Full-isolation type water quality detection processing circuit

Abstract

The utility model relates to a full-isolation type water quality detection circuit, which is characterized in that a main power supply module supplies power to a single chip microcomputer master control module and a display module, is electrically connected with a detection sensor signal processing module through a first power supply isolation module, and is electrically connected with a current loop module through a second power supply isolation module; the main power supply module is electrically connected with the isolation type 485 communication module through the third power supply isolation module; the single-chip microcomputer master control module is connected with the display module. The detection sensor signal processing module is in signal connection with the single-chip microcomputer master control module through the first digital isolation module. The current loop module is in signal connection with the single-chip microcomputer master control module through the second digital isolation module. The isolation type 485 communication module is in signal connection with the single-chip microcomputer master control module. According to the invention, isolation of interaction between the circuit and the external environment is realized, and effective isolation between functional modules of the circuit is ensured, so that the anti-interference capability in the working process is stronger, the detection data is more stable, and the operation test is more reliable.

Description

Technical Field

[0001] The utility model relates to an industrial isolation circuit, in particular to a fully isolated water quality detection and processing circuit. Background Art

[0002] Since water quality testing is often used in various complex industrial scenarios, it often requires multiple functions such as 485 communication and 4-20mA control loops, and most sensors used for water quality testing have characteristics such as high input impedance and weak signals. In the prior art, the technical solutions of water quality detectors commonly used at home and abroad do not effectively isolate the high source resistance of the sensor and external interference in the communication and control loops when dealing with such problems. External grounding shielding measures are often used to eliminate environmental interference, or large data fluctuations and unstable operation may occur during use.

[0003] Therefore, when processing the water quality detection circuit signal, how to effectively shield the on-site interference and eliminate the impact of the on-site on the circuit components is the technical problem that this application aims to solve. Summary of the invention

[0004] The purpose of the utility model is to provide a fully isolated water quality detection processing circuit, which can make the entire water quality detection process and signal transmission stable, display interaction smooth and stable, and can greatly enhance the anti-interference ability of the equipment.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] The utility model provides a fully isolated water quality detection and processing circuit, which includes a main power supply module, a single-chip main control module, a display module, a detection sensor signal processing module, a current loop module, and an isolated 485 communication module, wherein:

[0007] The main power supply module is electrically connected to the single-chip main control module and the display module to supply power to the single-chip main control module and the display module. The main power supply module is electrically connected to the detection sensor signal processing module through a first power isolation module, the main power supply module is electrically connected to the current loop module through a second power isolation module, and the main power supply module is electrically connected to the isolated 485 communication module through a third power isolation module.

[0008] The single chip microcomputer main control module is connected to the display module;

[0009] The detection sensor signal processing module is connected to the single chip main control module by signal through the first digital isolation module;

[0010] The current loop module is connected to the single-chip microcomputer main control module by signal through the second digital isolation module;

[0011] The isolated 485 communication module is signal-connected to the single-chip microcomputer main control module.

[0012] Optionally, the main power module adopts a finished 24V, 0.5A 12W switching power supply, the switching power supply is stepped down to 5V by a DCDC module, and then outputs a 3.3V voltage through a linear regulator to power the display module and the single-chip main control module.

[0013] Optionally, the serial communication port of the main chip of the single-chip main control module outputs a digital signal to the second digital isolation module for isolation, and the isolated digital signal is converted into a voltage value signal through a digital-to-analog converter and input into the voltage-to-current converter of the current loop module, and the voltage-to-current converter outputs a control current of 4~20mA.

[0014] Optionally, the serial communication port of the main chip of the isolated 485 communication module is connected to the input end of the differential bus transceiver, the output bus end of the differential bus transceiver is connected to the field communication equipment, and the input end of the main chip of the isolated 485 communication module is connected to the single-chip main control module.

[0015] Optionally, the detection sensor signal processing module includes an input-output amplifier, which collects sensor signals input by an external sensor head. The positive end of the input-output amplifier is connected to a high-impedance resistor. The output voltage of the input-output amplifier and the reference voltage constitute a differential signal input to an analog-to-digital converter. The digital signal obtained after the analog-to-digital conversion is isolated by the first digital isolation module, and the isolated digital signal is sent to the single-chip main control module via the serial communication port.

[0016] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0017] The fully isolated water quality detection circuit of the utility model carries out systematic and effective shielding and isolation in terms of power supply, grounding and signal processing, and adopts multiple measures such as A / D conversion, D / A conversion and digital isolation, so that the main control and display modules can effectively prevent external interference during the collection, processing and display process, which not only realizes the isolation of the interaction between the circuit and the external environment, but also ensures the effective isolation between the functional modules of the circuit itself, so that the working process has stronger anti-interference ability, the detection data is more stable, and the operation test is more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0019] Figure 1 It is a schematic diagram of the module connection structure of a fully isolated detection and processing circuit according to an embodiment of the utility model;

[0020] Figure 2 It is a schematic diagram of the circuit connection structure of the detection sensor signal processing module in one embodiment of the utility model;

[0021] Figure 3 is a schematic diagram of the circuit connection structure of the main power module according to one embodiment of the utility model;

[0022] Figure 4 is a schematic diagram of a circuit connection structure of a current loop module in one embodiment of the utility model;

[0023] Figure 5 It is a schematic diagram of the circuit connection structure of an isolated 485 communication module in one embodiment of the utility model.

[0024] The following are the descriptions of the reference numerals:

[0025] 1. Main power supply module, 2. Single chip main control module, 3. Display module, 4. Detection sensor signal processing module, 5. Current loop module, 6. Isolated 485 communication module, 71. First power supply isolation module, 72. Second power supply isolation module, 73. Third power supply isolation module, 81. First digital isolation module, 82. Second digital isolation module. DETAILED DESCRIPTION

[0026] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0028] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] This embodiment provides a fully isolated water quality detection and processing circuit, which includes a main power supply module 1, a single-chip main control module 2, a display module 3, a detection sensor signal processing module 4, a current loop module 5, and an isolated 485 communication module 6, wherein:

[0030] The main power module 1 is electrically connected to the single-chip main control module 2 and the display module 3 to provide power for the single-chip main control module 2 and the display module 3. The main power module 1 is electrically connected to the detection sensor signal processing module 4 through the first power isolation module 71. The main power module 1 is electrically connected to the current loop module 5 through the second power isolation module 72. The main power module 1 is electrically connected to the isolated 485 communication module 6 through the third power isolation module 73.

[0031] The single chip main control module 2 is connected to the display module 3;

[0032] The detection sensor signal processing module 4 is connected to the single chip main control module 2 by signal through the first digital isolation module 81;

[0033] The current loop module 5 is connected to the single chip main control module 2 by signal through the second digital isolation module 82;

[0034] The isolated 485 communication module 6 is connected to the single chip main control module 2 by signal.

[0035] In this embodiment, the devices used are as follows:

[0036] Main power module 1, such as Figure 3 As shown, a finished 24V, 0.5A 12W switching power supply is used, which is stepped down to 5V by the DCDC module of LM2596S-5.0. The output 5V voltage is output to 3.3V voltage through the AMS1117-3.3V linear regulator to power the display module 3 and the microcontroller main control module.

[0037] The single-chip main control module 2 uses the STM32F407VET6 chip, 3.3V power supply, 8M working crystal oscillator, and two 20PF adaptive capacitors. It mainly completes the setting, calculation, control and display control of the water quality detection system.

[0038] The display module 3 uses a 4.3-inch TFT liquid crystal display screen, 3.3V power supply, and is directly controlled by the single-chip main control module 2 to display the specific data detected by the water quality and the relevant setting parameters of the detection equipment.

[0039] The first power isolation module 71 and the third power isolation module 73 both use the 5V isolated power module B0505S-1W as the core component. The input end is connected to the 5V voltage output by the main power module 1, and the output end outputs an isolated 5V voltage to provide isolated power for the detection sensor signal processing module 4 and the isolated 485 communication module 6 to achieve power isolation.

[0040] The second power isolation module 72 uses the 24V isolated power module B2424S-1W as the core component. The input end is connected to the 24V voltage output by the main power module 1, and the output end outputs an isolated 24V voltage to provide isolated power for the 4~20mA current loop module 5 to achieve power isolation.

[0041] The first digital isolation module 81 uses the four-channel digital isolator ADUM1401 as the core device, the input end is the digital signal obtained by the detection sensor signal processing module 4, and the output end is connected to the serial communication port of the chip of the single-chip main control module 2 to achieve isolation of the detection signal from the single-chip main control module 2.

[0042] The second digital isolation module 82 uses the four-channel digital isolator ADUM1401 as the core device, the input end is connected to the chip serial communication port of the single-chip main control module 2, and the output end is connected to the 4~20mA current loop module 5 to achieve isolation between the current loop output and the single-chip main control module 2.

[0043] The detection sensor signal processing module 4 is constructed by a buffer amplifier AD8603 with high input impedance and ultra-low input bias current and a low-noise and low-power analog-to-digital converter AD7793. After analog-to-digital conversion, a digital signal of the detection information is obtained.

[0044] The 4~20mA current loop module 5 is composed of a 12-bit digital-to-analog converter DAC7512 and a precision voltage-to-current converter XTR111 as core components. The digital signal obtained by the second digital isolation module 82 is input into the digital-to-analog converter for conversion into a voltage signal, which is converted by XTR111 into a 4~20mA control current output. At the same time, XTR111 can output a 5V voltage for use by the analog-to-digital converter and the second digital isolation module 82 (current loop end).

[0045] The isolated 485 communication module 6 is based on an isolated differential bus transceiver ADM2483 as the core device. The logic end of the device is powered by a 3.3 V power supply, and the bus end is powered by an isolated 5 V power supply to achieve isolated 485 communication of the device.

[0046] Specifically, the detection sensor signal processing module 4 includes an input-output amplifier, which collects the sensor signal input by the external sensor head, the positive end of the input-output amplifier is connected to a high-impedance resistor, the output voltage of the input-output amplifier and the reference voltage constitute a differential signal input analog-to-digital converter, and the digital signal obtained after analog-to-digital conversion is isolated by the first digital isolation module 81, and the isolated digital signal is sent to the single-chip main control module 2 via the serial communication port. Figure 2 As shown, a single-channel, micro-power, rail-to-rail input-output amplifier AD8603 collects sensor signals. The positive input terminal of the input-output amplifier is connected to the R1 (1MΩ) resistor matching to offset the high source resistance of the sensor input terminal. The output voltage Vo of the input-output amplifier AD8603 and Vref (Vref=IOUT*R2) form a differential signal input analog-to-digital converter AD7793. The digital signal obtained after the analog signal is converted to a digital signal is input into the ADUM1401 digital isolation chip (the first digital isolation module 81) for isolation. The chip power supply on this side adopts the isolated VDD-ISO power supply. The isolated digital signal is input into the single-chip main control module 2 through the SPI serial communication port for calculation and processing.

[0047] The serial communication port of the STM32F407VET6 chip of the single-chip main control module 2 outputs the corresponding digital signal to the second digital isolation module 82 for isolation. The isolated digital signal is converted into a voltage value signal by the digital-to-analog converter of the current loop module and input into the voltage-to-current converter of the current loop module. The voltage-to-current converter outputs a 4-20mA current for control. Figure 4 As shown, the isolated current loop output is first isolated from the power supply, using B2424S-1W (second power supply isolation module 72), the input is the front stage 24V in the main power supply module 1, and the output is an isolated 24-GELI power supply. The isolation processing flow of the current loop signal is shown in the attached figure. Figure 4 As shown in , the serial communication port of the main chip outputs the corresponding digital signal of the current loop, and the digital signal is isolated by the ADUM1401 digital isolation chip (the second digital isolation module 82). The isolated digital signal is converted from digital signal to analog signal by the digital-to-analog converter DAC7512N chip, and the converted voltage value is input into the XTR111AIDGQR voltage-to-current converter, which outputs the corresponding 4~20mA current. In this current loop module 5, the signal is isolated by ADUM1401, the power supply is isolated by B2424S-1W, and the DAC5V voltage is output by the XTR111 chip.

[0048] The serial communication port of the main chip of the isolated 485 communication module 6 is connected to the input end of the differential bus transceiver, the output bus end of the differential bus transceiver is connected to the field communication device, and the input end of the main chip of the isolated 485 communication module 6 is connected to the single-chip main control module 2. Figure 5 As shown, the isolated 485 communication module 6 is firstly isolated from the power supply, using B0505S-1W (third power isolation module 73), the input is the secondary output +5V in the main unit module, and the output is the isolated VCC485 power supply. The isolated 485 communication module 6 is based on an isolated differential bus transceiver ADM2483 as the core device, and the serial communication ports RX and TX of the main chip are directly connected to the input end of the differential bus transceiver ADM2483. This direction is powered by the three-level output V3.3 V power supply in the main power module 1. The output bus end of the differential bus transceiver ADM2483 is connected to the field communication equipment, and the isolated VCC485 power supply is used to realize the isolated 485 communication of the equipment.

[0049] In summary, the fully isolated water quality detection circuit of the utility model has carried out systematic and effective shielding and isolation in terms of power supply, grounding and signal processing, and adopts multiple measures such as A / D conversion, D / A conversion and digital isolation, so that the main control and display module 3 can effectively prevent external interference during the collection, processing and display process, which not only realizes the isolation of the interaction between the circuit and the external environment, but also ensures the effective isolation between the functional modules of the circuit itself, so that the working process is more resistant to interference, the detection data is more stable, and the operation test is more reliable.

[0050] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with this technology to understand the content of the utility model and implement it accordingly. They cannot be used to limit the protection scope of the utility model. All equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A fully isolated water quality detection and processing circuit, characterized in that: It includes main power module, single chip main control module, display module, detection sensor signal processing module, current loop module, isolated 485 communication module, among which: The main power supply module is electrically connected to the single-chip main control module and the display module to supply power to the single-chip main control module and the display module. The main power supply module is electrically connected to the detection sensor signal processing module through a first power isolation module, the main power supply module is electrically connected to the current loop module through a second power isolation module, and the main power supply module is electrically connected to the isolated 485 communication module through a third power isolation module. The single chip microcomputer main control module is connected to the display module; The detection sensor signal processing module is connected to the single chip main control module by signal through the first digital isolation module; The current loop module is connected to the single-chip microcomputer main control module by signal through the second digital isolation module; The isolated 485 communication module is signal-connected to the single-chip main control module.

2. The fully isolated water quality detection and processing circuit according to claim 1 is characterized in that: The main power supply module adopts a finished 24V, 0.5A 12W switching power supply. The switching power supply is stepped down to 5V by a DCDC module, and then outputs a 3.3V voltage through a linear regulator to power the display module and the single-chip main control module.

3. The fully isolated water quality detection and processing circuit according to claim 1 is characterized in that: The serial communication port of the main chip of the single-chip main control module outputs a digital signal to the second digital isolation module for isolation. The isolated digital signal is converted into a voltage value signal through the digital-to-analog converter of the current loop module and input into the voltage-to-current converter of the current loop module. The voltage-to-current converter outputs a 4~20mA current for control.

4. The fully isolated water quality detection and processing circuit according to claim 1 is characterized in that: The serial communication port of the main chip of the isolated 485 communication module is connected to the input end of the differential bus transceiver, the output bus end of the differential bus transceiver is connected to the field communication equipment, and the input end of the main chip of the isolated 485 communication module is connected to the single-chip main control module.

5. The fully isolated water quality detection and processing circuit according to claim 1, characterized in that: The detection sensor signal processing module includes an input-output amplifier, which collects the sensor signal input by the external sensor head. The positive end of the input-output amplifier is connected to a high-impedance resistor. The output terminal voltage of the input-output amplifier and the reference voltage constitute a differential signal input to an analog-to-digital converter. The digital signal obtained after the analog-to-digital conversion is isolated by the first digital isolation module, and the isolated digital signal is sent to the single-chip main control module via the serial communication port.

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