Flow channel gas flow monitoring equipment

Abstract

The utility model provides a flow channel gas flow monitoring device which can completely and timely store data at low cost during power failure. Through the arrangement of the power failure storage module, a power failure signal is sent to the MCU control module in time when power failure occurs, and it is ensured that the MCU control module can execute data storage operation in time before complete power failure.

Description

Technical Field

[0001] The present application relates to the technical field of gas flow monitoring, and in particular to a flow channel gas flow monitoring device. Background Art

[0002] In the past 10 years, traditional flow sensors have gradually transformed into MEMS flow sensors. With the continuous improvement of microelectronics, the process level of MEMS flow sensors has greatly improved. MEMS flow meters (meters) have been widely used. In actual use, it is found that the preservation of the total flow threshold of the flow meter (meter) is an important function that is indispensable in the use of the equipment.

[0003] At present, the data storage of MEMS flow meters (meters) on the market generally uses off-chip storage chips (such as 24C02, 24256E, W25QXXX, etc.) to store data. Usually, during the program running, the total flow threshold data is written to the EEPROM once at intervals. When starting, the data in the off-chip EEPROM is read first (for example, the digital gas flow meter Sixiang MF5700MF5706MF5712 uses 3 minutes and 30 seconds to store data). This storage method saves the EEPROM at all times, and the life of the storage chip will be reduced. This interval data storage method will cause data loss once power is cut off or power is lost. The error of the stored data is related to the length of the interval storage time. There are also products that use a button battery or a farad capacitor in front of the microcontroller power supply circuit as a countermeasure to prevent the problem of data loss due to power failure. However, the countermeasure of the button battery storage method requires frequent replacement of batteries in actual applications, which is not convenient to use and also increases the cost of product use. Although the farad capacitor solution can easily realize the microcontroller power-off detection and data power-off preservation, there is a problem that the voltage gradually decreases as it discharges, so a more complex output circuit is required, which increases the overall cost of the product. Utility Model Content

[0004] In order to solve the problem in the prior art that the product cost increases in order to avoid the loss of stored data when the power is off, the utility model provides a flow channel gas flow monitoring device, which can ensure that the data is saved in time when the power is off at a relatively low cost.

[0005] The technical solution of the utility model is as follows: a flow channel gas flow monitoring device, which includes: a flow sensor and a gas flow monitoring meter header;

[0006] The gas flow monitoring meter header includes: a power input interface and an MCU control module;

[0007] The power input interface is connected to an external power source to supply power to other devices;

[0008] The flow sensor is electrically connected to the MCU control module, and the flow sensor converts the gas medium flow in the flow channel into an analog voltage signal and sends it to the MCU control module;

[0009] The MCU control module processes the received flow data signal to realize flow channel gas flow detection;

[0010] Features:

[0011] The gas flow monitoring meter header also includes: a power-off saving module;

[0012] The power-off saving module is used to provide a power-off signal for saving data to the MCU control module when the meter loses power;

[0013] The MCU control module receives the power-off signal sent by the power-off saving module and saves the data when the power is off;

[0014] The MCU control module includes: a control chip, capacitors C18 and C19; the power-off saving module includes: a monitoring and reset chip MAX813L, a voltage-dividing resistor, a Schottky diode D6 and an electrolytic capacitor C20; the resistors include R30 and R31; the control chip is implemented based on the STC15W4K chip, and the monitoring and reset chip U7 is implemented based on the MAX813L chip;

[0015] The 5th pin power failure output terminal PFO of the monitoring and reset chip is connected to the P3.2 interrupt INT0 pin of the control chip;

[0016] One end of the resistor R30 is connected to the 4th pin power fault input terminal PFI of the monitoring and reset chip and one end of the resistor R31; the other end of the resistor R30 is connected to the 2nd pin of the monitoring and reset chip and the anode of the Schottky diode D6 and then connected to the power supply VCC; the cathode of the Schottky diode D6 is connected to the positive electrode of the electrolytic capacitor C20 and the 15-pin power supply VCC terminal of the control chip; the negative electrode of the electrolytic capacitor C20 is grounded; the other end of the resistor R31 is grounded; and the 3rd pin of the monitoring and reset chip U7 is grounded.

[0017] It is further characterized by:

[0018] The gas flow monitoring meter header also includes: a 485 communication data output interface, an analog flow signal input interface, an AD conversion module and a 485 communication conversion module;

[0019] The analog flow signal transmission interface transmits the analog flow voltage signal of the flow sensor to the AD conversion module; the AD conversion module collects the analog flow voltage signal sent by the flow data transmission interface, converts it into a digital flow signal, and sends it to the MCU control module;

[0020] The 485 communication conversion module is used to convert the flow TTL signal sent by the MCU control module into 485 communication data and send it to the 485 data transmission interface; the 485 data transmission interface is used to send the instantaneous flow and total flow values ​​of the flow channel gas flow to the user terminal through the 485 bus;

[0021] The 485 communication data output interface is implemented based on the TYPE-C-31 interface, the 485 communication conversion module is implemented based on the max485ESA chip, the analog flow signal input interface is implemented based on PZ254V, and the AD conversion module is implemented based on CS1237-SO;

[0022] The gas flow monitoring meter header also includes: a temperature acquisition module, the temperature acquisition module is used to convert the ambient temperature signal into a digital signal and transmit it to the MCU control module;

[0023] The gas flow monitoring meter header also includes: a power supply voltage reduction module and a battery power collection module;

[0024] The power step-down module is used to convert the 12V voltage into a 5V voltage to provide power for all other components;

[0025] The battery power acquisition module is used to send the voltage signal of the battery power to the MCU control module;

[0026] The power supply step-down module is implemented based on the AMS1117 chip;

[0027] The gas flow monitoring meter header further includes: the display and display driving module, the display and display driving module is used to display the instantaneous flow rate, total flow rate, temperature and various control signals of the flow channel gas flow sent by the MCU control module;

[0028] The display and display driver module are implemented based on the PCF8576DT display driver.

[0029] The present application provides a flow channel gas flow monitoring device, which, by setting a power-off saving module, promptly sends a power-off signal to an MCU control module when a power outage occurs, ensuring that the MCU control module can promptly perform a data saving operation before the power is completely off; the power-off saving module is implemented based on MAX813L, the 5th pin power failure output terminal PFO of the MAX813L chip is connected to the P3.2 interrupt INT0 pin of the control chip, and the 4th pin power failure input terminal PFI is connected to the power supply VCC through the voltage-dividing resistors R31 and R30; once the power supply fails, the MAX813L chip based on Inherent characteristics: when the voltage of the power fault input terminal PFI of the 4th pin of MAX813L is lower than 1.25V, the signal of the power fault output terminal PFO of the 5th pin will change from high level to low level, that is, a falling edge signal will be generated and sent to the P3.2 interrupt INT0 pin of the control chip of the MCU control module; and the P3.2 interrupt INT0 pin of the MCU will immediately interrupt all running programs and perform data storage operations when it receives the falling edge trigger signal; this application can ensure that the control chip can receive the power-off signal in time by setting the power-off saving module, and then can complete the data saving operation in time. The circuit of the technical solution of this application is simple and the execution speed is fast, ensuring that the data can be saved completely and in time at a low cost when the power is off. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the module for setting up a table for flow channel gas flow monitoring;

[0031] Figure 2 It is a flow chart of the flow channel gas flow monitoring table;

[0032] Figure 3 A schematic diagram of the circuit connection between the monitoring and resetting chip U7 and the control chip U6;

[0033] Figure 4 Schematic diagram of the circuit connections of the main components of the flow channel gas flow monitoring meter. DETAILED DESCRIPTION

[0034] like Figure 1~Figure 4 As shown, the utility model includes a flow channel gas flow monitoring device, which is marked as: a flow channel gas flow monitoring meter in the figure, which includes: a flow sensor and a gas flow monitoring meter header.

[0035] In order to ensure that the gas flow monitoring meter header can save data in time when the power is off, a power-off saving module is set in the gas flow monitoring meter header in this application; the power-off saving module is used to provide a power-off signal for saving data to the MCU control module when the meter header loses power. The MCU control module receives the power-off signal sent by the power-off saving module and saves the data when the power is off.

[0036] like Figure 3 As shown, the MCU control module includes: control chip U6, capacitors C18 and C19; the power-off saving module includes: monitoring and reset chip MAX813L, voltage-dividing resistors, Schottky diode D6 and electrolytic capacitor C20; resistors include R30 and R31; the control chip U6 is implemented based on the STC15W4K chip, and the monitoring and reset chip U7 is implemented based on the MAX813L chip.

[0037] The 5th pin power fault output terminal PFO of the monitoring and reset chip U7 is connected to the P3.2 interrupt INT0 pin of the control chip U6; one end of the resistor R30 is connected to the 4th pin power fault input terminal PFI of the monitoring and reset chip U7 and one end of the resistor R31; the other end of the resistor R30 is connected to the 2nd pin of the monitoring and reset chip U7 and the anode of the Schottky diode D6 and then connected to the power supply VCC; the cathode of the Schottky diode D6 is connected to the positive electrode of the electrolytic capacitor C20 and the 15th pin power supply VCC terminal of the control chip U6; the negative electrode of the electrolytic capacitor C20 is grounded; the other end of the resistor R31 is grounded; the 3rd pin of the monitoring and reset chip U7 is grounded.

[0038] According to the basic characteristics of MAX813L, when the voltage of the power fault input (PFI) of the 4th pin of the monitoring and reset chip MAX813L is lower than 1.25V, the signal of the power fault output PFO of the 5th pin changes from high level to low level, generating a falling edge trigger signal to the P3.2 interrupt INT0 pin of the MCU; the P3.2 interrupt INT0 pin of the MCU receives the falling edge trigger signal sent by the power fault input (PFI) of the 4th pin of the monitoring and reset chip MAX813L, and immediately interrupts all running programs and executes only the data saving program. For example: the storage of the total flow threshold. The specific interruption of the existing program and the data saving action in the MCU control module can be realized based on the STC15W4K R&D technology of the existing technology.

[0039] The voltage-dividing resistors include R30 and R31. R30 and R31 are connected in series for voltage division. One end of R30 is connected to the power supply, and the other end is connected to R31. One end of R31 is connected to GND, and the other end is connected to R30. When the power supply voltage is normal, R31 keeps the divided voltage at about 1.5V. When the power supply voltage drops, the divided voltage of R31 also drops.

[0040] One end of Schottky diode D6 is connected to power supply VCC, and the other end is connected to electrolytic capacitor C20 and MCU. It is mainly used for Schottky diode D6 to conduct when power supply VCC is normally supplied, charging electrolytic capacitor C20 and supplying power to MCU at the same time. When power supply VCC is powered off or powered off, Schottky diode D6 is reversely cut off to block reverse discharge of electrolytic capacitor.

[0041] One end of the electrolytic capacitor C20 is connected to the Schottky diode D6 and the VCC pin of the MCU, and the other end is connected to GND. It is mainly used to charge the Schottky diode D6 when the power supply VCC is normally supplied. When the power supply VCC is powered off or powered off, the Schottky diode D6 is not turned on, and the electrolytic capacitor C20 only supplies power to the MCU. When the power supply VCC is powered off or powered off, the MCU can use the residual electricity discharged by the electrolytic capacitor C20 to quickly store the total flow threshold in the on-chip EEPROM for storage.

[0042] In the technical solution of this application, the data storage circuit of the MEMS flow meter is improved, and the power failure output (PFO) function of the 5th pin of the MAX813L chip is used (when the power is normal, the pin remains high, and when the power voltage becomes low or the power is off, the output high changes from high to low.), and the MCU falling edge interrupt is used to quickly save the data to the on-chip EEPROM of the MCU microcontroller. The method of storing data in this application has the advantages of simple circuit, fast storage speed, and few storage times (data is only saved when the power is off, which greatly reduces the number of storage times), which prolongs the working life of the MCU, and can completely save the data at the moment of power off, and it has been confirmed through experiments that there is almost no error.

[0043] The gas flow monitoring meter header also includes: 485 communication data output interface, analog flow signal input interface, power step-down module, MCU control module, display and display driver module, AD conversion module, 485 communication conversion module, temperature acquisition module, battery power acquisition module, alarm module, button control module and flow channel electrical switch module.

[0044] Inside the gas flow monitoring meter header, the analog flow signal transmission interface transmits the analog flow voltage signal sent by the flow sensor to the AD conversion module; the AD conversion module collects the analog flow voltage signal sent by the flow data transmission interface, converts it into a digital flow signal, and sends it to the MCU control module.

[0045] The 485 communication conversion module converts the flow TTL signal sent by the MCU control module into 485 communication data and sends it to the 485 data transmission interface; the 485 data transmission interface sends the instantaneous flow and total flow values ​​of the flow channel gas flow to the user terminal through the 485 bus.

[0046] The display and display driver module is used to display the instantaneous flow rate, total flow rate, temperature, alarm switch, battery power and various control signals of the flow channel gas flow sent by the MCU control module. The temperature acquisition module is used to convert the ambient temperature signal into a digital signal and transmit it to the MCU control module.

[0047] Under the control of the MCU control module, the alarm module will sound a buzzer alarm when the instantaneous flow exceeds the minimum or maximum threshold or the accumulated total flow exceeds the maximum threshold; the button control module is used to control the display parameters and set parameters through buttons.

[0048] The control signal is transmitted to the MCU control module through the 485 data transmission interface of the remote host; under the control of the MCU control module, the opening and closing of the flow channel electrical switch are controlled.

[0049] The flow sensor adopts micro-electromechanical system (MEMS) flow sensor chip technology and uses thermodynamic principles to convert the gas medium flow in the flow channel into an analog voltage signal and send it to the MCU control module; the MCU control module processes the received flow signal to realize the flow channel gas flow detection; the specific flow channel gas flow measurement method implementation details can be based on existing technology.

[0050] The MCU control module collects and processes the received flow signal, temperature signal, and power signal, and transmits the data to the display and display driver module for display. At the same time, the flow signal is converted into a TTL signal and sent to the 485 communication conversion module. When the instantaneous flow value is greater than or less than the flow alarm threshold, and the total flow is greater than the alarm threshold, the alarm signal is output to the alarm module for alarm.

[0051] In this embodiment, the 485 communication data output interface is implemented based on the TYPE-C-31 interface ( Figure 4 Marked as USBC1); 485 communication conversion module is based on max485ESA chip ( Figure 4 Marked as U5 in the figure); the analog flow signal input interface is implemented based on PZ254V ( Figure 4 Marked as H2); AD conversion module is implemented based on CS1237-SO ( Figure 4 Marked as U4); the display and display driver module adopts a segment code LCD screen, based on the PCF8576DT display driver; the temperature acquisition module is based on the LM75AD temperature sensor ( Figure 4 marked as U8 in the figure).

[0052] In specific implementation, the analog voltage output port Vout of the gas flow sensor is connected to the input port Vout of the analog flow signal input interface, and the analog voltage signal of the gas medium flow is transmitted to the input port Vout of the analog flow signal transmission interface;

[0053] The gas flow monitoring meter head is connected to an external power supply through a power input interface. The external power supply can be AC ​​power or a battery. The introduced power supply is connected to a power step-down module, which converts the 12V voltage into a 5V voltage to provide power for all other components.

[0054] The present application also provides a battery power acquisition module for sending the voltage signal of the battery power to the MCU control module for AD conversion; in specific implementation, the power step-down module is implemented based on the AMS1117 chip, and the battery power acquisition module is implemented based on the MCU acquisition resistor R2 end to ground voltage.

[0055] The segment code LCD screen adopts 1 / 3 bias and 1:4 back electrode working mode. The display driver chip has IIC bus function. The SDA of the display driver chip is electrically connected to the P0.3 port of the MCU, and the SCL of the display driver chip is electrically connected to the P0.2 port of the MCU. The MCU communicates with the display driver module through the IIC protocol to control the display mode and display content.

[0056] The channel positive input AINP and channel negative input AINN of the AD conversion module are respectively connected to the Vout and GND of the analog flow signal transmission interface. The SCLK and DRDY / DOUT of the SPI interface of the AD conversion module are respectively connected to P0.5 and P5.3 of the MCU. Among them, the MCU communicates with the AD conversion module through the SCLK and DRDY / DOUT of the SPI interface to configure it.

[0057] The 485 communication conversion module adopts a transmission method compatible with the Modebus protocol-RTU; the pins DI, RE / DE, and DO of the 485 communication conversion module are respectively connected to the P1.1, P4.7, and P1.0 of the MCU to communicate with the MCU and convert the TTL signal transmitted by the MCU into communication data in 485 format; the pins A and B of the 485 communication conversion module are respectively connected to the 485-A and 485-B of the 485 data transmission interface to send the data in 485 format to the 485 data transmission interface.

[0058] The temperature acquisition module is a temperature sensor with a high-speed IIC interface; the temperature acquisition module's pins SDA and SCL are connected to the MCU's P3.2 and P3.3 respectively, converting the temperature voltage signal directly into a digital signal for transmission.

[0059] The battery power acquisition module uses the ADC function of the MCU to collect voltage; the input end of the battery power acquisition module is connected to the positive terminal of the battery, and the output end is connected to P1.7 of the MCU to transmit the current voltage of the battery. Among them, the MCU converts the analog voltage transmitted by the battery power acquisition module into a digital signal through the internal ADC converter and sends it to the display and display driver module.

[0060] The alarm module is implemented based on a buzzer alarm. The buzzer alarm circuit includes a voltage source, a buzzer BUZZER1 and a transistor Q2; the first electrode of the transistor Q2 is electrically connected to the voltage source through the buzzer, the second electrode of the transistor Q2 is grounded, and the control electrode of the transistor Q2 is electrically connected to the P0.6 port of the MCU; wherein the MCU controls the buzzer to alarm when the instantaneous flow value is lower than or higher than the instantaneous flow alarm threshold and the total flow value is higher than the alarm threshold.

[0061] Key control module, keys SW2, SW3, SW4, SW5 are connected to P4.0, P3.6, P5.1, P2.3 of MCU respectively, where MCU detects the level of key to control the display and setting of meter parameters.

[0062] like Figure 1 and 2 As shown, the analog voltage signal of the flow sensor 100 is transmitted to the AD conversion module 230 of the gas flow monitoring meter header 200 via the analog flow signal input interface 220 for analog-to-digital conversion. The digital flow signal after analog-to-digital conversion is transmitted to the MCU control module 280 for processing and conversion into a TTL signal. The TTL signal is transmitted to the display and display drive module 310 for display, and is transmitted to the 485 communication conversion module 330 for conversion into 485 communication data through the 485 communication conversion module 330, and then transmitted to the user terminal via the 485 communication data output interface 270.

[0063] The MCU control module 280 processes the temperature signal and the power signal transmitted by the temperature acquisition module 310 and the battery power acquisition module 250 at the same time, and transmits them to the display and display drive module 320 for display; the MCU control module 280 also continuously detects whether the power-off preservation module 240 transmits a power-off signal. If it is detected that the power-off preservation module 240 transmits a power-off signal, all tasks being executed are immediately stopped to save data; the MCU control module 280 also continuously detects whether the key control module 260 is an execution signal. If it is detected that the key control module 260 transmits an execution signal, the alarm setting threshold, 485 communication address and baud rate are displayed and set.

[0064] The MCU control module 280 also controls the alarm module 290 to alarm according to the set threshold value; the MCU control module 280 also turns on and off the flow channel electrical switch 300 according to the flow channel electrical switch 300 control signal transmitted from the 485 communication data output interface 270.

[0065] The flow channel gas flow monitoring meter in this application adopts RS485 bus transmission and Modbus-RTU communication protocol, which can realize the terminal platform to remotely receive, analyze and process data from multiple sites, and remotely control the electrical linkage of each site through the RS485 bus, and support the function of querying and outputting data by the host computer; at the same time, it supports the LCD screen to display the instantaneous flow rate, cumulative total flow rate, ambient temperature and auxiliary alarm function of the gas. RS485 / MODBUS is a commonly used networking method. The RS485 transceiver adopts balanced transmission and differential reception, so it has the ability to suppress common-mode interference. In addition, the receiver has high sensitivity and can detect voltages as low as 200mV, so the transmission signal can be restored thousands of meters away. Using the RS485 bus, a pair of twisted pair cables can realize multi-station networking to form a distributed system, which has the advantages of simple equipment, low price and long-distance communication.

Claims

1. A flow channel gas flow monitoring device, comprising: Flow sensor and gas flow monitoring meter header; The gas flow monitoring meter header includes: a power input interface, an MCU control module, a 485 communication data output interface, an analog flow signal input interface, an AD conversion module and a 485 communication conversion module; The power input interface is connected to an external power source to power other devices; the flow sensor is electrically connected to the MCU control module, and the flow sensor converts the gas medium flow in the flow channel into an analog voltage signal and sends it to the MCU control module; The analog flow signal transmission interface transmits the analog flow voltage signal of the flow sensor to the AD conversion module; the AD conversion module collects the analog flow voltage signal sent by the flow data transmission interface, converts it into a digital flow signal, and sends it to the MCU control module; The 485 communication conversion module is used to convert the flow TTL signal sent by the MCU control module into 485 communication data and send it to the 485 data transmission interface; the 485 data transmission interface is used to send the flow channel gas flow data to the user terminal through the 485 bus; The MCU control module processes the received flow data signal to realize flow channel gas flow detection; Features: The gas flow monitoring meter header also includes: a power-off saving module; The power-off saving module is used to provide a power-off signal for saving data to the MCU control module when the meter loses power; The MCU control module receives the power-off signal sent by the power-off saving module and saves the data when the power is off; The MCU control module includes: a control chip, capacitors C18 and C19; the power-off saving module includes: a monitoring and reset chip MAX813L, a voltage-dividing resistor, a Schottky diode D6 and an electrolytic capacitor C20; the resistors include R30 and R31; the control chip is implemented based on the STC15W4K chip, and the monitoring and reset chip U7 is implemented based on the MAX813L chip; The 5th pin power failure output terminal PFO of the monitoring and reset chip is connected to the P3.2 interrupt INT0 pin of the control chip; One end of the resistor R30 is connected to the 4th pin power fault input terminal PFI of the monitoring and reset chip and one end of the resistor R31; the other end of the resistor R30 is connected to the 2nd pin of the monitoring and reset chip and the anode of the Schottky diode D6 and then connected to the power supply VCC; the cathode of the Schottky diode D6 is connected to the positive electrode of the electrolytic capacitor C20 and the 15-pin power supply VCC terminal of the control chip; the negative electrode of the electrolytic capacitor C20 is grounded; the other end of the resistor R31 is grounded; and the 3rd pin of the monitoring and reset chip U7 is grounded.

2. A flow channel gas flow monitoring device according to claim 1, characterized in that: The 485 communication data output interface is implemented based on the TYPE-C-31 interface, the 485 communication conversion module is implemented based on the max485ESA chip, the analog flow signal input interface is implemented based on PZ254V, and the AD conversion module is implemented based on CS1237-SO.

3. The flow channel gas flow monitoring device according to claim 1, characterized in that: The gas flow monitoring meter header also includes: a temperature acquisition module and the temperature acquisition module is used to convert the ambient temperature signal into a digital signal and transmit it to the MCU control module.

4. The flow channel gas flow monitoring device according to claim 1, characterized in that: The gas flow monitoring meter header also includes: a power supply voltage reduction module and a battery power collection module; The power step-down module is used to convert the 12V voltage into a 5V voltage to provide power for all other components; The battery power acquisition module is used to send the voltage signal of the battery power to the MCU control module.

5. A flow channel gas flow monitoring device according to claim 4, characterized in that: The power supply voltage reduction module is implemented based on the AMS1117 chip.

6. The flow channel gas flow monitoring device according to claim 1, characterized in that: The gas flow monitoring meter header also includes: a display and display driving module, and the display and display driving module is used to display the flow channel gas flow data, temperature and various control signals sent by the MCU control module.

7. A flow channel gas flow monitoring device according to claim 6, characterized in that: The display and display driver module are implemented based on the PCF8576DT display driver.

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