includes a voltage follower circuit 21 and a voltage-current conversion circuit 22 connected in sequence to the rear stage of the DAC digital-to-analog conversion module 16, and the control end of the microprocessor 11 is connected to the pre-PGA amplifier 14. The amplification factor can be adjusted through the programming interface, and a maximum voltage signal gain of 96 times can be achieved to obtain a more ideal signal amplitude for a series of signal conversion processing in the rear stage. The signal output circuit 2 adopts an integrated dual op amp circuit, the first stage op amp constitutes the voltage follower circuit 21, and the second stage op amp constitutes a voltage-to-current conversion circuit 22 that converts the voltage signal into a current signal. This transmitter is a three-wire 4-20mA output signal format. The voltage follower circuit formed by the first stage op amp reduces the impact of the output circuit on the previous stage; the second stage op amp constitutes a voltage-to-current conversion circuit that converts the voltage signal output by the signal amplification and conditioning circuit into a 4-20mA current signal. The ADC analog-to-digital conversion module 15 adopts a 14-bits ADC, and the DAC digital-to-analog conversion module 16 adopts a 12-bits DAC.

[0018] Implementation method 2: Figure 2 As shown, the digital conditioning circuit 1 of the three-wire transmitter adopts the JHM1102 processor. The JHM1102 core is Cortex M0+PGA, and the PGA, ADC, DAC and other peripherals are integrated internally. A single module can include the necessary functional modules in this design, reducing the coupling link between the processor and the peripherals. At the same time, a non-MCU design scheme is adopted, and the hardware logic of the signal processing process is solidified, and there will be no runaway or crash due to interference, thereby improving the reliability of the transmitter. The remaining structures and components are as described in Implementation 1 and will not be described again.

[0019] During operation: the differential signal of the front-end sensor is passed through the pre-PGA amplifier to adjust the amplification factor (the maximum voltage signal gain can be 96 times) to make the analog signal obtain a more ideal signal amplitude, and then the analog domain is converted to the digital domain in the post-ADC analog-to-digital conversion module. The output digital signal conversion is then processed by the microprocessor for nonlinear compensation and temperature compensation to reduce the difficulty of transmitter calibration and improve calibration efficiency. The compensated data is reconverted into an analog voltage signal output in the range of 0-5V through the post-DAC digital-to-analog conversion module, and the output signal is adjusted to a 4-20mA current signal output through the voltage-to-current conversion circuit to meet the needs of different output signals.

[0020] This three-wire transmitter overcomes the defects of traditional analog output transmitters' dependence on adjustable distance and long-term parameter drift of adjustable components. It has stable operation and accurate output. It uses ADC to convert analog signals into digital quantities, and then processes the digital quantities, performs digital-to-analog conversion, and voltage-to-current conversion, ultimately achieving efficient and stable signal output. The process of process signal conversion and output adjustment does not rely on physical adjustable devices, and avoids the problem of long-term parameter drift of adjustable components.

[0021] The above description shows the main features, basic principles, and advantages of the utility model. For those skilled in the art, it is obvious that the utility model is not limited to the details of the above exemplary embodiments or embodiments, and the utility model can be implemented in other specific forms without departing from the spirit or basic features of the utility model. Therefore, the above embodiments or embodiments should be regarded as exemplary and non-restrictive. The scope of the utility model is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the utility model. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0022] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A three-wire transmitter, characterized in that: It comprises a digital conditioning circuit (1) for performing analog-to-digital and digital-to-analog processing on a front-end sensor signal, and a signal output circuit (2) for data connection with a back-end instrument device, wherein the signal output circuit (2) is connected to the rear stage of the digital conditioning circuit (1), wherein: The digital conditioning circuit (1) is integrated with a microprocessor (11), a signal input port module (12), a filter module (13), a pre-PGA amplifier (14), an ADC analog-to-digital conversion module (15) connected in sequence to the front stage of the microprocessor (11), a DAC digital-to-analog conversion module (16) connected to the rear stage of the microprocessor (11), and a programming interface (17) connected in series to the microprocessor (11); the signal output circuit (2) comprises a voltage follower circuit (21) and a voltage-to-current conversion circuit (22) connected in sequence to the rear stage of the DAC digital-to-analog conversion module (16), and the control end of the microprocessor (11) is connected to the pre-PGA amplifier (14).

2. The three-wire transmitter according to claim 1 is characterized in that: The signal output circuit (2) adopts an integrated dual operational amplifier circuit, the first stage operational amplifier constitutes the voltage follower circuit (21), and the second stage operational amplifier constitutes a voltage-to-current conversion circuit (22) that converts a voltage signal into a current signal.

3. The three-wire transmitter according to claim 2 is characterized in that: The ADC analog-to-digital conversion module (15) adopts a 14-bits ADC, and the DAC digital-to-analog conversion module (16) adopts a 12-bits DAC.

4. The three-wire transmitter according to claim 3 is characterized in that: The digital conditioning circuit (1) adopts a JHM1102 processor.

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