A main board control loop of an industrial alarm controller

Abstract

The utility model relates to industrial control equipment mainboard circuit technical field, concretely relates to a kind of mainboard control loop of industrial alarm controller, including reference voltage module, operational amplifier signal conditioning module, power drive module, multiple protection module and state feedback and indicating module;Reference voltage module generates stable reference level, operational amplifier signal conditioning module realizes signal accurate amplification and conditioning, power drive module executes control instruction and drives load, multiple protection module realizes overcurrent, surge, reverse voltage protection, and state feedback and indicating module complete loop state monitoring and visual display.The utility model solves the problem that traditional mainboard control loop reference voltage is unstable, signal conditioning precision is low, protection mechanism is single, lacks state feedback, has signal processing precision, operating reliably, state monitorable characteristics, and is suitable for the mainboard system of various industrial control equipment.

Description

Technical Field

[0001] This utility model relates to the field of motherboard circuit technology for industrial control equipment, and in particular to a motherboard control circuit for an industrial alarm controller that integrates gas, temperature, and smoke detection with multiple protections. Background Technology

[0002] In industrial control equipment, the motherboard control loop is the core hardware link for instruction execution and signal processing, and its performance directly affects the reliability and safety of the entire system. However, practice has shown that traditional control loops have several inherent defects in design and application, which limit their effectiveness in high-standard industrial scenarios: 1. Insufficient reference voltage stability: Traditional circuits often use simple resistor dividers or ordinary voltage regulators to generate a reference level. These solutions are susceptible to power supply fluctuations and temperature changes, leading to reference voltage drift. Since subsequent signal conditioning circuits are highly dependent on the accuracy of the reference voltage, its instability will be directly conducted and amplified, causing a decrease in the overall accuracy of signal acquisition and judgment.

[0003] 2. Limited and low-precision signal conditioning: Most traditional circuits rely solely on single-stage operational amplifiers for signal amplification, lacking systematic filtering and level matching designs. This results in weak suppression of high-frequency noise and common-mode interference in the input signal, leading to a high risk of signal distortion and making it difficult to meet the needs of weak signal or high-precision detection scenarios.

[0004] 3. Inadequate circuit protection mechanisms: Traditional protection measures are often limited to basic overcurrent protection, such as a single fuse, lacking effective protection against transient voltage surges and reverse power connections that frequently occur in industrial production environments. This lack of protection makes the circuit highly susceptible to damage under complex electromagnetic environments or operational errors, making it difficult to guarantee system reliability.

[0005] 4. Lack of effective status feedback and indication: Traditional circuits are usually designed as "black boxes," meaning their internal operating status cannot be monitored externally in real time, such as during load interruptions or signal anomalies. When a fault occurs, the troubleshooting process is cumbersome and inefficient, severely impacting the maintainability and operational efficiency of the equipment.

[0006] In summary, existing motherboard control circuits have significant shortcomings in terms of reference stability, signal processing accuracy, comprehensive protection capabilities, and status visibility, failing to fully meet the stringent requirements of modern industrial, commercial, and energy storage detection and alarm controllers for high reliability, high precision, and ease of maintenance. Therefore, an innovative circuit design solution is urgently needed to address these systemic technical problems. Utility Model Content

[0007] In view of this, the purpose of this utility model is to overcome the shortcomings of the prior art and provide a motherboard control circuit for industrial, commercial and energy storage detection alarm controllers, so as to solve the defects of traditional control circuits such as unstable reference voltage, low signal conditioning accuracy, insufficient protection mechanism, poor anti-interference ability and lack of status feedback.

[0008] To achieve the above objectives, the present invention provides the following technical solutions: This utility model provides a mainboard control circuit for an industrial alarm controller, including a reference voltage module, an operational amplifier signal conditioning module, a power drive module, a multiple protection module, and a status feedback and indication module; The output terminal of the reference voltage module is electrically connected to the reference input terminal of the operational amplifier signal conditioning module; The signal output terminal of the operational amplifier signal conditioning module is electrically connected to the control input terminal of the power drive module. The load output terminal of the power drive module is used to connect to the back-end load circuit, and the power input terminal of the power drive module is electrically connected to the external line. The multiple protection modules are electrically connected to the power supply terminal of the power drive module and the external line, respectively. The monitoring terminal of the status feedback and indication module is electrically connected to the load output terminal of the power drive module and the signal output terminal of the operational amplifier signal conditioning module, respectively.

[0009] As a further embodiment of this utility model, the reference voltage module includes a reference voltage source, a voltage divider resistor group, and a filter capacitor; the voltage divider resistor group is connected in parallel between the cathode and the reference electrode of the reference voltage source, and the filter capacitor is connected in parallel between the cathode and the ground terminal of the reference voltage source.

[0010] As a further embodiment of this utility model, the reference voltage source is model TL431, and the reference voltage module consists of a reference voltage source U15, a filter capacitor C43, and a voltage divider resistor group consisting of voltage divider resistors R76, R78, and R89. The voltage divider resistor group is connected in parallel between the cathode and the reference electrode of the reference voltage source U1 to generate a stable reference voltage; the filter capacitor C43 is connected in parallel between the cathode of the reference voltage source U1 and ground to suppress voltage ripple.

[0011] As a further embodiment of this utility model, the operational amplifier signal conditioning module includes a low-power operational amplifier, a quad operational amplifier, and resistive and capacitive components; the non-inverting input terminals of the low-power operational amplifier and the quad operational amplifier are electrically connected to the output terminal of the reference voltage module, the inverting input terminals are connected to the series node of the input signal and the feedback resistor, and the output terminals are electrically connected to the control terminal of the power drive module.

[0012] As a further embodiment of this utility model, the operational amplifier signal conditioning module consists of low-power operational amplifiers U11A, U11B, quad operational amplifiers U12A, U12C, and U12D, as well as resistors and capacitors. The non-inverting input of the operational amplifier is connected to the output of the reference voltage module, and the inverting input is connected to the series node of the input signal and the feedback resistor. The signal is precisely conditioned by inverting proportional amplification, and the resistors and capacitors are used to filter the signal.

[0013] As a further embodiment of this utility model, the low-power operational amplifier is model SGM8272, the quad operational amplifier is model SGM8274, and the resistive and capacitive components include capacitor C38 and capacitor C41.

[0014] As a further embodiment of this utility model, the power drive module includes a power transistor, a MOSFET, and a current-limiting resistor; the base of the power transistor is electrically connected to the output terminal of the operational amplifier signal conditioning module, the collector of the power transistor is connected to an external power supply, and the emitter of the power transistor is connected to a load circuit.

[0015] As a further embodiment of this utility model, the power drive module consists of a power transistor V4, a MOSFET V9, a MOSFET V12 and a current-limiting resistor. The base of the power transistor is connected to the output terminal of the operational amplifier signal conditioning module, the collector is connected to a 24V power supply, and the emitter is connected to the load circuit through the current-limiting resistor to receive the conditioned signal and drive the load to switch on and off.

[0016] As a further embodiment of this utility model, the power transistor is model MJD122 and the MOSFET is model IRFR5501TR.

[0017] As a further embodiment of this utility model, the multi-protection module includes a fuse, a TVS diode, and a Schottky diode; the fuse is connected in series in the load circuit, the TVS diode is connected in parallel between the circuit and the ground terminal, and the Schottky diode is connected in reverse series in the power supply circuit.

[0018] As a further embodiment of this utility model, the multi-protection module consists of fuse F5, TVS diode DW4, TVS diode TVS9, TVS diode TVS10, TVS diode TVS11, and Schottky diode D7; fuse F5 is connected in series with the BUS1+ line to achieve overcurrent protection; TVS diodes are connected in parallel between the line and ground to suppress transient surge voltage; Schottky diode D7 is connected in reverse series with the power supply circuit to block reverse voltage surges.

[0019] As a further embodiment of this utility model, the status feedback and indication module includes an LED, a BC846B transistor, and a feedback resistor; the anode of the LED is connected to the power supply, and the cathode is connected to the loop node through the resistor; the base of the transistor is connected to the loop status signal terminal, and the collector is connected to the feedback interface.

[0020] As a further embodiment of this utility model, the status feedback and indication module consists of an LED 9, a transistor V6, a transistor V15, a transistor V14, and a feedback resistor; the anode of the LED 9 is connected to the power supply, and the cathode is connected to the loop node to realize a visual indication of the loop's on / off state; the base of the transistor is connected to the loop status signal, and the collector is connected to the feedback interface to transmit the status signal back to the main board control unit.

[0021] As a further embodiment of this utility model, the transistor is model BC846B.

[0022] Compared with the prior art, the mainboard control circuit of the industrial alarm controller provided by this utility model has the following beneficial effects: 1. The mainboard control circuit of this utility model improves the stability of the reference voltage and the accuracy of signal conditioning. The reference voltage module uses a precision reference voltage source in conjunction with a voltage divider network composed of high-precision resistors and filter capacitors to generate a highly stable reference level, effectively overcoming the reference drift problem caused by power supply fluctuations in traditional circuits. The operational amplifier signal conditioning module uses a low-power operational amplifier and a quad operational amplifier combined with feedback resistors to form an inverting proportional amplifier circuit, achieving precise linear amplification of the signal. At the same time, the filter network composed of RC components effectively filters out high-frequency noise, significantly reducing the risk of signal distortion and improving the signal acquisition and processing accuracy of the entire control circuit.

[0023] 2. This utility model's multi-protection module integrates a fuse, a TVS diode, and a Schottky diode, forming a comprehensive, multi-layered protection system against common faults such as overcurrent, transient surges, and reverse power connection. This significantly improves the circuit's tolerance and operational reliability in complex industrial electromagnetic environments. Furthermore, the status feedback and indication module enables loop status visualization. Through a switching circuit composed of transistors, the status signals of key loop points are converted into standard level signals and transmitted back to the mainboard control unit. This achieves remote, real-time monitoring of the loop status, providing a hardware foundation for fault early warning and diagnosis, and greatly improving system maintainability and fault diagnosis efficiency.

[0024] This invention improves signal processing accuracy through a highly stable reference source and precise conditioning circuit, enhances system reliability and anti-interference capability through multiple protection and filtering designs, and realizes visualization and remote monitoring of operating status through status indication and electrical signal feedback. It effectively solves the defects of traditional motherboard control circuits, such as unstable voltage, low signal conditioning accuracy, insufficient protection mechanism, poor anti-interference capability, and lack of status feedback. It is particularly suitable for industrial, commercial and energy storage detection and alarm controllers with high requirements for reliability, accuracy and maintainability.

[0025] These or other aspects of this invention will become more apparent from the following description of the embodiments. It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. In the drawings: Figure 1 This is a structural block diagram of the mainboard control circuit of an industrial alarm controller according to the present invention.

[0027] Figure 2 This is a circuit diagram of the mainboard control circuit of an industrial alarm controller according to this utility model. Detailed Implementation

[0028] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. However, it should be understood that the scope of protection of this utility model is not limited to the specific embodiments.

[0029] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0030] See Figure 1 and Figure 2 As shown, an embodiment of this application provides a mainboard control loop for an industrial alarm controller, including a reference voltage module, an operational amplifier signal conditioning module, a power drive module, a multiple protection module, and a status feedback and indication module. The output terminal of the reference voltage module is electrically connected to the reference input terminal of the operational amplifier signal conditioning module. The reference voltage module is used to generate a stable reference level, and the operational amplifier signal conditioning module is used to amplify, filter, and condition the input signal. The signal output terminal of the operational amplifier signal conditioning module is electrically connected to the control input terminal of the power drive module. The load output terminal of the power drive module is used to connect to the back-end load circuit, and the power input terminal of the power drive module is electrically connected to an external line. The power drive module is electrically connected to the operational amplifier signal conditioning module to receive the conditioned signal and drive the back-end load circuit. The multiple protection module is electrically connected to the power supply terminal of the power drive module and the external line, respectively, to implement overcurrent, transient surge, and reverse voltage protection. The monitoring terminal of the status feedback and indication module is electrically connected to the load output terminal of the power drive module and the signal output terminal of the operational amplifier signal conditioning module, respectively, to monitor the circuit status and provide visual indication.

[0031] In this embodiment, the reference voltage module includes a reference voltage source, a voltage divider resistor group, and a filter capacitor; the voltage divider resistor group is connected in parallel between the cathode and the reference electrode of the reference voltage source, and the filter capacitor is connected in parallel between the cathode and the ground terminal of the reference voltage source.

[0032] The reference voltage source is a TL431. The reference voltage module provides the TL431 reference voltage source and a voltage divider filter design to ensure the stability of the reference level and improve signal conditioning accuracy. The reference voltage module consists of a reference voltage source U15, a filter capacitor C43, and voltage divider resistors R76, R78, and R89. The voltage divider resistor group is connected in parallel between the cathode and the reference electrode of the reference voltage source U1 to generate a stable reference voltage. The filter capacitor C43 is connected in parallel between the cathode of the reference voltage source U1 and ground to suppress voltage ripple.

[0033] The working process of the reference voltage module is as follows: As the core component of the reference voltage module, the reference voltage source U15 has the following connection relationship and working logic of pin 1 (cathode), pin 2 (reference), and pin 3 (anode): The voltage divider resistor group consists of resistor R76 (1KΩ, 1% accuracy), resistor R78 (0Ω), and resistor R89 ​​(22KΩ), which are connected in parallel between the cathode (pin 1) and the reference (pin 2) of U15; among them, the resistance value of resistor R76 is 1KΩ and the accuracy is 1%; the resistance value of resistor R78 is 0Ω; and the resistance value of resistor R89 ​​is 22KΩ. Then, based on the reference voltage characteristics of the reference voltage source TL431, the voltage is 2.5V. A stable external reference voltage is generated through voltage division. In this embodiment, the output reference voltage is 2.5V×(R76+R89) / R89≈2.61V. The filter capacitor C43 has a capacitance of 100nF. The filter capacitor C43 is connected in parallel between the cathode (pin 1) of U15 and ground to suppress the ripple interference of the reference voltage and ensure the stability of the output level.

[0034] In this embodiment, the operational amplifier signal conditioning module includes a low-power operational amplifier, a quad operational amplifier, and resistive and capacitive components; the non-inverting input terminals of the low-power operational amplifier and the quad operational amplifier are electrically connected to the output terminal of the reference voltage module, the inverting input terminals are connected to the series node of the input signal and the feedback resistor, and the output terminals are electrically connected to the control terminal of the power drive module.

[0035] The operational amplifier signal conditioning module integrates amplification and filtering functions to reduce signal distortion. This module consists of low-power operational amplifiers U11A and U11B, four operational amplifiers U12A, U12C, and U12D, as well as resistive and capacitive components. The non-inverting input of each operational amplifier is connected to the output of the reference voltage module, and the inverting input is connected to the series connection between the input signal and the feedback resistor. Precise signal conditioning is achieved through inverting proportional amplification, while the resistive and capacitive components perform signal filtering. The low-power operational amplifier is model SGM8272, and the four operational amplifiers are model SGM8274. The resistive and capacitive components include capacitors C38 and C41.

[0036] The operational amplifier signal conditioning module works as follows: The operational amplifier signal conditioning module uses low-power operational amplifiers U11A and U11B (model SGM8272) and quad operational amplifiers U12A, U12C, and U12D (model SGM8274), along with an inverting proportional amplifier circuit based on quad operational amplifier U12D. The specific connection and signal processing logic are as follows: the non-inverting input (pin 13) of quad operational amplifier U12D is connected to the output of the reference voltage module; the inverting input (pin 12) is connected to the series connection between the input signal and feedback resistor R113; and the feedback resistor R114 is connected in parallel between the inverting input and the output. Between the terminals (pin 14), the feedback resistor R113 has a resistance of 43KΩ and the feedback resistor R114 has a resistance of 10KΩ; in this embodiment, the amplification factor is -4.3 times to achieve accurate amplification of the input signal; the capacitance of the RC component C42 is 100pF and is connected in parallel between the power supply terminal and ground of the low-power operational amplifier U12A; the capacitance of the RC component C38 is 1000pF and is connected in parallel between the inverting input terminal and the output terminal of the low-power operational amplifier U11A to filter out high-frequency interference in the signal and avoid signal distortion.

[0037] In this embodiment, the power drive module includes a power transistor, a MOSFET, and a current-limiting resistor. The base of the power transistor is electrically connected to the output terminal of the operational amplifier signal conditioning module, the collector of the power transistor is connected to an external power supply, and the emitter of the power transistor is connected to the load circuit. The power drive module consists of a power transistor V4, a MOSFET V9, a MOSFET V12, and a current-limiting resistor. The base of the power transistor is connected to the output terminal of the operational amplifier signal conditioning module, the collector is connected to a 24V power supply, and the emitter is connected to the load circuit through the current-limiting resistor to receive the conditioned signal and drive the load to switch on and off. The power transistor is model MJD122, and the MOSFET is model IRFR5501TR.

[0038] The power drive module operates as follows: A power transistor V4 (model MJD122) and two MOSFETs V9 and V12 (model IRFR5501TR) are used as the power drive module. Taking the power drive circuit of power transistor V4 as an example, the base of power transistor V4 is connected to the output of low-power operational amplifier U11B through a current-limiting resistor R79 (510Ω), the collector is connected to the VCC27V power supply, and the emitter is connected to the load circuit 24VP. The current-limiting resistor R79 has a resistance of 510Ω. When the low-power operational amplifier U11B outputs a high level, the base of power transistor V4 receives a conduction current, and power transistor V4 is saturated and turned on. The VCC27V power supply supplies power to the 24VP load circuit through power transistor V4. When the low-power operational amplifier U11B outputs a low level, power transistor V4 is turned off, and the load circuit is de-energized. The filter capacitor C36 has a capacitance of 100nF and is connected in parallel between the collector of power transistor V4 and ground to suppress voltage spikes during power switching.

[0039] In this embodiment, the multi-protection module includes a fuse, a TVS diode, and a Schottky diode; the fuse is connected in series in the load line, the TVS diode is connected in parallel between the line and the ground terminal, and the Schottky diode is connected in reverse series in the power supply circuit. The multi-protection module provides all-round protection against overcurrent, surge, and reverse voltage, thereby improving circuit reliability.

[0040] The multi-protection module consists of fuse F5, TVS diodes DW4, TVS9, TVS10, TVS11, and Schottky diode D7. Fuse F5 is connected in series with the BUS1+ line to achieve overcurrent protection; TVS diodes are connected in parallel between the line and ground to suppress transient surge voltage; and Schottky diode D7 is connected in reverse series with the power supply circuit to block reverse voltage surges.

[0041] The working process of the multi-protection module is as follows: The multi-protection module provides overcurrent protection, surge suppression, and reverse voltage isolation, achieving comprehensive protection. Specifically, for overcurrent protection: fuse F5 (selected type: 500mA / 30V, SMD1812 package) is connected in series with the BUS1+ line. When the line current exceeds the 500mA threshold, the fuse F5 melts due to heat, cutting off the load circuit and preventing damage to downstream devices from overcurrent. For transient surge suppression: TVS diode DW4 (selected type: 4.3V / 0.25W) is connected in parallel between the BUS_AD bus and ground. When a surge voltage exceeding 4.3V occurs on the bus, TVS diode DW4 rapidly avalanche breakdowns, diverting the surge current to ground while clamping the bus voltage to 4.3V. When the circuit is isolated by reverse voltage: Schottky diode D7 (selected as IN5819) is connected in series in reverse in the 24VM circuit. Its forward voltage drop is 0.2V and its reverse withstand voltage is 40V. When a reverse voltage occurs in the circuit, Schottky diode D7 is cut off, blocking the reverse current from impacting the front-end circuit.

[0042] In this embodiment, the status feedback and indication module includes an LED, a BC846B transistor, and a feedback resistor; the anode of the LED is connected to the power supply, and the cathode is connected to the loop node through the resistor; the base of the transistor is connected to the loop status signal terminal, and the collector is connected to the feedback interface. The status feedback and indication module realizes real-time monitoring and visual display of the loop status, which facilitates fault diagnosis.

[0043] The transistor is model BC846B. The status feedback and indication module consists of LED 9, transistor V6, transistor V15, transistor V14 and feedback resistor. The anode of LED 9 is connected to the power supply and the cathode is connected to the loop node to realize the visual indication of the loop on / off. The base of the transistor is connected to the loop status signal and the collector is connected to the feedback interface to transmit the status signal back to the main board control unit.

[0044] The working process of the status feedback and indication module is as follows: In the status feedback and indication module, during status indication: the anode of LED 9 is connected to a 24VM power supply, and the cathode is connected to the loop node through a current-limiting resistor R135 (10KΩ). When the 24VM loop is on, LED 9 receives a positive current and lights up, visually indicating the loop's operating status. During signal feedback: the base of transistor V15 (model BC846B) is connected to the BUS_wave signal through a resistor R147 (1KΩ), the collector is connected to the feedback interface IN, and the emitter is grounded. When BUS_wave is high, transistor V15 is on, and the feedback interface IN outputs a low level. When BUS_wave is low, transistor V15 is off, and the feedback interface IN outputs a high level, realizing the electrical signal feedback of the loop status.

[0045] This invention improves the stability of the reference voltage and the accuracy of signal conditioning in the motherboard control circuit. The reference voltage module uses a precision reference voltage source in conjunction with a voltage divider network composed of high-precision resistors and filter capacitors to generate a highly stable reference level, effectively overcoming the reference drift problem caused by power supply fluctuations in traditional circuits. The operational amplifier signal conditioning module uses a low-power operational amplifier and a quad operational amplifier combined with feedback resistors to form an inverting proportional amplifier circuit, achieving precise linear amplification of the signal. At the same time, the filter network composed of RC components effectively filters out high-frequency noise, significantly reducing the risk of signal distortion and improving the signal acquisition and processing accuracy of the entire control circuit.

[0046] This utility model's multi-protection module integrates a fuse, a TVS diode, and a Schottky diode, forming a comprehensive, multi-layered protection system against common faults such as overcurrent, transient surges, and reverse power connection. This significantly improves the circuit's tolerance and operational reliability in complex industrial electromagnetic environments. Furthermore, the status feedback and indication module enables loop status visualization. Through a switching circuit composed of transistors, the status signals of key loop points are converted into standard level signals and transmitted back to the mainboard control unit. This allows for remote, real-time monitoring of the loop status, providing a hardware foundation for fault early warning and diagnosis, and greatly improving system maintainability and troubleshooting efficiency.

[0047] This invention improves signal processing accuracy through a highly stable reference source and precise conditioning circuit, enhances system reliability and anti-interference capability through multiple protection and filtering designs, and realizes visualization and remote monitoring of operating status through status indication and electrical signal feedback. It effectively solves the defects of traditional motherboard control circuits, such as unstable voltage, low signal conditioning accuracy, insufficient protection mechanism, poor anti-interference capability, and lack of status feedback. It is particularly suitable for industrial, commercial and energy storage detection and alarm controllers with high requirements for reliability, accuracy and maintainability.

[0048] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A mainboard control circuit for an industrial alarm controller, characterized in that, It includes a reference voltage module, an operational amplifier signal conditioning module, a power drive module, a multiple protection module, and a status feedback and indication module; The output terminal of the reference voltage module is electrically connected to the reference input terminal of the operational amplifier signal conditioning module; The signal output terminal of the operational amplifier signal conditioning module is electrically connected to the control input terminal of the power drive module. The load output terminal of the power drive module is used to connect to the back-end load circuit, and the power input terminal of the power drive module is electrically connected to the external line. The multiple protection modules are electrically connected to the power supply terminal of the power drive module and the external line, respectively. The monitoring terminal of the status feedback and indication module is electrically connected to the load output terminal of the power drive module and the signal output terminal of the operational amplifier signal conditioning module, respectively.

2. The mainboard control circuit of the industrial alarm controller as described in claim 1, characterized in that, The reference voltage module includes a reference voltage source, a voltage divider resistor group, and a filter capacitor; the voltage divider resistor group is connected in parallel between the cathode and the reference electrode of the reference voltage source, and the filter capacitor is connected in parallel between the cathode and the ground terminal of the reference voltage source.

3. The mainboard control circuit of the industrial alarm controller as described in claim 2, characterized in that, The reference voltage source is model TL431. The reference voltage module consists of a reference voltage source U15, a filter capacitor C43, and a voltage divider resistor group consisting of voltage divider resistors R76, R78, and R89. The voltage divider resistor group is connected in parallel between the cathode and the reference electrode of the reference voltage source U1 to generate a stable reference voltage. The filter capacitor C43 is connected in parallel between the cathode of the reference voltage source U1 and ground to suppress voltage ripple.

4. The mainboard control circuit of the industrial alarm controller as described in claim 1, characterized in that, The operational amplifier signal conditioning module includes a low-power operational amplifier, a quad operational amplifier, and resistive and capacitive components; the non-inverting input terminals of the low-power operational amplifier and the quad operational amplifier are electrically connected to the output terminal of the reference voltage module, the inverting input terminals are connected to the series node of the input signal and the feedback resistor, and the output terminals are electrically connected to the control terminal of the power drive module.

5. The mainboard control circuit of the industrial alarm controller as described in claim 4, characterized in that, The operational amplifier signal conditioning module consists of low-power operational amplifiers U11A, U11B, quad operational amplifiers U12A, U12C, and U12D, as well as resistors and capacitors. The non-inverting input of the operational amplifier is connected to the output of the reference voltage module, and the inverting input is connected to the series node of the input signal and the feedback resistor. The signal is precisely conditioned by inverting proportional amplification, and the resistors and capacitors are used to filter the signal.

6. The mainboard control circuit of the industrial alarm controller as described in claim 1, characterized in that, The power drive module includes a power transistor, a MOSFET, and a current-limiting resistor; the base of the power transistor is electrically connected to the output terminal of the operational amplifier signal conditioning module, the collector of the power transistor is connected to an external power supply, and the emitter of the power transistor is connected to a load circuit.

7. The mainboard control circuit of the industrial alarm controller as described in claim 6, characterized in that, The power drive module consists of a power transistor V4, a MOSFET V9, a MOSFET V12, and a current-limiting resistor. The base of the power transistor is connected to the output terminal of the operational amplifier signal conditioning module, the collector is connected to a 24V power supply, and the emitter is connected to the load circuit through the current-limiting resistor. It receives the conditioned signal and drives the load to switch on and off.

8. The mainboard control circuit of the industrial alarm controller as described in claim 1, characterized in that, The multiple protection module includes a fuse, a TVS diode, and a Schottky diode. The fuse is connected in series in the load circuit, the TVS diode is connected in parallel between the circuit and the ground terminal, and the Schottky diode is connected in reverse series in the power supply circuit. The multiple protection module consists of fuse F5, TVS diodes DW4, TVS9, TVS10, TVS11, and Schottky diode D7. The TVS diode connected in parallel between the circuit and ground suppresses transient surge voltages; the Schottky diode D7 is connected in reverse series in the power supply circuit to block reverse voltage surges.

9. The mainboard control circuit of the industrial alarm controller as described in claim 1, characterized in that, The status feedback and indication module includes an LED, a BC846B transistor, and a feedback resistor; the anode of the LED is connected to the power supply, and the cathode is connected to the loop node through the resistor; the base of the transistor is connected to the loop status signal terminal, and the collector is connected to the feedback interface.

10. The mainboard control circuit of the industrial alarm controller as described in claim 9, characterized in that, The status feedback and indication module consists of LED 9, transistor V6, transistor V15, transistor V14 and feedback resistor; the anode of LED 9 is connected to the power supply and the cathode is connected to the loop node to realize the visual indication of the loop on / off; the base of the transistor is connected to the loop status signal and the collector is connected to the feedback interface to transmit the status signal back to the main board control unit.

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