Topology identification automatic addressing system and method for two buses with branches

Abstract

The invention discloses a two-bus topology identification automatic addressing system and method with branches, and relates to the field of fire alarm, and the system comprises a fire alarm controller, two buses, and a communication unit. The two buses are integrally of a tree-shaped structure, the fire alarm controller is located at the root of the tree-shaped structure, and the communication units are located at the branches or branches of the tree-shaped structure; the fire alarm controller supplies power to the communication unit through two buses and carries out communication. A communication instruction is sent to the communication unit, response data is received, the serial number of the communication unit is identified, automatic addressing is carried out, and the front-back connection relation of the communication unit is identified, so that the topological structure of the communication unit is obtained. According to the invention, the debugging starting period of the fire alarm two-bus can be greatly shortened, and the system maintenance work is simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of fire alarm, and more particularly to an automatic addressing system and method with branched two-bus topology recognition. Background Art

[0002] In the fire automatic alarm and linkage system, the two-bus technology is usually used. The two-bus refers to two lines that can both supply power and communicate, and can realize two-way transmission of signals. The principle of two-bus communication is: the sending end of the fire alarm controller, which is generally the loop card installed in the fire alarm controller, serially outputs the instructions and data to be transmitted to the two-bus in the form of a carrier; the receiving end, which is generally the fire detector, manual alarm button, input and output module, etc. (collectively referred to as the communication unit) installed on site, can receive power from the bus, receive commands sent by the loop card, and send response data to the loop card.

[0003] The fire protection bus 2 is usually drawn from the loop card inside the fire alarm controller, and the output voltage is usually 24V. All communication units are connected to the bus in parallel, and each communication unit must set its own unique communication short address through a dip switch or an electronic encoder. The unit address is usually in the range of 1 to 255. When the fire protection system is in operation, the loop card queries the status of the communication unit one by one in the order of the short address, or issues a control command to a certain communication unit. Once a certain communication unit alarms, the automatic fire alarm controller can quickly detect the location of the fire, or send a command to the communication unit (output module) to start a certain fire extinguishing equipment.

[0004] However, when debugging the fire alarm system, it is necessary to set the short address of each communication unit by dialing or using an electronic encoder, and then register it on the controller. On-site debugging is complicated and cumbersome, and it is difficult to diagnose when problems occur. Moreover, for buses using the dial-up method, the wiring topology can only be viewed based on the design drawings. In some older and complex fire alarm systems, maintenance personnel have no way of knowing the wiring direction on site, and even the short addresses and locations of some units, making it extremely difficult to operate and maintain the fire alarm system.

[0005] Therefore, how to quickly obtain the wiring topology and address the communication units to reduce the workload during system commissioning and subsequent operation and maintenance is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] In view of this, the present invention provides a system and method for automatic addressing with branched two-bus topology identification, which can realize topology structure identification and automatic addressing of communication units on fire alarms.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention discloses a branched two-bus topology identification automatic addressing system, comprising: a fire alarm controller, two buses, and a communication unit;

[0009] The two buses are in a tree structure as a whole, the fire alarm controller is located at the root of the tree structure, and the communication unit is located at the trunk or branch of the tree structure;

[0010] The fire alarm controller supplies power to the communication unit and communicates through the two buses; by sending communication instructions to the communication unit and receiving response data, it identifies the serial number of the communication unit, performs automatic addressing, and identifies the front and back connection relationship of the communication unit to obtain the topological structure of the communication unit.

[0011] Furthermore, the fire alarm controller includes: a main control board, and a circuit card, an information output module, a key input module, a control output module, and a power supply module connected to the main control board;

[0012] The loop card modulates the communication command sent by the main control board to generate a corresponding voltage waveform; analyzes the current pulse sent by the communication unit to obtain the communication unit response data; and supplies power to the two buses;

[0013] The main control board sends out alarm information through the information output module, receives external instructions through the key input module, and controls the fire extinguishing equipment through the control output module;

[0014] The power module supplies power to the main control board.

[0015] Further, the loop card includes: a main control unit, and a power supply and a main control board communication interface, a modulation circuit, and a signal conditioning unit connected to the main control unit;

[0016] The main control unit receives the main control board instructions and power supply through the power supply and the main control board communication interface; modulates the communication instructions through the modulation circuit; and conditions the current pulse through the signal conditioning unit.

[0017] Furthermore, the communication unit has a built-in memory, an MCU, and an electronic switch;

[0018] The memory stores the unique serial number set at the factory and the communication short address obtained after automatic addressing;

[0019] The MCU decodes the instruction sent by the loop card, sends out corresponding current pulses as response data according to the data stored in the memory, or controls the electronic switch to open / close, so as to disconnect or connect subsequent communication units.

[0020] The present invention also discloses a method for automatic addressing of a two-bus topology with branches, comprising:

[0021] Step 1: The loop card powers up the second bus. When all communication units are initially powered up, the built-in electronic switch disconnects the subsequent communication units.

[0022] Step 2: The fire alarm controller identifies the serial number of the newly discovered communication unit through the communication command and addresses the newly discovered communication unit;

[0023] If 0 new communication units are found, it means that the addressing of this branch is completed;

[0024] If a new communication unit is found, a unique communication short address is assigned to the communication unit and the process goes to step 3;

[0025] If multiple new communication units are found, it means a branch has occurred, and go to step 4;

[0026] Step 3: The fire alarm controller sends a communication command to close the electronic switch of the newly addressed communication unit, connect to the subsequent communication unit, and enter step 2;

[0027] Step 4: assigning unique communication addresses to the newly discovered multiple communication units respectively, and repeating step 5 until all the branches where the newly discovered multiple communication units are located are automatically addressed;

[0028] Step 5: The fire alarm controller sends a communication command to close the electronic switch of a newly discovered communication unit, connect the subsequent communication unit and enter step 2, and automatically address the branch where the communication unit is located.

[0029] Furthermore, identifying the serial number of the newly discovered communication unit through the communication instruction includes: sending a bit-by-bit serial number identification instruction and confirming the serial number of the newly discovered communication unit according to whether a current pulse is received on the second bus, until the serial numbers of all the newly discovered units are determined.

[0030] Furthermore, the addressed communication unit no longer participates in serial number identification.

[0031] Further, when the loop card attempts to send commands to all serial numbers but does not receive corresponding response current pulses, it indicates that no new communication unit is found.

[0032] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a system and method for automatic addressing with branched two-bus topology identification, wherein the fire alarm controller can both supply power to the communication unit and communicate with the communication unit through the two buses; and the fire alarm controller can also automatically identify the serial number of the communication unit and perform automatic addressing according to the control command and the response of the communication unit, thereby identifying the topological structure of the communication unit. Through topology identification and automatic addressing, the debugging and opening cycle of the fire alarm two-bus is greatly shortened, and the system maintenance work is simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 This is a wiring diagram of a two-bus branch method according to an embodiment of the present invention.

[0035] Figure 2 Schematic diagram of the structure of a loop card according to an embodiment of the present invention.

[0036] Figure 3 The figure is a schematic diagram of an electronic switch of a communication unit according to an embodiment of the present invention.

[0037] Figure 4 FIG. 2 is a schematic diagram of another electronic switch of a communication unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The embodiment of the present invention discloses a branched two-bus topology recognition automatic addressing system, such as Figure 1 As shown, it includes: a fire alarm controller, two buses, and a communication unit;

[0040] The two buses are in a tree-like structure as a whole, the fire alarm controller is located at the root of the tree structure, and the communication unit is located at the trunk or branch of the tree structure;

[0041] The fire alarm controller supplies power to the communication unit and communicates through the second bus; by sending communication instructions to the communication unit and receiving response data, it identifies the serial number of the communication unit, performs automatic addressing, and identifies the front and back connection relationship of the communication unit to obtain the topological structure of the communication unit.

[0042] In a specific embodiment, the fire alarm controller includes: a main control board, and a circuit card connected to the main control board, an information output module, a key input module, a control output module, and a power supply module;

[0043] The loop card modulates the communication command sent by the main control board to generate the corresponding voltage waveform; analyzes the current pulse sent by the communication unit to obtain the communication unit response data; and supplies power to the second bus;

[0044] The main control board sends out alarm information through the information output module, receives external commands through the key input module, and controls the fire extinguishing equipment through the control output module;

[0045] The power module supplies power to the main control board.

[0046] In a specific embodiment, Figure 2 As shown, the loop card includes: a main control unit, a power supply connected to the main control unit, a main control board communication interface, a modulation circuit, and a signal conditioning unit;

[0047] The main control unit receives the main control board instructions and power supply through the power supply and the main control board communication interface; modulates the communication instructions through the modulation circuit; and conditions the current pulse through the signal conditioning unit.

[0048] In a specific embodiment, Figure 3-4 As shown, the communication unit has a built-in memory, an MCU, and an electronic switch. In this embodiment, the electronic switch is a MOS switch, but it can also be other electronic switches;

[0049] The memory stores the unique serial number set at the factory and the communication short address obtained after automatic addressing;

[0050] The MCU decodes the instructions sent by the loop card, sends out corresponding current pulses as response data according to the data stored in the memory, or controls the electronic switch to open / close, thereby disconnecting or connecting subsequent communication units.

[0051] The embodiment of the present invention also discloses a method for automatic addressing of a two-bus topology with branches, comprising:

[0052] Step 1: The loop card powers up the second bus. When all communication units are initially powered up, the subsequent communication units are disconnected.

[0053] Step 2: The fire alarm controller identifies the serial number of the newly discovered communication unit through the communication command and addresses the newly discovered communication unit;

[0054] If 0 new communication units are found, it means that the addressing of this branch is completed;

[0055] If a new communication unit is found, a unique communication short address is assigned to the communication unit and the process goes to step 3;

[0056] If multiple new communication units are found, it means a branch has occurred, and go to step 4;

[0057] Step 3: The fire alarm controller sends a communication command to close the electronic switch of the newly addressed communication unit, connect to the subsequent communication unit, and enter step 2;

[0058] Step 4: assigning unique communication addresses to the newly discovered multiple communication units respectively, and repeating step 5 until all the branches where the newly discovered multiple communication units are located are automatically addressed;

[0059] Step 5: The fire alarm controller sends a communication command to close the electronic switch of a newly discovered communication unit, connect the subsequent communication unit and enter step 2, and automatically address the branch where the communication unit is located.

[0060] This method can identify the topology of the two buses and implement an addressing scheme based on the topological position.

[0061] In a specific embodiment, identifying the serial number of a newly discovered communication unit through a communication instruction includes: sending a bit-by-bit serial number identification instruction, and confirming the serial number of the newly discovered communication unit based on whether a current pulse is received on the second bus, until the serial numbers of all newly discovered units are determined.

[0062] In a specific embodiment, the addressed communication unit no longer participates in the serial number identification.

[0063] In a specific embodiment, when the loop card attempts to send commands to all serial numbers but does not receive corresponding response current pulses, it indicates that no new communication unit is found.

[0064] In a specific embodiment, the serial number is a unique binary digital sequence greater than 1; taking the case where the serial number is 3 digits, there is at most one branch between any two communication units, and there are no other branches on the branch as an example, topology identification and automatic addressing are explained.

[0065] S1. The loop card powers up the second bus. When powered up, the electronic switch in the communication unit disconnects the subsequent communication units by default.

[0066] S2, the loop card identifies the newly discovered communication unit serial number through the command. If 0 serial numbers are found, it means that the addressing of this branch is completed and there is no subsequent communication unit; if 1 serial number is found, a communication short address is compiled for this serial number, for example, the first communication short address is 1, the second is 2, and so on. After the addressing is completed, enter S3; if 2 serial numbers are found, it means that a branch has appeared, and enter S4;

[0067] S3, the loop card sends a command to the newly addressed communication unit, closes the electronic switch, connects to the subsequent communication unit, and then enters S2.

[0068] S4, the loop card respectively programs the communication short addresses of the two newly discovered communication units as n and n+1, and repeats S5 until the automatic addressing of the branch with the communication short addresses n and n+1 is completed;

[0069] S5, the fire alarm controller sends a communication command to close the electronic switch of a newly discovered communication unit, connect the subsequent communication unit to enter step 2, and automatically address the branch where the communication unit is located;

[0070] Specifically, the loop card sends a command to the communication unit with a short address of n, closes the electronic switch, and enters S2. After the addressing of this branch is completed, the loop card sends a command to the communication unit with a short address of n+1, closes the electronic switch, and enters S2 until the addressing is completed.

[0071] There are two methods for identifying the newly discovered unit serial number in step S2, which can be further decomposed as follows:

[0072] For ease of explanation, assume the sequence number is b2b1b0 (binary).

[0073] Plan A

[0074] In this scheme, the unaddressed communication unit will not exit and each command will be responded.

[0075] S2.A.1 loop card sends a command to the newly connected communication unit, so that the unit with serial number b2 as 1 sends a current pulse; if the loop card receives the current pulse, it goes to S2.A.2; if the loop card does not receive the current pulse, it goes to S2.A.3;

[0076] S2.A.2 indicates that there is a branch unit with serial number 1XX (binary). The loop card continues to send instructions to let the communication unit with serial number b2b1 11 send out a current pulse; if the loop card receives the current pulse, it goes to S2.A.4; if the loop card does not receive the current pulse, it goes to S2.A.5;

[0077] S2.A.3 indicates that there may be a branch unit with serial number 0XX (binary). The loop card continues to send instructions to let the communication unit with serial number b2b1 01 send a current pulse; if the loop card receives the current pulse, it goes to S2.A.6; if the loop card does not receive the current pulse, it goes to S2.A.7;

[0078] S2.A.4 indicates that there is a branch unit with serial number 11X (binary). The loop card continues to send instructions to let the communication unit with serial number b2b1b0 of 111 send out a current pulse; if the loop card receives the current pulse, it will compile a short address for this unit and then enter S2.A.1; if the loop card does not receive the current pulse, it will let the communication unit with serial number b2b1b0 of 110 send out a current pulse; if the loop card receives the current pulse, it will compile a short address for this unit and then enter S2.A.1;

[0079] S2.A.5 indicates that there may be a branch unit with a serial number of 10X (binary). The loop card continues to send instructions to let the communication unit with serial number b2b1b0 of 101 send out a current pulse; if the loop card receives the current pulse, it will program a short address for this unit and then enter S2.A.1; if the loop card does not receive the current pulse, it will let the communication unit with serial number b2b1b0 of 100 send out a current pulse; if the loop card receives the current pulse, it will program a short address for this unit and then enter S2.A.1;

[0080] S2.A.6 indicates that there may be a branch unit with a serial number of 01X (binary). The loop card continues to send instructions to let the communication unit with serial number b2b1b0 of 011 send out a current pulse; if the loop card receives the current pulse, it will compile a short address for this unit and then enter S2.A.1; if the loop card does not receive the current pulse, it will let the communication unit with serial number b2b1b0 of 010 send out a current pulse; if the loop card receives the current pulse, it will compile a short address for this unit and then enter S2.A.1;

[0081] S2.A.7 indicates that there may be a branch unit with serial number 00X (binary). The loop card continues to send instructions to let the communication unit with serial number b2b1b0 001 send a current pulse; if the loop card receives the current pulse, it will compile a short address for this unit and then enter S2.A.1; if the loop card does not receive the current pulse, the addressing of all new units is completed.

[0082] Because in scheme A, 1 is recognized first from the highest to the lowest bit of the sequence number, so all the sequence numbers are always recognized from the largest to the smallest. If scheme A is slightly modified, 0 is recognized first from the highest to the lowest bit of the sequence number, so all the sequence numbers are always recognized from the smallest to the largest.

[0083] In Solution A, each time the loop card sends out a serial number recognition instruction, it must carry the previously recognized serial number bit value. If the factory serial number of the unit is long, such as 48 bits or even longer, the serial number recognition instruction will be very long, which will reduce the efficiency of serial number recognition. In order to optimize this problem, Solution B was developed.

[0084] Plan B

[0085] S2.B.1, the loop card sends a command to the newly connected communication unit, so that the unit with serial number b2 as 1 sends a current pulse. This command also starts a new round of serial number identification, so that the communication unit that exited the previous round of serial number identification can resume function; if the loop card receives the current pulse, enter S2.B.2, if the loop card does not receive the current pulse, enter S2.B.3;

[0086] S2.B.2 indicates that there is a branch unit with a serial number of 1XX (binary). The loop card continues to send instructions to let the communication unit with serial number b2b1 of 11 send out a current pulse. The communication unit with b2 not 1 that receives this instruction exits this round of serial number identification; if the loop card receives a current pulse, it enters S2.B.4; if the loop card does not receive a current pulse, it enters S2.B.5;

[0087] S2.B.3 indicates that there is no branch unit with serial number 1XX (binary), but there may be a branch unit with serial number 0XX (binary). The loop card continues to send instructions to let the unit with serial number b2b1 01 send current pulses. If the loop card receives the current pulse, it goes to S2.B.6; if the loop card does not receive the current pulse, it goes to S2.B.7;

[0088] S2.B.4, indicating that there is a branch unit with serial number 11X (binary). The loop card continues to send instructions to let the communication unit with serial number b1b0 of 11 send out current pulses. The communication unit with b1 not 1 that receives this command exits this round of serial number recognition; if the loop card receives a current pulse, it means that there is a unit with serial number 111 (binary). Program a short address for the unit and then enter S2.B.1; if the loop card does not receive a current pulse, the loop card continues to send instructions to let the communication unit with serial number b1b0 of 10 send out current pulses. If the loop card receives a current pulse, it means that there is a unit with serial number 110 (binary). Program a short address for the unit and enter S2.B.1;

[0089] S2.B.5, indicating that there is no branch unit with serial number 11X (binary), but there may be a branch unit with serial number 10X (binary). The loop card continues to send instructions to let the unit with serial number b1b0 of 01 send current pulses. If the loop card receives the current pulse, it means that there is a unit with serial number 101 (binary). Short-program the address of the unit and then enter S2.B.1; if the loop card does not receive the current pulse, the loop card continues to send instructions to let the unit with serial number b1b0 of 00 send current pulses. If the loop card receives the current pulse, it means that there is a unit with serial number 100 (binary). Short-program the address of the unit and enter S2.B.1;

[0090] S2.B.6, indicating that there is a branch unit with serial number 01X (binary). The loop card continues to send instructions to let the communication unit with serial number b1b0 of 11 send out current pulses. The communication unit with b1 not 1 that receives this command exits this round of serial number identification; if the loop card receives a current pulse, it means that there is a unit with serial number 011 (binary). Program a short address for the unit and then enter S2.B.1; if the loop card does not receive a current pulse, the loop card continues to send instructions to let the communication unit with serial number b1b0 of 10 send out current pulses. If the loop card receives a current pulse, it means that there is a unit with serial number 010 (binary). Program a short address for the unit and enter S2.B.1;

[0091] S2.B.7, indicating that there is no branch unit with serial number 01X (binary), but there may be a branch unit with serial number 00X (binary). The loop card continues to send instructions to let the unit with serial number b1b0 of 01 send current pulses. If the loop card receives the current pulse, it means that there is a unit with serial number 001 (binary), and the unit is short-addressed, and then enters S2.B.1; if the loop card does not receive the current pulse, the addressing of all new units is completed.

[0092] In solution B, the serial number identification instructions issued by the loop card each time are very short, and the recognition efficiency is relatively high. Regardless of how many digits the serial number has, the number of commands required to identify each serial number will basically not exceed the number of binary digits of the serial number.

[0093] Solution B prioritizes 1 from high to low in the sequence number, so all sequence numbers are always recognized from large to small. If Solution B is slightly modified, prioritizes 0 from high to low in the sequence number, then all sequence numbers are always recognized from small to large.

[0094] Furthermore, it can be further simplified based on the number of current pulses received simultaneously. If only one current pulse is received, it is known that a unique serial number has been identified, and the address can be shortened immediately, saving the time of subsequent instructions to set the serial number and quickly implementing addressing.

[0095] Both Scheme A and Scheme B can realize the identification and addressing of multiple branches. The derived application scenario is that all units are directly connected to the second bus, and the loop card first sends instructions to each unit one by one to close all electronic switches (or the unit can directly short-circuit the electronic switch). Then, the total number of communication units on the second bus is determined based on the identification serial number, and then the addressing is performed based on the serial number, or in combination with other features.

[0096] In a specific embodiment, addressing can be performed based on a serial number without performing topology identification.

[0097] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0098] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A branched two-bus topology recognition automatic addressing system, characterized in that: include: Fire alarm controller, two buses, communication unit; The two buses are in a tree structure as a whole, the fire alarm controller is located at the root of the tree structure, and the communication unit is located at the trunk or branch of the tree structure; The fire alarm controller supplies power to the communication unit and communicates through the two buses; by sending communication instructions to the communication unit and receiving response data, it identifies the serial number of the communication unit, performs automatic addressing, and identifies the front and back connection relationship of the communication unit to obtain the topological structure of the communication unit.

2. The automatic addressing system for identifying a two-bus topology with branches according to claim 1 is characterized in that: The fire alarm controller comprises: a main control board, and a circuit card connected to the main control board, an information output module, a key input module, a control output module, and a power supply module; The loop card modulates the communication command sent by the main control board to generate a corresponding voltage waveform; analyzes the current pulse sent by the communication unit to obtain the communication unit response data; and supplies power to the two buses; The main control board sends out alarm information through the information output module, receives external instructions through the key input module, and controls the fire extinguishing equipment through the control output module; The power module supplies power to the main control board.

3. The automatic addressing system for identifying a two-bus topology with branches according to claim 2 is characterized in that: The loop card includes: a main control unit, a power supply connected to the main control unit, a main control board communication interface, a modulation circuit, and a signal conditioning unit; The main control unit receives the main control board instructions and power supply through the power supply and the main control board communication interface; modulates the communication instructions through the modulation circuit; and conditions the current pulse through the signal conditioning unit.

4. The automatic addressing system for identifying a two-bus topology with branches according to claim 2, characterized in that: The communication unit has a built-in memory, an MCU, and an electronic switch; The memory stores the unique serial number set at the factory and the communication short address obtained after automatic addressing; The MCU decodes the instruction sent by the loop card, sends out corresponding current pulses as response data according to the data stored in the memory, or controls the electronic switch to open / close, so as to disconnect or connect subsequent communication units.

5. A method for automatic addressing of a two-bus topology with branches, using a system for automatic addressing of a two-bus topology with branches as claimed in any one of claims 1 to 4, characterized in that: include: Step 1: The loop card powers up the second bus. When all communication units are initially powered up, the built-in electronic switch disconnects the subsequent communication units. Step 2: The fire alarm controller identifies the serial number of the newly discovered communication unit through the communication command and addresses the newly discovered communication unit; If 0 new communication units are found, it means that the addressing of this branch is completed; If a new communication unit is found, a unique communication short address is assigned to the communication unit and the process goes to step 3; If multiple new communication units are found, it means a branch has occurred, and go to step 4; Step 3: The fire alarm controller sends a communication command to close the electronic switch of the newly addressed communication unit, connect to the subsequent communication unit, and enter step 2; Step 4: assigning unique communication addresses to the newly discovered multiple communication units respectively, and repeating step 5 until all the branches where the newly discovered multiple communication units are located are automatically addressed; Step 5: The fire alarm controller sends a communication command to close the electronic switch of a newly discovered communication unit, connect the subsequent communication unit and enter step 2, and automatically address the branch where the communication unit is located.

6. The method for automatic addressing of a two-bus topology with branches according to claim 5, characterized in that: The identifying the serial number of the newly discovered communication unit by the communication instruction includes: sending a bit-by-bit serial number identification instruction and confirming the serial number of the newly discovered communication unit according to whether a current pulse is received on the second bus until the serial numbers of all the newly discovered units are determined.

7. The method for automatic addressing of a two-bus topology with branches according to claim 6, characterized in that: The addressed communication unit no longer participates in the serial number identification.

8. The method for automatic addressing of a two-bus topology with branches according to claim 6, characterized in that: When the loop card has tried to send commands to all serial numbers and has not received corresponding response current pulses, it indicates that no new communication unit has been found.

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