Fire detection two-bus loop hardware diagnosis circuit and diagnosis method thereof

Abstract

The invention provides a fire detection two-bus loop hardware diagnosis circuit and a diagnosis method thereof. The fire detection two-bus loop hardware diagnosis circuit comprises a central processing unit, a two-bus module, a short circuit detection module, a power supply module, a grounding detection module, an open circuit detection module, a relay group and equipment, the first connecting end of the two-bus module is respectively connected with the power supply module and the short circuit detection module; the short circuit detection module is connected with the central processing unit; the central processor is connected with the grounding detection module and the open circuit detection module. The open circuit detection module is connected with the relay group; and the relay group is respectively connected with the equipment and the second connecting end of the two-bus module. According to the invention, three common problems of the two-bus loop can be diagnosed and processed in a centralized manner, and a single central processing unit is adopted for processing, so that three common problems of open circuit, short circuit and grounding of the two-bus loop can be diagnosed, and the diagnosis cost is ingeniously reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire detection alarm display controller, and specifically, relates to a fire detection two-bus loop hardware diagnosis circuit and a diagnosis method thereof, and more specifically, to a two-bus loop diagnosis method, namely, a fire detection alarm display controller two-bus loop diagnosis method. Background Art

[0002] The two-bus only uses two wires for on-site communication, saving construction costs and cable costs, bringing great convenience to on-site construction and subsequent maintenance; it has a wide range of applications in the field of fire detection alarm display control.

[0003] Compared with other wiring systems, the two-bus is a bus technology that combines the power supply line and the signal line into one, realizing the sharing of signal and power supply. In practical applications, the two-bus is usually a "two-in and two-out" wiring method. A two-bus loop device connected to the two-bus loop will have four wiring points. Often in engineering projects, there are many loop devices connected to the two-bus loop. During project construction and system use, it is easy to cause line disconnection, line head virtual connection, line short circuit or poor line insulation causing leakage. If such a fire detection alarm display controller does not have loop diagnosis capabilities, it will be difficult for engineering and technical personnel and maintenance personnel to detect it, which will cause abnormal power supply and power loss of some or all two-bus loop devices, and the loop equipment will not work properly.

[0004] Patent document CN113655752A discloses a two-bus device and its self-checking method and building automatic control system; the two-bus device provided by the scheme includes: a two-bus, a two-bus module for controlling the input and output of the two-bus, a detection module connected to the input and output of the two-bus module in a switchable manner, and a power supply module for power supply. The scheme avoids the difficulty of troubleshooting the fault of the entire system due to the fault of the two-bus device after the two-bus device is powered on by self-checking, and can quickly and accurately detect the fault of the two-bus device; however, it does not have loop diagnosis capability, and if a fire occurs, it cannot play the fire detection alarm display control function, which may cause significant property losses and casualties.

[0005] This problem needs to be solved urgently. Summary of the invention

[0006] In view of the defects in the prior art, the object of the present invention is to provide a fire detection two-bus loop hardware diagnosis circuit and a diagnosis method thereof.

[0007] A fire detection two-bus loop hardware diagnostic circuit provided according to the present invention comprises: a central processing unit, a two-bus module, a short circuit detection module, a power supply module, a ground detection module, an open circuit detection module, a relay group and equipment;

[0008] The first connection ends of the two bus modules are respectively connected to the power supply module and the short circuit detection module; the short circuit detection module is connected to the central processing unit; the central processing unit is respectively connected to the grounding detection module and the open circuit detection module; the open circuit detection module is connected to the relay group; the relay group is respectively connected to the device and the second connection ends of the two bus modules.

[0009] Preferably, the two-bus module comprises: a two-bus level output circuit, a first operational amplifier circuit and a triode;

[0010] The two-bus level output circuit is connected to the first operational amplifier circuit; the first operational amplifier circuit is connected to the base of the transistor; the collector of the transistor is the first connection end; and the emitter of the transistor is the second connection end.

[0011] Preferably, the short circuit detection module comprises: a second operational amplifier circuit, a voltage limiting protection circuit and a sampling resistor;

[0012] The sampling resistor is connected to the second operational amplifier circuit; the second operational amplifier circuit is connected to the voltage limiting protection circuit; the sampling resistor is respectively connected to the power supply module and the first connection end of the second bus module; the power supply module is used to provide power.

[0013] Preferably, the ground detection module comprises: a first voltage divider circuit, a first voltage follower and a third relay;

[0014] The central processor is connected to the first voltage divider circuit and the third relay respectively; the first voltage divider circuit is connected to the first voltage follower; the first voltage follower is connected to the third relay; the third relay is grounded;

[0015] The open circuit detection module includes: a second voltage divider circuit and a second voltage follower;

[0016] The central processing unit is connected to a second voltage-dividing circuit; and the second voltage-dividing circuit is connected to the second voltage follower.

[0017] Preferably, the relay group comprises: a second relay and a first relay;

[0018] The second relay is connected to the second voltage follower; the second relay is connected to the first relay;

[0019] The device is used for fire detection alarm display; the first relay is connected to the device; and the device is connected to the second relay.

[0020] Preferably, the second connection ends of the two bus modules are connected to the first relay and the second relay respectively.

[0021] A method for detecting short circuit of a two-bus circuit for fire detection provided by the present invention is implemented based on the hardware diagnosis circuit for the two-bus circuit for fire detection, and includes:

[0022] The central processor controls the normally open end of the first relay to close and the normally open end of the second relay to open; the second bus module controls the normally open end of the first relay to close and sends a downlink command pulse voltage signal to the device; based on the downlink command pulse voltage signal, the device changes the current through the pulse width to form a current signal to reply to the second bus module to achieve communication; the current change range is 8mA to 20mA;

[0023] The sampling resistor of the short-circuit detection module converts the current signal into a voltage signal; the first operational amplifier circuit calculates the voltage signal, and transmits the calculation result to the central processing unit through the voltage limiting protection circuit;

[0024] According to the voltage signal, the short circuit detection module is made to determine whether there is a short circuit. If the result is yes, an alarm is given; if the result is no, no processing is performed.

[0025] Preferably, the central processor is capable of periodically switching the first relay according to a preset cycle;

[0026] The short circuit detection module determines whether there is a short circuit, that is, the short circuit detection module determines whether the voltage is higher than 10V. If the result is yes, there is no short circuit and no processing is done. If the result is no, there is a short circuit and an alarm is given.

[0027] A fire detection two-bus loop grounding detection method provided by the present invention is implemented based on the fire detection two-bus loop hardware diagnosis circuit, and includes:

[0028] The central processing unit controls the normally open end of the first relay to close and the normally open end of the second relay to open;

[0029] The central processing unit controls the normally open end of the third relay to close, and the first voltage follower of the grounding detection module isolates the external voltage and outputs the voltage to the first voltage divider circuit; the first voltage divider circuit performs voltage division processing to obtain a voltage division result; the central processing unit receives the voltage division result, and determines whether the grounding condition is normal based on the voltage division result, that is, determines whether the value of the voltage division result is 1V-3V. If the result is yes, an alarm is issued, and if the result is no, no processing is performed.

[0030] A fire detection two-bus loop open circuit detection method provided by the present invention is implemented based on the fire detection two-bus loop hardware diagnosis circuit, including: allowing a central processing unit to control the normally open end of a first relay to close and the normally open end of a second relay to open; allowing the input end of a device to be connected to the normally open end of the first relay; allowing the output end of the device to be connected to the normally open end of the second relay; based on the second relay, allowing the second voltage follower of the open circuit detection module to transmit a signal to the second voltage divider circuit to obtain a second voltage divider signal; the central processing unit receives the second voltage divider signal and determines whether the voltage value is 0. If the result is yes, an alarm is issued, and if the result is no, no processing is performed.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention can centrally diagnose and process three common problems of two-bus loops, and adopts a single central processing unit to process them, aiming to diagnose the three common problems of two-bus loops, namely, open circuit, short circuit and grounding, and ingeniously reduces the diagnosis cost.

[0033] 2. The diagnostic method of the present invention has high real-time performance and can quickly discover fault problems and respond to them.

[0034] 3. The present invention solves three common problems of two-bus loops, such as line disconnection, loose connection of wire ends, line short circuit or leakage caused by poor line insulation, thereby ensuring the normal operation of the two-bus equipment in the loop. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0036] Figure 1 A schematic diagram of the composition of the fire detection alarm display controller provided by the present invention;

[0037] Figure 2 This is a schematic diagram of a two-bus loop diagnostic circuit provided by the present invention. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0039] Some specific embodiments of the fire detection alarm display controller two-bus loop diagnosis method described in the present invention are provided below.

[0040] Embodiment 1, the fire detection alarm display controller of the present invention is as follows Figure 1 As shown, including:

[0041] CPU module, which is used for centralized information processing of the fire detection alarm display controller and for information exchange with the loop communication unit and the display unit;

[0042] The loop communication unit includes a loop communication baseboard and a loop communication processing board, which are used to communicate with the CPU module and the loop bus device respectively, collect information reported by the loop device and report it to the CPU host module;

[0043] Power supply module, used to supply power to the fire detection alarm display controller and loop equipment;

[0044] Display unit, used for displaying status information of fire detection alarm display controller;

[0045] The two-bus loop device, referred to as the device or loop device, is connected to the loop communication processing board in the loop communication unit. The two-bus signal line is led out from the loop communication unit and connected to the loop input end of the loop device, and then the loop output end of the loop device is connected to the loop input end of the next loop device, and so on. The entire loop is connected in a ring connection. The device includes: smoke temperature detectors, manual alarm buttons and alarms.

[0046] like Figure 2 As shown, a two-bus loop hardware diagnostic circuit of a fire detection alarm display controller provided by the present invention comprises:

[0047] The central processing unit controls the two-bus level output circuit to output the two-bus loop command pulse signal in real time; the controller relay drive circuit opens or closes the relay; samples the input voltage value and performs analog-to-digital conversion, determines the detection results of each circuit, and reports any abnormality immediately.

[0048] The two-bus level output circuit is used in combination with the No. 2 operational amplifier circuit, that is, the second operational amplifier circuit and the transistor. The two-bus level output circuit is connected to the input end of the No. 2 operational amplifier circuit in the same direction, the reverse input end of the No. 2 operational amplifier is connected to the transmitter of the transistor, and the output end is connected to the base of the transistor. After receiving the control signal of the central processor, the two-bus level output circuit has the ability to correctly generate the two-bus loop command pulse signal. According to the requirements of the two-bus protocol, the voltage amplitude of the two-bus loop command pulse signal is defined.

[0049] The relay group, consisting of two identical relays, controls the access to the field equipment of the loop. During normal operation, only relay No. 1, i.e. the first relay, is opened, and relay No. 2, i.e. the second relay, is opened when an open circuit fault occurs in the loop.

[0050] The open circuit detection circuit, i.e., the open circuit detection module, detects the voltage amplitude of the circuit field equipment connected to the No. 2 relay terminal, buffers and isolates the input voltage through the No. 2 voltage follower, i.e., the second voltage follower, and then passes through the No. 2 voltage divider circuit, i.e., the second voltage divider circuit for voltage division processing. The central processing unit then determines the open circuit condition through analog-to-digital converter conversion.

[0051] The short-circuit detection circuit, i.e. the short-circuit detection module, is composed of operational amplifier circuit No. 1, i.e. the first operational amplifier circuit and a voltage-limiting protection circuit. It mainly collects the voltage value after conversion by the sampling resistor, amplifies the voltage value according to a certain amplification factor, passes through the voltage-limiting protection circuit, protects the central processing unit pin, and then transmits it to the central processing unit.

[0052] The ground detection circuit is composed of relay No. 3, voltage follower No. 1 and voltage divider circuit No. 1. A group of contacts in relay No. 3 are normally open and grounded, the common end is connected to the positive input end of voltage follower No. 1, and voltage divider circuit No. 1 is connected to the output end of voltage follower No. 1.

[0053] The sampling resistor is used to convert the current signal generated by the two-bus loop device into a voltage signal for the short-circuit detection circuit to perform calculations and conversions.

[0054] Drive relay No. 1 to operate, the normally open end is closed, and the normally open end of relay No. 2 remains open;

[0055] The second bus level output circuit is combined with the No. 2 operational amplifier circuit, connected to the emitter of the transistor, and then connected to the common end of the No. 1 relay and the common end of the No. 2 relay. When the normally open end of the No. 1 relay is closed to the common end, a downlink command pulse voltage signal is sent to the second bus loop device;

[0056] The two-bus loop equipment adopts a ring connection, with the input end connected to the normally open end of relay No. 1 and the output end connected to the normally open end of relay No. 2;

[0057] An open circuit detection circuit is applied to the normally open end of relay No. 2, first passing through a voltage follower, and then transmitted to the central processor through voltage divider circuit No. 2;

[0058] The central processor detects the value after processing by the No. 2 voltage divider circuit and determines whether the value is abnormal. Under normal circumstances, the voltage value of the loop open detection is 0. This indicates that there is a breakpoint on the second bus loop. At this time, the fire detection alarm display controller is reported for fault display to inform relevant personnel to check the second bus loop line;

[0059] At the same time, the central processing unit sends a high-level control signal to control the relay drive circuit, drive the No. 2 relay to operate, close the normally open end, and supply power to the second bus loop device through the No. 2 relay, so that power can be supplied to both ends of the second bus loop;

[0060] The short circuit detection scheme of the second bus loop of the fire detection alarm display controller includes:

[0061] When the fire detection alarm display controller is in normal working state, the central processor sends a high-level control signal to control the relay drive circuit, drive the No. 1 relay to operate, the normally open end is closed, and the normally open end of the No. 2 relay remains open;

[0062] The second bus level output circuit is combined with the No. 2 operational amplifier circuit and connected to the common terminal of the No. 1 relay. When the normally open terminal is closed with the common terminal, a downlink command pulse voltage signal is sent to the second bus loop device.

[0063] After receiving the downlink command pulse voltage signal, the second bus loop device usually returns the code by increasing the second bus loop current with a pulse width to achieve the purpose of communication;

[0064] When the second bus loop device pulls up the current, the sampling resistor converts the pulled up current signal into a voltage signal, the No. 1 operational amplifier circuit performs the operation, and transmits the result to the central processing unit through the voltage limiting protection circuit; the pull-up current range is 8mA to 20mA.

[0065] If the loop current is too high, the central processor will detect this abnormal voltage to determine that there is a short circuit in the second bus loop equipment, and report it to the fire detection alarm display controller, displaying fault information to inform relevant personnel to check the second bus loop line; the abnormal voltage is lower than 10V.

[0066] The central processing unit controls relay No. 1 to switch periodically, on the one hand, disconnecting from the second bus loop device; on the other hand, periodically detecting the loop current. When the loop current returns to normal, normal communication with the second bus loop device can be achieved.

[0067] The fire detection alarm display controller two-bus loop grounding detection scheme includes:

[0068] When the fire detection alarm display controller is in normal working state, the central processor sends a high-level control signal to control the relay drive circuit, drive the No. 1 relay to operate, the normally open end is closed, and the normally open end of the No. 2 relay remains open;

[0069] In the ground detection circuit, the No. 3 relay is used to connect the normally open end to the ground, and the common end is connected to the No. 1 voltage follower;

[0070] The central processor controls the relay driving circuit of relay No. 3 within a certain period of time, driving relay No. 3 to operate, and after the normally open end is closed, the ground detection circuit starts to detect the earth voltage;

[0071] First, the external voltage is buffered and isolated through voltage follower No. 1, and the voltage is output to voltage divider circuit No. 1;

[0072] The voltage dividing circuit No. 1 performs voltage dividing processing and transmits the voltage dividing result to the central processing unit;

[0073] The central processing unit obtains the output result and determines whether it is abnormal based on the voltage value and range specified during bus communication. Specifically, it detects and determines whether the voltage division value of the ground voltage is 1V-3V. If the result is yes, it is determined that the ground voltage is abnormal, and reports it to the fire detection alarm display controller, displaying fault information to inform relevant personnel to check the second bus loop line; if the result is no, no processing is done.

[0074] Embodiment 2, a fire detection alarm display controller two-bus loop hardware diagnostic circuit according to the present invention, comprises:

[0075] The central processing unit controls the two-bus level output circuit to output the two-bus loop command pulse signal; the controller relay drive circuit opens or closes the relay; samples the output voltage value of the operational amplifier and performs analog-to-digital conversion, determines the detection results of each circuit, and reports immediately if an abnormality occurs. The two-bus level output circuit is used in combination with the No. 2 operational amplifier circuit and the transistor. The two-bus level output circuit is connected to the input end of the No. 2 operational amplifier circuit in the same direction, the reverse input end of the No. 2 operational amplifier is connected to the transmitter of the transistor, and the output end is connected to the base of the transistor. After receiving the control signal of the central processing unit, the two-bus level output circuit has the ability to correctly output the two-bus loop command pulse signal. According to the requirements of the two-bus protocol, the voltage amplitude of the two-bus loop command pulse signal is defined, and 20V is set as the high level and 10V is set as the low level.

[0076] The relay group, consisting of two identical relays, controls the access to the field equipment in the loop. During normal operation, only relay No. 1 is turned on, and relay No. 2 is turned on when an open circuit fault occurs in the loop.

[0077] The open circuit detection circuit detects the voltage amplitude of the circuit field equipment connected to the No. 2 relay terminal. Under normal circumstances, the voltage is not less than 10V. The input voltage is buffered and isolated by the No. 2 voltage follower, and then processed by the No. 2 voltage divider circuit. The central processing unit determines the open circuit condition after the analog-to-digital converter conversion.

[0078] The short-circuit detection circuit is composed of operational amplifier circuit No. 1 and voltage-limiting protection circuit. It mainly collects the voltage value after conversion by the sampling resistor, amplifies the voltage value according to a certain amplification factor, passes through the voltage-limiting protection circuit, protects the CPU pin, and then transmits it to the CPU.

[0079] The ground detection circuit is composed of relay No. 3, voltage follower No. 1 and voltage divider circuit No. 1. A group of contacts in relay No. 3 are normally open and grounded, the common end is connected to the positive input end of voltage follower No. 1, and voltage divider circuit No. 1 is connected to the output end of voltage follower No. 1.

[0080] The sampling resistor is used to convert the current signal generated by the two-bus loop device into a voltage signal for the short-circuit detection circuit to perform calculations and conversions.

[0081] Embodiment 3, the method for detecting open circuit of the second bus loop of the fire detection alarm display controller of the present invention comprises:

[0082] Step 1: When the fire detection alarm display controller is in normal working state, the central processing unit sends a high-level control signal to control the relay drive circuit, driving relay No. 1, that is, the first relay to operate, the normally open end is closed, and relay No. 2, that is, the normally open end of the second relay remains open;

[0083] Step 2: The second bus level output circuit is combined with the No. 2 operational amplifier circuit, i.e., the second operational amplifier circuit, which is connected to the emitter of the transistor, and connected to the common end of the No. 1 relay and the common end of the No. 2 relay. When the normally open end of the No. 1 relay is closed to the common end, a downlink command pulse voltage signal is sent to the second bus loop device;

[0084] Step 3: The two-bus loop equipment adopts a ring connection, with the input end connected to the normally open end of relay No. 1 and the output end connected to the normally open end of relay No. 2;

[0085] An open circuit detection circuit is applied to the normally open end of relay No. 2, first passing through a voltage follower, and then transmitted to the central processor through voltage divider circuit No. 2;

[0086] Step 4: The CPU detects the value after the No. 2 voltage divider circuit processes and determines whether the value is abnormal. Under normal circumstances, the voltage value of the loop open detection is 0. This indicates that there is a breakpoint on the second bus loop. At this time, the fire detection alarm display controller is reported for fault display to inform relevant personnel to check the second bus loop line;

[0087] Step 5: The central processing unit sends a high-level control signal to control the relay drive circuit, drive relay No. 2 to operate, close the normally open end, and supply power to the second bus loop device through relay No. 2, thereby realizing power supply at both ends of the second bus loop.

[0088] Embodiment 4, the method for detecting short circuit of two bus loops of the fire detection alarm display controller of the present invention comprises:

[0089] Step A1: When the fire detection alarm display controller is in normal working state, the central processing unit sends a high-level control signal to control the relay drive circuit, drive the No. 1 relay to operate, the normally open end is closed, and the normally open end of the No. 2 relay remains open;

[0090] Step A2: The second bus level output circuit is combined with the No. 2 operational amplifier circuit, i.e., the second operational amplifier circuit, and connected to the common terminal of the No. 1 relay. When the normally open terminal is closed to the common terminal, a downlink command pulse voltage signal is sent to the second bus loop device.

[0091] Step A3: After receiving the downlink command pulse voltage signal, the second bus loop device increases the second bus loop current by 10mA through the pulse width and performs a return code to achieve the purpose of communication; the pulse width is determined according to the protocol requirements.

[0092] Step A4: When the second bus loop device pulls up the current, the sampling resistor converts the pulled-up current signal into a voltage signal, and the No. 1 operational amplifier circuit, that is, the first operational amplifier circuit, performs the operation, and transmits the result to the central processing unit through the voltage limiting protection circuit;

[0093] Step A5: If the loop current is too high, the central processor will detect the abnormal voltage to determine that there is a short circuit in the second bus loop device, and report it to the fire detection alarm display controller, displaying the fault information to inform relevant personnel to check the second bus loop line;

[0094] Step A6: At the same time, the central processor controls relay No. 1 to switch periodically, on the one hand, disconnecting from the second bus loop device; on the other hand, periodically detecting the loop current, if the loop current returns to normal, communicating normally with the second bus loop device.

[0095] Embodiment 5, the fire detection alarm display controller two-bus loop grounding detection method of the present invention comprises:

[0096] Step B1: When the fire detection alarm display controller is in normal working state, the central processing unit sends a high-level control signal to control the relay drive circuit, drive the No. 1 relay to operate, the normally open end is closed, and the No. 2 relay, i.e. the second relay, remains open;

[0097] Step B2: Relay No. 3 in the ground detection circuit, i.e., the third relay, is used to connect the normally open end to the ground, and the common end is connected to voltage follower No. 1;

[0098] Step B3: The central processor controls the relay driving circuit of relay No. 3 within a certain period of time to drive relay No. 3 to operate, and after the normally open end is closed, the ground detection circuit starts to detect the earth voltage;

[0099] Step B4: First, the external voltage is buffered and isolated through the No. 1 voltage follower, i.e., the first voltage follower, and the voltage is output to the No. 1 voltage divider circuit;

[0100] Step B5: No. 1 voltage dividing circuit, i.e., the first voltage dividing circuit, performs voltage dividing processing and transmits the voltage dividing result to the central processing unit;

[0101] Step B6: The central processing unit obtains the output result, determines whether there is any abnormality in the result, and reports it to the fire detection alarm display controller, which displays the fault information to inform relevant personnel to check the second bus loop line.

[0102] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0103] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A fire detection two-bus loop hardware diagnostic circuit, characterized in that: include: Central processing unit, two-bus module, short circuit detection module, power supply module, ground detection module, open circuit detection module, relay group and equipment; The first connection ends of the two bus modules are respectively connected to the power supply module and the short circuit detection module; the short circuit detection module is connected to the central processing unit; the central processing unit is respectively connected to the grounding detection module and the open circuit detection module; the open circuit detection module is connected to the relay group; the relay group is respectively connected to the device and the second connection ends of the two bus modules.

2. The fire detection two-bus loop hardware diagnostic circuit according to claim 1, characterized in that: The two-bus module comprises: a two-bus level output circuit, a first operational amplifier circuit and a triode; The two-bus level output circuit is connected to the first operational amplifier circuit; the first operational amplifier circuit is connected to the base of the transistor; the collector of the transistor is the first connection end; and the emitter of the transistor is the second connection end.

3. The fire detection two-bus loop hardware diagnostic circuit according to claim 1, characterized in that: The short circuit detection module includes: a second operational amplifier circuit, a voltage limiting protection circuit and a sampling resistor; The sampling resistor is connected to the second operational amplifier circuit; the second operational amplifier circuit is connected to the voltage limiting protection circuit; the sampling resistor is respectively connected to the power supply module and the first connection end of the second bus module; the power supply module is used to provide power.

4. The fire detection two-bus loop hardware diagnostic circuit according to claim 1, characterized in that: The ground detection module comprises: a first voltage divider circuit, a first voltage follower and a third relay; The central processor is connected to the first voltage divider circuit and the third relay respectively; the first voltage divider circuit is connected to the first voltage follower; the first voltage follower is connected to the third relay; the third relay is grounded; The open circuit detection module includes: a second voltage divider circuit and a second voltage follower; The central processing unit is connected to a second voltage-dividing circuit; and the second voltage-dividing circuit is connected to the second voltage follower.

5. The fire detection two-bus loop hardware diagnostic circuit according to claim 4, characterized in that: The relay group includes: a second relay and a first relay; The second relay is connected to the second voltage follower; the second relay is connected to the first relay; The device is used for fire detection alarm display; the first relay is connected to the device; and the device is connected to the second relay.

6. The fire detection two-bus loop hardware diagnostic circuit according to claim 5, characterized in that: The second connection ends of the two bus modules are respectively connected to the first relay and the second relay.

7. A method for detecting short circuit of a two-bus circuit of fire detection, which is realized based on the hardware diagnosis circuit of the two-bus circuit of fire detection according to any one of claims 1 to 6, characterized in that: include: The central processing unit controls the normally open end of the first relay to close and the normally open end of the second relay to open; Instruct the second bus module to close the normally open end of the first relay and send a downlink command pulse voltage signal to the device; Based on the downlink command pulse voltage signal, the device changes the current through the pulse width to form a current signal to reply to the second bus module to achieve communication; the current change range is 8mA to 20mA; The sampling resistor of the short-circuit detection module converts the current signal into a voltage signal; the first operational amplifier circuit calculates the voltage signal, and transmits the calculation result to the central processing unit through the voltage limiting protection circuit; According to the voltage signal, the short circuit detection module is made to determine whether there is a short circuit. If the result is yes, an alarm is given; if the result is no, no processing is performed.

8. The method for detecting short circuit of two bus loops in fire detection according to claim 7, characterized in that: The central processor can periodically switch the first relay according to a preset cycle; The short circuit detection module determines whether there is a short circuit, that is, the short circuit detection module determines whether the voltage is higher than 10V. If the result is yes, there is no short circuit and no processing is done. If the result is no, there is a short circuit and an alarm is given.

9. A fire detection two-bus loop grounding detection method, which is implemented based on the fire detection two-bus loop hardware diagnosis circuit according to any one of claims 1 to 6, characterized in that: include: The central processing unit controls the normally open end of the first relay to close and the normally open end of the second relay to open; The central processing unit controls the normally open end of the third relay to close, and the first voltage follower of the grounding detection module isolates the external voltage and outputs the voltage to the first voltage divider circuit; the first voltage divider circuit performs voltage division processing to obtain a voltage division result; the central processing unit receives the voltage division result, and determines whether the grounding condition is normal based on the voltage division result, that is, determines whether the value of the voltage division result is 1V-3V. If the result is yes, an alarm is issued, and if the result is no, no processing is performed.

10. A method for detecting an open circuit of a two-bus circuit of fire detection, which is implemented based on the hardware diagnostic circuit of the two-bus circuit of fire detection according to any one of claims 1 to 6, characterized in that: include: The central processing unit controls the normally open end of the first relay to close and the normally open end of the second relay to open; Connecting the input terminal of the device to the normally open terminal of the first relay; connecting the output terminal of the device to the normally open terminal of the second relay; Based on the second relay, the second voltage follower of the open circuit detection module transmits a signal to the second voltage divider circuit to obtain a second voltage divider signal; the central processing unit receives the second voltage divider signal and determines whether the voltage value is 0V. If the result is yes, an alarm is issued, and if the result is no, no processing is performed.

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