A remote circuit parameter monitoring system based on RS485 communication

Abstract

The present invention discloses a long-distance circuit parameter monitoring system based on RS485 communication, the system includes a temperature monitoring module, a humidity monitoring module, a current and voltage monitoring module, a main control module and a communication module, wherein the temperature monitoring module and the humidity monitoring module are respectively used to detect the temperature data and humidity data of the environment in which the analog front-end circuit is located; the current and voltage monitoring module is used to detect the current and voltage data of the analog front-end circuit; the main control module is used to receive the temperature data, the humidity data and the current and voltage data, and process the received data, and transmit the processed data to the upper level processing unit through the communication module, so as to realize long-distance circuit parameter monitoring. The present invention can be applied to low temperature and harsh environment, and by monitoring the temperature and humidity data of the analog front-end cavity, and the current and voltage data of the analog front-end circuit, it can realize the abnormal judgment of the analog front-end circuit and the monitoring of the operating environment, thereby providing an important reference for the operation and maintenance of the equipment.

Description

Technical Field

[0001] The invention relates to the technical field of circuit parameter monitoring, and in particular to a long-distance circuit parameter monitoring system based on RS485 communication. Background Art

[0002] Very Low Frequency (VLF) waves refer to electromagnetic waves with a frequency range of 3kHz to 30kHz. They can be generated by natural phenomena (such as lightning) or artificially (such as station signals and electromagnetic interference). They are widely used in the fields of solar activity monitoring, ionosphere detection, and marine communications. In order to effectively receive VLF signals, the antenna receiving signal needs to be amplified, filtered, and a series of preprocessing is performed through the analog front end so that the receiver can obtain clean, stable, and accurate data. All subsequent analyses of VLF signals rely on the normal operation of the analog front end. Therefore, judging the abnormal conditions of the analog front end and monitoring the operating environment of the front-end circuit play an important role in equipment operation and maintenance and system reliability assurance, and can provide data support and reference for subsequent circuit upgrades.

[0003] The analog front end of the ground-based VLF detection system is usually installed in the field and is exposed to harsh environments such as low temperature and high humidity for a long time. The main operating temperature range of the traditional circuit monitoring system is -20℃~40℃, which cannot meet the monitoring needs in the above working environment and is insufficient in measurement accuracy and transmission rate. Summary of the invention

[0004] The present invention aims to solve the technical problems in the related art at least to a certain extent. To this end, the purpose of the present invention is to provide a long-distance circuit parameter monitoring system based on RS485 communication, which can be applied to low-temperature harsh environments. By monitoring the temperature and humidity data of the analog front-end cavity and the current and voltage data of the analog front-end circuit, the abnormal judgment of the analog front-end circuit and the monitoring of the operating environment can be realized, thereby providing an important reference for the operation and maintenance of the equipment.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A long-distance circuit parameter monitoring system based on RS485 communication, comprising:

[0007] The temperature monitoring module and the humidity monitoring module are used to detect the temperature data and humidity data of the environment where the analog front-end circuit is located respectively;

[0008] A current and voltage monitoring module, used to detect current and voltage data of the analog front-end circuit;

[0009] A main control module and a communication module, wherein the main control module is connected to the temperature monitoring module, the humidity monitoring module, the current and voltage monitoring module and the communication module respectively, and the main control module is used to receive the temperature data, the humidity data and the current and voltage data, and process the received data, and transmit the processed data to the upper-level processing unit through the communication module to realize long-distance circuit parameter monitoring.

[0010] Optionally, the humidity monitoring module adopts an SE555 model chip, and the RESET end of the humidity monitoring module is connected to the VCC end of the humidity monitoring module; the DISCH end of the humidity monitoring module is connected to the VCC end of the humidity monitoring module through a first resistor; the DISCH end of the humidity monitoring module is also connected to the first end of a second resistor, the second end of the second resistor is grounded through a first capacitor, and is connected to the THRES end and TRIG end of the humidity monitoring module; the VCC end of the humidity monitoring module is also connected to the OUT end of the humidity monitoring module through a third resistor; the CONT end of the humidity monitoring module is grounded through a second capacitor; wherein, the first capacitor is a humidity-sensitive capacitor.

[0011] Optionally, the current and voltage monitoring module includes a current monitoring unit and an analog-to-digital conversion unit, the current monitoring unit adopts an INA193AMDBVREP model chip, the VIN- terminal of the current monitoring unit is connected to the analog front-end circuit; a fourth resistor is connected between the VIN+ terminal and the VIN- terminal of the current monitoring unit; the OUT terminal of the current monitoring unit is connected to the current detection terminal of the analog-to-digital conversion unit; and multiple voltage detection terminals of the analog-to-digital conversion unit are connected to the analog front-end circuit.

[0012] Optionally, the communication module is an RS485 communication module, and the communication module adopts an ADM3066E model chip.

[0013] Optionally, the RO and DI ends of the communication module are connected to the main control module; the high differential port and the low differential port of the communication module are connected to the power supply and the ground through a fifth resistor and a sixth resistor, respectively; the low differential port and the high differential port are grounded through a first diode and a third diode, respectively, and a second diode is connected between the low differential port and the high differential port; the low differential port and the high differential port are also connected to a common mode filter, and the common mode filter is also connected to a gas discharge tube and a seventh resistor, wherein both ends of the seventh resistor serve as output ends of the communication module.

[0014] Optionally, the first diode to the third diode are transient suppression diodes.

[0015] Optionally, the temperature monitoring module uses a TMP1075DGKR chip.

[0016] Optionally, each module is arranged on a PCB board, and the PCB board is a gold-immersion board made of a ceramic substrate.

[0017] Optionally, the temperature monitoring module, humidity monitoring module, current and voltage monitoring module and communication module are evenly arranged around the main control module on the PCB board.

[0018] Optionally, a polyimide protective layer is provided on the surface of each module chip.

[0019] The present invention has at least the following technical effects:

[0020] The invention provides a long-distance circuit parameter monitoring system based on RS485 communication, the system comprises a temperature monitoring module, a humidity monitoring module, a current and voltage monitoring module, a main control module and a communication module, wherein the main control module is used for controlling the operation and data transmission of other modules, the temperature and humidity monitoring module is used for completing the data collection of the temperature and humidity of the cavity where the analog front-end circuit is located, the current and voltage monitoring module is used for completing the data collection of the current and voltage of the analog front-end circuit, and then after receiving and processing the data collected by other modules, the main control module transmits the processed data to an upper-level processing unit through an RS485 long-distance transmission module, i.e., a communication module. The present invention adopts a low-temperature resistant design, in which a wide-temperature device is selected in device selection to be suitable for more severe working environments, especially low-temperature environments. It can work normally in a temperature range of -40°C to 105°C, and can realize the measurement of multi-channel temperature, humidity, and current and voltage parameters, so as to facilitate the judgment of abnormal conditions of the analog front-end circuit according to the collected current and voltage data, and monitor the operating environment of the analog front-end circuit according to the temperature and humidity data. In addition, the wide-temperature device selected by the present invention can improve data measurement accuracy and transmission efficiency, wherein the measurement accuracy of temperature, humidity, current and voltage can reach ±0.25°C, ±1.5% RH, 1.5% and 1.22mV respectively, which can better remotely monitor the working status of the analog front end, and can provide important reference and basis for the accuracy judgment of detection data, later maintenance and system upgrade.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The structure block diagram of the long-distance circuit parameter monitoring system based on RS485 communication according to an embodiment of the present invention.

[0023] Figure 2 Schematic diagram of the circuit structure of the temperature monitoring module according to an embodiment of the present invention.

[0024] Figure 3The figure is a schematic diagram of the circuit structure of the humidity monitoring module according to an embodiment of the present invention.

[0025] Figure 4 Schematic diagram of the circuit structure of a current monitoring unit according to an embodiment of the present invention.

[0026] Figure 5 Schematic diagram of the circuit structure of an analog-to-digital conversion unit according to an embodiment of the present invention.

[0027] Figure 6 The figure is a schematic diagram of the circuit structure of a communication module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present embodiment is described in detail below, and examples of the embodiment are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0029] A long-distance circuit parameter monitoring system based on RS485 communication according to the present embodiment will be described below with reference to the accompanying drawings.

[0030] Figure 1 The structure block diagram of the long-distance circuit parameter monitoring system based on RS485 communication according to an embodiment of the present invention.

[0031] like Figure 1 As shown, the remote circuit parameter monitoring system 100 based on RS485 communication includes a temperature monitoring module 10, a humidity monitoring module 20, a current and voltage monitoring module 30, a main control module 40 and a communication module 50. Among them, the temperature monitoring module 10 and the humidity monitoring module 20 are respectively used to detect the temperature data and humidity data of the environment where the analog front-end circuit is located; the current and voltage monitoring module 30 is used to detect the current and voltage data of the analog front-end circuit; the main control module 40 is respectively connected to the temperature monitoring module 10, the humidity monitoring module 20, the current and voltage monitoring module 30 and the communication module 50, and the main control module 40 is used to receive temperature data, humidity data and current and voltage data, and process the received data, and transmit the processed data to the upper-level processing unit through the communication module 50 to realize remote circuit parameter monitoring.

[0032] Specifically, the system is a multi-channel, multi-parameter long-distance circuit monitoring system based on the MPC89E58AP single-chip microcomputer as the main control module 40. The monitoring system is built around the MPC89E58AP single-chip microcomputer, i.e., the main control module 40. Each parameter monitoring module and the data transmission module are connected to the main control module 40 through an I / O (input / output) port. The main control module 40 controls the data collection and return of the temperature monitoring module 10, the humidity monitoring module 20, and the current and voltage monitoring module 30 through instructions, and processes the data. Then, the processed data is transmitted to the upper-level processing unit in sequence through the RS485 (a serial communication protocol) transmission module, i.e., the communication module 50.

[0033] In order to enable the system to work in an extremely cold environment, a series of low temperature resistance schemes are adopted in the overall design of the system. It can be understood that the above modules are all arranged on the PCB (printed circuit board) board, and the low temperature resistance scheme is as follows: first, in the selection of PCB materials, a ceramic substrate is used, and the board surface is treated with immersion gold, that is, the PCB board adopts an immersion gold board prepared by a ceramic substrate to improve the PCB's oxidation resistance and corrosion resistance, and prevent the PCB from falling off under low temperature environments. Performance degradation caused by tin particles falling off. Secondly, when designing the circuit, the layout of the heating device is considered, and each module is evenly arranged around the main control module 40 with the main control module 40 as the center, so as to achieve thermal balance, reduce the temperature gradient effect on the board, and prevent PCB damage caused by excessive temperature changes. Finally, the selection and processing of components, the minimum operating temperature of the main chip selected by each module in the design can reach -55 ° C. On this basis, polyimide is also applied on the surface of each chip, and a polyimide protective layer is set to prevent material problems caused by temperature changes, and then the low temperature resistance of each module can be guaranteed through further processing.

[0034] The following is a detailed description of each module in this embodiment.

[0035] The main control module 40 in this embodiment has an operating temperature of -40°C to 105°C, a simple structure, low power consumption, and a maximum operating frequency of up to 48MHz in 12T mode and up to 24MHz in 6T mode, where T is the clock cycle. As a control unit, the main control module 40 is connected to the temperature monitoring module 10, the humidity monitoring module 20, the current and voltage monitoring module 30, and the communication module 50 through the I / O port. The specific connection method is: connected to the temperature monitoring module 10 and the humidity monitoring module 20 through a set of IIC (an integrated circuit bus) bus and two timer pins, connected to the current and voltage monitoring module 30 through the SPI (a synchronous data bus) bus, and connected to the communication module 50 through the UART (a universal serial data bus) protocol port and the control port.

[0036] The main control module 40 in this embodiment uses the MPC89E58AP single-chip microcomputer. The main design of the single-chip microcomputer lies in the peripheral circuits of several special pins and 36 common I / O ports. When used, the pins above P00~P07, P10~P17, P20~P27, P30~P37, P40~P43 are connected to the power supply VCC through a pull-up resistor, and the role of the external timer and external interrupt is not considered. The crystal oscillator interface of the single-chip microcomputer is connected to a 22.1184MHz passive crystal oscillator, and two 20pF capacitors are used to connect. The burning of the single-chip microcomputer requires the use of an ISP (burning) burner, and 3 pin headers are reserved on the PCB board for it to connect the VCC, GND and TXD (transmit data) pins of the main control module 40 respectively.

[0037] Further, such as Figure 2 As shown, the main body of the temperature monitoring module 10 is a TMP1075DGKR temperature sensor with three address pins. Through different wiring designs, up to 32 temperature sensors can be suspended on an IIC bus. The digital output of each temperature measurement conversion is stored in a read-only temperature register. During operation, the single-chip microcomputer sends an 8-bit write address, an 8-bit temperature register address, and an 8-bit read address to the chip in sequence. The temperature register stores the output of the most recent conversion. After confirming the single-chip microcomputer instruction, the chip will continuously send two 8-bit data to the single-chip microcomputer, i.e., the main control module 40. Of these 16 bits of data, only 12 MLBs (most significant bits) are used to indicate the temperature, and the remaining 4 LSBs (least significant bits) are set to zero. The actual value can be calculated based on the collected temperature data:

[0038] T=0.0625·S T (1)

[0039] Where T is the actual temperature, S T is the collected temperature data. If the temperature is below zero, first take the two's complement format and then substitute it into the above formula for calculation. The chip package volume is only 3×5×1.1mm 3 , which enables the module to be miniaturized and easily integrated into other applications, and the wide power supply voltage range of 2.15V to 5.5V ensures compatibility with various circuits.

[0040] Specifically, in actual application, for the temperature sensor chip, its SDA, SCL and ALERT ports can be pulled high to connect to the common I / O port of the main control module 40, corresponding to an IIC bus and an alarm port. The chip has three address pins, and only physical address selection is considered in the design. By connecting the three pins to the power supply VCC or GND respectively, there are a total of 8 optional addresses. Figure 2The circuit is constructed as shown, and its write address is 0x90. The main control module 40 sends the write address through the IIC bus and then sends the temperature register address 0x00. Finally, it transmits the read address 0x91, and the 16-bit temperature value data returned from the temperature sensor chip is received. After obtaining the data, first determine whether the first bit is 1. If it is 1, take the complement code, then shift the data right by 4 bits and put it into the above formula (1) to calculate the actual temperature value.

[0041] Further, such as Figure 3 As shown, the humidity monitoring module 20 uses a 555 multivibrator circuit to measure the capacitance of a humidity-sensitive capacitor, thereby calculating the relative humidity. The humidity-sensitive capacitor has a sensitivity of 0.25pF / %RH and is suitable for -80℃~150℃. The humidity monitoring module 20 uses a 555 timer chip SE555, which can stably output a square wave with an adjustable duty cycle through circuit design. By connecting its output to the timer pin of the main control module 40, the square wave frequency can be obtained, and then the capacitance of the humidity-sensitive capacitor connected in the circuit can be obtained, thereby calculating the relative humidity.

[0042] Specifically, in humidity monitoring, such as Figure 3 The peripheral circuit of the SE555 chip is shown. Specifically, the RESET terminal of the humidity monitoring module 20 is connected to the VCC terminal of the humidity monitoring module 20; the DISCH terminal of the humidity monitoring module 20 is connected to the VCC terminal of the humidity monitoring module 20 through the first resistor R1; the DISCH terminal of the humidity monitoring module 20 is also connected to the first end of the second resistor R2, the second end of the second resistor R2 is grounded through the first capacitor C1, and is connected to the THRES terminal and TRIG terminal of the humidity monitoring module 20; the VCC terminal of the humidity monitoring module 20 is also connected to the OUT terminal of the humidity monitoring module 20 through the third resistor R3; the CONT terminal of the humidity monitoring module 20 is grounded through the second capacitor C2.

[0043] The first capacitor C1 is a humidity-sensitive capacitor, the first resistor R1 and the second resistor R2 are both 5KΩ, and the calculation formula of the humidity-sensitive capacitor, namely the first capacitor C1, is:

[0044]

[0045] Wherein, C is the capacitance of the humidity-sensitive capacitor, k is the unit of resistance, and Frequency is the square wave frequency input to the main control module 40, that is, the frequency of the oscillation signal. The frequency calculation is performed by the main control module 40, and the OUT terminal of the humidity monitoring module 20 is connected to the timer 0 pin or the timer 1 pin of the main control module 40, in order to trigger the 16-bit counter built into the main control module 40. First, set timer 2 in the timer interrupt mode, and make it count for 1s by setting several interrupts, and then set the other two timers in the 16-bit counter mode. During operation, the 16-bit counter counts each time it overflows, and finally calculates the total number of pulses within 1s through the overflow number and the 16-bit data of the counter, which is the frequency Frequency of the oscillation signal. Then, the capacitance of the humidity-sensitive capacitor is calculated according to the frequency Frequency of the oscillation signal, and then the relative humidity data can be obtained according to the capacitance of the humidity-sensitive capacitor. When the main control module 40 completes the calculation, it transmits the data to the data transmission port of the communication module 50 for remote communication with the host computer, that is, the upper level processing unit.

[0046] It should be noted that the above two modules together constitute a temperature and humidity module. During use, the required circuit is built at the test point and connected to the I / O port of the main control module 40 through a pin header. Multiple temperature monitors can be suspended on the same IIC bus, and each humidity monitor requires a corresponding timer pin connection. The temperature and humidity module has an accuracy of up to ±1.5% RH and ±0.25°C, and has an extremely wide temperature range, which can work at -40°C to 105°C, and is suitable for various environments for temperature and humidity monitoring.

[0047] Furthermore, the current and voltage monitoring module 30 is divided into two parts: a current monitoring unit and an analog-to-digital conversion unit. For the circuit to be monitored, the current measurement requires a current detection unit to be built on the line and connected to the analog-to-digital conversion unit through a pin header, and the voltage measurement requires the measurement point to be led out with a pin header and directly connected to the analog-to-digital conversion unit.

[0048] In this embodiment, the main body of the current monitoring unit is the current sensing amplifier INA193AMDBVREP chip, the operating temperature is -55℃~125℃, the module uses a current sampling resistor with a very small resistance value to be connected in series to the measured loop, and then uses the current sensing amplifier to amplify the voltage across the resistor in proportion and output it to the analog-to-digital conversion unit. Finally, the DC current size is calculated based on the voltage collected by the analog-to-digital conversion unit, and its accuracy can reach up to ±1%. Then there is the voltage monitoring function, and its function realization depends on the analog-to-digital conversion chip TLV2556MPWREP. The module transmits data to the main control module 40 through the SPI protocol, the clock frequency can reach 15MHz, the operating temperature is -55℃~125℃, and the voltage to be measured is connected to the monitoring board and then connected to the voltage detection channel. The chip has a resolution of 12 bits and an accuracy of ±1LSB. If its internal reference voltage is not used, the 5V power supply of the front-end baseboard can be used, and its resolution can reach 0.00122V, that is, the accuracy is 0.00122V.

[0049] When the chip is working, first pull the corresponding CS pin low, and then configure the working mode of the analog-to-digital conversion chip by setting the CFGR1 and CFGR2 registers inside the chip. By setting these two registers, the reference voltage of the chip, the channel port for collecting data, the data length and the data start bit can be selected. When setting this chip, the power supply VCC can be selected as the reference voltage, and the 8 channel data can be read cyclically and transmitted to the main control module 40 as 16-bit data. Since the chip itself has only 12 bits, the data returned must first be shifted right by four bits, and then the voltage value is calculated using the principle formula of the successive approximation register type analog-to-digital conversion chip:

[0050]

[0051] According to the current sensing amplifier gain and the current sampling resistor, the current value of the current measurement channel can be calculated:

[0052]

[0053] Among them, S V is the data collected by the analog-to-digital conversion unit, Gain is the current sensing amplifier gain, R4 is the current sampling resistor, V is the amplified voltage, and I is the current measured by the analog front end.

[0054] Specifically, Figure 4As shown, the VIN- terminal of the current monitoring unit, i.e., INA193AMDBVREP, is connected to the analog front-end circuit; the fourth resistor R4, i.e., the current sampling resistor, is connected between the VIN+ terminal and the VIN- terminal of the current monitoring unit; the OUT terminal of the current monitoring unit is connected to the current detection terminal of the analog-to-digital conversion unit, and the multiple voltage detection terminals of the analog-to-digital conversion unit are connected to the analog front-end circuit. Among them, the OUT terminal of the current monitoring unit outputs the amplified voltage data to the analog-to-digital conversion unit, and the analog-to-digital conversion unit processes and outputs it to the main control module 40. The main control module 40 can obtain the analog front-end current by performing calculations according to the above formulas (3) and (4).

[0055] In this design, the current and voltage monitoring module 30 uses the power supply VCC as the external reference level. Figure 5 As shown, the external reference level selection of TLV2556MPWREP is determined by REF+ and REF-. REF+ is connected to the power supply VCC, and REF- is connected to GND. The reference level is the difference between the two, which is 5V. DATA-IN, DATA-OUT, I / O-CLOCK and CS on the chip are four communication ports of the SPI protocol. They are respectively connected to P01, P00, P02 and P42 of the main control module 40 for control. The EOC / (INT) port is a status output, which is used to indicate the end of the conversion (EOC) or interrupt (INT) to the main control module 40. It is directly connected to the I / O port of the main control module 40 or left floating. Figure 5 As shown in the figure, of the 11 channel ports of the analog-to-digital conversion chip, only 8 are used to measure external signals in the design. AIN0~3 are voltage detection terminals for measuring voltage, AIN5~8 are current detection terminals for measuring voltage with current conversion, and the other 3 can be directly left floating. The 8 channel pins are grounded through a pull-down resistor, so that the data read is 0 in the no-data state.

[0056] The voltage monitoring does not require additional circuits, and only requires connecting the four channels of the analog-to-digital conversion chip through the pin header J4. The current measurement requires the following setup at the test location: Figure 4 In the circuit shown, the current sampling resistor is connected to the circuit, and the VIN+ and VIN- of the chip are connected to the two ends of the resistor to measure its voltage division. Then, the OUT end of the current monitoring unit is used as the output pin. Among them, the voltage output converted by the current is connected to one of the four channels of the analog-to-digital conversion chip as the above voltage measurement.

[0057] During the monitoring process, the main control module 40 sends configuration information to the analog-to-digital conversion chip, i.e., the analog-to-digital conversion unit register, through the SPI protocol. According to the chip manual, it is initialized first, and the instruction 0xFC is written to configure the register CFGR2, so that the analog-to-digital conversion chip uses an external reference voltage and can configure the register CFGR1; then the instruction 0x0C is written to make the analog-to-digital conversion chip read the channel 0 data in 16-bit format, and then the data of each channel is read in turn in a loop. Finally, the main control module 40 processes these data and transmits them to the data transmission port of the communication module 50.

[0058] Further, the communication module 50 can output the data integrated by the main control module 40 differentially, or receive the command of the host computer. The communication module 50 in this embodiment can adopt the RS485 chip ADM3066E that can work at -55℃~125℃, which is a half-duplex communication mode, and the maximum communication rate can reach 50Mbps. Only one I / O port is used to control its reception or transmission, and the transmission of data connects the two I / O ports of the main control module 40. The communication module 50 can directly communicate with the RS485 at a distance through the UART protocol. In actual use, the analog front end communicates with the receiver through a 100m cable, and the RS485 module can provide stable and reliable information transmission in this process.

[0059] like Figure 6 As shown, the RO and DI terminals of the communication module 50 are connected to the main control module 40; the high differential port A and the low differential port B of the communication module 50 are connected to the power supply VCC and the ground through the fifth resistor R5 and the sixth resistor R6 respectively; the low differential port B and the high differential port A are grounded through the first diode D1 and the third diode D3 respectively, and the second diode D2 is connected between the low differential port B and the high differential port A; the low differential port B and the high differential port A are also connected to the common mode filter L, and the common mode filter L is also connected to the gas discharge tube GTD1 and the seventh resistor R7, wherein the two ends of the seventh resistor R7 serve as the output terminals of the communication module 50, namely RS485_A and RS485_B. It should be noted that the first diode D1 to the third diode D3 are transient suppression diodes.

[0060] Specifically, the communication module 50 in this embodiment is an RS485 differential transmission module. The VIO pin of the chip is not needed in the design and can be left floating. The receiving pin RO and the transmitting pin DI are respectively connected to the two serial port pins of the main control module 40. Since it is a half-duplex chip, its two enable pins are connected together and controlled by an I / O port. Furthermore, the high and low differential ports of the chip are respectively connected to VCC and ground through a resistor, so that it can stably transmit differentially in the absence of data. Then, as shown in FIG. Figure 6As shown, three transient suppression diodes D1-D3, a common mode filter L, a gas discharge tube GTD1 and a 120Ω matching resistor, namely the seventh resistor R7, are connected. Among them, the transient suppression diodes D1-D3 and the gas discharge tube GTD1 can be used to prevent lightning strikes, and the common mode filter L and the matching resistor, namely the seventh resistor R7, can be used to filter out the common mode noise in the circuit and improve the quality and stability of the signal. In this embodiment, the communication module 50 pulls up the transmission enable bit at the beginning and is always in the transmission state. When receiving the processed data from the main control module 40, the communication module 50 immediately transmits it differentially, and its rate is determined by the baud rate of the serial port protocol of the main control module 40.

[0061] In summary, the present invention provides a long-distance circuit parameter monitoring system based on RS485 communication, the system comprising a temperature monitoring module, a humidity monitoring module, a current and voltage monitoring module, a main control module and a communication module, wherein the main control module is used to control the operation and data transmission of other modules, the temperature and humidity monitoring module is used to complete the data collection of the temperature and humidity of the cavity where the analog front-end circuit is located, the current and voltage monitoring module is used to complete the data collection of the current and voltage of the analog front-end circuit, and then the main control module receives and processes the data collected by other modules, and transmits the processed data to the upper-level processing unit through the RS485 long-distance transmission module, i.e., the communication module. The present invention adopts a low-temperature resistant design, in which a wide-temperature device is selected in device selection to be suitable for more severe working environments, especially low-temperature environments. It can work normally in a temperature range of -40°C to 105°C, and can realize the measurement of multi-channel temperature, humidity, and current and voltage parameters, so as to facilitate the judgment of abnormal conditions of the analog front-end circuit according to the collected current and voltage data, and monitor the operating environment of the analog front-end circuit according to the temperature and humidity data. In addition, the wide-temperature device selected by the present invention can improve data measurement accuracy and transmission efficiency, wherein the measurement accuracy of temperature, humidity, current and voltage can reach ±0.25°C, ±1.5% RH, 1.5% and 1.22mV respectively, which can better remotely monitor the working status of the analog front end, and can provide important reference and basis for the accuracy judgment of detection data, later maintenance and system upgrade.

[0062] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0063] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A long-distance circuit parameter monitoring system based on RS485 communication, characterized in that: include: The temperature monitoring module and the humidity monitoring module are used to detect the temperature data and humidity data of the environment where the analog front-end circuit is located respectively; A current and voltage monitoring module, used to detect current and voltage data of the analog front-end circuit; A main control module and a communication module, wherein the main control module is connected to the temperature monitoring module, the humidity monitoring module, the current and voltage monitoring module and the communication module respectively, and the main control module is used to receive the temperature data, the humidity data and the current and voltage data, process the received data, and transmit the processed data to the upper-level processing unit through the communication module to realize long-distance circuit parameter monitoring; The humidity monitoring module adopts SE555 chip, the RESET end of the humidity monitoring module is connected to the VCC end of the humidity monitoring module; the DISCH end of the humidity monitoring module is connected to the VCC end of the humidity monitoring module through a first resistor; the DISCH end of the humidity monitoring module is also connected to the first end of the second resistor, the second end of the second resistor is grounded through a first capacitor, and is connected to the THRES end and TRIG end of the humidity monitoring module; the VCC end of the humidity monitoring module is also connected to the OUT end of the humidity monitoring module through a third resistor; the CONT end of the humidity monitoring module is grounded through a second capacitor; wherein the first capacitor is a humidity-sensitive capacitor; The main control module adopts the MPC89E58AP single-chip microcomputer. When measuring humidity, the main control module is used to first set timer 2 in timer interrupt mode, set several interrupts to make timer 2 count for 1s, and then set timer 0 and timer 1 in 16-bit counter mode, perform 16-bit counting on timer 0 and timer 1 and count the overflow number each time it overflows, and calculate the total number of pulses within the 1s counting time of timer 2 through the overflow number and 16-bit counting data, so as to obtain the frequency of the oscillation signal, and facilitate the capacitance of the humidity-sensitive capacitor according to the frequency of the oscillation signal, and obtain the humidity data.

2. The long-distance circuit parameter monitoring system based on RS485 communication as claimed in claim 1, characterized in that, The current and voltage monitoring module includes a current monitoring unit and an analog-to-digital conversion unit. The current monitoring unit adopts an INA193AMDBVREP model chip. The VIN- terminal of the current monitoring unit is connected to the analog front-end circuit; a fourth resistor is connected between the VIN+ terminal and the VIN- terminal of the current monitoring unit; the OUT terminal of the current monitoring unit is connected to the current detection terminal of the analog-to-digital conversion unit; and multiple voltage detection terminals of the analog-to-digital conversion unit are connected to the analog front-end circuit.

3. The long-distance circuit parameter monitoring system based on RS485 communication as claimed in claim 1, characterized in that, The communication module is an RS485 communication module, and the communication module adopts an ADM3066E chip.

4. The long-distance circuit parameter monitoring system based on RS485 communication as claimed in claim 3, characterized in that: The RO terminal and the DI terminal of the communication module are connected to the main control module; the high differential port and the low differential port of the communication module are connected to the power supply and the ground through the fifth resistor and the sixth resistor respectively; The low differential port and the high differential port are grounded through a first diode and a third diode respectively, and a second diode is connected between the low differential port and the high differential port; The low differential port and the high differential port are also connected to a common mode filter, and the common mode filter is also connected to a gas discharge tube and a seventh resistor, wherein two ends of the seventh resistor serve as output ends of the communication module.

5. The long-distance circuit parameter monitoring system based on RS485 communication as claimed in claim 4, characterized in that: The first diode to the third diode are transient voltage suppressor diodes.

6. The long-distance circuit parameter monitoring system based on RS485 communication as claimed in claim 1, characterized in that: The temperature monitoring module adopts TMP1075DGKR chip.

7. The long-distance circuit parameter monitoring system based on RS485 communication as claimed in claim 1, characterized in that: Each module is arranged on a PCB board, and the PCB board is a gold-immersion board made of a ceramic substrate.

8. The long-distance circuit parameter monitoring system based on RS485 communication as claimed in claim 7, characterized in that: The temperature monitoring module, humidity monitoring module, current and voltage monitoring module and communication module are evenly arranged around the main control module on the PCB board.

9. The long-distance circuit parameter monitoring system based on RS485 communication as described in any one of claims 1 to 8, characterized in that: A polyimide protection layer is provided on the surface of each module chip.

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