Monitor

Abstract

The application provides a monitor comprising a first power supply interface electrically connected to a first conversion unit and a power-off detection unit; the output end of the first conversion unit is electrically connected to the power supply unit and used for providing input of the power supply unit and switching signals of the standby battery; the power supply unit is electrically connected to the MCU unit and the power-off detection unit and is used for supplying power to the MCU unit and the power-off detection unit; the RTC battery unit comprises a first diode, and the anode of the first diode is electrically connected with the power supply unit; the anode of the second diode is electrically connected with the anode of the battery, and the cathode of the second diode is electrically connected with the cathode of the first diode and is electrically connected to the MCU unit; the MCU unit is electrically connected with a communication module. According to the monitor, through the dual-diode design of the RTC battery unit, dual-power-supply backup is realized, parameter loss is prevented, data integrity and equipment stability are improved, manual intervention is reduced, use convenience is improved, and overall reliability is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of monitoring instruments, in particular to a monitoring instrument. BACKGROUND

[0002] The TVOC monitoring instrument can be applied to environmental monitoring in industrial production process. By monitoring the concentration change of volatile organic compounds (TVOC) in indoor air online, the enterprise can help to master the quality status of production environment in real time and take timely measures to protect the health of employees and production safety.

[0003] The current TVOC online monitoring instrument generally uses external power supply and built-in battery for power supply. When the external power supply is disconnected, the battery can still supply power to the internal components. The RTC circuit can be omitted for separate power supply from the circuit design. Once the external power supply and the built-in battery are both powered off, the RTC inside cannot work, and all parameters inside will return to the initial state. When powered on again, the parameters need to be reset, which will adversely affect the use. CONTENT OF THE UTILITY MODEL

[0004] In view of the above problems, the present application is proposed to provide a monitoring instrument which overcomes the above problems or at least partially solves the above problems, comprising:

[0005] A first power interface is electrically connected to the first conversion unit and the power failure detection unit;

[0006] The first conversion unit has an output end electrically connected to the power supply unit, and is used for providing a switching signal of the input of the power supply unit and the backup battery;

[0007] The power supply unit is electrically connected to the MCU unit and the power failure detection unit, and is used for providing power supply for the MCU unit and the power failure detection unit;

[0008] Further comprising an RTC battery unit, the RTC battery unit comprises a first diode, an anode of the first diode is electrically connected to the power supply unit; a second diode, an anode of the second diode is electrically connected to a positive electrode of the battery, a cathode of the second diode is electrically connected to a cathode of the first diode, and the cathode of the second diode is electrically connected to the MCU unit;

[0009] The MCU unit is electrically connected with a communication module.

[0010] Preferably, the power failure detection unit comprises a detection loop and a feedback loop;

[0011] The detection loop comprises an output end of the battery of the battery management unit, an anode of a clamping diode and one end of a first voltage dividing resistor; the other end of the first voltage dividing resistor is electrically connected to one end of a second voltage dividing resistor, which is used for providing a first control signal of the feedback loop, wherein the other end of the second voltage dividing resistor is grounded.

[0012] The feedback loop comprises a first MOS transistor, whose drain is electrically connected to the MCU unit and through a first current-limiting resistor to the output of the power supply unit, and whose source is grounded; the gate of the first MOS transistor is electrically connected to the feedback loop for providing a first control signal.

[0013] Preferably, the power supply unit comprises:

[0014] a surge suppression unit and a first power module are electrically connected in sequence from the output of the first conversion unit;

[0015] The first power module comprises a first power chip, whose input is electrically connected to the output of the first conversion unit, and whose output is used to provide 5V power supply;

[0016] an LDO module, whose input is electrically connected to the output of the first power chip, and which is used to provide 3.3V power supply.

[0017] Preferably, the gate of the first MOS transistor is also electrically connected with a first pull-down resistor.

[0018] Preferably, the input of the first power chip is electrically connected to the output of the first conversion unit through a second MOS transistor, specifically, the input of the first power chip is electrically connected to the source of the second MOS transistor, and the drain of the second MOS transistor is electrically connected to the output of the first conversion unit.

[0019] The gate of the second MOS transistor is grounded or grounded through a second current-limiting resistor.

[0020] Preferably, the battery management unit comprises:

[0021] a battery management chip, whose input is electrically connected to the first power interface, and whose output is electrically connected to the source of a third MOS transistor as a battery output;

[0022] The drain of the third MOS transistor is electrically connected to the input of a second power chip, and the output of the second power chip is electrically connected to the source of a fourth MOS transistor.

[0023] The source of a fifth MOS transistor is electrically connected to the output of the first conversion unit, the drain of the fourth MOS transistor and the drain of the fifth MOS transistor are electrically connected, and the electrical connection to the power supply unit is provided.

[0024] The gates of the third MOS transistor, the fourth MOS transistor and the fifth MOS transistor are electrically connected to the position of the switching signal provided by the first conversion unit.

[0025] Preferably, the first conversion unit comprises an anode of a rectifier diode electrically connected to one end of the first power supply interface and the third voltage dividing resistor, and a cathode of the rectifier diode providing an output terminal of the first conversion unit.

[0026] The other end of the third voltage dividing resistor is electrically connected to one end of the fourth voltage dividing resistor and provides a switching signal; the other end of the fourth voltage dividing resistor is grounded.

[0027] Preferably, it further comprises an RS485 communication circuit.

[0028] The RS485 communication circuit comprises a 485 chip, an RX pin and a TX pin of which are electrically connected to the MCU unit respectively, and the RX pin and the TX pin are respectively electrically connected with a first pull-up resistor and a second pull-up resistor.

[0029] The 485 chip provides an A terminal and a B terminal to an external RS485 port, wherein the A terminal is electrically connected with a third pull-up resistor, and the B terminal is electrically connected with a second pull-down resistor.

[0030] Preferably, it further comprises an indicator circuit.

[0031] The indicator circuit provides an LED indicator interface, one end of which is electrically connected to the power supply unit through a third current limiting resistor, and the other end is electrically connected to a drain of a sixth MOS tube.

[0032] The source of the sixth MOS tube is grounded, the gate of the sixth MOS tube is electrically connected to the MCU unit, and the gate of the sixth MOS tube is further electrically connected with a third pull-down resistor.

[0033] Preferably, it further comprises an anti-disassembly circuit.

[0034] The anti-disassembly circuit comprises a detection resistor, one end of which is electrically connected to the power supply unit, and the other end is electrically connected to the MCU unit and one end of an anti-disassembly detection terminal, and the other end of the anti-disassembly detection terminal is grounded.

[0035] The present application has the following advantages:

[0036] In the embodiments of the present application, compared with the prior art in which only the battery built-in in the device is used to supply power for the RTC circuit, and there is no independent RTC power supply problem, the present application provides a solution for the monitor, specifically: a first power interface is electrically connected to a first conversion unit and a power failure detection unit; the first conversion unit is electrically connected to a power supply unit at the output end, for providing a switching signal of the input of the power supply unit and the backup battery; the power supply unit is electrically connected to the MCU unit and the power failure detection unit, for providing power supply for the MCU unit and the power failure detection unit; further comprising an RTC battery unit, the RTC battery unit comprises a first diode, the anode of which is electrically connected to the power supply unit; a second diode, the anode of which is electrically connected to the positive electrode of the battery, the cathode of which is electrically connected to the cathode of the first diode, and is electrically connected to the MCU unit; the MCU unit is electrically connected with a communication module. The monitor realizes double power backup through the double diode design of the RTC battery unit, prevents parameter loss, improves data integrity and device stability, reduces manual intervention, improves use convenience, and enhances overall reliability. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the description of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0038] Figure 1 is a MCU unit circuit diagram of a monitor provided by an embodiment of the present application;

[0039] Figure 2 is a 4G module circuit diagram of a monitor provided by an embodiment of the present application;

[0040] Figure 3 is an RTC battery unit circuit diagram of a monitor provided by an embodiment of the present application;

[0041] Figure 4 is a first conversion unit circuit diagram of a monitor provided by an embodiment of the present application;

[0042] Figure 5 is a battery management unit and power failure detection unit circuit diagram of a monitor provided by an embodiment of the present application;

[0043] Figure 6 is a first power module circuit diagram of a monitor provided by an embodiment of the present application;

[0044] Figure 7 is an LDO module circuit diagram of a monitor provided by an embodiment of the present application;

[0045] Figure 8 is a RS485 communication circuit diagram of a monitoring instrument provided by an embodiment of the present application;

[0046] Figure 9 is a indicator lamp circuit diagram of a monitoring instrument provided by an embodiment of the present application;

[0047] Figure 10 is a feedback loop circuit diagram of a monitoring instrument provided by an embodiment of the present application;

[0048] Figure 11 is a anti-disassembly circuit diagram of a monitoring instrument provided by an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the objects, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0050] Referring to Figures 1 to 11 , a monitoring instrument provided by an embodiment of the present application is shown, which comprises: a first power interface VCCIN, which is electrically connected to a first conversion unit, a battery management unit and a power-off detection unit; the first conversion unit, whose output end VCCOUT is electrically connected to a power supply unit, is used to provide a switching signal BATSW of the input of the power supply unit and a backup battery; the power supply unit is electrically connected to an MCU unit U21 and the power-off detection unit, and is used to provide power supply for the MCU unit U21 and the power-off detection unit.

[0051] Further comprising an RTC battery unit, the RTC battery unit comprises a first diode D1, whose anode is electrically connected to the power supply unit; a second diode D2, whose anode is electrically connected to the positive electrode of the battery, whose cathode is electrically connected to the cathode of the first diode D1 and is electrically connected to the VBAT pin of the MCU unit U21, that is, the first pin of U21 as shown. Figure 1 The MCU unit U21 is electrically connected with a communication module, which is used to send monitoring data to a data center or a user end, for example, as shown, the communication module can be preferably a 4G module. Figure 2

[0052] In the embodiment of the present application, the RTC circuit is powered by the RCT battery unit and the external power supply, as shown. Figure 3 ​As shown, the first diode D1 is electrically connected to the power supply unit to provide 3.3V power supply for the RTC circuit, and another path through the battery and the second diode D2 provides 3V power supply for the RTC circuit. Common RTC power supply can preferably be a button cell. Since the 3.3V power supply voltage provided by the power supply unit is higher than the 3V provided by the battery (here, the voltage drop of D1 and D2 is not considered, even if the voltage drop of D1 and D2 is considered, the voltage of 3.3V is still higher than that of 3V after the same voltage drop), when the external power supply exists, the external 3.3V power supply is provided, and when the external power supply does not exist, the battery power supply is provided. In addition, the battery management unit can provide multiple battery connections. On the one hand, an external power supply can be connected to provide power for the above monitoring instrument, and on the other hand, the battery can be used to supply power for the monitoring instrument. When the external power supply is powered off, the output end VCCOUT of the first conversion unit cannot provide power supply to the power supply unit, and the switch signal BATSW provided by the power supply unit to the battery management unit switches the battery management unit to supply power. After the above power-off detection unit detects, the battery in the battery management unit is switched to supply power, and the above circuit can be connected to multiple batteries.

[0053] It should be noted that, as described above Figure 3 , when two or more power supplies are provided for the target, since electrical energy is a kind of potential energy, generally, the higher voltage side forms the power supply loop. The battery in the battery management unit and the battery in the RTC battery unit are different independent batteries. Among them, the battery in the battery management unit is used to supply power for the whole monitoring instrument (including the RTC circuit), and the battery in the RTC battery unit is used to supply power for the RTC circuit.

[0054] Next, one of the monitoring instruments in the exemplary embodiments of the present application will be further described.

[0055] In the embodiment of the present application, a monitoring instrument comprises: a first power supply interface VCCIN electrically connected to a first conversion unit mainly composed of a rectifier diode D5, a third voltage dividing resistor R26 and a fourth voltage dividing resistor R9. Specifically, the first conversion unit comprises an anode of the rectifier diode D5 electrically connected to the first power supply interface VCCIN and one end of the third voltage dividing resistor R26, and a cathode of the rectifier diode D5 providing an output end VCCOUT of the first conversion unit; the other end of the third voltage dividing resistor R26 is electrically connected to one end of the fourth voltage dividing resistor R9 and provides a switching signal BATSW; the other end of the fourth voltage dividing resistor R9 is grounded GND; the cathode of the diode D5 provides the output end VCCOUT of the first conversion unit; the other end of the third voltage dividing resistor R26 is electrically connected to one end of the fourth voltage dividing resistor R9 and provides the switching signal BATSW; the fourth voltage dividing resistor R9; the above-mentioned battery management unit and power-off detection unit; the output end VCCOUT of the first conversion unit is electrically connected to a power supply unit for providing an input of the power supply unit and a switching signal BATSW of a backup battery; the power supply unit is electrically connected to the MCU unit U21 and the power-off detection unit for providing power supply for the MCU unit U21 and the power-off detection unit; wherein, as shown in the Figure 5 , the power-off detection unit comprises a detection loop and a feedback loop; the detection loop comprises a battery output end B+ of the battery management unit, an anode of a clamping diode D6 and one end of a first voltage dividing resistor R48; the other end of the first voltage dividing resistor R48 is electrically connected to one end of a second voltage dividing resistor R55 for providing a first control signal ETT of the feedback loop, wherein the other end of the second voltage dividing resistor R55 is grounded GND.

[0056] As shown in the Figure 10 , the feedback loop comprises a drain of a first MOS tube Q5 electrically connected to an ET pin (as shown in the Figure 1 46th pin) of the MCU unit U21 and electrically connected to an output end of the power supply unit through a first current limiting resistor R43, i.e. a position providing 3.3V power supply output, i.e. a VOUT pin of the LDO module U2, a source of the first MOS tube Q5 is grounded GND; a gate of the first MOS tube Q5 is electrically connected to the feedback loop providing the first control signal ETT.

[0057] When the external power supply provided by the first power interface VCCIN is normal, such as 12V, the output end VCCOUT of the rectifier diode D5 of the first conversion unit outputs 12V to the power supply unit, and provides a high level of the switch signal BATSW to the battery management unit through the position between the third voltage dividing resistor R26 and the fourth voltage dividing resistor R9; when the first power interface VCCIN cannot provide external power supply, at this time, the voltage between the third voltage dividing resistor R26 and the fourth voltage dividing resistor R9 is 0V, that is, the switch signal BATSW is low (0 level),

[0058] The first control signal ETT of the feedback loop is provided between the first voltage dividing resistor R48 and the second voltage dividing resistor R55.

[0059] Because the battery management unit can charge the battery, that is, the voltage of the output end of the battery management chip U4 is higher than that of the battery power supply when the external power supply is connected, so that the voltage in the two states is not higher than the voltage of VCCIN, so that the first control signal ETT changes when the external VCCIN is powered off and when the battery is powered, so that the gate control voltage of the first MOS tube Q5 changes, so that the ET pin of the MCU unit U21 can detect whether the device is in a power-off state. The resistor R52 serves as a pull-up resistor to ensure the signal strength of the ET pin, which can be detected.

[0060] In the embodiment of the application, as shown in Figure 5 The battery management unit includes: a battery management chip U4, the input end of which is electrically connected to the first power interface VCCIN, and the output end of which is the battery output end B+ electrically connected to the source electrode of the third MOS tube Q1; the drain electrode of the third MOS tube Q1 is electrically connected to the input end of the second power supply chip U11, and the output end of the second power supply chip U11 is electrically connected to the source electrode of the fourth MOS tube Q4; the source electrode of the fifth MOS tube Q2 is electrically connected to the output end VCCOUT of the first conversion unit, and the drain electrode of the fourth MOS tube Q4 and the drain electrode of the fifth MOS tube Q2 are electrically connected and provided to the power supply unit, wherein the OUTX end is electrically connected to the input end of the first power supply chip U10 (not shown in the figure); the gate electrode of the third MOS tube Q1, the gate electrode of the fourth MOS tube Q4 and the gate electrode of the fifth MOS tube Q2 are electrically connected to the position of the switch signal BATSW provided by the first conversion unit.

[0061] When the switch signal BATSW is high, the third MOS tube Q1, the fourth MOS tube Q4 and the fifth MOS tube Q2 are not conductive, so that the battery output end B+ cannot be output through the MOS tube; when BATSW is low, the third MOS tube Q1, the fourth MOS tube Q4 and the fifth MOS tube Q2 are conductive, and the first power supply chip U10 is provided with power supply, and due to the one-way conduction ability of the rectifier diode D5, the power supply of the battery cannot be reversely connected to the first power supply interface VCCIN.

[0062] In the embodiment of the application, as shown in Figure 6 and Figure 7 The power supply unit comprises, from the output end VCCOUT of the first conversion unit, a surge suppression unit (not shown in the figure) and a first power supply module connected in sequence; the first power supply module comprises a first power supply chip U10, an input end of which is electrically connected to the output end VCCOUT of the first conversion unit, and an output end thereof is used to provide 5V power supply; an LDO module U2, an input end of which is electrically connected to the output end of the first power supply chip U10, is used to provide 3.3V power supply, wherein the output end of the first power supply chip U10 provides power supply for the 4G module and other positions in addition to 5V provided for the LDO conversion 3.3V, and the 3.3V power supply provided by the LDO provides power supply for the MCU, the RTC and the 485 and the like; the LDO can be preferably an XC6206P33 series chip or an LM7833 chip and the like.

[0063] Further, the gate of the first MOS tube Q5 is also electrically connected with a first pull-down resistor R50, wherein the pull-down resistor R50 can be used for rapid discharge of the ground GND when the first control signal ETT is terminated or the gate is empty, and the first MOS tube Q5 is affected by the interference signal.

[0064] It should be noted that the pull-down resistor is grounded at one end, which is a common knowledge, and thus the application will not be described in detail.

[0065] In the embodiment of the application, as shown in Figure 6 The input end of the first power supply chip U10 is electrically connected to the output end VCCOUT of the first conversion unit through the second MOS tube Q3, specifically, the input end of the first power supply chip U10 is electrically connected to the source of the second MOS tube Q3, and the drain of the second MOS tube Q3 is electrically connected to the output end VCCOUT of the first conversion unit; the gate of the second MOS tube Q3 is grounded through the ground GND or grounded through the second current-limiting resistor R32, and the second MOS tube Q3 can be connected through the first power supply chip U10, and the second MOS tube Q3 here can play a buffering role, which is somewhat similar to the function of preventing surge.

[0066] In the embodiments of the present application, as shown in Figure 8 The RS485 communication circuit further includes a 485 chip U25, the RX pin and the TX pin of which are electrically connected to the MCU unit U21, and the RX pin and the TX pin are electrically connected with a first pull-up resistor R35 and a second pull-up resistor R39, respectively. The 485 chip U25 provides an A terminal and a B terminal to an external RS485 port, wherein the A terminal is electrically connected with a third pull-up resistor R36, and the B terminal is electrically connected with a second pull-down resistor R37. The pull-up resistor can be used to increase the signal voltage, thereby enhancing the signal strength. The above-mentioned RS485 communication circuit can enable the monitoring instrument to perform wired communication, and RS485 has the advantages of simple line, long communication distance, and good anti-interference performance. A single node can reach a communication distance of more than 1 km without relay.

[0067] In the embodiments of the present application, as shown in Figure 9 The indication lamp circuit provides an LED indication lamp interface, for example, a CN13 or an LED indication lamp as shown in Figure 9 The interface on the circuit is used for connecting an LED, which can be directly replaced by an LED. One end of the interface is electrically connected to the power supply unit, specifically to the 3.3V output terminal of the LDO module U2, and the other end is electrically connected to the drain of the sixth MOS tube Q6. The source of the sixth MOS tube Q6 is grounded GND, and the gate of the sixth MOS tube Q6 is electrically connected to the MCU unit U21. The gate of the sixth MOS tube Q6 is also electrically connected with a third pull-down resistor R53.

[0068] In the embodiments of the present application, as shown in Figure 11 The anti-disassembly circuit includes a detection resistor R51, one end of which is electrically connected to the power supply unit, for example, the 3.3V output terminal of the LDO module U2, and the other end is electrically connected to the KAI signal terminal of the MCU unit U21 and one end of the anti-disassembly detection terminal CN4. The other end of the anti-disassembly detection terminal CN4 is grounded.

[0069] It should be noted that the anti-disassembly detection terminal CN4 can be replaced by a conductor or a resistor or an internal jumper switch, which is connected to the device shell by physical means. When it is not disassembled, the detection resistor R51 is grounded through the resistor or conductor in the anti-disassembly detection terminal CN4, that is, the KAI signal is grounded, so that the KAI signal level becomes 0 level or a lower level. When it is disassembled, the element in the above-mentioned anti-disassembly detection terminal CN4, such as a jumper, is pulled out from the terminal, so that the detection resistor is empty, and the KAI signal is not grounded, forming a null state, and the KAI signal remains at a high level.

[0070] Although preferred embodiments of the application have been described in detail, those skilled in the art will appreciate that various modifications and alterations can be made to the embodiments without departing from the scope of the application. Accordingly, the appended claims are intended to encompass all such modifications and alterations.

[0071] Finally, it should be noted that the terms "first", "second", and the like, herein do not denote any order, quantity, combination, or importance, but rather are used to distinguish one element from another, and are not intended to denote the presence of any such ordering, quantity, combination, or importance. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0072] The above detailed description of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form described. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.​

Claims

1. A monitoring instrument, characterized in that, include: The first power interface is electrically connected to the first conversion unit and the power failure detection unit; The first conversion unit has its output terminal electrically connected to the power supply unit, and is used to provide the power supply unit with input and the switching signal of the backup battery; The power supply unit is electrically connected to the MCU unit and the power failure detection unit, and is used to provide power to the MCU unit and the power failure detection unit. It also includes an RTC battery cell, which includes a first diode whose anode is electrically connected to the power supply unit; The second diode has its anode electrically connected to the positive terminal of the battery, its cathode electrically connected to the cathode of the first diode, and is also electrically connected to the MCU unit. The MCU unit is electrically connected to a communication module.

2. The monitoring instrument according to claim 1, characterized in that, The power failure detection unit includes: a detection circuit and a feedback circuit; The detection circuit includes a path from the battery output terminal of the battery management unit to the anode of the clamping diode and one end of the first voltage divider resistor; the other end of the first voltage divider resistor is electrically connected to one end of the second voltage divider resistor to provide a first control signal for the feedback circuit, wherein the other end of the second voltage divider resistor is grounded. The feedback loop includes a first MOSFET whose drain is electrically connected to the MCU unit and electrically connected to the output terminal of the power supply unit through a first current-limiting resistor; the source of the first MOSFET is grounded; and the gate of the first MOSFET is electrically connected to the feedback loop that provides the first control signal.

3. The monitoring instrument according to claim 1 or 2, characterized in that, The power supply unit includes: The surge suppression unit and the first power module are sequentially electrically connected from the output terminal of the first conversion unit; The first power module includes a first power chip, whose input terminal is electrically connected to the output terminal of the first conversion unit, and whose output terminal is used to provide 5V power supply; The LDO module has its input terminal electrically connected to the output terminal of the first power chip to provide 3.3V power.

4. The monitoring instrument according to claim 2, characterized in that, The gate of the first MOS transistor is also electrically connected to a first pull-down resistor.

5. The monitoring instrument according to claim 3, characterized in that, The input terminal of the first power chip is electrically connected to the output terminal of the first conversion unit through the second MOSFET. Specifically, the input terminal of the first power chip is electrically connected to the source of the second MOSFET, and the drain of the second MOSFET is electrically connected to the output terminal of the first conversion unit. The gate of the second MOS transistor is grounded either through ground or through a second current-limiting resistor.

6. The monitoring instrument according to claim 2, characterized in that, The battery management unit includes: The battery management chip has its input terminal electrically connected to the first power interface, and its output terminal, which is the battery output terminal, electrically connected to the source of the third MOSFET. The drain of the third MOSFET is electrically connected to the input terminal of the second power chip, and the output terminal of the second power chip is electrically connected to the source of the fourth MOSFET. The source of the fifth MOSFET is electrically connected to the output of the first conversion unit, and the drains of the fourth MOSFET and the fifth MOSFET are electrically connected, providing an electrical connection to the power supply unit. The gates of the third MOS transistor, the fourth MOS transistor, and the fifth MOS transistor are electrically connected to the position of the switching signal provided by the first conversion unit.

7. The monitoring instrument according to claim 6, characterized in that, The first conversion unit includes a rectifier diode whose anode is electrically connected to a first power interface and one end of a third voltage divider resistor, and the cathode of the rectifier diode provides the output terminal of the first conversion unit; The other end of the third voltage divider resistor is electrically connected to one end of the fourth voltage divider resistor and provides a switching signal; the other end of the fourth voltage divider resistor is grounded.

8. The monitoring instrument according to claim 1, characterized in that, It also includes RS485 communication circuitry; The RS485 communication circuit includes a 485 chip, whose RX pin and TX pin are electrically connected to the MCU unit, and the RX pin and TX pin are electrically connected to a first pull-up resistor and a second pull-up resistor, respectively. The 485 chip provides terminals A and B to an external RS485 port. Terminal A is powered on and connected to a third pull-up resistor, and terminal B is powered on and connected to a second pull-down resistor.

9. The monitoring instrument according to claim 1, characterized in that, It also includes indicator light circuits; The indicator circuit provides an LED indicator interface, one end of which is electrically connected to the power supply unit through a third current-limiting resistor, and the other end is electrically connected to the drain of the sixth MOS transistor. The source of the sixth MOS transistor is grounded, the gate of the sixth MOS transistor is electrically connected to the MCU unit, and the gate of the sixth MOS transistor is also electrically connected to a third pull-down resistor.

10. The monitoring instrument according to claim 1, characterized in that, It also includes anti-tamper circuitry; The anti-tamper circuit includes a detection resistor, one end of which is electrically connected to the power supply unit, and the other end of which is electrically connected to the MCU unit and one end of the anti-tamper detection terminal. The other end of the anti-tamper detection terminal is grounded.

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