Outdoor complete equipment environment data collection and control circuit

Abstract

The application discloses an outdoor complete equipment environment data acquisition and control circuit and belongs to the field of environment data acquisition.The circuit takes a single-chip microcomputer as a main control chip, combines IIC multiplexing, temperature and humidity acquisition, surface temperature acquisition, relay control, TLL to 485 and other circuits to form a complete outdoor complete equipment environment data acquisition and control circuit.A power supply circuit realizes DC 5-36V wide voltage input adaptation through two-stage linear voltage stabilizers, combines multi-stage filter capacitor design, effectively filters out power supply noise and outputs stable 5V and 3.3V voltages.The IIC multiplexing circuit guarantees the signal integrity of the IIC bus through a 10kΩ pull-up resistor, and 8 channels can be extended to 8-way same address IIC devices, so that the address conflict problem of multiple same address IIC sensors is solved and the demand of outdoor equipment multi-region monitoring is met.

Description

TECHNICAL FIELD

[0001] The present application relates to environmental data collection, in particular to an outdoor complete equipment environmental data collection and control circuit. BACKGROUND

[0002] Sensor expansion is limited: when multiple IIC sensors with the same address (such as temperature and humidity sensors) are connected to the same bus, address conflicts often occur, resulting in a maximum of only 2-4 devices being connected, which cannot meet the needs of multi-region monitoring of outdoor equipment.

[0003] Poor signal compatibility: the working voltage (3.3V) of temperature and humidity sensors, surface temperature sensors and other devices is different from the voltage (5V) of some control circuits, and direct connection can easily cause signal distortion or device damage.

[0004] Insufficient safety: the relay control circuit and the main control circuit are not isolated, strong electrical interference can easily reverse-broken the single-chip microcomputer, and there is a lack of surge protection, outdoor lightning strikes and voltage spikes can easily cause the circuit to fail.

[0005] Weak anti-interference ability: the PT100 platinum resistance acquisition circuit is designed with discrete components, the lead resistance error is large, and the 485 bus is not provided with terminal matching and surge protection, so the signal attenuation is serious during long-distance transmission.

[0006] Poor power adaptability: existing circuits mostly use fixed input voltage (such as 5V or 12V), which cannot adapt to the wide range of power supply (5-36V) of outdoor equipment, and an additional power conversion module is needed, increasing the cost and size.

[0007] Low integration: temperature and humidity acquisition, surface temperature acquisition, relay control and other functional modules are designed independently, which is complex in wiring and is not conducive to miniaturized installation. SUMMARY

[0008] The present application aims to provide an outdoor complete equipment environmental data collection and control circuit, which solves the problems of limited sensor expansion, poor signal compatibility and insufficient safety of existing outdoor complete equipment environmental data collection and control circuits.

[0009] Technical scheme: the circuit takes single-chip microcomputer as main control chip, and forms a complete set of outdoor complete equipment environment data acquisition and control circuit through combination of IIC multiplexing, temperature and humidity acquisition, surface temperature acquisition, relay control, TLL to 485 circuit, etc. The power supply circuit stabilizes DC 5-36V input voltage to DC 5V output voltage through the first linear voltage stabilizer, and stabilizes DC 5V voltage to DC 3.3V voltage through the second linear voltage stabilizer for use of different chips; the IIC multiplexing circuit is connected to the SCL and SDA of the main controller through the public end SCL and SDA of the multiplexer, realizes IIC communication, and forms different addresses through high and low level combination of the address selection pin of the multiplexer, so that the multiplexer can be expanded to 8-way same address IIC device; the temperature and humidity acquisition circuit supplies power to the integrated digital temperature and humidity sensor through the linear voltage stabilizer, realizes bidirectional level conversion through the double-channel field effect transistor combined with resistance control, and the integrated digital temperature and humidity sensor includes 24-bit ADC, digital compensation module and IIC interface, is responsible for amplifying, analog-digital converting and digital signal processing of analog signals generated by the humidity and temperature sensing elements, and communicates with the main control chip through the IIC interface; the surface temperature acquisition circuit uses platinum resistance PT100 integrated chip, has built-in signal conditioning and AD conversion functions, integrates constant current excitation source, reference voltage and noise filter circuit, and communicates with the main control chip through the SPI interface; the relay control circuit realizes electrical isolation through the optocoupler isolation chip, connects the input end to the GPIO control signal of the main control chip, and controls the relay coil action through the photoelectric triode of the output end; the TLL to 485 circuit realizes conversion between TTL level and RS-485 level through the conversion chip, and controls the sending and receiving direction of data through the control flow direction pin.

[0010] Further, the external input DC 5-36V voltage of the power supply circuit is connected to the first linear voltage stabilizer through the anti-reverse diode, realizes wide voltage input adaptation, and the input end and the output end are both connected in parallel with 10 mu F capacitors for power supply noise filtering, so as to output stable DC 5V voltage; the DC 5V voltage is connected to the second linear voltage stabilizer, and the input and output ends are each connected in parallel with a 10 mu F electrolytic capacitor and a 100 nF ceramic capacitor for filtering, so as to output stable DC 3.3V voltage. All components are connected to the system ground in common, so as to ensure consistent potential.

[0011] Further, a 10 μF filter capacitor is connected in parallel across the power supply of the multiplexer in the IIC multiplexing circuit. The SCL and SDA pins of the multiplexer are connected to the SCL and SDA pins of the master chip, and are connected to the 5V power supply through a 10k resistor to realize the pull-up of the IIC bus and ensure the signal integrity and communication stability. The 8 channels CH0-CH7 pins of the multiplexer are respectively connected to a 2P screw terminal with a foot spacing of 5.08 mm for connecting the IIC interface of the temperature and humidity sensor. A DC 3.3V voltage is led out from the power supply to supply power to the temperature and humidity sensor, and a 2P terminal is also connected to form a complete temperature and humidity sensor interface.

[0012] Further, a 1 μF filter capacitor is connected in parallel across the input and output terminals of the linear voltage regulator in the temperature and humidity collection circuit to filter out power supply noise. The IIC bus level of the temperature and humidity sensor is 3.3V. To be compatible with the external IIC bus level, the input terminal of the linear voltage regulator is connected to the drain D of the double-channel field effect transistor, and one channel is connected to the SCL pin of the external IIC bus, and the other channel is connected to the SDA pin. The output terminal is connected to the source S and gate G of the double-channel field effect transistor, and one channel is connected to the SCL pin of the internal IIC bus, and the other channel is connected to the SDA pin to realize IIC bidirectional level conversion and ensure communication signal compatibility. The pull-up of the IIC bus is also realized through a 10k resistor to ensure the stability of the communication logic.

[0013] Further, the surface temperature collection circuit is powered by a 3.3V power supply to the platinum resistance integrated chip, and a 0.1 μF filter capacitor is connected in parallel to suppress power supply noise. The constant current output pin flows through a precision reference resistor to generate a stable reference voltage between the positive and negative reference input pins, which is used for RTD resistance calculation. The negative reference input terminal is grounded to form a reference resistance voltage dividing loop. The positive constant current output pin is connected to the high end of the PT100, the constant current output 2 pin is connected to the PT100 offset end, and the negative constant current output pin is connected to GND to form an excitation loop. The RTD input positive pin is connected to the low end of the PT100, and the RTD input negative pin is connected to GND to realize the collection of the PT100 voltage value. The SCLK, SDI, and SDO pins of the integrated chip are respectively connected to the SCLK, MOSI, and MISO pins of the master chip, and 8 groups of surface temperature collection circuits are connected in parallel. The CS pins of the 8 integrated chips are respectively connected to different GPIO pins of the master chip to realize chip selection by pulling down the pin level.

[0014] Further, the optocoupler isolation chip in the relay control circuit includes 4-way optocoupler isolation, the positive pole of each optocoupler input end is connected to the GPIO port of the master control chip, the negative pole is connected to GND through a 1k current limiting resistor, and the light-emitting diode is controlled to be on or off through the high and low level of the GPIO; the phototriode collector of the optocoupler output end is connected to a 5V power supply, the emitter is connected to the base of an NPN triode through a 4.7k resistor, the triode emitter is connected to GND through a 47k resistor, which ensures reliable cutoff when there is no control signal, the triode collector is connected to the negative pole of the relay coil, and the positive pole of the relay coil is connected to a 5V power supply; a reverse parallel continuous diode is connected in parallel across the relay coil to absorb the reverse electromotive force when the power is off, avoiding triode breakdown, and a relay state indication loop composed of a 10k resistor and a light-emitting diode is connected in parallel; the relay contact (COM, NO, NC) is connected to a 3P screw terminal with a 5.08mm pin pitch, which provides a reliable connection for the controlled execution device to access the control contact.

[0015] Further, the TTL-to-485 chip in the TLL-to-485 circuit converts TTL level serial port data (TX / RX) into RS-485 differential signals (A / B), and the receive enable (active low) and transmit enable (active high) pins of the conversion chip are connected in parallel and then connected to the GPIO port of the master control chip, realizing direction control through level change; the receive output of the conversion chip is connected to the RX port of the master control chip serial port, and the transmit input is connected to the TX port of the master control chip serial port, realizing serial port communication between the conversion chip and the master control chip; the A end of the conversion chip is connected to a 5V power supply through a 360-ohm current limiting resistor, the B end is connected to GND through a 360-ohm current limiting resistor, and the AB end is connected to a 3P terminal, and the remaining 1P terminal is connected to GND, and a 120-ohm bus matching resistor is connected in parallel between the A end and the B end, which is used to match the characteristic impedance of the 485 bus.

[0016] Advantages:

[0017] (1) The power supply circuit realizes DC 5-36V wide voltage input adaptation through two-stage linear voltage stabilizers, effectively filters out power supply noise through multi-stage filter capacitor design, outputs stable 5V and 3.3V voltage, meets the power supply needs of different devices, solves the poor adaptability problem of existing circuits, and does not need additional power conversion modules, reducing cost and size.

[0018] (2) The IIC multiplexing circuit guarantees the integrity of the IIC bus signal through a 10kΩ pull-up resistor, and 8 channels can be expanded to 8-way IIC devices with the same address, solving the address conflict problem of multiple IIC sensors with the same address, meeting the multi-area monitoring needs of outdoor equipment, and facilitating sensor installation and maintenance through standardized terminal design.

[0019] (3) The temperature and humidity acquisition circuit realizes IIC bidirectional level conversion through double-channel field effect tubes, is compatible with 3.3V and external bus levels, guarantees stable power supply in combination with a linear voltage stabilizer and a filter capacitor, and ensures communication logic reliability through a 10kΩ pull-up resistor, solves the problem of poor signal compatibility, and improves the accuracy and stability of temperature and humidity acquisition.

[0020] (4) The surface temperature acquisition circuit adopts a platinum resistance integrated chip, has built-in constant current excitation, signal conditioning and AD conversion functions, is powered by 3.3V in combination with a filter capacitor to suppress noise, eliminates lead resistance error through a precision reference resistor and a three-wire connection, solves the problems of weak anti-interference ability and low measurement accuracy of traditional discrete component design, and realizes high-precision surface temperature acquisition.

[0021] (5) The relay control circuit realizes strong and weak electric isolation through optical coupling isolation, ensures reliable cutoff of a triode when there is no control signal through a 47kΩ pull-down resistor, avoids damage to devices by reverse electromotive force through a freewheeling diode protection circuit, and facilitates intuitive monitoring of the relay state through a state indication loop, solves the problem of insufficient safety, and improves the anti-interference ability and reliability of the circuit.

[0022] (6) The TLL to 485 circuit realizes data transmission direction switching through control of the flow direction pin, improves bus anti-interference and long-distance transmission stability through a 360Ω current limiting resistor and a 120Ω bus matching resistor, solves the problem of serious signal attenuation of traditional 485 circuits, and guarantees the reliability of long-distance communication of outdoor equipment. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the circuit connection relationship of environmental monitoring in an outdoor box-type substation;

[0024] Figure 2 is a schematic diagram of a power supply circuit;

[0025] Figure 3 is a schematic diagram of an IIC multiplexing circuit;

[0026] Figure 4 is a schematic diagram of a temperature and humidity acquisition circuit;

[0027] Figure 5 is a schematic diagram of a surface temperature acquisition circuit;

[0028] Figure 6 is a schematic diagram of a relay control circuit;

[0029] Figure 7 is a schematic diagram of a TTL to 485 circuit. DETAILED DESCRIPTION

[0030] In order to make the technical scheme of the present application clearer, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0031] Embodiment

[0032] Taking outdoor box-type substation environment monitoring as an example, the box-type substation is divided into a low-voltage chamber, a high-voltage chamber and a transformer chamber, and 8 channels of temperature and humidity sensors need to be arranged, which are respectively installed on the upper and lower sides of the low-voltage chamber, the upper and lower sides of the high-voltage chamber, the upper and lower sides of the transformer chamber and 2 channels outside; 8 channels of surface temperature sensors are respectively installed on the top plate and side plate of the low-voltage chamber, the top plate and side plate of the high-voltage chamber, the top plate and side plate of the transformer chamber and 2 channels of the side wall of the transformer; 12 channels of relay outputs include fan control and dehumidification control of 3 compartments, and temperature alarm and humidity alarm of 3 compartments. The connection relationship between the circuits is shown in Figure 1 . Among them, DL1 is a power supply circuit, DL2 is an IIC multiplexing circuit, DL3 is a temperature and humidity acquisition circuit, DL4 is a surface temperature acquisition circuit, DL5 is a relay control circuit, and DL6 is a TLL-485 conversion circuit. The main control chip adopts a 32-bit single-chip microcomputer with a model of STM32F103C8T6, a main frequency of 72MHz, and interfaces of IIC, SPI, UART, etc.

[0033] The power supply circuit is shown in Figure 2 . The input DC 5-36V power supply is connected to the 2P terminal CN1, the positive electrode is connected to the input end of the first linear voltage stabilizer U1 (CJ7805) through the anti-reverse diode D1 (SS34), the input and output ends of U1 are respectively connected in parallel with C1 and C2 capacitors (10μF), and the output end of U1 is connected to the input end of the second linear voltage stabilizer U2 (AMS1117-3.3). The input end of U2 is connected in parallel with C3 (10μF) and C4 (100nF) capacitors, and the output end of U2 is connected in parallel with C5 (100nF) and C6 (10μF) capacitors. The power supply circuit adopts DC 5-36V wide voltage input design, uses two-stage linear voltage stabilizers and multi-stage filter capacitors to realize stable 5V and 3.3V output, and meets the power supply requirements of different devices.

[0034] The IIC multiplexing circuit is shown in Figure 3As shown, the 3.3V power supply is connected to the VCC pin of the multiplexing chip U3 (TCA9548A), and a C7 (10μF) filter capacitor is connected in parallel between the VCC and GND pins to supply power to the chip. The SDA and SCL pins of U3 are connected to the 3.3V power supply after being pulled up by R5 and R6 (10kΩ), ensuring the idle level of the IIC bus. The address selection pins A0, A1, and A2 of U3 are connected to ground through R1, R2, and R3 (10kΩ) respectively, realizing the configuration of the slave address fixed as 0x70. The RESET# pin of U3 is pulled up to 3.3V through R4 (10kΩ), realizing the chip reset function. The 8-channel SD0 / SC0-SD7 / SC7 of U3 are respectively connected to the 3 and 4 pins of the CN2-CN9 terminal, and each group of 1 and 2 pins are connected to the 3.3V power supply to supply power to the temperature and humidity circuit. This realizes the multiplexing and expansion of up to 8 IIC devices with the same address, allowing the host chip to communicate with different IIC devices by switching the U3 channel. The IIC multiplexing circuit uses the TCA9548A chip to realize the expansion of 8 IIC devices with the same address, solving the problem of IIC device access conflict.

[0035] The temperature and humidity acquisition circuit is as shown in Figure 4 As shown, the external power supply voltage is converted to the 3.3V voltage required by the temperature and humidity sensor U5 (AHT20) by the linear voltage regulator U4 (662K), and the input and output of U4 are connected in parallel with C8 and C9 (1μF) and C10 (100nF) filter capacitors respectively to ensure stable power supply for U5. The VDD and GND pins of U5 are connected to U4-3V3 and the system ground respectively to realize power supply. The SCL and SDA pins of U5 are connected to the internal U5-SCL and U5-SDA of the level conversion circuit, and the external J1-SCL and J1-SDA of the level conversion circuit are connected to any channel of the external IIC multiplexer to realize IIC communication. The level conversion is composed of a double-channel field effect transistor Q1 (2N7002DW) and a 10k resistor RN1, and the external voltage 3V3 is connected to the two drain electrodes D1 and D2 of Q1 after being connected to the resistor, the internal voltage U4-3V3 is connected to the two source electrodes S1 and S2 of Q1 after being connected to the resistor, and the internal voltage is directly connected to the two gate electrodes G1 and G2 of Q1, realizing the IIC bidirectional level conversion between the internal and external sides, so that U5 can adapt to the IIC bus communication of different level systems. The temperature and humidity acquisition circuit uses a double-channel field effect transistor to realize IIC bidirectional level conversion, cooperates with a linear voltage regulator, filter capacitors, and a 10kΩ pull-up resistor to ensure stable operation, and improves the accuracy and stability of temperature and humidity acquisition.

[0036] The surface temperature acquisition circuit is as shown in Figure 5As shown, the platinum resistance temperature acquisition chip U6 (MAX31865) power supply pins VDD, DVDD are connected to 3V3 power supply, while C11, C12 (100nF) capacitors are connected in parallel respectively to suppress power supply noise and signal interference. The BIAS, REFIN+ pins of U6 are connected in parallel and then connected to the REFIN-, ISENSOR pins through the reference resistor R7 (430Ω) to build a reference voltage and constant current excitation loop, providing an accurate measurement reference for platinum resistance temperature measurement. The FORCE+, FORCE2 pins of U6 are connected in parallel and then connected to the No. 1 pin of the terminal CN10 (connected to the PT100 same color end), the RTDIN+ is connected to the No. 2 pin of the CN10 (connected to the PT100 same color end), the RTDIN-, FORCE- are connected in parallel and then connected to the No. 3 pin of the CN10 (connected to the PT100 different color end), and the capacitor C13 (100nF) is connected in parallel between the No. 2 and No. 3 pins of the CN10 to reduce interference during signal transmission, forming a three-wire PT100 access loop. The CS, SCLK, SDI pins of U6 are connected to the GPIO port of the master chip through diodes D2, D3, D4 (1N4148WS) to ensure the unidirectionality of the signal and play the role of voltage clamping protection, while being connected to 3V3 through resistors R9, R10, R11 (10k) to pull the SPI interface of U6 to high level, ensuring the stability of the pin level state and avoiding the occurrence of floating level, cooperating with the SDO pin directly connected to the master chip to jointly constitute the SPI communication interface for transmitting the collected data. The surface temperature acquisition circuit uses a platinum resistance integrated chip with multiple functions, cooperates with a precision reference resistor, a three-wire connection and a filter capacitor to realize high-precision acquisition.

[0037] The relay control circuit is as follows Figure 6As shown, the opto-isolation chip U7 (LTV-247) includes 4-way opto-isolation, the master control chip controls the GPIO port to connect IN1-IN4 control signal input end, respectively access U7 each way input positive, the input negative through current limiting resistor R11, R13, R15, R17 (1k) access GND, form opto-isolation input control loop. The 4-way output end of U7 collector respectively access 5V power supply, the emitter through R12, R14, R16, R18 (4.7k) resistance connects NPN triode Q1-Q4 (S8050) base, triode emitter through resistance R19-R22 (47k) ground, the collector connects relay RLY1-RLY4 (SRD-05VDC-SL-C) coil negative, coil positive access 5V power supply, constitute relay drive loop. Each relay coil both ends reverse parallel freewheeling diode D5-D8 (1N4001), absorb the reverse electromotive force generated when the coil power off, while parallel by current limiting resistor R23-R26 (10k), light emitting diode LED1-LED4 (LED0603-RD_BLUE) constitute the indication circuit. The common end of relay auxiliary contact 5 pin access 3P terminal 2 pin, 3 pin normally closed access terminal 3 pin, 2 pin normally open access terminal 1 pin, for connecting different controlled equipment or for alarm output. The relay control circuit realizes strong and weak electric isolation through opto-isolation, uses pull-down resistor to ensure that the triode can be reliably cut off, cooperates with freewheeling diode and state indication circuit, guarantees the safety and reliability of the circuit.

[0038] TLL to 485 circuit as Figure 7 As shown, the power pin VCC of TTL to 485 chip U8 (MAX485) access 5V power supply, while parallel capacitor C14 (100nF) for filtering. The receiving output end RO and the sending input end DI of U8 respectively access the serial port RX and TX of the master control chip, realizing the serial communication between the two devices, the receiving enable end RE# and the sending enable end DE are connected in parallel and then access the control flow direction GPIO port of the master control chip, for controlling the data receiving and sending direction. The differential signal output end A and B of U8 respectively access 5V and GND through resistor R29, R27 (360Ω), while A and B are connected in parallel with R28 (120Ω) matching resistor between them, for impedance matching and bus protection, A and B signals are connected to the 485 communication host through CN15 wiring terminal, realizing the bidirectional conversion of TTL level and 485 level and the bus communication function. TLL to 485 circuit realizes data receiving and sending direction switching through control flow direction pin, improves the bus performance by means of current limiting resistor and bus matching resistor, guarantees the reliability of long distance communication.

[0039] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An outdoor complete set of equipment environmental data acquisition and control circuit, the circuit using a microcontroller as the main control chip, including power supply, IIC multiplexing, temperature and humidity acquisition, surface temperature acquisition, relay control, and TLL to 485 conversion circuit, characterized in that, The power supply circuit stabilizes the DC5-36V input voltage to a DC5V output voltage through a first linear regulator, and then stabilizes the DC5V voltage again to a DC3.3V voltage through a second linear regulator. The IIC multiplexing circuit connects to the SCL and SDA pins of the main controller via the multiplexer's common terminals SCL and SDA for IIC communication. The multiplexer's address selection pins form different addresses through combinations of high and low levels. The temperature and humidity acquisition circuit powers the integrated digital temperature and humidity sensor through a linear regulator and uses dual MOSFETs combined with a resistor array to control bidirectional level switching. The integrated digital temperature and humidity sensor includes a 24-bit ADC, a digital compensation module, and an IIC interface, responsible for transmitting humidity and temperature data. The analog signal generated by the sensing element is amplified, converted from analog to digital, and processed into a digital signal, and communicates with the main control chip through the IIC interface; the surface temperature acquisition circuit uses a platinum resistance PT100 integrated chip, which has built-in signal conditioning and AD conversion functions, and integrates a constant current excitation source, reference voltage, and noise filtering circuit, and communicates with the main control chip through the SPI interface; the relay control circuit achieves electrical isolation through an optocoupler isolation chip, the input terminal is connected to the GPIO control signal of the main control chip, and the phototransistor at the output terminal is turned on by light to control the relay coil to operate; the TTL to RS-485 circuit realizes the conversion between TTL level and RS-485 level through a conversion chip, and controls the data transmission and reception direction through the control flow pin; The temperature and humidity acquisition circuit uses a 1μF filter capacitor connected in parallel at both the input and output terminals of the linear regulator to filter out power supply noise. The IIC bus level of the temperature and humidity sensor is 3.3V. To be compatible with the external IIC bus level, the linear regulator input is connected to the drain (D) of the dual-channel MOSFET, with one channel connected to the external IIC bus SCL pin and the other to the SDA pin. The output is connected to the source (S) and gate (G) of the dual-channel MOSFET, with one channel connected to the internal IIC bus SCL pin and the other to the SDA pin, thus achieving bidirectional IIC level conversion.

2. The outdoor complete set of equipment environmental data acquisition and control circuit according to claim 1, characterized in that, The power supply circuit receives an external DC 5-36V voltage, which is connected to the first linear regulator via a reverse polarity protection diode to achieve wide voltage input adaptation. A 10μF capacitor is connected in parallel at both the input and output terminals to filter power supply noise, resulting in a stable DC 5V output voltage. The DC 5V voltage is then connected to the second linear regulator, with a 10μF electrolytic capacitor and a 100nF ceramic capacitor connected in parallel at both the input and output terminals for filtering, resulting in a stable DC 3.3V output voltage.

3. The outdoor complete set of equipment environmental data acquisition and control circuit according to claim 1, characterized in that, In the IIC multiplexing circuit, a 10μF filter capacitor is connected in parallel across the power supply terminals of the multiplexer. The SCL and SDA pins of the multiplexer are connected to the SCL and SDA pins of the main control chip, and simultaneously connected to a 5V power supply via a 10k resistor to achieve pull-up on the IIC bus. The eight channels CH0-CH7 pins of the multiplexer are each connected to a 2P screw-type terminal block with a 5.08mm pin pitch for connecting to the IIC interface of the temperature and humidity sensor. A DC 3.3V voltage is drawn from the power supply to power the temperature and humidity sensor, also connected to a 2P terminal block, forming a complete temperature and humidity sensor interface.

4. The outdoor complete set of equipment environmental data acquisition and control circuit according to claim 1, characterized in that, The surface temperature acquisition circuit is powered by a 3.3V power supply to the platinum resistance integrated chip, with a 0.1μF filter capacitor connected in parallel to suppress power supply noise. The constant current output pin flows through a precision reference resistor, generating a stable reference voltage between the positive and negative reference input pins for RTD resistance calculation. Simultaneously, the negative terminal of the reference input is grounded, forming a reference resistor voltage divider circuit. The positive pin of the constant current output is connected to the high end of the PT100, the 2nd pin of the constant current output is connected to the cancellation terminal of the PT100, and the negative pin of the constant current output is connected to GND, forming an excitation circuit. The positive pin of the RTD input is connected to the low end of the PT100, and the negative pin of the RTD input is connected to GND, thereby realizing the acquisition of the PT100 voltage value. The SCLK, SDI, and SDO pins of the integrated chip are connected to the SCLK, MOSI, and MISO pins of the main control chip, respectively. At the same time, eight sets of surface temperature acquisition circuits are connected in parallel. The CS pins of the eight integrated chips are connected to different GPIO pins of the main control chip, and chip selection is achieved by pulling the pin level low.

5. The outdoor complete set of equipment environmental data acquisition and control circuit according to claim 1, characterized in that, The optocoupler isolation chip in the relay control circuit includes four optocoupler isolation channels. The positive terminal of each optocoupler input is connected to the GPIO port of the main control chip, and the negative terminal is connected to GND through a 1k current-limiting resistor. The on / off state of the LED is controlled by the high and low levels of the GPIO. The collector of the optotransistor at the output terminal is connected to a 5V power supply, and the emitter is connected to the base of an NPN transistor through a 4.7k resistor. The emitter of the transistor is connected to GND through a 47k resistor to ensure reliable cutoff when there is no control signal. The collector of the transistor is connected to the negative terminal of the relay coil, and the positive terminal of the relay coil is connected to a 5V power supply. A reverse-parallel freewheeling diode is connected in parallel across the two ends of the relay coil to absorb the reverse electromotive force when the power is off, preventing the transistor from being damaged. At the same time, a relay status indication circuit consisting of a 10k resistor and an LED is connected in parallel. The relay contacts are connected to 3P screw-type terminals with a pin spacing of 5.08mm for the controlled actuator to connect to the control contacts.

6. The outdoor complete set of equipment environmental data acquisition and control circuit according to claim 1, characterized in that, The TTL-to-485 converter in the TTL-to-485 circuit converts TTL-level serial data into RS-485 differential signals. The receive enable and transmit enable pins of the converter chip are connected in parallel and then connected to the GPIO port of the main control chip. Direction control is achieved through level changes. The receive output of the converter chip is connected to the RX port of the serial port of the main control chip, and the transmit input is connected to the TX port of the serial port of the main control chip, realizing serial communication between the converter chip and the main control chip. Terminal A of the converter chip is connected to a 5V power supply through a 360-ohm current-limiting resistor, and terminal B is connected to GND through a 360-ohm current-limiting resistor. Terminals A and B are simultaneously led out to a 3P terminal block, and the remaining 1P terminal block is connected to GND. A 120-ohm bus matching resistor is connected in parallel between terminals A and B to match the characteristic impedance of the 485 bus.

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