WO2022134379A1 - 总线通信电路及装置 - Google Patents

总线通信电路及装置 Download PDF

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Publication number
WO2022134379A1
WO2022134379A1 PCT/CN2021/086004 CN2021086004W WO2022134379A1 WO 2022134379 A1 WO2022134379 A1 WO 2022134379A1 CN 2021086004 W CN2021086004 W CN 2021086004W WO 2022134379 A1 WO2022134379 A1 WO 2022134379A1
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WIPO (PCT)
Prior art keywords
voltage
master station
signal
resistor
module
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PCT/CN2021/086004
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English (en)
French (fr)
Inventor
潘鑫龙
贺助理
杨永江
李志鹏
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威胜集团有限公司
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Application filed by 威胜集团有限公司 filed Critical 威胜集团有限公司
Priority to MX2022009773A priority Critical patent/MX2022009773A/es
Publication of WO2022134379A1 publication Critical patent/WO2022134379A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H04L12/40006—Architecture of a communication node
    • H04L12/40039—Details regarding the setting of the power status of a node according to activity on the bus

Definitions

  • the present application relates to the field of circuit electronics, and in particular, to bus communication circuits and devices.
  • the existing M-BUS bus communication mode of the remote meter reading system is a master-slave half-duplex transmission bus, which adopts the calling/response method to realize double-end communication, that is, after the master station sends an inquiry, the slave station sends the master station to the master station. transfer data.
  • the master station can send the bus voltage to the slave station to supply power to the slave station, and send a logic signal of "1" or "0" to the slave station through the change of the voltage amplitude of the bus voltage to realize data transmission.
  • the slave station can send a "1" or "0" logic signal to the master station by adding pulse current to the normal slave station current.
  • the master station can send signals to the slave station through the bus and supply power to the slave station at the same time, so that the battery set in the terminal instrument of the slave station is only used as a backup power supply, which reduces the work requirements of the slave station such as regular maintenance and battery replacement. .
  • the main purpose of the present application is to provide a bus communication circuit and device, which aims to solve the problems of insufficient anti-interference ability and self-adaptive adjustment ability of the existing bus communication method.
  • the present application provides a bus communication circuit, including a master station signal sending module, a communication protection module, a signal conversion resistor, a master station signal receiving module and a program-controlled reference voltage adjustment module;
  • the input end of the signal sending module of the master station is connected to the signal sending end of the master station, the output end of the signal sending module of the master station is connected to the first end of the communication protection module through the signal conversion resistor, and the communication
  • the second end of the protection module is connected to the slave station, and the first end of the communication protection module is also connected to the first input end of the signal receiving module of the master station and the input end of the program-controlled reference voltage adjustment module.
  • the output end of the reference voltage adjustment module is connected with the second input end of the master station signal receiving module, and the output end of the master station signal receiving module is connected with the signal receiving end of the master station;
  • the master station signal sending module is used to adjust the first output voltage according to the data signal sent by the master station;
  • the communication protection module is used for sending the first output voltage to the slave station, so that the slave station can convert the data signal sent by the master station according to the first output voltage, and is also used for the data signal sent by the slave station. Adjust the first output current;
  • the signal conversion resistor is used for step-down adjustment of the first output voltage according to the first output current to obtain a first signal voltage or a second signal voltage;
  • the program-controlled reference voltage adjustment module is used to adjust the output reference voltage to be between the first signal voltage and the second signal voltage
  • the master station signal receiving module is configured to receive the first signal voltage or the second signal voltage and compare it with a reference voltage to obtain a data signal sent by the slave station and send it to the master station.
  • the program-controlled reference voltage adjustment module includes a first diode and a plurality of resistance unit circuits connected in parallel;
  • the anode of the first diode is connected to the first end of the communication protection module, the cathode of the first diode is respectively connected to the first end of each resistance unit circuit, and the first end of each resistance unit circuit is connected. Both ends are connected to the second input end of the master station signal receiving module;
  • the program-controlled reference voltage adjustment module is configured to adjust the equivalent resistance of the program-controlled reference voltage adjustment module by controlling the on-off of a plurality of the resistance unit circuits.
  • each of the resistor unit circuits includes an adjustment resistor, a first switch tube, a first resistor, a second resistor, a first capacitor, and a first control unit;
  • the cathode of the first diode is respectively connected to the first end of the first capacitor, the first end of the first resistor and the first end of the first switch tube, and the first end of the first switch tube
  • the control terminal is respectively connected to the second terminal of the first capacitor, the second terminal of the first resistor and the first terminal of the second resistor, and the second terminal of the second resistor is connected to the first control terminal.
  • the control end of the unit is connected, the controlled end of the first control unit is connected with the master station, and the second end of the first switch tube is connected with the second input end of the signal receiving module of the master station;
  • the first control unit is configured to control the turn-on and turn-off of the first switch tube according to the control signal sent by the master station.
  • the first control unit is a first optocoupler or a second switch tube.
  • the adjustment resistances in each of the resistance unit circuits are different from each other.
  • the master station signal receiving module includes a first comparator, a third resistor, a fourth resistor, a second capacitor and a second optocoupler;
  • the first input end of the first comparator is connected to the first end of the communication protection module through the third resistor, and the second input end of the first comparator is respectively connected to the first end of each resistance unit circuit.
  • the two terminals are connected, the second terminal of the first comparator is grounded through a fourth resistor, the second capacitor is connected in parallel with the fourth resistor, and the output terminal of the first comparator is connected to the output terminal of the second optocoupler.
  • the controlled end is connected, and the control end of the second optocoupler is connected with the signal receiving end of the master station;
  • the second optocoupler is used for sending corresponding high and low level signals to the signal receiving end of the master station according to the high and low level signals output by the first comparator.
  • the master station signal sending module includes a third optocoupler, a voltage regulator chip, a first voltage regulator diode and a second voltage regulator diode;
  • the controlled end of the third optocoupler is connected to the signal sending end of the master station, the output positive electrode and the output negative electrode of the third optocoupler are respectively connected to the negative electrode and the positive electrode of the second voltage stabilizer diode, and the voltage stabilizer
  • the input terminal of the chip is connected to the bus voltage
  • the ground terminal of the voltage regulator chip is connected to the negative electrode of the first voltage regulator diode
  • the positive electrode of the first voltage regulator diode is connected to the negative electrode of the second voltage regulator diode.
  • the anode of the second voltage stabilizer diode is grounded, and the output end of the voltage stabilizer chip is the output end of the master station signal sending module.
  • the communication protection module includes a second diode, a transient diode, a third capacitor and a thermistor;
  • the anode of the second diode is the first end of the communication protection module, the anode of the second diode is grounded through the third capacitor, and the cathode of the second diode is grounded through the thermal
  • the varistor is connected to the anode of the slave station, the cathode of the slave station is grounded, and the cathode of the second diode is also grounded through the transient diode.
  • the communication protection module is further configured to receive the first output voltage to supply power to the slave station.
  • the present application also provides a bus communication device, the bus communication device includes a master station, a slave station, and a bus communication circuit respectively connected to the master station and the slave station, the bus The communication circuit is configured as a bus communication circuit as described above.
  • the reference voltage obtained by the master station signal receiving module can be adjusted in the face of signal interference caused by different slave station equipment terminals or different external environments.
  • the bus communication circuit can be adapted to various slave devices, and the application of the bus communication circuit can be improved. sex.
  • the communication circuit can ensure the maximum noise tolerance and anti-interference ability.
  • FIG. 1 is a schematic block diagram of an embodiment of a bus communication circuit of the present application
  • FIG. 2 is a schematic diagram of the circuit structure of the embodiment of FIG. 1;
  • FIG. 3 is a schematic diagram of a circuit structure of an embodiment of the first control unit in the embodiment of FIG. 2;
  • FIG. 4 is a schematic diagram of a circuit structure of another embodiment of the first control unit in the embodiment of FIG. 2 .
  • the present application provides a bus communication circuit, which is applied to a bus communication device, and the bus communication device can realize data communication between a master station and multiple slave stations.
  • the bus communication circuit includes a master station signal sending module 10 , a communication protection module 20 , a signal conversion resistor R, a master station signal receiving module 30 and a program-controlled reference voltage adjustment module 40 .
  • the input end of the master station signal sending module 10 is connected with the signal sending end of the master station 50, the output end of the master station signal sending module 10 is connected with the first end of the communication protection module 20 through the signal conversion resistor R, and the first end of the communication protection module 20 is connected.
  • the two ends are connected to the slave station 60 , and the first end of the communication protection module 20 is also connected to the first input end of the master station signal receiving module 30 and the input end of the program-controlled reference voltage adjustment module 40 , and the output end of the program-controlled reference voltage adjustment module 40 It is connected with the second input end of the master station signal receiving module 30 , and the output end of the master station signal receiving module 30 is connected with the signal receiving end of the master station 50 .
  • the master station 50 can send a corresponding data signal, such as a logic signal "1” or "0", to the input of the master station signalling module 10 .
  • the master station signal sending module 10 correspondingly adjusts the outputted first output voltage according to the data signal. That is, the first output voltage output by the master station signal sending module 10 when it receives the logic signal "1" is not the same as the first output voltage when it receives the logic signal "0", and has a larger voltage amplitude difference value to enable the back end to recognize two different first output voltages.
  • the communication protection module 20 can realize the reception and transmission of data signals.
  • the communication protection module 20 can send the first output voltage to the slave station 60, and the slave station 60 can send the first output voltage according to the voltage amplitude of the first output voltage.
  • the value can determine the corresponding data signal to realize the data transmission process from the master station 50 to the slave station 60 .
  • the communication protection module 20 may also receive a data signal sent by the slave station 60, and adjust the first output current according to the data signal.
  • the first output voltage is the output voltage of the output terminal of the master signal sending module 10
  • the first output current is the current on the current loop formed by the master signal sending module 10 , the signal conversion resistor R and the communication protection module 20 .
  • the data signal sent by the slave station 60 can be a logic signal "0" or "1".
  • the first output current can remain unchanged; when the signal "0" is sent, the The consumption of a pulse current is added to the original first output current, and the signal data sent by the slave station 60 can be determined by detecting the current amplitude of the first output current.
  • the magnitude of the voltage reduction of the first output voltage after passing through the signal conversion resistor R is the product of the resistance value of the signal conversion resistor R and the current value of the normal first output current.
  • the voltage drop across the signal conversion resistor R increases, and the increased voltage amplitude is the product of the current value of the pulse current and the resistance value of the signal conversion resistor R. That is, when a pulse current is generated in the current loop, the voltage drop generated on the signal conversion resistor R increases, so that the voltage value at one end of the signal conversion resistor R away from the signal transmitting module 10 of the master station is relative to the voltage when no pulse current is generated. value is further reduced.
  • the master station signal receiving module 30 can receive two different first output voltages after being stepped down by the signal conversion resistor R, which are the first signal voltage and the second signal voltage, respectively.
  • the first signal voltage is the voltage received by the master station signal receiving module 30 after the first output voltage passes through the voltage drop of the signal conversion resistor R when the slave station 60 generates a pulse current;
  • the second signal voltage is the slave station 60 voltage.
  • the first output voltage is the voltage received by the master station signal receiving module 30 after passing through the voltage drop of the signal conversion resistor R.
  • the output reference voltage is adjusted by the program-controlled reference voltage adjustment module 40, so that when the pulse current is not generated, the second signal voltage received by the master station signal receiving module 30 is higher than the reference voltage; and when the pulse current is generated , the first signal voltage received by the master station signal receiving module 30 is lower than the reference voltage, that is, the reference voltage is adjusted so that the magnitude of the reference voltage is between the first signal voltage and the second signal voltage.
  • the actual signal voltage By comparing the actual signal voltage with the reference voltage, it can be determined that the actual signal voltage is the second signal voltage when it is greater than the reference voltage, and the first signal voltage when it is less than the reference voltage, and then determines whether a pulse current is generated in the current loop. , to obtain the data signal sent by the slave station 60 .
  • the master station signal receiving module 30 determines the data signal sent by the slave station 60 , it can send it to the signal receiving end of the master station 50 , so as to realize the data transmission process from the slave station 60 to the master station 50 .
  • the amplitude of the generated pulse current is not the same, so the voltage amplitude of the first output voltage after the step-down will change, that is, the first signal voltage and The second signal voltage varies with the size of the slave meter.
  • the master station signal receiving module 30 cannot judge whether a pulse current is generated according to the comparison between the signal voltage and the reference voltage, and thus cannot determine whether the slave Data signal from station 60.
  • the output reference voltage is adjusted so that the size of the reference voltage is between the first signal voltage and the second signal voltage, which can be passed through This actual signal voltage determines that the slave station 60 sends a data signal. That is, for the equipment terminals of different slave stations 60, the reference voltage is tested and adjusted by the process control reference voltage adjustment module 40, and the reference voltages corresponding to the equipment terminals of different slave stations 60 can be obtained respectively, so that the bus communication circuit can adapt to Equipped with equipment terminals of different slave stations 60, the applicability of the bus communication circuit is improved.
  • the number of slave stations 60 can be set to one or more, and each slave station 60 is connected to one end of the signal conversion resistor R through its corresponding communication protection module 20, and the signal conversion resistor The other end of R is connected with the signal sending module 10 of the master station.
  • the reference voltage when the reference voltage is set between the first signal voltage and the second signal voltage, if the voltage difference between the reference voltage and the first signal voltage is small, the first signal voltage will be affected by the superposition of noise signals in the external environment. When the voltage increases, the voltage of the first signal after superimposing the interference signal is likely to be greater than the reference voltage, thereby affecting the determination of the data signal by the signal receiving module 30 of the master station. That is, the reference voltage not only needs to be set between the first signal voltage and the second signal voltage, but also needs to have a certain voltage difference with both the first signal voltage and the second signal voltage to provide noise tolerance.
  • the maximum theoretical noise tolerance value can be obtained, and the maximum theoretical noise tolerance value is the first signal voltage and the second signal voltage. A half of the voltage difference between the two signal voltages, thereby improving the anti-interference ability of the bus communication circuit.
  • the reference voltage obtained by the signal receiving module 30 of the master station can be adjusted. make adjustments.
  • the bus communication circuit can be adapted to various devices of the slave stations 60, and the applicability of the bus communication circuit can be improved.
  • the size of the reference voltage can be close to the average value of the first signal voltage and the second signal voltage, a larger theoretical noise tolerance value can be obtained, and the anti-interference ability of the bus communication circuit can be improved.
  • the above-mentioned program-controlled reference voltage adjustment module 40 may include a first diode D1 and a plurality of resistance unit circuits 41 connected in parallel with each other.
  • the anode of the first diode D1 is connected to the first end of the communication protection module 20
  • the cathode of the first diode D1 is respectively connected to the first end of each resistance unit circuit 41
  • the second end of each resistance unit circuit 41 is respectively connected. Both terminals are connected to the second input terminal of the master station signal receiving module 30 .
  • the program-controlled reference voltage adjustment module 40 can control the on-off of the plurality of resistance unit circuits 41 to adjust the equivalent resistance of the program-controlled reference voltage adjustment module 40 .
  • the overall equivalent resistance of the program-controlled reference voltage adjustment module 40 is the resistance value of the parallel connection of the equivalent resistances of each on-resistance unit circuit 41 .
  • the second end-to-ground input impedance of the master station signal receiving module 30 and the equivalent resistance of the program-controlled reference voltage adjustment module 40 form a voltage divider circuit, and the equivalent resistance of the program-controlled reference voltage adjustment module 40 is the pull-up resistor.
  • the input impedance to ground of the second end of the receiving module 30 is the pull-down resistor, and the reference voltage obtained by the second end of the master station signal receiving module 30 is the voltage value of the first output voltage divided by the voltage dividing circuit .
  • the reference voltage can be reduced by increasing the overall equivalent resistance of the program-controlled reference voltage adjustment module 40 ; and the reference voltage can be increased by reducing the overall equivalent resistance of the program-controlled reference voltage adjustment module 40 .
  • the program-controlled reference voltage adjustment module 40 can generate a plurality of different equivalent resistances by controlling the on-off of the plurality of resistance unit circuits 41 . After arranging the equivalent resistances that can be generated from small to large, the reference voltage can be determined by testing whether the reference voltage obtained in the case of each equivalent resistance is between the first signal voltage and the second signal voltage. Voltage range of voltage values.
  • each resistance unit circuit 41 when the equivalent resistance of each resistance unit circuit 41 is not the same, there are a total of 8 combinations. By omitting the equivalent infinite resistance when all three resistance unit circuits 41 are disconnected, there are 7 kinds of equivalent resistance combinations. After arranging the 7 combinations in order of magnitude, an effective combination can be obtained by traversing and testing each equivalent resistance combination. For example, in the 1st and 2nd combinations with smaller equivalent resistance among the 7 combinations, the generated reference voltage is not between the first signal voltage and the second signal voltage, while the generated reference voltages in the 3rd to 7th combinations The reference voltage is located between the first signal voltage and the second signal voltage.
  • the reference voltages corresponding to the combinations 3-7 can realize the signal data transmission of the device terminal of the slave station 60 .
  • the reference voltage corresponding to the fifth combination can also be selected from the third to seventh combinations, so that the reference voltage is closer to the average value of the first signal voltage and the second signal voltage, so that the master station signal receiving module The 30 has some noise margin capability when comparing the actual signal voltage to a reference voltage.
  • Each resistor unit circuit 41 described above includes an adjustment resistor Ri, a first switch transistor Q1 , a first resistor R1 , a second resistor R2 , a first capacitor C1 and a first control unit 42 .
  • the cathode of the first diode D1 is respectively connected to the first end of the first capacitor C1, the first end of the first resistor R1 and the first end of the first switch tube Q1, and the control end of the first switch tube Q1 is respectively connected to the first end of the first switch tube Q1.
  • the second end of the capacitor C1, the second end of the first resistor R1, and the first end of the second resistor R2 are connected, and the second end of the second resistor R2 is connected to the control end of the first control unit 42.
  • the first control unit The controlled end of 42 is connected to the master station 50 , and the second end of the first switch tube Q1 is connected to the second input end of the signal receiving module 30 of the master station.
  • the master station 50 can control the on-off of each resistance unit circuit 41 by sending a control signal.
  • the first switch transistor Q1 may be a PNP transistor or a P-channel MOS transistor.
  • FIG. 2 shows a circuit schematic diagram of the resistor unit circuit 41 when the first switch transistor Q1 is a PNP transistor.
  • the master station 50 can send a turn-on signal or a turn-off signal to the first control unit 42, and when the first control unit 42 receives the turn-on signal, it can ground the control end of the first switch tube Q1 to turn on the first switch tube Q1 ; When the first control unit 42 receives the cut-off signal, the control terminal of the first switch tube Q1 can be empty, so that the first switch tube Q1 is turned off.
  • the master station 50 in the program-controlled reference voltage adjustment module 40 composed of three resistance unit circuits 41 , the master station 50 can respectively control the first control unit 42 in each resistance unit circuit 41 through the CTR1 , CTR2 and CTR3 ports respectively. .
  • the first capacitor C1 and the first resistor R1 can prevent the control terminal of the first switch transistor Q1 from vibrating due to external signals, and avoid malfunction of the first switch transistor Q1.
  • the first diode D1 is a charging diode
  • the first capacitor C1 is an energy storage capacitor
  • the pulse current is usually 11 mA to 20 mA.
  • the voltage on the first resistor R1 is the second signal voltage
  • the first capacitor C1 is charged.
  • the pulse current is generated to reduce the second signal voltage to the first signal voltage
  • the first capacitor C1 can discharge the voltage on the first resistor R1 to maintain the second signal voltage.
  • the first resistor R1 and the second resistor R2 form a voltage divider circuit, wherein the resistance value of the first resistor R1 is much larger than that of the second resistor R2, so that when the second resistor R2 is grounded, the first switch tube Q1 controls the level of the terminal When the level is low, the first switch transistor Q1 is turned on. When the second resistor R2 is not grounded, the control terminal level of the first switch transistor Q1 is at a high level, and the first switch transistor Q1 is turned off.
  • the above-mentioned signal conversion resistor R may be a wire-wound resistor, and the resistance parameter of the wire-wound resistor may be 100 ⁇ -3W.
  • the first resistor R1 can be set to be at least ten times larger than the second resistor R2, and the second resistor R2 can be set to at least 10K ⁇ , so that after the second resistor R2 divides the voltage, the control terminal level on the first switch tube Q1 is lower than the lead level.
  • the turn-on level value ensures that the first switch tube Q1 is saturated and turned on.
  • the first diode D1 can be a Schottky diode with a small reverse current and a reduced forward voltage, such as a BAT54 Schottky diode with a forward voltage drop of about 0.2V and a reverse leakage current of less than 0.1 ⁇ A.
  • the first switch transistor Q1 may be a PNP transistor, such as a germanium transistor with a voltage drop of 0.1V-0.2V when a small current is saturated and turned on.
  • the resistance unit circuit 41 When the first switch transistor Q1 is turned on, the resistance unit circuit 41 is in a conducting state. When some of the resistance unit circuits 41 of the plurality of resistance unit circuits 41 are in the conducting state, the overall equivalent resistance of the plurality of resistance unit circuits 41 is the resistance value in which the adjustment resistances Ri of the conducting resistance unit circuits 41 are connected in parallel with each other.
  • the adjustment resistances Ri in each resistance unit circuit 41 may be set to be different from each other.
  • the resistance values of the adjustment resistors Ri are all different, when the number of resistance unit circuits 41 is n, the number of combinations of all equivalent resistances that can be obtained is 2 n , and when all the resistance unit circuits 41 are disconnected The combined number of effective equivalent resistances after removing the infinite equivalent resistance is 2 n -1.
  • the reference voltage in the combination y is already higher than the first signal voltage and the second signal voltage, the larger reference voltage is undoubtedly also unsatisfactory, and other combinations of the equivalent resistance combination whose equivalent resistance is smaller than the combination y are no longer required. Carry out tests to save test time and improve test efficiency.
  • the first control unit 42 can be the first optocoupler N1 , and when the master station 50 sends a turn-on signal to the first optocoupler N1 , the first optocoupler N1 can The second end of the second resistor R2 is grounded; and when the master station 50 sends a cutoff signal to the first optocoupler N1, the first optocoupler N1 can leave the second end of the second resistor R2 empty.
  • the first control unit 42 may be the second switch tube Q2, and when the master station 50 sends a turn-on signal to the second switch tube Q2, The second switch Q2 can ground the second end of the second resistor R2; when the master station 50 sends a cutoff signal to the second switch Q2, the second switch Q2 can empty the second end of the second resistor R2.
  • the second switch transistor Q2 may also be a triode or a MOS transistor, and FIG. 4 only shows a circuit schematic diagram of the first control unit 42 when the second switch transistor is a triode.
  • the above-mentioned master station signal receiving module 30 may include a first comparator A1 , a third resistor R3 , a fourth resistor R4 , a second capacitor C2 and a second optocoupler N2 .
  • the first input terminal of the first comparator A1 is connected to the first terminal of the communication protection module 20 through the third resistor R3, and the second input terminal of the first comparator A1 is respectively connected to the second terminal of each resistance unit circuit 41.
  • the second end of the first comparator A1 is grounded through the fourth resistor R4, the second capacitor C2 is connected in parallel with the fourth resistor R4, the output end of the first comparator A1 is connected to the controlled end of the second optocoupler N2, the second The control end of the optocoupler N2 is connected to the signal receiving end of the master station 50 .
  • the first input terminal of the first comparator A1 can receive the first signal voltage or the second signal voltage, and the second input terminal can receive the reference voltage. After the first comparator A1 receives the actual signal voltage at the first end, it can be determined that the actual signal voltage is the first signal voltage or the second signal voltage by comparing with the reference voltage. When the actual signal voltage is greater than the reference voltage, the actual signal voltage is the second signal voltage; when the actual signal voltage is less than the reference voltage, the actual signal voltage is the first signal voltage.
  • the first comparator A1 When the first comparator A1 receives the first signal voltage, it can output a low-level signal; and when it receives the second signal voltage, it can output a high-level signal.
  • the second optocoupler N2 When the second optocoupler N2 receives a low-level signal, it can send a corresponding low-level signal to the signal receiving end of the master station 50; when the second optocoupler N2 receives a high-level signal, it can send a corresponding low-level signal to the master station 50
  • the signal receiving end sends the corresponding high-level signal, and the transmission of the logic signal can be realized through the high-low level signal.
  • the second optocoupler N2 can isolate the master station 50 from the bus communication circuit.
  • the reference voltage and the actual signal voltage of the input end of the first comparator A1 are both about 30V.
  • the optocoupler isolation part can be added or cancelled adaptively to suit different application scenarios. For example, when strong and weak current safety isolation is required, optocoupler isolation is required.
  • the output end of the first comparator A1 is directly connected to the signal receiving end of the master station 50 to reduce device cost.
  • the above-mentioned master station signal sending module 10 may include a third optocoupler N3, a voltage regulator chip U1, a first voltage regulator diode ZD1 and a second voltage regulator diode ZD2.
  • the controlled end of the third optocoupler N3 is connected to the signal transmitting end of the master station 50 , the output positive pole and the output negative pole of the third optocoupler N3 are respectively connected to the negative pole and positive pole of the second Zener diode ZD2, and the input of the regulator chip U1 Terminate the bus voltage, the ground terminal of the voltage stabilizing chip U1 is connected to the negative electrode of the first zener diode ZD1, the positive electrode of the first zener diode ZD1 is connected to the negative electrode of the second zener diode ZD2, and the positive electrode of the second zener diode ZD2 Grounding, the output end of the voltage regulator chip U1 is the output end of the main station signal sending module 10 .
  • the ground terminal of the voltage regulator chip U1 is grounded through two voltage regulator diodes.
  • the ground-to-ground voltage of the voltage-stabilizing chip U1 is the sum of the breakdown voltages of the two voltage-stabilizing diodes.
  • the signal sending end of the master station 50 can send high and low level signals as logic signals "0" or "1".
  • the third optocoupler N3 receives the low-level signal, the third optocoupler N3 can short-circuit the second Zener diode ZD2. At this time, the voltage of the ground terminal of the voltage regulator chip U1 to the ground is the breakdown voltage of a voltage regulator diode.
  • the third optocoupler N3 receives a high-level signal, the voltage of the output terminal of the Zener chip U1 to ground is 31V;
  • the third optocoupler N3 receives a low level signal, the second Zener diode ZD2 is short-circuited, and the voltage of the output terminal of the Zener chip U1 to ground is 18V.
  • the logic signal sent by the signal sending end of the master station 50 can be determined by detecting the output voltage of the voltage regulator chip U1, thereby realizing the signal transmission process.
  • the TX end in FIG. 2 is the signal transmitting end of the master station 50
  • the RX end is the signal receiving end of the master station 50
  • the above-mentioned first optocoupler N1 may be a common optocoupler.
  • the second optocoupler N2 and the third optocoupler N3 can be ordinary optocouplers, or high-speed optocouplers can be selected according to the actual communication baud rate.
  • the above communication protection module 20 may include a second diode D2, a transient diode TVS, a third capacitor C3 and a thermistor PTC.
  • the anode of the second diode D2 is the first end of the communication protection module 20, the anode of the second diode D2 is grounded through the third capacitor C3, and the cathode of the second diode D2 is connected to the slave station 60 through the thermistor PTC
  • the anode of the slave station 60 is connected to the ground, the cathode of the slave station 60 is grounded, and the cathode of the second diode D2 is also grounded through the transient diode TVS.
  • the transient diode TVS can absorb the static electricity, lightning strike and other spike pulse signals generated between the interface of the master station 50 and the slave station 60 to protect the communication circuit.
  • the resistance of the thermistor PTC increases with the increase of temperature, and finally disconnects the circuit to protect the power supply of the master station 50 and avoid external short circuit and overload damage to the power supply of the master station 50 . It is understood that when the temperature of the thermistor PTC decreases, the current loop can be turned on again.
  • the third capacitor C3 plays a filtering role and can filter the AC interference signal.
  • the slave station 60 when the slave station 60 receives the first output voltage, the voltage will change with the distance and the bus current, and the slave station 60 can detect whether the voltage differs from the dynamic reference voltage by a preset voltage threshold.
  • the corresponding logic signal "0" or “1” is determined.
  • the slave station 60 can realize dynamic level recognition through the interface chip TSS721A.
  • the dynamic reference voltage of the interface chip is obtained by charging the capacitor in the chip with the voltage received from the access position of the slave station 60.
  • the baud rate is greater than 300, there is a higher value for every 11 bits in the transmitted bit stream.
  • the output voltage can ensure that the dynamic reference voltage is stable in the vicinity of the higher output voltage.
  • the interface chip receives the actual output voltage, it can determine whether the corresponding logic signal "0" or "1" is received by judging whether the difference between the actual output voltage and the dynamic reference voltage exceeds 10V.
  • the first signal voltage or the second signal voltage sent by the signal sending module 10 of the master station is higher than the working voltage of the equipment of the slave station 60, and the static standby current of the slave station 60 is the first signal voltage or the second signal voltage.
  • the step-down first output voltage obtained by the communication protection module 20 can also be used as the working voltage of the slave station 60 to supply power to the slave station 60 after being stabilized by the two Zener diodes.
  • the calculation formula of the reference voltage received by the second end of the first comparator A1 may be:
  • Umark is the first output voltage
  • Imark is the first output current
  • R is the resistance value of the signal conversion resistor R
  • Ud1 is the conduction voltage drop of the first diode D1
  • Uq1 is the conduction of the first switch tube Q1 Voltage drop
  • Rb is the equivalent resistance of the fourth resistor R4, the equivalent DC impedance of the second capacitor C2, and the input impedance to ground of the first comparator A1 in parallel
  • the combination of R is the resistance unit circuit 41 that is all turned on.
  • the equivalent resistance after the adjustment resistor Ri is connected in parallel.
  • the present application also provides a bus communication device, the bus communication device includes a master station 50, a slave station 60, and a bus communication circuit respectively connected to the master station 50 and the slave station 60, and the structure of the bus communication circuit can be Referring to the above embodiments, details are not repeated here. As a matter of course, since the bus communication device of this embodiment adopts the technical solution of the above-mentioned bus communication circuit, the bus communication device has all the beneficial effects of the above-mentioned bus communication circuit.

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Abstract

本申请公开了一种总线通信电路，包括主站信号发送模块、通信保护模块、信号转换电阻、主站信号接收模块以及程控参考电压调整模块；主站信号发送模块的输入端与主站的信号发送端连接，主站信号发送模块的输出端通过信号转换电阻分别与通信保护模块、程控参考电压调整模块以及主站信号接收模块连接，程控参考电压调整模块还与主站信号接收模块连接，主站信号接收模块的输出端与主站的信号接收端连接。

Description

总线通信电路及装置
本申请要求于2020年12月25日提交中国专利局、申请号为202011573828.8、申请名称为“总线通信电路及装置”的中国专利申请的优先权，其全部内容通过引用结合在申请中。
技术领域
本申请涉及电路电子领域，尤其涉及总线通信电路及装置。
背景技术
现有的远程抄表系统M-BUS总线通信方式，是一种主从式半双工传输总线，采用主叫/应答的方式实现双端通信，即主站发出询问后，从站向主站传输数据。其中，主站可以向从站发送总线电压为从站进行供电，并通过总线电压的电压幅值变化向从站发送“1”或“0”的逻辑信号，以实现数据传输。从站则可以通过在正常的从站电流中加入脉冲电流的方式向主站发送“1”或“0”的逻辑信号。即，主站可以通过总线向从站发送信号的同时为从站进行供电，以使得从站的终端仪表中设置的电池仅作为备用电源使用，降低了从站端的定期维护、更换电池等工作需求。
然而，在现有的远程抄表所使用的终端仪表中，不同的仪表由于规格型号不同，其所产生的脉冲电流并不相同，而总线通信中实现脉冲电流识别的模块在脉冲电流发生变化时无法准确识别逻辑信号。并且由于总线长度较长，外部环境所产生的噪声信号较高，在噪声信号的影响下也容易发生数据传输异常。即，现有的总线通信方式在面对不同规格的从站仪表或不同环境的噪声干扰时，适用性较低。
申请内容
本申请的主要目的在于提供一种总线通信电路及装置，旨在解决现有的总线通信方式抗干扰能力和自适应调整能力不足的问题。
为了实现上述目的，本申请提供一种总线通信电路，包括主站信号发送模块、通信保护模块、信号转换电阻、主站信号接收模块以及程控参考电压调整模块；
所述主站信号发送模块的输入端与主站的信号发送端连接，所述主站信号发送模块的输出端通过所述信号转换电阻与所述通信保护模块的第一端连接，所述通信保护模块的第二端与从站连接，所述通信保护模块的第一端还与所述主站信号接收模块的第一输入端以及所述程控参考电压调整模块的输入端连接，所述程控参考电压调整模块的输出端与所述主站信号接收模块的第二输入端连接，所述主站信号接收模块的输出端与主站的信号接收端连接；
所述主站信号发送模块，用于根据主站发出的数据信号调整第一输出电压；
所述通信保护模块，用于将所述第一输出电压发送至从站，以使从站根据所述第一输出电压转换得到主站发出的数据信号，还用于根据从站发出的数据信号调整第一输出电流；
所述信号转换电阻，用于根据所述第一输出电流对所述第一输出电压进行降压调整，以得到第一信号电压或第二信号电压；
所述程控参考电压调整模块，用于调整输出的参考电压为第一信号电压和第二信号电压之间；
所述主站信号接收模块，用于接收所述第一信号电压或所述第二信号电压并与参考电压进行比较，以得到从站发出的数据信号并发送至主站。
在一实施例中，所述程控参考电压调整模块包括第一二极管以及多个相互并联的电阻单元电路；
所述第一二极管的正极与所述通信保护模块的第一端连接，所述第一二极管的负极分 别与每个电阻单元电路的第一端连接，每个电阻单元电路的第二端均与所述主站信号接收模块的第二输入端连接；
所述程控参考电压调整模块，用于通过控制多个所述电阻单元电路的通断以调节所述程控参考电压调整模块的等效电阻。
在一实施例中，每个所述电阻单元电路包括调整电阻、第一开关管、第一电阻、第二电阻、第一电容以及第一控制单元；
所述第一二极管的负极分别与所述第一电容的第一端、所述第一电阻的第一端以及所述第一开关管的第一端连接，所述第一开关管的控制端分别与所述第一电容的第二端、所述第一电阻的第二端以及所述第二电阻的第一端连接，所述第二电阻的第二端与所述第一控制单元的控制端连接，所述第一控制单元的受控端与主站连接，所述第一开关管的第二端与所述主站信号接收模块的第二输入端连接；
所述第一控制单元，用于根据主站发送的控制信号控制所述第一开关管的导通和关断。
在一实施例中，所述第一控制单元为第一光耦或第二开关管。
在一实施例中，每个所述电阻单元电路中的调整电阻互不相同。
在一实施例中，所述主站信号接收模块包括第一比较器、第三电阻、第四电阻、第二电容以及第二光耦；
所述第一比较器的第一输入端通过所述第三电阻与所述通信保护模块的第一端的连接，所述第一比较器的第二输入端分别与每个电阻单元电路的第二端连接，所述第一比较器的第二端通过第四电阻接地，所述第二电容与所述第四电阻并联，所述第一比较器的输出端与所述第二光耦的受控端连接，所述第二光耦的控制端与主站的信号接收端连接；
所述第二光耦，用于根据所述第一比较器输出的高低电平信号向主站的信号接收端发送相应的高低电平信号。
在一实施例中，所述主站信号发送模块包括第三光耦、稳压芯片、第一稳压二极管以及第二稳压二极管；
所述第三光耦的受控端与主站的信号发送端连接，所述第三光耦的输出正极和输出负极分别与所述第二稳压二极管的负极和正极连接，所述稳压芯片的输入端接总线电压，所述稳压芯片的接地端与所述第一稳压二极管的负极连接，所述第一稳压二极管的正极与所述第二稳压二极管的负极连接，所述第二稳压二极管的正极接地，所述稳压芯片的输出端为所述主站信号发送模块的输出端。
在一实施例中，所述通信保护模块包括第二二极管、瞬态二极管、第三电容及热敏电阻；
所述第二二极管的正极为所述通信保护模块的第一端，所述第二二极管的正极通过所述第三电容接地，所述第二二极管的负极通过所述热敏电阻与从站的正极连接，从站的负极接地，所述第二二极管的负极还通过所述瞬态二极管接地。
在一实施例中，所述通信保护模块，还用于接收所述第一输出电压为从站供电。
此外，为实现上述目的，本申请还提供一种总线通信装置，所述总线通信装置包括主站、从站以及与分别与所述主站和所述从站连接的总线通信电路，所述总线通信电路被配置为如上所述的总线通信电路。
本申请通过设置程控参考电压调整模块，在面对不同的从站设备终端或者不同的外部环境造成的信号干扰时，能够对主站信号接收模块所获得的参考电压进行调整。通过调整参考电压的大小，使其位于第一信号电压和第二信号电压之间的最佳值，能够使得总线通信电路适配于各种不同的从站设备中，提升该总线通信电路的适用性。通过调整参考电压的大小，使其接近第一信号电压和第二信号电压的最佳值，能够保证通信电路获得最大的 噪声容限和抗干扰能力。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图示出的结构获得其他的附图。
图1为本申请总线通信电路一实施例的模块示意图；
图2为图1实施例的电路结构示意图；
图3为图2实施例中第一控制单元一实施例的电路结构示意图；
图4为图2实施例中第一控制单元另一实施例的电路结构示意图。
本申请目的的实现、功能特点及优点将结合实施例，参照附图做进一步说明。
附图标号说明：
标号 名称 标号 名称
10 主站信号发送模块 Ri 调整电阻
20 通信保护模块 D1～D2 第一二极管～第二二极管
30 主站信号接收模块 Q1～Q2 第一开关管～第二开关管
40 程控参考电压调整模块 R1～R4 第一电阻～第四电阻
41 电阻单元电路 C1～C3 第一电容～第三电容
42 第一控制单元 N1～N3 第一光耦～第三光耦
PTC 热敏电阻 ZD1 第一稳压二极管
U1 稳压芯片 ZD2 第二稳压二极管
A1 第一比较器 TVS 瞬态二极管
R 信号转换电阻 50 主站
60 从站    
具体实施方式
应当理解，此处所描述的具体实施例仅仅用以解释本申请，并不用于限定本申请。
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请的一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
需要说明，本申请实施例中所有方向性指示(诸如上、下、左、右、前、后……)仅用于解释在某一特定姿态(如附图所示)下各部件之间的相对位置关系、运动情况等，如果该特定姿态发生改变时，则该方向性指示也相应地随之改变。
另外，在本申请中涉及“第一”、“第二”等的描述仅用于描述目的，而不能理解为指示或暗示其相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。另外，各个实施例之间的技术方案可以相互结合，但是必须是以本领域普通技术人员能够实现为基础，当技术方案的结合出现相互矛盾或无法实现时应当认为这种技术方案的结合不存在，也不在本申请要求的保护范围之内。
本申请提供一种总线通信电路，应用于总线通信装置中，该总线通信装置可以实现一个主站与多个从站之间的数据通信。
参见图1，在一实施例中，所述总线通信电路包括主站信号发送模块10、通信保护模块20、信号转换电阻R、主站信号接收模块30以及程控参考电压调整模块40。主站信号发送模块10的输入端与主站50的信号发送端连接，主站信号发送模块10的输出端通过信号转换电阻R与通信保护模块20的第一端连接，通信保护模块20的第二端与从站60 连接，通信保护模块20的第一端还与主站信号接收模块30的第一输入端以及程控参考电压调整模块40的输入端连接，程控参考电压调整模块40的输出端与主站信号接收模块30的第二输入端连接，主站信号接收模块30的输出端与主站50的信号接收端连接。
主站50可以向主站信号发送模块10的输入端发送相应的数据信号，例如逻辑信号“1”或“0”。主站信号发送模块10根据该数据信号对输出的第一输出电压进行相应调整。即，主站信号发送模块10在接收到逻辑信号“1”时输出的第一输出电压与接收到逻辑信号“0”时输出的第一输出电压并不相同，且具有较大的电压幅度差值，以使后端能够识别两种不同的第一输出电压。
通信保护模块20可以实现数据信号的接收和发送，在通信保护模块20接收到第一输出电压时，可以将该第一输出电压发送给从站60，从站60根据第一输出电压的电压幅值可以确定对应的数据信号，以实现主站50至从站60的数据传输过程。
通信保护模块20还可以接收从站60发出的数据信号，并根据该数据信号调整第一输出电流。其中，第一输出电压为主站信号发送模块10的输出端的输出电压，第一输出电流则为主站信号发送模块10、信号转换电阻R以及通信保护模块20所组成的电流回路上的电流。例如，从站60发送的数据信号可以为逻辑信号“0”或“1”，从站60在发送信号“1”时，可以保持第一输出电流不变；在发送信号“0”时，则在原有的第一输出电流上增加一个脉冲电流的消耗，通过检测第一输出电流的电流幅值，即可确定从站60发送的信号数据。
在从站60未产生脉冲电流时，第一输出电压在经过信号转换电阻R后电压降低的幅值为信号转换电阻R的电阻值与正常第一输出电流的电流值的乘积。而在从站60产生脉冲电流时，信号转换电阻R上的压降增大，增大的电压幅值为脉冲电流的电流值与信号转换电阻R的电阻值的乘积。即，在电流回路中产生脉冲电流时，信号转换电阻R上产生的压降增大，从而使得信号转换电阻R远离主站信号发送模块10的一端的电压值相对于未产生脉冲电流时的电压值进一步降低。
主站信号接收模块30可以接收两种不同的经过信号转换电阻R降压后的第一输出电压，分别为第一信号电压和第二信号电压。其中，第一信号电压为从站60产生脉冲电流时，第一输出电压在经过信号转换电阻R的压降后主站信号接收模块30所接收到的电压；第二信号电压则为从站60未产生脉冲电流时，第一输出电压在经过信号转换电阻R的压降后主站信号接收模块30所接收到的电压。可以理解的是，在电流回路中产生脉冲电流时，信号转换电阻R上的压降增大，第一信号电压在经过信号转换电阻R后的电压降低幅值更大，即第一信号电压低于第二信号电压。
通过程控参考电压调整模块40对输出的参考电压进行调整，可以使得在未产生脉冲电流时，主站信号接收模块30所接收到的第二信号电压高于该参考电压；而在产生脉冲电流时，主站信号接收模块30所接收到的第一信号电压低于该参考电压，即通过调整参考电压使得参考电压的大小为第一信号电压和第二信号电压之间。通过将实际信号电压与参考电压进行大小比较，即可确定该实际信号电压在大于参考电压时为第二信号电压，在小于参考电压时为第一信号电压，进而确定电流回路中是否产生脉冲电流，以得到从站60所发出的数据信号。主站信号接收模块30在确定从站60发出的数据信号后，可以将其发送至主站50的信号接收端，以实现从站60至主站50的数据传输过程。
需要说明的是，对于不同规格的从站仪表，所产生的脉冲电流的幅值并不相同，因而使得降压后的第一输出电压的电压幅值将会发生变化，即第一信号电压和第二信号电压随从站仪表的规格变化而变化。此时若第一信号电压和第二信号电压均大于或均小于参考电压，则会使得主站信号接收模块30无法根据信号电压与参考电压的大小比较来判断是否产生脉冲电流，从而无法确定从站60所发出的数据信号。而通过程控参考电压调整模块40，在面对不同的从站60的终端设备时，通过调整输出的参考电压，使得该参考电压的大小为第一信号电压和第二信号电压之间，能够通过该实际信号电压确定从站60发送数 据信号。即，针对不同的从站60的设备终端，通过程控参考电压调整模块40对参考电压进行测试调整，能够得到不同的从站60的设备终端分别对应的参考电压，以使得该总线通信电路能够适配于不同的从站60的设备终端中，提升该总线通信电路的适用性。
如图1所示，在总线通信电路中，从站60的数量可以设置为一个或多个，每个从站60通过与其对应的通信保护模块20与信号转换电阻R的一端连接，信号转换电阻R的另一端则与主站信号发送模块10连接。
同样地，在参考电压设置于第一信号电压和第二信号电压之间时，若参考电压与第一信号电压的电压差较小，则在第一信号电压因外部环境的噪声信号的叠加而导致电压增大时，容易出现叠加干扰信号后的第一信号电压大于参考电压，从而影响主站信号接收模块30对数据信号的判断。即，参考电压不仅需要设置于第一信号电压和第二信号电压之间，还需要与第一信号电压和第二信号电压均具有一定的电压差，以提供噪声容限。可以理解的是，通过将参考电压设置为第一信号电压和第二信号电压的平均值，能够获得最大的理论噪声容限值，该最大的理论噪声容限值即为第一信号电压和第二信号电压的电压之差的二分之一，从而提升该总线通信电路的抗干扰能力。
在本实施例中，通过设置程控参考电压调整模块40，在面对不同的从站60的设备终端或者不同的外部环境造成的信号干扰时，能够对主站信号接收模块30所获得的参考电压进行调整。通过调整参考电压的大小，使其位于第一信号电压和第二信号电压之间，能够使得总线通信电路适配于各种不同的从站60的设备中，提升该总线通信电路的适用性。通过调整参考电压的大小，使其接近第一信号电压和第二信号电压的平均值，能够获得较大的理论噪声容限值，提升该总线通信电路的抗干扰能力。
一并参照图1和图2，上述程控参考电压调整模块40可以包括第一二极管D1以及多个相互并联的电阻单元电路41。第一二极管D1的正极与通信保护模块20的第一端连接，第一二极管D1的负极分别与每个电阻单元电路41的第一端连接，每个电阻单元电路41的第二端均与主站信号接收模块30的第二输入端连接。
程控参考电压调整模块40可以控制多个电阻单元电路41的通断，以调节程控参考电压调整模块40的等效电阻。该程控参考电压调整模块40整体的等效电阻即为每个导通的电阻单元电路41的等效电阻并联后的电阻值。主站信号接收模块30的第二端对地输入阻抗与程控参考电压调整模块40的等效电阻构成一个分压电路，程控参考电压调整模块40的等效电阻即为上拉电阻，主站信号接收模块30的第二端的对地输入阻抗即为下拉电阻，则主站信号接收模块30的第二端所获得的参考电压即为第一输出电压通过该分压电路进行分压后的电压值。
可以理解的是，对于分压电路，在下拉电阻的阻值不变时，上拉电阻增大，则分压后的输出电压降低。即，通过增大程控参考电压调整模块40整体的等效电阻即可实现参考电压的降低；而减小程控参考电压调整模块40整体的等效电阻即可实现参考电压的增大。程控参考电压调整模块40通过控制多个电阻单元电路41的通断，可以生成多个不同的等效电阻。在将可生成的等效电阻由小到大进行排列后，通过测试每一种等效电阻的情况下所得到的参考电压是否位于第一信号电压和第二信号电压之间，即可确定参考电压的电压取值范围。以3个电阻单元电路41为例，在每个电阻单元电路41的等效电阻并不相同的情况下，一共存在8种组合。将3个电阻单元电路41均断开时的等效无穷大电阻舍去，则存在7种等效电阻组合。将7种组合按照大小顺序排列后，通过遍历测试每个等效电阻组合可以得到有效的组合。例如，在7种组合中等效电阻较小的第1、2种组合下，所生成的参考电压不位于第一信号电压和第二信号电压之间，而第3-7种组合下所生成的参考电压位于第一信号电压和第二信号电压之间。则可以确定第3-7种组合对应的参考电压能够实现该从站60的设备终端的信号数据传输。进一步地，还可以将第3-7种组合中选择第5种组合对应的参考电压，以使该参考电压更为接近第一信号电压和第二信号电压的平均 值，使得主站信号接收模块30在对实际信号电压与参考电压进行比较时具有一定的噪声容限能力。
上述每个电阻单元电路41包括调整电阻Ri、第一开关管Q1、第一电阻R1、第二电阻R2、第一电容C1以及第一控制单元42。第一二极管D1的负极分别与第一电容C1的第一端、第一电阻R1的第一端以及第一开关管Q1的第一端连接，第一开关管Q1的控制端分别与第一电容C1的第二端、第一电阻R1的第二端以及第二电阻R2的第一端连接，第二电阻R2的第二端与第一控制单元42的控制端连接，第一控制单元42的受控端与主站50连接，第一开关管Q1的第二端与主站信号接收模块30的第二输入端连接。
主站50可以通过发送控制信号控制每个电阻单元电路41的通断。第一开关管Q1可以为PNP型三极管或P沟道MOS管，图2中示出了第一开关管Q1为PNP型三极管时电阻单元电路41的电路原理图。主站50可以向第一控制单元42发送导通信号或截止信号，第一控制单元42接收到导通信号时可以将第一开关管Q1的控制端接地，以使第一开关管Q1导通；第一控制单元42接收到截止信号时可以将第一开关管Q1的控制端置空，以使第一开关管Q1截止。如图2所示，在3个电阻单元电路41组成的程控参考电压调整模块40中，主站50可以分别通过CTR1、CTR2以及CTR3端口分别控制每个电阻单元电路41中的第一控制单元42。
第一电容C1和第一电阻R1能够防止外部信号导致第一开关管Q1的控制端发生抖动，避免第一开关管Q1的误动作。
可以理解的是，第一二极管D1为充电二极管，第一电容C1为储能电容，脉冲电流通常为11mA～20mA。在未产生脉冲电流时，第一电阻R1上的电压为第二信号电压，则第一电容C1进行充电。在产生脉冲电流使得第二信号电压降低为第一信号电压时，第一电容C1可以通过放电使得第一电阻R1上的电压保持在第二信号电压。第一电阻R1和第二电阻R2构成分压电路，其中第一电阻R1的电阻值远大于第二电阻R2的电阻值，从而使得第二电阻R2接地时，第一开关管Q1控制端电平为低电平，第一开关管Q1导通。在第二电阻R2未接地时，第一开关管Q1的控制端电平为高电平，第一开关管Q1截止。
可以理解的是，上述信号转换电阻R可以为绕线电阻，该绕线电阻的电阻参数可以为100Ω-3W。第一电阻R1可以设置为至少大于第二电阻R2的十倍，第二电阻R2可以设置为至少10KΩ，以使第二电阻R2分压后第一开关管Q1上的控制端电平低于导通电平值，保证第一开关管Q1饱和导通。第一二极管D1可以为反向电流较小，正向导通压降低的肖特基二极管，如正向导通压降约为0.2V，反向漏电流小于0.1μA的BAT54肖特基二极管。第一开关管Q1可以为PNP型三极管，如小电流饱和导通时压降为0.1V～0.2V的锗管。每个电阻单元电路41中的第一电容C1能够避免干扰误动作的影响。主站信号接收模块30中的第四电阻R4和第二电容C2在选用时，要求时间常数τ＝RC较大，以使得电容所能够储存的能量更多。
在第一开关管Q1导通时，该电阻单元电路41为导通状态。在多个电阻单元电路41中的部分电阻单元电路41为导通状态时，该多个电阻单元电路41整体等效电阻即为导通的电阻单元电路41的调整电阻Ri相互并联的电阻值。
需要说明的是，为了得到不同的等效电阻组合，每个电阻单元电路41中的调整电阻Ri可以设置为互不相同。在调整电阻Ri的阻值均不相同的情况下，电阻单元电路41的数量为n个时，所能够得到的所有等效电阻的组合数量为2 n，将所有电阻单元电路41均断开时的无穷大等效电阻除去后的有效等效电阻的组合数量为2 n-1。
可以理解的是，在电阻单元电路41的数量较多时，2 n-1较大，采用遍历方式测量每种组合的等效电阻对应的参考电压是否满足需求需要耗费大量时间。则在确定每种组合的等效电阻并按照大小顺序排列后，还可以通过分段测试提升确定有效组合的效率。例如，选择两个相邻的等效电阻组合x和y，其中组合x的等效电阻低于组合y的等效电阻。若组 合x和组合y下所得到的参考电压均大于第一信号电压和第二信号电压，则将等效电阻进一步减少时，会使得参考电压进一步增大。由于组合y下参考电压已经高于第一信号电压和第二信号电压，则更大的参考电压毫无疑问同样不满足需求，则等效电阻组合中等效电阻小于组合y的其他组合不再需要进行测试，以节省测试时间，提升测试效率。
请参照图3，在总线通信电路具有隔离需求时，上述第一控制单元42可以为第一光耦N1，主站50向第一光耦N1发送导通信号时，第一光耦N1可以将第二电阻R2的第二端接地；而主站50向第一光耦N1发送截止信号时，第一光耦N1可以将第二电阻R2的第二端置空。
请参照图4，在总线通信电路不需要将控制部分与通信部分进行隔离时，上述第一控制单元42可以为第二开关管Q2，主站50向第二开关管Q2发送导通信号时，第二开关管Q2可以将第二电阻R2的第二端接地；主站50向第二开关管Q2发送截止信号时，第二开关管Q2可以将第二电阻R2的第二端置空。其中，第二开关管Q2也可以为三极管或MOS管，图4中仅示出第二开关管为三极管时第一控制单元42的电路原理图。
参照图2，上述主站信号接收模块30可以包括第一比较器A1、第三电阻R3、第四电阻R4、第二电容C2以及第二光耦N2。第一比较器A1的第一输入端通过第三电阻R3与通信保护模块20的第一端的连接，第一比较器A1的第二输入端分别与每个电阻单元电路41的第二端连接，第一比较器A1的第二端通过第四电阻R4接地，第二电容C2与第四电阻R4并联，第一比较器A1的输出端与第二光耦N2的受控端连接，第二光耦N2的控制端与主站50的信号接收端连接。
第一比较器A1的第一输入端可以接收第一信号电压或第二信号电压，第二输入端则可以接收参考电压。第一比较器A1在第一端接收到实际信号电压后，通过与参考电压进行大小比较即可确定该实际信号电压为第一信号电压或第二信号电压。当实际信号电压大于参考电压时，该实际信号电压即为第二信号电压；当实际信号电压小于参考电压时，该实际信号电压即为第一信号电压。
在第一比较器A1接收到第一信号电压时，可以输出低电平信号；而在接收到第二信号电压时，则可以输出高电平信号。第二光耦N2在接收到低电平信号时，可以向主站50的信号接收端发送相应的低电平信号；第二光耦N2在接收到高电平信号时，可以向主站50的信号接收端发送相应的高电平信号，通过高低电平信号即可实现逻辑信号的传输。
可以理解的是，上述实施例中第二光耦N2能够将主站50与总线通信电路进行隔离，第一比较器A1输入端的参考电压和实际信号电压均为30V左右的电压，通过设置光耦隔离能够避免通信部分中该较高的电压对主站50的低压信号产生影响。根据是否具有隔离需求，可以适应性地增设或取消光耦隔离部分，以适用不同的应用场景。例如在需要进行强弱电的安规隔离时，则需要设置光耦隔离。第一比较器A1的输出端直接与主站50的信号接收端连接，以减少器件成本。
上述主站信号发送模块10可以包括第三光耦N3、稳压芯片U1、第一稳压二极管ZD1以及第二稳压二极管ZD2。第三光耦N3的受控端与主站50的信号发送端连接，第三光耦N3的输出正极和输出负极分别与第二稳压二极管ZD2的负极和正极连接，稳压芯片U1的输入端接总线电压，稳压芯片U1的接地端与第一稳压二极管ZD1的负极连接，第一稳压二极管ZD1的正极与第二稳压二极管ZD2的负极连接，第二稳压二极管ZD2的正极接地，稳压芯片U1的输出端为主站信号发送模块10的输出端。
在第三光耦N3的输出正极和输出负极未导通时，稳压芯片U1的接地端通过两个稳压二极管接地。此时稳压芯片U1的接地端对地电压为两个稳压二极管的击穿电压之和。主站50的信号发送端可以发送高低电平信号作为逻辑信号“0”或“1”。在第三光耦N3接收到低电平信号时，第三光耦N3可以将第二稳压二极管ZD2进行短路。此时稳压芯片U1的接地端对地电压为一个稳压二极管的击穿电压。例如，在两个稳压二极管的击穿电压为 13V，总线电压为31V时，若第三光耦N3接收到高电平信号，则稳压芯片U1的输出端对地电压为31V；而若第三光耦N3接收到低电平信号，则第二稳压二极管ZD2短路，稳压芯片U1的输出端对地电压为18V。通过检测稳压芯片U1的输出电压即可确定主站50的信号发送端发送的逻辑信号，从而实现信号的传输过程。
可以理解的是，图2中TX端即为主站50的信号发送端，RX端即为主站50的信号接收端。上述第一光耦N1可以为普通光耦。第二光耦N2和第三光耦N3可以为普通光耦，也可以根据实际通信波特率选择高速光耦。
上述通信保护模块20可以包括第二二极管D2、瞬态二极管TVS、第三电容C3及热敏电阻PTC。第二二极管D2的正极为通信保护模块20的第一端，第二二极管D2的正极通过第三电容C3接地，第二二极管D2的负极通过热敏电阻PTC与从站60的正极连接，从站60的负极接地，第二二极管D2的负极还通过瞬态二极管TVS接地。
瞬态二极管TVS能够吸收主站50与从站60的接口之间所产生的静电、雷击等尖峰脉冲信号，以保护通信电路。在电流回路上的电流过大时，热敏电阻PTC的阻值随温度增加而增大，并最终断开电路，以保护主站50的电源，避免外部短路和过载损坏主站50的电源。可以理解的是，当热敏电阻PTC的温度降低时，电流回路可再次接通。第三电容C3起到滤波作用，能够将交流干扰信号进行过滤。
需要说明的是，从站60在接收第一输出电压时，该电压会随着距离和总线电流的变化而变化，则从站60可以通过检测该电压与动态参考电压是否相差预设电压阈值来确定对应的逻辑信号“0”或“1”。例如，从站60可以通过接口芯片TSS721A实现动态电平识别。该接口芯片的动态参考电压由从站60接入位置所接收的电压对芯片内的电容进行充电所获得，在波特率大于300的情况下，传输的bit流中每11位存在一个较高的输出电压，即可保证动态参考电压稳定在该较高输出电压附近。而在接口芯片接收到实际的输出电压时，通过判断该实际的输出电压与动态参考电压相差是否超过10V，即可确定接收对应的逻辑信号“0”或“1”。
可以理解的是，在上述实施例中，主站信号发送模块10发送的第一信号电压或第二信号电压均高于从站60的设备的工作电压，且从站60的静态待机电流为第一输出电流，则通信保护模块20所获取到的经过降压后的第一输出电压在经过两个稳压二极管稳压后，还可作为从站60的工作电压为从站60供电。
如图2所示，在一实施例中，第一比较器A1的第二端所接收到的参考电压的计算公式可以为：
Figure PCTCN2021086004-appb-000001
其中，Umark为第一输出电压，Imark为第一输出电流，R为信号转换电阻R的电阻值，Ud1为第一二极管D1的导通压降，Uq1为第一开关管Q1的导通压降，Rb为第四电阻R4、第二电容C2的等效直流阻抗以及第一比较器A1的对地输入阻抗并联后的等效电阻，R组合则为所有导通的电阻单元电路41中的调整电阻Ri并联后的等效电阻。
本申请还提供一种总线通信装置，该总线通信装置包括主站50、从站60以及与分别与所述主站50和所述从站60连接的总线通信电路，该总线通信电路的结构可参照上述实施例，在此不再赘述。理所应当地，由于本实施例的总线通信装置采用了上述总线通信电路的技术方案，因此该总线通信装置具有上述总线通信电路所有的有益效果。
以上仅为本申请的可选实施例，并非因此限制本申请的专利范围，凡是利用本申请说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其他相关的技术领域，均同理包括在本申请的专利保护范围内。

Claims (10)

  1. 一种总线通信电路，其中，包括主站信号发送模块、通信保护模块、信号转换电阻、主站信号接收模块以及程控参考电压调整模块；
    所述主站信号发送模块的输入端与主站的信号发送端连接，所述主站信号发送模块的输出端通过所述信号转换电阻与所述通信保护模块的第一端连接，所述通信保护模块的第二端与从站连接，所述通信保护模块的第一端还与所述主站信号接收模块的第一输入端以及所述程控参考电压调整模块的输入端连接，所述程控参考电压调整模块的输出端与所述主站信号接收模块的第二输入端连接，所述主站信号接收模块的输出端与主站的信号接收端连接；
    所述主站信号发送模块，用于根据主站发出的数据信号调整第一输出电压；
    所述通信保护模块，用于将所述第一输出电压发送至从站，以使从站根据所述第一输出电压转换得到主站发出的数据信号，还用于根据从站发出的数据信号调整第一输出电流；
    所述信号转换电阻，用于根据所述第一输出电流对所述第一输出电压进行降压调整，以得到第一信号电压或第二信号电压；
    所述程控参考电压调整模块，用于调整输出的参考电压为第一信号电压和第二信号电压之间；
    所述主站信号接收模块，用于接收所述第一信号电压或所述第二信号电压并与参考电压进行比较，以得到从站发出的数据信号并发送至主站。
  2. 如权利要求1所述的总线通信电路，其中，所述程控参考电压调整模块包括第一二极管以及多个相互并联的电阻单元电路；
    所述第一二极管的正极与所述通信保护模块的第一端连接，所述第一二极管的负极分别与每个电阻单元电路的第一端连接，每个电阻单元电路的第二端均与所述主站信号接收模块的第二输入端连接；
    所述程控参考电压调整模块，用于通过控制多个所述电阻单元电路的通断以调节所述程控参考电压调整模块的等效电阻。
  3. 如权利要求2所述的总线通信电路，其中，每个所述电阻单元电路包括调整电阻、第一开关管、第一电阻、第二电阻、第一电容以及第一控制单元；
    所述第一二极管的负极分别与所述第一电容的第一端、所述第一电阻的第一端以及所述第一开关管的第一端连接，所述第一开关管的控制端分别与所述第一电容的第二端、所述第一电阻的第二端以及所述第二电阻的第一端连接，所述第二电阻的第二端与所述第一控制单元的控制端连接，所述第一控制单元的受控端与主站连接，所述第一开关管的第二端与所述主站信号接收模块的第二输入端连接；
    所述第一控制单元，用于根据主站发送的控制信号控制所述第一开关管的导通和关断。
  4. 如权利要求3所述的总线通信电路，其中，所述第一控制单元为第一光耦或第二开关管。
  5. 如权利要求3所述的总线通信电路，其中，每个所述电阻单元电路中的调整电阻互不相同。
  6. 如权利要求2所述的总线通信电路，其中，所述主站信号接收模块包括第一比较器、第三电阻、第四电阻、第二电容以及第二光耦；
    所述第一比较器的第一输入端通过所述第三电阻与所述通信保护模块的第一端的连接，所述第一比较器的第二输入端分别与每个电阻单元电路的第二端连接，所述第一比较器的第二端通过第四电阻接地，所述第二电容与所述第四电阻并联，所述第一比较器的输 出端与所述第二光耦的受控端连接，所述第二光耦的控制端与主站的信号接收端连接；
    所述第二光耦，用于根据所述第一比较器输出的高低电平信号向主站的信号接收端发送相应的高低电平信号。
  7. 如权利要求1～6中任一项所述的总线通信电路，其中，所述主站信号发送模块包括第三光耦、稳压芯片、第一稳压二极管以及第二稳压二极管；
    所述第三光耦的受控端与主站的信号发送端连接，所述第三光耦的输出正极和输出负极分别与所述第二稳压二极管的负极和正极连接，所述稳压芯片的输入端接总线电压，所述稳压芯片的接地端与所述第一稳压二极管的负极连接，所述第一稳压二极管的正极与所述第二稳压二极管的负极连接，所述第二稳压二极管的正极接地，所述稳压芯片的输出端为所述主站信号发送模块的输出端。
  8. 如权利要求1～6中任一项所述的总线通信电路，其中，所述通信保护模块包括第二二极管、瞬态二极管、第三电容及热敏电阻；
    所述第二二极管的正极为所述通信保护模块的第一端，所述第二二极管的正极通过所述第三电容接地，所述第二二极管的负极通过所述热敏电阻与从站的正极连接，从站的负极接地，所述第二二极管的负极还通过所述瞬态二极管接地。
  9. 如权利要求8所述的总线通信电路，其中，所述通信保护模块，还用于接收所述第一输出电压为从站供电。
  10. 一种总线通信装置，其中，所述总线通信装置包括主站、从站以及与分别与所述主站和所述从站连接的总线通信电路，所述总线通信电路被配置为如权利要求1～9任一项所述的总线通信电路。
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