Two-bus high-real-time communication system and method

Abstract

The invention discloses a two-bus high-real-time communication system and method, and relates to the field of fire alarm communication alarm. The system comprises a loop card module and a communication module, the loop card module is used for generating a voltage waveform for modulating a communication command between a bus loop + and a bus loop-; the communication module is connected between a bus loop + and a bus loop-and is used for analyzing a command sent by the loop card and sending a current response; and the loop card module is also used for analyzing the current response to obtain alarm information. According to the invention, the alarm response time is compressed to 700 milliseconds, the real-time performance is improved by 8 times, and precious time is won for taking fire safety measures.

Description

Technical Field

[0001] The present invention relates to the field of fire alarm communication, and more particularly to a two-bus high real-time communication system and method. Background Art

[0002] In the fire automatic alarm and linkage system, the two-bus technology is usually used. The two-bus means that two lines can be used for both power supply and communication, realizing two-way transmission of signals. Figure 1 .

[0003] The principle of two-bus communication: The sending end of the fire alarm controller is generally the loop card installed in the fire alarm controller, which serially outputs the instructions and data to be transmitted to the two-bus in the form of a carrier. The receiving end is generally the detector, manual alarm button, input and output module, etc. (collectively referred to as the communication unit) installed on site. While receiving power from the bus, it can also receive commands sent by the loop card and send response data to the loop card. In this way, the requirements of sharing the power supply and signal bus are met.

[0004] The fire protection bus 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. Each communication unit must set its own independent communication address through a dip switch or an electronic encoder. The unit address is usually in the range of 1 to 255. The communication unit address on the bus is unique and cannot be repeated. 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 address, or issues a control command to a certain communication unit. Once a communication unit alarms, the automatic fire alarm controller quickly detects the location of the fire, or sends a command to the communication unit to start a certain fire extinguishing equipment.

[0005] The two buses connected to the loop cards in the current automatic fire alarm system usually use twisted pair or parallel lines, which can be hundreds of meters or thousands of meters long. Dozens or even more than 200 communication units can usually be connected to the two buses. In order to ensure stable communication, the communication rate of the bus is usually around hundreds to 1000 bps.

[0006] Let's use an example to estimate the real-time performance of communication. Assuming there are 250 communication units on a bus, at a communication rate of 1000 bps, the fire alarm controller needs 20 bits of communication time to query one unit, so it takes 250x20 / 1000=5 seconds to query all units. The bus cannot communicate all the time, and time must be left to power the bus. Therefore, a complete query may take more than 6 to 8 seconds.

[0007] Assuming that the query is currently starting from communication unit 1, and unit 250 sends an alarm signal, the controller will need 6 to 8 seconds to find the alarm unit. The alarm response time of this method is 6 to 8 seconds.

[0008] The real-time performance of the automatic fire alarm system is an important indicator. How to detect the alarm as early as possible and take safety measures earlier to reduce fire losses is urgently needed to be studied by technical personnel in this field. Summary of the invention

[0009] In view of this, the present invention provides a dual-bus high real-time communication system and method to solve the problems existing in the background technology.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A two-bus high real-time communication system comprises: a loop card module and a communication unit; the loop card is used to generate a voltage waveform for modulating a communication command between buses loop+ and loop-; the communication unit is connected between buses loop+ and loop-, and is used to parse the command sent by the loop card and issue a current response; the loop card module is also used to analyze the current response and obtain alarm information.

[0012] Optionally, the loop card module is provided with a first main control module, a modulation circuit, a signal conditioning circuit and a power supply; the first main control module is connected to the modulation circuit, the signal conditioning circuit and the power supply respectively.

[0013] Optionally, the communication unit module is provided with a second main control module, a detection unit, an action unit, RX1, RX2 and RX3; the second main control module is respectively connected with the detection unit, the action unit, the RX1, the RX2 and the RX3; the RX1 is used to parse the command header, the RX2 is used to parse the command issued by the loop card, and the RX3 is used to issue a current pulse. There are multiple implementation methods for the communication unit module circuit.

[0014] A two-bus high real-time communication method, using any one of the two-bus high real-time communication systems described above, comprises the following steps:

[0015] The loop card sends a broadcast alarm query command to the communication unit. All alarm communication units send a current pulse code reply in the same time slot. Units without alarms do not respond. The alarm query command is very short, usually within 20 bits. Based on the bus speed of 1000 bps, the alarm query can be completed within 20ms.

[0016] If the loop card finds alarm response data, it knows that an alarm has occurred in a communication unit on the bus, but the address of the alarm unit is not yet known.

[0017] Optionally, the communication unit fault report and status report are processed in the same order.

[0018] Optionally, after the communication unit module parses the loop card module command, it sends back a current pulse in the time slot. After the current pulse enters the loop-end of the loop card module, a signal voltage is formed on the sampling resistor. After being shaped by the signal conditioning circuit, it is sent to the first main control module to complete the on-site return data analysis.

[0019] The loop card continues to send broadcast query alarm communication unit address instructions, and the alarm communication units on the bus send current pulse code responses in the corresponding time slots according to their own address sequence; the loop card can calculate the address of the alarm communication unit by detecting the position of the received current pulse in the time slot. This command is estimated based on 256 receiving time slots (each time slot is 1 bit), the total length of the command is less than 300 bits, and the query time (including the command part) is about 300ms.

[0020] In this way, in the address range of 1 to 255 on the bus, no matter which address has an alarm, the loop card can complete the alarm within 320ms. Of course, the loop card cannot communicate all the time, and it is necessary to reserve some high-level time between communication time periods to power the communication unit on site. If half of the time is reserved as power supply time, the loop card in normal monitoring status can also achieve an alarm response time within 700ms.

[0021] It can be seen from the above technical solution that compared with the prior art, the present invention provides a two-bus high real-time communication system and method, which compresses the alarm response time to within 700ms, and the real-time performance is nearly 10 times higher than the 6 to 8 seconds of the polling method, thus winning precious time for taking fire safety measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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.

[0023] Figure 1 It is a general schematic diagram of the automatic fire alarm and linkage system in the prior art;

[0024] Figure 2 It is a circuit block diagram of the loop card in the present invention;

[0025] Figure 3 is a circuit block diagram of a communication unit of the present invention;

[0026] Figure 4 It is a timing diagram of the data waveform sent and received by the loop card of the present invention;

[0027] Figure 5a The circuit diagram of the loop card output signal modulation of the present invention;

[0028] Figure 5b This is a circuit diagram of the loop card return code current pulse sampling circuit of the present invention;

[0029] Figure 6 The communication unit detection circuit diagram of the present invention;

[0030] Figure 7 It is a circuit diagram of the communication unit return code current pulse transmission of the present invention;

[0031] Figure 8 It is a timing diagram of RX1, RX2 and TX waveforms of the communication unit of the present invention;

[0032] Fig. 9 A first alternative circuit diagram of the loop card modulation circuit of the present invention;

[0033] Fig.10 A second alternative circuit diagram of the loop card modulation circuit of the present invention;

[0034] Fig.11 Optimizing the detection circuit diagram for the communication unit of the present invention;

[0035] Fig.12 This is a schematic diagram of the timing sequence of the alarm communication unit address query waveform of the present invention;

[0036] Fig.13 This is a diagram showing an alternative implementation of the timing sequence of sending and receiving data waveforms by the loop card of the present invention. DETAILED DESCRIPTION

[0037] 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.

[0038] The embodiment of the present invention discloses a two-bus high real-time communication system, such as Figure 1-Figure 13 As shown, including: loop card module ( Figure 2 ) and communication unit ( Figure 3); the loop card is used to generate a voltage waveform modulated with a communication command between the bus loop+ and loop-; the communication unit is connected between the bus loop+ and loop-, and is used to parse the command sent by the loop card and issue a current response; the loop card module is also used to analyze the current response and obtain an alarm message.

[0039] Furthermore, the loop card module is provided with a first main control module, a modulation circuit, a signal conditioning circuit and a power supply; the first main control module is connected to the modulation circuit, the signal conditioning circuit and the power supply respectively.

[0040] Furthermore, the communication unit is provided with a second main control module, a detection unit, an action unit, an RX1 circuit, an RX2 circuit and a TX circuit; the RX1 circuit is used to parse the command synchronization header, the RX2 circuit is used to parse the command issued by the loop card, and the TX is used to issue a current pulse code response.

[0041] The circuit diagram of the loop card is as follows: Figure 2 The loop card is mainly responsible for supplying power to the second bus, issuing commands and receiving code responses from the communication units on the second bus. Figure 5a and Figure 5b An implementation of the loop card sending and receiving circuits is shown.

[0042] like Figure 5a-Figure 5b As shown, ( Figure 5a The circuit in Fig. 9 or Fig.10 Substitution) Where P1 and P2 are the digital output ports of the MCU, with a high of 3.3V and a low of 0V. R6 and R7 have equal resistance values. The U1.1 op amp operates at 24V and is designed as a common-mode amplifier with an amplification factor of about 7.2. By combining the different output states of P1 and P2, the voltage shown in Table 1 can be obtained.

[0043] Table 1 Voltage of combination P1 and P2

[0044] P1 P2 Voltage at point A Loop+Voltage Low Low 3.3V 23.7V high Low 1.65V 11.9V - high 0V 0V

[0045] MCU timing control P1 and P2, can modulate the attached Figure 4 The waveform output by the middle loop card.

[0046] After receiving the waveform at the loop+ terminal, the communication unit can send current pulses to respond to the loop card's instructions after parsing the command. Figure 5b As shown, this current flows from loop- into the loop card, generating a sampling voltage on R11. U1.2 is designed as a common-mode amplifier, which amplifies the sampling voltage on R11 to a suitable value and sends it to the ADC port of the MCU for sampling, so that we can know whether the field unit sends a current signal.

[0047] Figure 5a R15 in the figure is a PTC thermistor used for bus short circuit protection. Q1 is used to expand the output current. D2 is used to improve the falling edge in the waveform. Figure 5b D1 is used to protect the ADC port of the MCU. When the output of U1.2 is greater than 3.3V, the excess voltage will flow to the 3.3V power supply, thereby protecting the ADC port from overvoltage and burning.

[0048] The circuit diagram of the bus communication unit is as follows: Figure 3 The communication unit works by drawing power from the second bus through the power supply circuit. It receives the command synchronization header through the RX1 circuit, analyzes the data sent by the loop card through the RX2 circuit, and after processing the loop card command, sends a current pulse sequence back to the loop card through the TX circuit for response.

[0049] Figure 6 It is a way to realize the RX1 and RX2 circuits.

[0050] Attached Figure 6 The ratio of R1 to R2 is set to about 4 times. The ratio of R3 to R10 is set to about 1 times. R1, R2, R3, and R10 are all selected to be relatively large resistors to achieve low power consumption. RX1 and RX2 are connected to the digital input port of the MCU in the communication unit. Considering the internal voltage limit protection of the MCU port, the maximum voltage is estimated to be 3.3V. In this way, RX1 and RX2 obtain the voltages shown in Table 2.

[0051] Table 2 RX1 and RX2 voltage

[0052] loop voltage RX1 RX2 24V 3.3V High 3.3V High 12V 2.4V High 0V Low 0V 0V Low 0V Low

[0053] Most current MCUs are CMOS circuits, and the input high-level threshold is VCC*2 / 3, which is approximately 2.2V. From the above table, we can see that RX1 detects a command header below 12V, while RX2 detects data between 12V and 24V.

[0054] The MCU in the communication unit can parse out the loop card instructions by analyzing the high and low level sequences output by RX1 and RX2.

[0055] Figure 7 It is an implementation of the RX code return circuit.

[0056] Figure 7 TX is the digital output port of the communication unit MCU, and the output voltage is 3.3 V. R5 is selected as a smaller resistor, so the pulse current is: I≈(3.3V-0.7V) / R4.

[0057] 0.7V is the Vbe voltage drop of transistor Q1. Usually I can be set to about 10 mA to tens of mA.

[0058] The waveform diagram related to the communication between the loop card and the communication unit is as follows: Figure 8 Attached Figure 8 In the figure, loop+ is the waveform on the bus, which is also the waveform at both ends of the communication unit; RX1 is the detected command header mark; RX2 is the detected command data; TX is the current pulse return code response signal sent by the communication unit.

[0059] Fig.11 yes Figure 6 An improved circuit.

[0060] Figure 6 When the bus is long and there are many units, the voltage drop of the bus current on the line is large, which will cause the voltage at both ends of the communication unit to drop significantly. When the high voltage of the bus drops to about 14V, RX2 cannot detect the correct data level. Fig.11 The circuit can greatly solve this problem.

[0061] In adopting Fig.11 When the circuit is connected, the high level of the loop card is set to 24V, the middle level is set to about 7.5V, and the low level is set to 0V. Even if the high voltage of the bus drops to 11V, RX1 and RX2 can still detect the correct voltage. This greatly reduces the requirement for the total resistance of the two bus lines and can greatly extend the length of the two buses.

[0062] In another embodiment, it includes a loop card and a communication unit; the loop card generates a voltage waveform modulated with a communication instruction and sends it to the second bus; the communication unit is connected to the second bus, and is used to parse the instruction sent by the loop card and send a current pulse as a return code response; the loop card is also used to analyze the current pulse return code of the communication unit to obtain the data responded by the communication unit.

[0063] The loop card and the communication unit have a master-slave two-way data communication. The loop card usually sends out a broadcast query command, and the event unit can send out a current pulse code reply to notify the loop card that an event has occurred on the bus. Then the loop card can send out an event address query command, and by calculating the time slot number of the event unit's response, the address number of the event unit can be obtained.

[0064] Furthermore, the loop card sends three levels to the second bus: high level (the highest voltage between the two buses); 0 level (0V); medium level (a level between the high level and the 0 level, usually a fraction of the high level). The loop card controls the time width sequence of the three levels to form the loop card instruction and send it to the second bus.

[0065] Among them, the broadcast communication instruction is characterized by a start bit of a 0-level pulse of a certain width, which serves as a command header to notify the on-site communication unit to start receiving commands; followed by a high-low change sequence from a high level to a medium level, which serves as instructions and data; after the data ends, there is a level jump, which serves as the start mark of the communication unit's response current pulse. The current pulse sequence responded by the communication unit is the data responded by the on-site unit. The change in the pulse width of each part, the segmentation or grouping of the command, the data attached to the command, and the response of the communication unit, all still fall within the scope of this claim.

[0066] The present invention quickly determines the alarm unit address through the following two steps:

[0067] All communication units connected to the loop card on the second bus issue a broadcast alarm query command. After receiving the alarm query command, the communication unit responds with a current pulse to determine whether an alarm has occurred. If an alarm occurs, it responds. If no alarm occurs, it does not respond. All communication units can respond in the same time slot. All communication units responding in multiple time slots also fall within the scope of protection of the present invention.

[0068] If the loop card finds that there is an alarm unit responding, it will issue a broadcast query alarm communication unit address command. The alarm communication unit will send a current pulse signal in the time slot of its own address number. The loop card can determine the address of the alarm unit by calculating the time slot number. This solution can ensure that any communication unit connected to the bus alarms, regardless of whether the alarm unit address is large or small, can obtain the alarm unit address with one command, and realize the determination of the alarm location.

[0069] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0070] 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 two-bus high real-time communication system, characterized in that: include: A loop card module and a communication unit module; the loop card module is used to generate a voltage waveform modulated with a communication command between the bus loop+ and loop-; the communication unit module is connected between the bus loop+ and loop-, and is used to parse the command sent by the loop card and issue a current response; the loop card module is also used to analyze the current response and obtain alarm information.

2. A two-bus high real-time communication system according to claim 1, characterized in that: The loop card module is provided with a first main control module, a modulation circuit, a signal conditioning circuit and a power supply; the first main control module is connected to the modulation circuit, the signal conditioning circuit and the power supply respectively.

3. A two-bus high real-time communication system according to claim 1, characterized in that: The communication unit module is provided with a second main control module, a detection unit, an action unit, RX1, RX2 and RX3; the second main control module is respectively connected to the detection unit, the action unit, the RX1, the RX2 and the RX3; the RX1 is used to parse the command header, the RX2 is used to parse the command issued by the loop card, and the RX3 is used to issue a current pulse. There are multiple implementation methods for the communication unit module circuit.

4. A two-bus high real-time communication method, using a two-bus high real-time communication system according to any one of claims 1 to 3, characterized in that: The following steps are involved: The loop card module continuously issues query commands in the form of broadcast to the communication unit module, and the communication unit with an alarm sends a current pulse response; If the loop card module finds an alarm response signal, it will issue a broadcast query alarm unit address command, and the alarm communication unit will issue a current impulse response in the time slot of its own address sequence; the loop card calculates the alarm unit address based on the time slot sequence number of the received current pulse; Query the detailed alarm information of the fire alarm communication unit and complete the alarm.

5. A two-bus high real-time communication method according to claim 4, characterized in that: The communication unit fault reporting and status reporting are processed in the same order.

6. A two-bus high real-time communication method according to claim 4, characterized in that: After the communication unit module parses the loop card module command, it sends back a current pulse in the time slot. After the current pulse enters the loop-end of the loop card module, a signal voltage is formed on the sampling resistor. After being shaped by the signal conditioning circuit, it is sent to the first main control module to complete the on-site return data analysis.

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