Digital-to-analog conversion device and gas detector

Abstract

The utility model discloses a digital-to-analog conversion device, which is suitable for a gas detector, and comprises a central processing unit (CPU) controller, and a power supply module, a CPU controller, a data storage module, a digital signal input module and an analog signal output module which are respectively connected with the CPU controller, the output end of the digital signal input module is connected with one input end of the CPU controller, and the output end of the analog signal output module is connected with the other input end of the CPU controller. The output end of the CPU controller is connected with the input end of the analog signal output module, the output end of the power supply module is connected with the other input end of the CPU controller, and the CPU controller is interactively connected with the data storage module; wherein the digital signal input module inputs 1-8 paths of digital signals through a serial port, and the analog signal output module is an 8-path 4-20mA output module and converts multiple paths of digital signals into multiple paths of analog current signals.

Description

Technical Field

[0001] This utility model relates to the field of digital-to-analog conversion technology, and in particular to a digital-to-analog conversion device and a gas detector. Background Technology

[0002] Because the gas detector outputs a 4-20mA current signal, the receiving section converts this current signal into a digital signal before displaying it on a terminal device, such as a PC or the FC4128 signal acquisition station. This means only one detector corresponds to one receiving section. When multiple receiving devices simultaneously require the same 4-20mA signal from the gas detector, the current signal sharding reduces the signal strength of other receiving devices, failing to meet application requirements. Therefore, a device is needed to convert a single input signal into multiple 4-20mA output signals for other devices to acquire. Utility Model Content

[0003] The purpose of this invention is to provide a digital-to-analog converter and a gas detector that converts multiple digital signals into multiple analog current signals.

[0004] This invention provides a digital-to-analog converter suitable for gas detectors, comprising a CPU controller and a power supply module, a data storage module, a digital signal input module, and an analog signal output module respectively connected to the CPU controller.

[0005] The output terminal of the digital signal input module is connected to one input terminal of the CPU controller, the output terminal of the CPU controller is connected to the input terminal of the analog signal output module, the output terminal of the power supply module is connected to the other input terminal of the CPU controller, and the CPU controller is interactively connected to the data storage module.

[0006] The digital signal input module inputs 1-8 channels of digital signals via a serial port, while the analog signal output module is an 8-channel 4-20mA output module.

[0007] Preferably, the CPU controller includes an MCU module, capacitor C3, resistor R8, capacitor C7, capacitor C8, and resistor R50. The first port of the MCU module is connected to the V33-MCU signal terminal, and the first port of the MCU module is grounded via capacitor C3. The second, third, fourth, twelfth, thirteenth, twentieth, twenty-first, and twenty-second ports of the MCU module are respectively connected to the corresponding ports of the 485 communication circuit. One side of the seventh port of the MCU module is connected to the power supply via resistor R8, and the other side of the seventh port of the MCU module is connected to capacitor C7 and grounded. The eighth port of the MCU module is grounded, and the ninth port of the MCU module is connected to the VDDA signal terminal via capacitor C8. The MCU module's 23rd port is grounded, and its 24th port is connected to the V33-MCU signal terminal. The 10th, 11th, 14th, 15th, 16th, 17th, 18th, 19th, 38th, 39th, 40th, 41st, 42nd, 43rd, 45th, and 46th ports of the MCU module are respectively connected to the corresponding ports of the analog signal output module. The 36th port of the MCU module is connected to the V33-MCU signal terminal. The V33-MCU signal terminal is connected to the VDDA signal terminal via resistor R50, and resistor R50 is connected to two capacitors connected in parallel and grounded.

[0008] Preferably, the analog signal output module includes a diode TVS7, a diode D18, a transistor Q7, an amplifier IC9B, a transistor Q11, an amplifier IC9A, and a digital-to-analog converter IC11. Diode TVS7 and capacitor C6 are connected in parallel and connected to the negative terminal of diode D18. The positive terminal of diode D18 is connected to the collector of transistor Q7. The base of transistor Q7 is connected to the output terminal of amplifier IC9B, and the base of transistor Q7 and capacitor C59 are connected to the negative input terminal of amplifier IC9B. Simultaneously, the negative input terminal of amplifier IC9B and resistor R36 are connected to the emitter of transistor Q7. The positive input terminal of amplifier IC9B is connected to... Resistor R33 and capacitor C48 are connected and grounded. The positive input terminal of amplifier IC9B is connected to the collector of transistor Q11. The emitter of transistor Q11 is connected to the output terminal of amplifier IC9A via resistor R42 and capacitor C50. The base of transistor Q11 is connected to the output terminal of amplifier IC9A. The positive input terminal of amplifier IC9A is connected to the OUT port of digital-to-analog converter IC11 via resistor R38. The GND port of digital-to-analog converter IC11 is grounded. The VDD port of digital-to-analog converter IC11 is connected to capacitor C57 and grounded. The SDA / SCL ports of digital-to-analog converter IC11 are connected to the corresponding ports on the MCU module.

[0009] Preferably, the 485 communication circuit includes a transistor Q2, an optocoupler U6, a transceiver IC2, optocouplers U5 and U7, and a common-mode inductor L2. The 482CS terminal of the MCU module is connected to one end of resistor R30, and the other end of resistor R30 is connected to the base of transistor Q2. The emitter of transistor Q2 is grounded. The collector of transistor Q2 is connected to the input terminal of optocoupler U6 via resistor R28. The output terminal of optocoupler U6 is connected to the third and fourth ports of transceiver IC2. The first port of IC2 is connected to the output of optocoupler U5. The fourth port of transceiver IC2 is connected to the fifth port of optocoupler U7. The eighth port of transceiver IC2 is connected to the power supply. The seventh port of transceiver IC2 is connected to the second port of common mode inductor L2 via resistor FSS. The sixth port of transceiver IC2 is connected to the first port of common mode inductor L2 via resistor FS7. The fifth port of transceiver IC2 is grounded. The third and fourth ports of common mode inductor L2 are connected to the 4852B and 4852A terminals of the MCU module.

[0010] Preferably, the first port of the optocoupler U5 is connected to the resistor R24 ​​and connected to the power supply, the third port of the optocoupler U5 is connected to the first port of the transceiver IC2, the fourth port of the optocoupler U5 is grounded, the fifth port of the optocoupler U5 is connected to the 4852RX terminal of the MCU module, and the sixth port of the optocoupler U5 is connected to the power supply.

[0011] Preferably, the first port of the optocoupler U7 is connected to resistor R32 and connected to a power supply, the third port of the optocoupler U7 is connected to the 4852TX terminal of the MCU module, the fourth port of the optocoupler U7 is grounded, the fifth port of the optocoupler U7 is connected to resistor R31 and connected to a power supply, and the fifth port of the optocoupler U7 is connected to the fourth port of transceiver IC2, and the sixth port of the optocoupler U7 is connected to a power supply.

[0012] Preferably, the transceiver IC2 is model MAX3485-C1121852.

[0013] Preferably, the MCU module is an STM32F103.

[0014] Preferably, the digital-to-analog converter IC11 is model MCP4726.

[0015] This invention also provides a gas detector, including the aforementioned digital-to-analog converter.

[0016] This utility model, by adopting the above technical solution, has the following advantages and positive effects compared with the prior art: The digital-to-analog converter provided by this utility model can simultaneously process multiple signal sources by inputting 1-8 channels of digital signals through a serial port, meeting the needs of complex systems and realizing the conversion of multiple digital signals into multiple analog current signals. For example, in a gas detector, different sensors may output different digital signals, which can all be converted into analog current signals by this device, realizing the synchronous monitoring of multiple gas parameters; the use of a high-performance digital-to-analog converter MCP4726 ensures the accuracy of the conversion of digital signals into analog current signals, which helps to accurately reflect parameters such as gas concentration, improves the accuracy of gas detection, and provides a reliable foundation for subsequent data analysis and processing; the analog signal output module is... The device features an 8-channel 4-20mA output module. 4-20mA current signals are a common standard in industrial control, offering excellent anti-interference capabilities and long transmission distances, making the signal less susceptible to external interference and ensuring signal stability and reliability. An STM32F103 MCU module serves as the CPU controller, possessing powerful computing and processing capabilities. It can quickly process input digital signals and control the digital-to-analog conversion process, performing real-time processing of multiple digital signals to ensure data timeliness and accuracy. The CPU controller is tightly integrated with the power supply module, data storage module, digital signal input module, and analog signal output module, coordinating the work between these modules to ensure stable and efficient operation of the entire digital-to-analog converter, guaranteeing that each component fully utilizes its functions. Attached Figure Description

[0017] Figure 1 This is a block diagram illustrating the principle of the analog-to-digital converter in this embodiment of the present invention.

[0018] Figure 2 This is an internal circuit diagram of the CPU controller in an embodiment of the present invention;

[0019] Figure 3 This is an internal circuit diagram of the analog signal output module in an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the 485 communication circuit in an embodiment of this utility model. Detailed Implementation

[0021] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the vehicle logo switching device and control method proposed in this utility model. The advantages and features of this utility model will become clearer from the following description and claims.

[0022] like Figure 1As shown, this utility model provides a digital-to-analog converter suitable for gas detectors, including a CPU controller and a power supply module, a data storage module, a digital signal input module, and an analog signal output module respectively connected to the CPU controller.

[0023] The output terminal of the digital signal input module is connected to one input terminal of the CPU controller, the output terminal of the CPU controller is connected to the input terminal of the analog signal output module, the output terminal of the power supply module is connected to the other input terminal of the CPU controller, and the CPU controller is interactively connected to the data storage module.

[0024] The digital signal input module receives 1-8 channels of digital signals via a serial port. This is useful when multiple devices simultaneously acquire signals from the same gas detector, allowing for the placement of a corresponding number of gas detectors in one location, with each receiving device corresponding to one detector. The analog signal output module is an 8-channel 4-20mA output module that converts multiple digital signals into multiple analog current signals. By converting the digital signals into 8 independent 4-20mA analog signals, each signal can be transmitted and processed independently, avoiding signal interference and accuracy degradation caused by multiple receiving devices connected in series. In gas detection applications, high-precision signal conversion can more accurately reflect parameters such as gas concentration, providing a reliable data foundation for subsequent monitoring and control. The digital signal input module transmits external digital signals to the CPU controller, and the analog signal output module outputs independent analog signals. This effectively avoids the situation where increased resistance due to increased cable length leads to a decrease in the overall current signal, making signal transmission more stable and reliable, and reducing the possibility of measurement errors and system failures caused by resistance changes.

[0025] Those skilled in the art will understand that when multiple receiving devices simultaneously require the same current output signal from a gas detector, theoretically, the signal acquisition terminals of multiple receiving devices can be connected in series. However, when two or more receiving devices are connected in series, the resistance of the entire current loop increases with the length of the cable, while the power supply voltage of the detector outputting the signal remains constant. This results in a decrease in the current signal of the entire current loop. However, by using a digital-to-analog signal conversion device, the digital signal calculated by the PC or FC4128 can be converted into 1-8 independent signals. The principle of the above scheme is as follows: Upon power-up, the chip and peripheral circuits are initialized. It is determined whether the serial port has received data. If data is received, the data in the eight registers is updated directly, converted into the corresponding eight 4-20mA signals, and output. The watchdog timer function is then executed. If the received data is not the eight data signals to be converted, it is checked whether the received data is the eight data signals to be converted. If it is, the data in the eight registers is updated, converted into the corresponding eight 4-20mA signals, and output. The watchdog timer function is then executed. If it is not, it is determined whether it is a channel calibration command. If it is, the corresponding channel is calibrated and the watchdog timer function is executed. Otherwise, the watchdog timer function is executed directly.

[0026] See Figure 2As shown, the CPU controller includes an MCU module, capacitor C3, resistor R8, capacitor C7, capacitor C8, and resistor R50. The first port of the MCU module is connected to the V33-MCU signal terminal, and is also grounded via capacitor C3. The second, third, fourth, twelfth, thirteenth, twentieth, twenty-first, and twenty-second ports of the MCU module are respectively connected to the corresponding ports of the 485 communication circuit. One side of the seventh port of the MCU module is connected to the power supply via resistor R8, and the other side is connected to capacitor C7 and grounded. The eighth port of the MCU module is grounded. The ninth port of the MCU module is connected to the VDDA signal terminal via capacitor C8 and... The MCU module's 23rd port is grounded, and its 24th port is connected to the V33-MCU signal terminal. The 10th, 11th, 14th, 15th, 16th, 17th, 18th, 19th, 38th, 39th, 40th, 41st, 42nd, 43rd, 45th, and 46th ports are respectively connected to the corresponding ports of the analog signal output module. The 36th port of the MCU module is connected to the V33-MCU signal terminal. The V33-MCU signal terminal is connected to the VDDA signal terminal via resistor R50, and resistor R50 is connected to two capacitors connected in parallel and grounded. The MCU module is an STM32F103. As the core chip of the CPU controller, the STM32F103 has multiple ports precisely connected to the corresponding ports of the 485 communication circuit and the analog signal output module. For example, specific ports are dedicated to connecting to the 485 communication circuit, ensuring accurate reception and transmission of digital signals. This targeted port layout ensures signal integrity and accuracy during transmission, reducing the possibility of signal interference and distortion. The clever connection of capacitors C3, C7, and C8, as well as resistors R8 and R50, provides a stable power supply and ground for the MCU module. For example, grounding one end of C3 and connecting the other end to the first port of the MCU module effectively filters out noise and interference signals from the power supply, ensuring stable operation of the MCU module. Simultaneously, the combination of resistor R8 and capacitors C7 and C8 further optimizes power supply stability, providing reliable power support for the internal circuitry of the MCU module, thereby improving the accuracy of signal processing.

[0027] like Figure 3As shown, the analog signal output module includes diode TVS7, diode D18, transistor Q7, amplifier IC9B, transistor Q11, amplifier IC9A, and digital-to-analog converter IC11. Diode TVS7 and capacitor C6 are connected in parallel and connected to the negative terminal of diode D18. The positive terminal of diode D18 is connected to the collector of transistor Q7. The base of transistor Q7 is connected to the output terminal of amplifier IC9B, and the base of transistor Q7 and capacitor C59 are connected to the negative input terminal of amplifier IC9B. Simultaneously, the negative input terminal of amplifier IC9B and resistor R36 are connected to the emitter of transistor Q7. The positive input terminal of amplifier IC9B and resistor R36 are connected to the emitter of transistor Q7. R33 and capacitor C48 are connected and grounded. The positive input terminal of amplifier IC9B is connected to the collector of transistor Q11. The emitter of transistor Q11 is connected to the output terminal of amplifier IC9A via resistor R42 and capacitor C50. The base of transistor Q11 is connected to the output terminal of amplifier IC9A. The positive input terminal of amplifier IC9A is connected to the OUT port of digital-to-analog converter IC11 via resistor R38. The GND port of digital-to-analog converter IC11 is grounded. The VDD port of digital-to-analog converter IC11 is connected to capacitor C57 and grounded. The SDA / SCL ports of digital-to-analog converter IC11 are connected to the corresponding ports on the MCU module. Diodes TVS7 and D18 are connected in parallel and, together with capacitor C6, form an overvoltage protection circuit. When the voltage in the circuit exceeds a set threshold, TVS7 can quickly conduct, discharging the excess voltage, thereby protecting subsequent circuit components from overvoltage impacts. This effectively prevents damage to the circuit caused by voltage fluctuations or instantaneous high-voltage pulses, improving the reliability and stability of the circuit. Capacitor C6 also plays a crucial role in overvoltage protection, absorbing voltage spikes to some extent and slowing down the voltage rise rate. Working in conjunction with diodes TVS7 and D18, it further enhances the overvoltage protection effect. Simultaneously, capacitor C6 also acts as a filter during normal circuit operation, reducing noise and interference in the power supply. The collector of transistor Q7 is connected to the anode of diode D18, its base is connected to the output of amplifier IC9B, and its emitter is connected to the negative input of amplifier IC9B through resistor R36. This allows transistor Q7 to act as a buffer, isolating the output signal of amplifier IC9B from subsequent circuits. When signal fluctuations or interference occur in the circuit, transistor Q7 can stabilize the signal, reducing the impact of interference on subsequent circuits and ensuring stable signal transmission.Amplifier IC9B operates in inverting mode. Its negative input terminal is connected to the emitter of transistor Q7 via resistor R36, and its positive input terminal is connected to ground via resistor R33 and capacitor C48. This results in the input signal undergoing two amplification stages: first, initial amplification by transistor Q7, and then further amplification by amplifier IC9B. This dual-stage amplification significantly enhances signal strength, improves signal drive capability, and ensures that the signal is less susceptible to attenuation and interference during transmission. Unlike amplifier IC9B, amplifier IC9A operates in non-inverting mode. The collector of transistor Q11 is connected to the output of amplifier IC9A, its emitter is connected to resistor R42 and capacitor C50, and its base is connected to the output of amplifier IC9A. Non-inverting amplification maintains the signal phase while further increasing the signal amplitude. The combined use of amplifiers IC9A and IC9B achieves precise signal amplification and stable output. The OUT port of IC11 is connected to the positive input terminal of amplifier IC9A, and the digital signal is transmitted to IC11 for processing via resistor R38. The digital-to-analog converter IC11 features high precision and low noise, accurately converting digital signals into analog signals to meet the signal accuracy requirements of gas detectors. Simultaneously, the GND port of IC11 is grounded, and the VDD port is connected to capacitor C57 and grounded. This connection method ensures stable operation of IC11 and improves the accuracy and reliability of the digital-to-analog conversion. The analog signal output module adopts a modular design, with each component independent yet tightly connected. For example, diodes TVS7 and D18, transistor Q7, amplifier IC9B, transistor Q11, amplifier IC9A, and the digital-to-analog converter IC11 are all connected independently to form the entire module. This modular design allows users to configure and adjust the circuit according to actual needs, replacing components of different models or parameters to meet different application scenarios. In summary, the analog signal output module, through reliable circuit protection, stable signal transmission, precise signal amplification and conversion, flexible configuration, and convenient control, provides efficient and stable performance support for the digital-to-analog conversion device of the gas detector, helping to improve the accuracy and reliability of gas detection and meet the gas detection needs in different environments.

[0028] like Figure 4As shown, the 485 communication circuit includes transistor Q2, optocoupler U6, transceiver IC2, optocoupler U5, optocoupler U7, and common-mode inductor L2. The 482CS terminal of the MCU module is connected to one end of resistor R30, and the other end of resistor R30 is connected to the base of transistor Q2. The emitter of transistor Q2 is grounded. The collector of transistor Q2 is connected to the input terminal of optocoupler U6 via resistor R28. The output terminal of optocoupler U6 is connected to the third and fourth ports of transceiver IC2. The first port of transceiver IC2 is connected to the output of optocoupler U5. The fourth port of transceiver IC2 is connected to the fifth port of optocoupler U7. The eighth port of transceiver IC2 is connected to the power supply. The seventh port of transceiver IC2 is connected to the second port of common-mode inductor L2 via resistor FSS. The sixth port of transceiver IC2 is connected to the first port of common-mode inductor L2 via resistor FS7. The fifth port of transceiver IC2 is grounded. The third and fourth ports of common-mode inductor L2 are connected to the 4852B and 4852A terminals of the MCU module. The addition of optocouplers U6, U5, and U7 achieves electrical isolation between the signal and the power supply. The optocoupler transmits signals through the coupling of a light-emitting diode and a photosensitive element. There is no electrical connection between the input side (light-emitting diode) and the output side (photosensitive element), effectively preventing interference signals from the power supply side from coupling into the signal transmission line through the ground wire or other paths, ensuring the stability and accuracy of signal transmission. In the 485 communication circuit, the optocoupler prevents external high voltages and surge currents from impacting the transceiver IC2 and the MCU module. When abnormal voltages occur in the circuit, the optocoupler acts as an isolation device, preventing damage to subsequent circuit components and improving the overall circuit reliability and anti-interference capability. The common-mode inductor L2 plays a crucial electrical isolation role in the 485 communication circuit. It further isolates the MCU module from other circuit components, reducing mutual interference between different circuits. The common-mode inductor L2 also has a filtering effect on the transmitted signal. It can suppress high-frequency noise and interference signals, making the transmitted signal cleaner and more stable. This helps improve the quality of 485 communication and reduce data transmission errors and communication failures. Transistor Q2, as a driving element, provides sufficient current to drive the optocoupler U6. One end of resistor R30 is connected to the 482CS pin of the MCU module, and the other end is connected to the base of transistor Q2, allowing the signal output from the MCU module to control the conduction and cutoff of transistor Q2. When transistor Q2 is turned on, the collector current flows through resistor R28, providing sufficient drive current for optocoupler U6, ensuring that the optocoupler can work normally, enhancing the driving capability of the circuit, and ensuring stable signal transmission.The emitter of transistor Q2 is grounded, making signal transmission more stable. During circuit operation, after the base of transistor Q2 receives the signal from the MCU module, it can stably control the magnitude of the collector current, thereby providing a stable drive signal for the optocoupler. This helps reduce signal distortion and interference, and improves the accuracy and reliability of signal transmission. Transceiver IC2 is one of the core components of the 485 communication circuit, responsible for signal transmission and reception. The output of optocoupler U6 is connected to the third and fourth ports of transceiver IC2 for signal transmission; the output of optocoupler U5 is connected to the first port of transceiver IC2 for signal reception, ensuring that transceiver IC2 can stably receive and transmit signals, achieving reliable data transmission.

[0029] Specifically, the first port of optocoupler U5 is connected to resistor R24 ​​and then to a power supply; the third port of optocoupler U5 is connected to the first port of transceiver IC2; the fourth port of optocoupler U5 is grounded; the fifth port of optocoupler U5 is connected to the 4852RX terminal of the MCU module; and the sixth port of optocoupler U5 is connected to a power supply. The connection between the first port of optocoupler U5 and resistor R24 ​​provides a stable operating voltage for the LED inside the optocoupler. Resistor R24 ​​limits the current, preventing excessive current from damaging the LED. A reasonable resistor value ensures that the LED operates within its normal current range, maintaining stable luminous intensity and thus guaranteeing the normal operation of the optocoupler. The grounding of the fourth port of optocoupler U5 provides a stable reference potential for the internal circuitry. Grounding effectively reduces interference from external electromagnetic fields, improving the accuracy and stability of signal transmission. Furthermore, good grounding prevents static electricity buildup, protecting the internal electronic components from electrostatic discharge damage. The third port of optocoupler U5 is connected to the first port of transceiver IC2. This connection ensures that the signal output from the optocoupler can be accurately transmitted to transceiver IC2. The photosensitive element inside the optocoupler, upon receiving light emitted from the LED, stably converts the optical signal into an electrical signal and outputs it to the third port. By optimizing the internal structure and parameter design of the optocoupler, signal transmission efficiency and strength can be improved, ensuring that the signal is not easily attenuated or distorted during transmission. The fifth port of optocoupler U5 is connected to the 4852RX pin of the MCU module, allowing signals received from the MCU module to be transmitted through the optocoupler. Optocoupler U5 provides electrical isolation between the MCU module and transceiver IC2, preventing electrical short circuits or mutual interference between the circuits containing the MCU module and transceiver IC2. When a circuit fails, the isolation provided by the optocoupler prevents the fault from spreading to another circuit, thus protecting the safe operation of the entire system.

[0030] Specifically, the first port of optocoupler U7 is connected to resistor R32 and then to a power supply. The third port of optocoupler U7 is connected to the 4852TX pin of the MCU module. The fourth port of optocoupler U7 is grounded. The fifth port of optocoupler U7 is connected to resistor R31 and then to a power supply, and the fifth port of optocoupler U7 is also connected to the fourth port of transceiver IC2. The sixth port of optocoupler U7 is connected to a power supply. The connection between the first port of optocoupler U7 and resistor R32 provides a stable operating voltage for the LED inside the optocoupler. The function of resistor R32 is to limit the current and prevent the LED from being damaged by excessive current. By precisely selecting the resistor value, the LED can operate under an appropriate current, ensuring stable light emission and providing a reliable light source for signal transmission. The fifth port is connected to resistor R31 and then to the power supply. This fifth port is also connected to the fourth port of transceiver IC2. Resistor R31 here also serves as a current limiter, ensuring power stability between optocoupler U7 and transceiver IC2. This helps improve the overall circuit's anti-interference capability, reduces signal distortion or communication errors caused by power fluctuations, and ensures stable operation of the optocoupler and transceiver. The third port of optocoupler U7 is connected to the 4852TX pin of the MCU module, allowing the signal output from the MCU module to drive the LED inside the optocoupler. The light emitted by the LED is received by a photosensitive element and converted into an electrical signal, thus achieving signal transmission. This ensures stable signal transmission from the MCU module to the optocoupler, improving signal driving capability and transmission efficiency. The fourth port of transceiver IC2 is connected to the fifth port of optocoupler U7, so that the signal output by the optocoupler can be accurately transmitted to transceiver IC2. After receiving the light emitted by the light-emitting diode, the photosensitive element inside the optocoupler can stably convert the optical signal into an electrical signal and output it to the fifth port, ensuring the accuracy and integrity of the signal during transmission and reducing the possibility of signal distortion and bit errors.

[0031] Specifically, the transceiver IC2 is model MAX3485-C1121852.

[0032] Specifically, the digital-to-analog converter IC11 is model MCP4726.

[0033] The present invention also provides a gas detector, including the digital-to-analog converter as described in the above embodiments, which will not be repeated here.

[0034] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. A digital-to-analog conversion device, characterized by, The application relates to a gas detector, which comprises a CPU controller and a power module, a CPU controller, a data storage module, a digital signal input module and an analog signal output module connected with the CPU controller respectively. The output end of the digital signal input module is connected with an input end of the CPU controller, the output end of the CPU controller is connected with an input end of the analog signal output module, the output end of the power module is connected with another input end of the CPU controller, and the CPU controller is connected with the data storage module. The digital signal input module inputs 1-8 digital signals through a serial port, and the analog signal output module is an 8-way 4-20mA output module.

2. The digital-to-analog conversion device of claim 1, wherein, The CPU controller comprises an MCU module, a capacitor C3, a resistor R8, a capacitor C7, a capacitor C8 and a resistor R50. The first port of the MCU module is connected with a V33-MCU signal end, and the first port of the MCU module is grounded through the capacitor C3. The second port, the third port, the fourth port, the twelfth port, the thirteenth port, the twentieth port, the twenty-first port and the twenty-second port of the MCU module are connected with corresponding ports of a 485 communication circuit respectively. One side of the seventh port of the MCU module is connected with the resistor R8 and connected with a power supply, and the other side of the seventh port of the MCU module is connected with the capacitor C7 and grounded. The eighth port of the MCU module is grounded. The ninth port of the MCU module is connected with a VDDA signal end, and the ninth port of the MCU module is grounded through the capacitor C8. The twenty-third port of the MCU module is grounded. The twenty-fourth port of the MCU module is connected with the V33-MCU signal end. The tenth port, the eleventh port, the fourteenth port, the fifteenth port, the sixteenth port, the seventeenth port, the eighteenth port, the nineteenth port, the thirty-eighth port, the thirty-ninth port, the fortieth port, the forty-first port, the forty-second port, the forty-third port, the forty-fifth port and the forty-sixth port of the MCU module are connected with corresponding ports of the analog signal output module respectively. The thirty-sixth port of the MCU module is connected with the V33-MCU signal end, wherein the V33-MCU signal end is connected with the VDDA signal end through the resistor R50, and the resistor R50 is connected with two capacitors in parallel and grounded.

3. The digital-to-analog conversion device of claim 1, wherein, The analog signal output module comprises a diode TVS7, a diode D18, a triode Q7, an amplifier IC9B, a triode Q11, an amplifier IC9A and a digital-analog converter IC11, the diode TVS7 and the capacitor C6 are connected in parallel and connect the negative pole of the diode D18, the positive pole of the diode D18 is connected with the collector of the triode Q7, the base of the triode Q7 is connected with the output end of the amplifier IC9B, and the base of the triode Q7 is connected with the capacitor C59 which connects the negative input end of the amplifier IC9B, at the same time, the negative input end of the amplifier IC9B is connected with the resistor R36 to the emitter of the triode Q7, the positive input end of the amplifier IC9B is connected with the resistor R33 and the capacitor C48 and grounded, and the positive input end of the amplifier IC9B is connected with the collector of the triode Q11, the emitter of the triode Q11 is connected with the resistor R42, the capacitor C50 and the output end of the amplifier IC9A, the base of the triode Q11 is connected with the output end of the amplifier IC9A, the positive input end of the amplifier IC9A is connected with the resistor R38 to the OUT port of the digital-analog converter IC11, the GND port of the digital-analog converter IC11 is grounded, the VDD port of the digital-analog converter IC11 is connected with the capacitor C57 and grounded, and the SDA port / SCL port of the digital-analog converter IC11 is connected with the corresponding port of the MCU module.

4. The digital-to-analog conversion apparatus of claim 2, wherein, The 485 communication circuit comprises a triode Q2, an optical coupler U6, a transceiver IC2, an optical coupler U5, an optical coupler U7 and a common mode inductor L2, the 482CS end of the MCU module is connected with one end of the resistor R30, the other end of the resistor R30 is connected with the base of the triode Q2, the emitter of the triode Q2 is grounded, the collector of the triode Q2 is connected with the resistor R28 to the input end of the optical coupler U6, the output end of the optical coupler U6 is connected with the third and fourth ports of the transceiver IC2, the first port of the transceiver IC2 is connected with the output end of the optical coupler U5, the fourth port of the transceiver IC2 is connected with the fifth port of the optical coupler U7, the eighth port of the transceiver IC2 is connected with the power supply, the seventh port of the transceiver IC2 is connected with the resistor FSS to the second port of the common mode inductor L2, the sixth port of the transceiver IC2 is connected with the resistor FS7 to the first port of the common mode inductor L2, the fifth port of the transceiver IC2 is grounded, and the third and fourth ports of the common mode inductor L2 are connected with the 4852B end and the 4852A end of the MCU module.

5. The digital-to-analog conversion apparatus of claim 4, wherein, The first port of the optical coupler U5 is connected with the resistor R24 and grounded, the third port of the optical coupler U5 is connected with the first port of the transceiver IC2, the fourth port of the optical coupler U5 is grounded, the fifth port of the optical coupler U5 is connected with the 4852RX end of the MCU module, and the sixth port of the optical coupler U5 is connected with the power supply.

6. The digital-to-analog conversion device of claim 4, wherein, The first port of the optical coupler U7 is connected with the resistor R32 and connected with the power supply, the third port of the optical coupler U7 is connected with the 4852TX end of the MCU module, the fourth port of the optical coupler U7 is grounded, the fifth port of the optical coupler U7 is connected with the resistor R31 and connected with the power supply, and the fifth port of the optical coupler U7 is connected with the fourth port of the transceiver IC2, and the sixth port of the optical coupler U7 is connected with the power supply.

7. The digital-to-analog conversion device of claim 4, wherein, The model of the transceiver IC2 is MAX3485-C1121852.

8. The digital-to-analog conversion device of claim 2, wherein, The model of the MCU module is STM32F103.

9. The digital-to-analog conversion device of claim 3, wherein, The model of the digital-analog converter IC11 is MCP4726.

10. A gas detector, characterized by The digital-analog conversion device as claimed in any one of claims 1 to 9.

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