MBus master station device with overload detection and overload protection functions

Abstract

The present invention discloses an MBus master station device with overload detection and overload protection functions, including a processor, a master station sending circuit, a master station receiving circuit, an overload detection circuit, an overload protection circuit and a remote meter; the master station sending circuit is used to receive a switch control signal sent by the processor, and send data to the remote meter according to the switch control signal; the master station receiving circuit is used to receive a response signal returned by the remote meter in response to a meter reading instruction, and collect meter-end data according to the response signal and send it to the processor; the overload detection circuit is used to collect the voltage of the master station sending circuit and output a detection status signal to the processor; the overload protection circuit is used to receive a protection trigger signal sent by the processor to cut off the MBus master station power supply according to the protection trigger signal. The device of the present invention has a simple structure, strong anti-interference ability, can stably and accurately detect and protect overloads in real time, ensure that the equipment is not damaged, and solve the stability problem of the equipment in complex scene environments.

Description

Technical Field

[0001] The invention belongs to the technical field of data communication, and in particular relates to an MBus master station device with overload detection and overload protection functions. Background Art

[0002] MBus master station is a communication technology for data collection and exchange of intelligent meters. It has the advantages of strong anti-interference ability, long communication distance, flexible power supply mode, etc. However, due to the complex on-site environment of centralized remote meter reading system and the problem of non-standard equipment installation by operators, it may cause equipment overload or short circuit, thus damaging the equipment. The traditional MBus master station overload circuit is designed with discrete components, and its circuit is often complex, resulting in increased cost. At the same time, the use of more discrete components is likely to increase the error of detection accuracy, resulting in low reliability and failure to protect the equipment, thus affecting the stability of the system. Summary of the invention

[0003] The main purpose of the present invention is to provide an MBus master station device with overload detection and overload protection functions, aiming to overcome the shortcomings of the prior art.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] An MBus master station device with overload detection and overload protection functions comprises a processor, a master station sending circuit, a master station receiving circuit, an overload detection circuit, an overload protection circuit and a remote instrument;

[0006] The master station sending circuit has a first input terminal connected to the processor and a first output terminal connected to the remote meter, and is used to receive a switch control signal sent by the processor and send data to the remote meter according to the switch control signal;

[0007] The master station receiving circuit has an input end connected to the remote meter and an output end connected to the processor, and is used to receive a response signal returned by the remote meter in response to a meter reading instruction, and collect meter data according to the response signal and send it to the processor;

[0008] The overload detection circuit has an input end connected to the second output end of the master station sending circuit, and an output end connected to the processor, and is used to collect the voltage of the master station sending circuit and output a detection status signal to the processor;

[0009] The overload protection circuit has an input end connected to the processor and an output end connected to the second input end of the master station sending circuit, and is used to receive a protection trigger signal sent by the processor to cut off the MBus master station power supply according to the protection trigger signal.

[0010] The processor is respectively connected to the first input end of the master station sending circuit, the output end of the master station receiving circuit, the output end of the overload detection circuit and the input end of the overload protection circuit.

[0011] Preferably, the master station sending circuit includes a first switch circuit, a second switch circuit, a third switch circuit, a power supply control circuit and a step-down circuit;

[0012] The first switch circuit is connected to the processor and the input end of the second switch circuit; the second switch circuit is connected to the first power supply end of the power control circuit and the input end of the overload detection circuit; the third switch circuit is connected to the output end of the overload protection circuit and the input end of the overload detection circuit; the second power supply end of the power control circuit is connected to the input end of the overload detection circuit through the step-down circuit.

[0013] Preferably, the first switch circuit comprises a first voltage-dividing resistor, a second voltage-dividing resistor and a first switch tube; one end of the second voltage-dividing resistor is connected to the processor, and the other end is grounded through the first voltage-dividing resistor; a first electrode of the first switch tube is connected between the first voltage-dividing resistor and the second voltage-dividing resistor, a second electrode is grounded, and a third electrode is connected to the second switch circuit;

[0014] The step-down circuit is composed of a first step-down tube, a first thermistor, a second step-down tube, a third step-down tube, a second thermistor and a bypass capacitor, which are connected by wires;

[0015] The second switch circuit includes a first current limiting resistor, a first voltage-stabilizing tube, a first shunt resistor and a second switch tube; one end of the first current limiting resistor is connected to the first switch circuit, and the other end is connected to between the first electrode and the second electrode of the second switch tube through the first voltage-stabilizing tube and the first shunt resistor; the third electrode of the second switch tube is connected between the second buck tube and the third buck tube;

[0016] The third switching circuit includes a second current limiting resistor, a second voltage-stabilizing diode, a second shunt resistor and a third switching tube; one end of the second current limiting resistor is connected to the output end of the overload protection circuit, and the other end is connected to the first electrode and the second electrode of the third switching tube through the second voltage-stabilizing diode and the second shunt resistor; the third electrode of the third switching tube is connected to the negative electrode of the MBus bus.

[0017] Preferably, the master station receiving circuit includes a dual-channel filtering circuit, a comparison amplifier circuit and a time base circuit; the input end of the dual-channel filtering circuit is connected to the remote instrument, and the output end is connected to the processor through the comparison amplifier circuit and the time base circuit.

[0018] Preferably, the dual-channel filter circuit comprises a third voltage-dividing resistor, a fourth voltage-dividing resistor and two second-order high-pass filter circuits; the two second-order high-pass filter circuits are each composed of two resistors and two capacitors, which are connected by wires; the third voltage-dividing resistor is connected between the two second-order high-pass filter circuits and is grounded through the fourth voltage-dividing resistor;

[0019] The comparison amplifier circuit includes a dual operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a first feedback resistor; the first pin of the dual operational amplifier is connected to the second pin of the dual operational amplifier through the first feedback resistor; the second pin of the dual operational amplifier is connected to the first second-order high-pass filter circuit through the first resistor; the third pin of the dual operational amplifier is connected to the second second-order high-pass filter circuit through the third resistor, and is grounded through the fourth resistor; the fourth pin of the dual operational amplifier is connected to a voltage divider circuit through the fifth resistor and the sixth resistor; the fifth pin of the dual operational amplifier is grounded; the sixth pin of the dual operational amplifier is connected to the first pin of the dual operational amplifier through the second resistor, and is connected between the fifth resistor and the sixth resistor;

[0020] The timing circuit includes a timer, a third current limiting resistor, a fourth current limiting resistor and a first clamping diode; the first pin of the timer is connected to the comparison amplifier circuit through the third current limiting resistor and is grounded through the first clamping diode; the second pin of the timer is connected to the first pin; the third pin of the timer is connected to the processor through the fourth current limiting resistor.

[0021] Preferably, the overload detection circuit includes an operational comparator, a fifth voltage-dividing resistor, a sixth voltage-dividing resistor, a seventh voltage-dividing resistor, an eighth voltage-dividing resistor, and a level conversion circuit; one end of the fifth voltage-dividing resistor is connected to the second output end of the main station sending circuit, and the other end is grounded through the sixth voltage-dividing resistor; one end of the seventh voltage-dividing resistor is connected to a power supply, and the other end is grounded through the eighth voltage-dividing resistor; the first pin of the operational comparator is connected between the fifth voltage-dividing resistor and the sixth voltage-dividing resistor, the second pin is connected between the seventh voltage-dividing resistor and the eighth voltage-dividing resistor, and the third pin is connected to the processor through the level conversion circuit.

[0022] Preferably, the level conversion circuit includes a low-high level conversion circuit and a high-low level conversion circuit; the low-high level conversion circuit is composed of a fourth switch tube, a seventh resistor, a fifth current limiting resistor, and an eighth resistor, which are connected by wires and are used to convert the low level output by the third pin of the operational comparator into a high level;

[0023] The high-low level conversion circuit is composed of a fifth switch tube, a ninth resistor, a tenth resistor and an eleventh resistor, which are connected by wires and are used to convert the high level output by the third pin of the operational comparator into a low level.

[0024] Preferably, the overload protection circuit includes a twelfth resistor, a sixth current limiting resistor and a sixth switch tube; the first electrode of the sixth switch tube is connected to the processor through the twelfth resistor and the sixth current limiting resistor, the second electrode is connected to the second input end of the main station sending circuit, and the third electrode is grounded.

[0025] Preferably, the MBus master station device with overload detection and overload protection functions also includes a power supply circuit, which is respectively connected to the processor, the master station sending circuit, the master station receiving circuit, the overload detection circuit and the overload protection circuit to provide working power.

[0026] By adopting the above scheme, the present invention has the following beneficial effects: the device of the present invention has a simple structure, strong anti-interference ability, can stably and accurately detect and protect overload in real time, can effectively ensure that the equipment is not damaged, and solves the stability problem of the equipment in complex scene environments. At the same time, when the abnormality is resolved, it has automatic recovery ability, thereby reducing human intervention and reducing debugging costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0028] Figure 1 It is a system principle block diagram of the present invention;

[0029] Figure 2 It is a principle block diagram of the master station sending circuit of the present invention;

[0030] Figure 3 A circuit schematic diagram of a master station sending circuit of the present invention;

[0031] Figure 4 It is a principle block diagram of the master station receiving circuit of the present invention;

[0032] Figure 5 It is a circuit principle diagram of the master station receiving circuit of the present invention;

[0033] Figure 6 is a circuit schematic diagram of the overload detection circuit of the present invention;

[0034] Figure 7 The figure is a circuit diagram of the overload protection circuit of the present invention.

[0035] In the figure: 10, processor; 20, master station sending circuit; 30, master station receiving circuit; 40, overload detection circuit; 50, overload protection circuit; 60, remote instrument; 21, first switch circuit; 22, second switch circuit; 23, third switch circuit; 24, power supply control circuit; 25, step-down circuit; 31, dual-channel filter circuit; 32, comparison amplifier circuit; 33, time base circuit; 41, level conversion circuit. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0037] Figures 1 to 7 The MBus master station device with overload detection and overload protection functions in this embodiment is shown. It can be understood that the MBus master station device with overload detection and overload protection functions is used in a centralized remote meter reading system. Specifically, the MBus master station device with overload detection and overload protection functions includes a processor 10, a master station sending circuit 20, a master station receiving circuit 30, an overload detection circuit 40, an overload protection circuit 50 and a remote meter 60.

[0038] like Figure 1 As shown, Figure 2 and Figure 3 As shown, the master station sending circuit 20, the first input terminal MBus_TXD is connected to the processor 10, and the first output terminal MBus- is connected to the remote meter 60, for receiving the switch control signal sent by the processor 10, and sending the meter end data to the remote meter 60 according to the switch control signal. Specifically, when the processor 10 sends the meter reading instruction to the remote meter according to the preset protocol, the processor 10 outputs the corresponding switch control signal according to the preset protocol to control the master station sending circuit 20 to send data to the remote meter according to the switch control signal. Optionally, the preset protocol is CJ / T188 (Technical Conditions for Data Transmission of Household Metering Instruments) or other protocols.

[0039] like Figure 2As shown, the master station sending circuit 20 includes a first switch circuit 21, a second switch circuit 22, a third switch circuit 23, a power control circuit 24 and a step-down circuit 25. Among them, the first switch circuit 21 is connected to the input end of the processor 10 and the second switch circuit 22, and can be turned on or off according to the switch control signal output by the processor 10. The second switch circuit 22 is connected to the first power supply terminal 36V of the power control circuit 24 and the input end of the overload detection circuit 40, and can be turned on or off according to the signal output by the first switch circuit 21. The second power supply terminal 13V of the power control circuit 24 is connected to the input end of the overload detection circuit 40 through the step-down circuit 25. The third switch circuit 23 is connected to the output end of the overload protection circuit 50 and the input end of the overload detection circuit 40, and can be turned on or off according to the signal output from the output end of the overload protection circuit 50. It is understandable that when the processor 10 sends a meter reading instruction to the remote meter 60 according to the preset protocol, the processor 10 outputs a corresponding switch control signal (i.e., a TTL signal) according to the protocol, and controls the on or off of the first switch circuit 21 through the network MBus_TXD, thereby controlling the on or off of the second switch circuit 22, and outputting the modulated voltage 13V / 36V regularly. The MBus bus standard stipulates that when the MBus host sends "1", the host will output a bus voltage of 36V, that is, the second switch circuit 22 and the third switch circuit 23 are turned on; when the MBus host sends "0", the host will output the MBus bus voltage to 12V through the step-down circuit 25, that is, the second switch circuit 22 is turned off and the third switch circuit 23 is turned on.

[0040] It can be seen that in the master station sending circuit 20, the meter end identifies data by detecting the voltage change value of the bus rather than the absolute value of the bus voltage. In this way, even if the absolute value of the voltage at the meter end does not reach 36V due to the distance and cable impedance, the meter reading instruction sent by the Mbus master station to the remote meter 60 (such as an intelligent wired remote water meter, electricity meter, gas meter, etc.) can be normally identified.

[0041] like Figure 3 As shown, the first switch circuit 21 includes a first voltage-dividing resistor R1, a second voltage-dividing resistor R2 and a first switch tube Q1. Among them, one end of the second voltage-dividing resistor R2 is connected to the processor 10, and the other end is grounded through the first voltage-dividing resistor R1. The first electrode of the first switch tube Q1 is connected between the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2, the second electrode is grounded, and the third electrode is connected to the second switch circuit 22. Optionally, the first switch tube Q1 is an NPN-type triode; accordingly, the first electrode of the first switch tube Q1 is the base (i.e., the B pole) of the NPN-type triode, the second electrode of the first switch tube Q1 is the emitter (i.e., the E pole) of the NPN-type triode, and the third electrode of the first switch tube Q1 is the collector (i.e., the C pole) of the NPN-type triode.

[0042] The step-down circuit 25 is composed of a first step-down tube D2, a first thermistor NTC1, a second step-down tube D3, a third step-down tube D4, a second thermistor NTC2 and a bypass capacitor EC1, which are connected by wires. One end of the bypass capacitor EC1 is grounded, and the other end is connected between the first thermistor NTC1 and the second step-down tube D3, which is used to filter out high-frequency noise in the input signal. Optionally, the first step-down tube D2, the second step-down tube D3 and the third step-down tube D4 are all diodes, and the bypass capacitor is a polar capacitor.

[0043] The second switch circuit 22 includes a first current limiting resistor R3, a first voltage regulator tube D1, a first shunt resistor R4 and a second switch tube Q2. Among them, one end of the first current limiting resistor R3 is connected to the first switch circuit 21, and the other end is connected to the first electrode and the second electrode of the second switch tube Q2 through the first voltage regulator tube D1 and the first shunt resistor R4. The third electrode of the second switch tube Q2 is connected between the second buck tube D3 and the third buck tube D4. Optionally, the second switch tube Q2 is an N-channel field effect tube; accordingly, the first electrode of the second switch tube Q2 is the gate (i.e., G pole) of the N-channel field effect tube, the second electrode of the second switch tube Q2 is the drain (i.e., D pole) of the N-channel field effect tube, and the third electrode of the second switch tube Q2 is the source (i.e., S pole) of the N-channel field effect tube. In one embodiment, there is a parasitic diode between the source and the drain of the N-channel field effect tube to prevent the current between the source and the drain of the N-channel field effect tube from being too large and damaging the N-channel field effect tube.

[0044] The third switch circuit 23 includes a second current limiting resistor R6, a second voltage regulator tube D2, a second shunt resistor R5 and a third switch tube Q3. One end of the second current limiting resistor R6 is connected to the output end of the overload protection circuit 50, and the other end is connected to the first electrode and the second electrode of the third switch tube Q3 through the second voltage regulator tube D2 and the second shunt resistor R5. The third electrode of the third switch tube Q3 is connected to the negative pole MBus- of the MBus bus. Optionally, the third switch tube Q3 is an N-channel field effect tube.

[0045] It is understandable that the master station sending circuit 20 can control the automatic switching of 13V / 36V by a field effect transistor (MOS tube) to realize the modulation of the MBus master station transmitting signal.

[0046] like Figure 1 , Figure 4 and Figure 5 As shown, the master station receiving circuit 20 has an input end connected to the remote meter 60 and an output end MBus_RXD connected to the processor 10, and is used to receive a response signal returned by the remote meter 60 in response to the meter reading instruction, and collect meter data according to the response signal and send it to the processor 10.

[0047] like Figure 4 As shown, the master station receiving circuit 30 includes a dual-channel filtering circuit 31, a comparison amplifier circuit 32 and a time base circuit 33. Among them, the input end of the dual-channel filtering circuit 31 is connected to the remote meter 60, and the output end is connected to the processor 10 through the comparison amplifier circuit 32 and the time base circuit 33. Specifically, under the normal load condition of the MBus master station, the network MBus+ single-ended signal is converted into two differential signals through the dual-channel filtering circuit and sent to the comparison amplifier circuit 32, and then the two differential signals are converted into single-ended amplified signals through the comparison amplifier circuit 32, and finally converted into digital signals through the time base circuit 33 and sent to the processor 10.

[0048] like Figure 5 As shown, the dual-channel filter circuit 31 includes a third voltage-dividing resistor R8, a fourth voltage-dividing resistor R9 and two second-order high-pass filter circuits. Among them, the first second-order high-pass filter circuit is composed of two capacitors C1 and C2, two resistors R10 and R11, which are connected by wires. The second second-order high-pass filter circuit is composed of two capacitors C3 and C4, two resistors R12 and R13, which are connected by wires. The third voltage-dividing resistor R8 is connected between the two second-order high-pass filter circuits and grounded through the fourth voltage-dividing resistor R9.

[0049] Optionally, the master station receiving circuit 30 further includes a bidirectional voltage regulator Z1, wherein the bidirectional voltage regulator Z1 is connected to the negative pole of the bus voltage MBus- and the positive pole of the bus voltage MBus+, and is grounded through a resistor R7.

[0050] The comparison amplifier circuit 32 includes a dual operational amplifier U1, a first resistor R14, a second resistor R16, a third resistor R17, a fourth resistor R18, a fifth resistor R19, a sixth resistor R20 and a first feedback resistor R15. Among them, the first pin of the dual operational amplifier U1 is connected to the second pin of the dual operational amplifier U1 through the first feedback resistor R15. The second pin of the dual operational amplifier U1 is connected to the first second-order high-pass filter circuit through the first resistor R14. The third pin of the dual operational amplifier U1 is connected to the second second-order high-pass filter circuit through the third resistor R17, and is grounded through the fourth resistor R18. The fourth pin of the dual operational amplifier U1 is connected to a voltage divider circuit through the fifth resistor R19 and the sixth resistor R20. Optionally, the voltage divider circuit includes two voltage divider resistors R21 and R22, one end of the voltage divider resistor R21 is grounded, and the other end is connected to the power supply VCC through the voltage divider resistor R22. The fourth pin of the dual operational amplifier U1 is connected between the voltage divider resistors R21 and R22 through the fifth resistor R19 and the sixth resistor R20. The fifth pin of the dual operational amplifier U1 is grounded. The sixth pin of the dual operational amplifier U1 is connected to the first pin of the dual operational amplifier U1 through the second resistor R16, and is connected between the fifth resistor R19 and the sixth resistor R20. Optionally, the dual operational amplifier U1 is NE5532, and accordingly, the first pin of the dual operational amplifier U1 is the first pin of NE5532 (i.e., output A), the second pin of the dual operational amplifier U1 is the second pin of NE5532 (i.e., reverse input A), the third pin of the dual operational amplifier U1 is the third pin of NE5532 (i.e., forward input A), the fourth pin of the dual operational amplifier U1 is the seventh pin of NE5532 (i.e., output B), the fifth pin of the dual operational amplifier U1 is the fifth pin of NE5532 (i.e., forward input B), and the sixth pin of the dual operational amplifier U1 is the sixth pin of NE5532 (i.e., reverse input B). Specifically, the two differential signals of the dual-channel filter circuit 31 reach the second and third pins of NE5532 respectively, and then the collected signals are output from the sixth and seventh pins of NE5532 through the amplification comparison of NE5532, thereby being converted into single-ended amplified signals.

[0051] The time base circuit 33 includes a timer U2, a third current limiting resistor R23, a fourth current limiting resistor R24 ​​and a first clamping diode D6. Among them, the first pin of the timer U2 is connected to the comparison amplifier circuit 32 through the third current limiting resistor R23, and is grounded through the first clamping diode D6. The second pin of the timer U2 is connected to the first pin. The third pin of the timer U2 is connected to the processor 10 through the fourth current limiting resistor R24. Optionally, the timer U2 is NE555, and accordingly, the first pin of the timer U2 is the 6th pin of NE555 (i.e., reset lock), the second pin of the timer U2 is the 2nd pin of NE555 (i.e., trigger point), and the third pin of the timer U2 is the 3rd pin of NE555 (i.e., output end).

[0052] like Figure 1 and Figure 6 As shown, the overload detection circuit 40 has an input end connected to the second output end MBus_DET of the master station sending circuit 20 , and an output end MBus_PRO connected to the processor 10 , and is used to collect the voltage of the master station sending circuit 20 and output a detection status signal to the processor 10 .

[0053] like Figure 6As shown, the overload detection circuit 40 includes an operational comparator U3, a fifth voltage-dividing resistor R25, a sixth voltage-dividing resistor R26, a seventh voltage-dividing resistor R27, an eighth voltage-dividing resistor R28, and a level conversion circuit 41. Among them, one end of the fifth voltage-dividing resistor R25 is connected to the second output terminal MBus_DET of the master station sending circuit 20, and the other end is grounded through the sixth voltage-dividing resistor R26. One end of the seventh voltage-dividing resistor R27 is connected to the power supply VCC, and the other end is grounded through the eighth voltage-dividing resistor R28. The first pin of the operational comparator U3 is connected between the fifth voltage-dividing resistor R25 and the sixth voltage-dividing resistor R26, the second pin of the operational amplifier is connected between the seventh voltage-dividing resistor R27 and the eighth voltage-dividing resistor R28, and the third pin is connected to the processor 10 through the level conversion circuit 41. Optionally, the operational comparator U3 is a dual voltage comparator LM393, and accordingly, the first pin of the operational comparator U3 is the 5th pin of LM393, the second pin of the operational comparator U3 is the 6th pin of LM393, and the third pin of the operational comparator U3 is the 7th pin of LM393. Specifically, when the MBus master station is normally loaded, the fluctuation range of the voltage value of the network MBus_DET is normal, and the voltage is input to the 5th pin of the comparator LM393 through the voltage divider ratio of the fifth voltage divider resistor R25 and the sixth voltage divider resistor R26. At this time, the voltage at the positive input terminal of the 5th pin of the comparator LM393 is greater than the voltage at the reverse input terminal of the 6th pin of the operational comparator LM393, and the 7th pin of the comparator LM393 will output a high level. On the contrary, when the MBus master is overloaded or short-circuited, the voltage value of the network MBus_DET fluctuates below the range, and the voltage is input to the 5th pin of the operational comparator LM393 through the voltage ratio of the fifth voltage-dividing resistor R25 and the sixth voltage-dividing resistor R26. At this time, the voltage at the positive input end of the 5th pin of the comparator LM393 is less than the voltage at the reverse input end of the 6th pin of the comparator LM393, and the 7th pin of the comparator LM393 will output a low level. Due to the high or low level output by the 7th pin of the comparator LM393, the signal compatibility and detection stability of the CPU are increased through the level conversion circuit composed of transistors. The changes in the two states are finally sent to the CPU for judgment in real time through the MBus_Protcet network, in preparation for protecting the MBus master from damage.

[0054] It can be seen that in the overload detection circuit 40, a specific voltage range is compared after being divided by a specific resistance value, and very few discrete components are used, which can not only ensure the stability and accuracy of state detection, but also reduce equipment costs.

[0055] like Figure 6As shown, the level conversion circuit 41 includes a low-high level conversion circuit and a high-low level conversion circuit. The low-high level conversion circuit is composed of a fourth switch tube Q4, a seventh resistor R29, a fifth current limiting resistor R30, and an eighth resistor R31, which are connected by wires and are used to convert the low level output by the third pin of the operational comparator U3 into a high level. Among them, the first electrode of the fourth switch tube Q4 is connected to the third pin of the operational comparator U3 through the seventh resistor R29 in series and the fifth current limiting resistor R30 in parallel, the second electrode of the fourth switch tube Q4 is grounded, and the third electrode of the fourth switch tube Q4 is connected to the first electrode of the fifth switch tube Q5 by pulling up the eighth resistor R31 and pulling down the ninth resistor R32. Optionally, the fourth switch tube Q4 is an NPN type triode.

[0056] The high-low level conversion circuit is composed of a fifth switch tube Q4, a ninth resistor R32, a tenth resistor R33 and an eleventh resistor R34, which are connected by wires and are used to convert the high level output by the third pin of the operational comparator U3 into a low level. Among them, the second electrode of the fifth switch tube Q5 is connected to the processor 10 through the eleventh resistor R34 in series and the tenth resistor R33 in parallel, and the third electrode of the fifth switch tube Q5 is connected to the power supply. Optionally, the fifth switch tube Q5 is a PNP type triode, and accordingly, the first electrode of the fifth switch tube Q5 is the base (i.e., the B pole) of the PNP type triode, the second electrode of the fifth switch tube Q5 is the emitter (i.e., the E pole) of the PNP type triode, and the third electrode of the fifth switch tube Q5 is the collector (i.e., the C pole) of the PNP type triode.

[0057] like Figure 1 and Figure 7 As shown, the overload protection circuit 50 has an input terminal MBus_EN connected to the processor 10, and an output terminal connected to the second input terminal MBus_CTL of the master station sending circuit 20, and is used to receive a protection trigger signal sent by the processor 10 to cut off the MBus master station power supply according to the protection trigger signal.

[0058] like Figure 7 As shown, the overload protection circuit 50 includes a twelfth resistor R35, a sixth current limiting resistor R36 and a sixth switch tube Q6. Among them, the first electrode of the sixth switch tube Q6 is connected to the processor through the twelfth resistor R35 and the sixth current limiting resistor R36, the second electrode is connected to the second input terminal MBus_CTL of the master station sending circuit 20, and the third electrode is grounded. Optionally, the sixth switch tube Q6 is an NPN transistor.

[0059] Specifically, when the processor 10 detects that the MBus master station is abnormal (i.e., the MBus master station is overloaded or short-circuited) through the overload detection circuit 40, the processor 10 will use microsecond-level intelligent analysis to input a low level to the sixth switch tube Q6 through the network MBus_EN, at which time the sixth switch tube Q6 is turned off, thereby cutting off the power supply of the MBus master station to ensure that the device is not damaged. When the processor 10 detects that the MBus master station is normally loaded through the overload detection circuit 40, the network MBus_EN outputs a high level to the sixth switch tube Q6, at which time the sixth switch tube Q6 is turned on. It is understandable that the sixth switch tube Q6 is turned on or off according to the protection trigger signal sent by the processor 10, thereby controlling the third switch tube Q3 in the master station sending circuit 20 to be turned on or off, which can effectively protect the MBus master station from being cut off after being overloaded or short-circuited to achieve the overload protection function.

[0060] like Figures 1 to 7 As shown, the processor 10 is respectively connected to the first input terminal MBus_TXD of the master station sending circuit 20, the output terminal MBus_RXD of the master station receiving circuit 30, the output terminal MBus_PRO of the overload detection circuit 40, and the input terminal MBus_EN of the overload protection circuit 50. Optionally, the processor 10 adopts an Atmel processor. Specifically, when the MBus master station is under normal load, the processor 10 is used to send a meter reading instruction to the remote meter 60 through the master station sending circuit 20, and receive a response signal returned by the remote meter 60 through the master station receiving circuit 30 after responding to the meter reading instruction; when the MBus master station is overloaded or short-circuited, the processor 10 is used to receive the detection status sent by the overload detection circuit 40, and send a protection trigger signal to the overload protection circuit 50 by analyzing the detection status, so as to cut off the power supply of the MBus master station according to the protection trigger signal.

[0061] Optionally, the MBus master station device with overload detection and overload protection functions also includes a power supply circuit (not shown), which is respectively connected to the processor 10, the master station sending circuit 20, the master station receiving circuit 30, the overload detection circuit 40 and the overload protection circuit 50 for providing working power.

[0062] It can be seen that the MBus master station device with overload detection and overload protection functions provided by the present invention, when the Mbus master station is normally loaded, the processor 10 sends a meter reading instruction to the downstream remote meter 60 according to the preset protocol, and outputs a corresponding switch control signal according to the preset protocol to control the master station sending circuit 20 to send data to the remote meter according to the switch control signal. After the remote meter 60 performs different types of meter reading actions according to the meter reading instruction sent uplink and completes the response, the master station receiving circuit 30 collects the meter end data and sends the data to the processor 10; and when the Mbus master station is overloaded or short-circuited, the Mbus master station voltage is detected abnormally through the overload detection circuit 40, and the detection status is returned to the processor 10 for analysis, and finally the protection trigger signal sent by the processor 10 is received by the overload protection circuit 30 to cut off the power supply of the Mbus master station to achieve the protection effect. The device of the present invention has a simple structure and strong anti-interference ability, can stably and accurately detect and protect overloads in real time, can effectively ensure that the equipment is not damaged, and solves the stability problem of the equipment in complex scene environments. At the same time, when the abnormality is resolved, it has the ability to automatically recover, thereby reducing human intervention and lowering debugging costs.

[0063] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An MBus master station device with overload detection and overload protection functions, characterized in that: It includes a processor, a master station sending circuit, a master station receiving circuit, an overload detection circuit, an overload protection circuit and a remote instrument; The master station sending circuit has a first input terminal connected to the processor and a first output terminal connected to the remote meter, and is used to receive a switch control signal sent by the processor and send data to the remote meter according to the switch control signal; The master station receiving circuit has an input end connected to the remote meter and an output end connected to the processor, and is used to receive a response signal returned by the remote meter in response to a meter reading instruction, and collect meter data according to the response signal and send it to the processor; The overload detection circuit has an input end connected to the second output end of the master station sending circuit, and an output end connected to the processor, and is used to collect the voltage of the master station sending circuit and output a detection status signal to the processor; The overload protection circuit has an input end connected to the processor and an output end connected to the second input end of the master station sending circuit, and is used to receive a protection trigger signal sent by the processor to cut off the MBus master station power supply according to the protection trigger signal; The processor is respectively connected to the first input end of the master station sending circuit, the output end of the master station receiving circuit, the output end of the overload detection circuit and the input end of the overload protection circuit; In the master station sending circuit, the meter end identifies data by detecting the voltage change value of the bus instead of the absolute value of the bus voltage; the master station sending circuit includes a third switch circuit, the third switch circuit is connected to the output end of the overload protection circuit and the input end of the overload detection circuit; the third switch circuit includes a second current limiting resistor, a second voltage regulator tube, a second shunt resistor and a third switch tube; The master station receiving circuit includes a dual-channel filtering circuit, a comparison amplifier circuit and a time base circuit; The overload detection circuit includes an operational comparator, a fifth voltage-dividing resistor, a sixth voltage-dividing resistor, a seventh voltage-dividing resistor, an eighth voltage-dividing resistor, and a level conversion circuit; in the overload detection circuit, a specific voltage range is compared after being divided by a specific resistance value, and very few discrete components are used; The overload protection circuit includes a twelfth resistor, a sixth current limiting resistor and a sixth switch tube; The sixth switch tube is controlled to be turned on or off according to the protection trigger signal sent by the processor, thereby controlling the third switch tube in the sending circuit of the master station to be turned on or off.

2. The MBus master station device with overload detection and overload protection functions according to claim 1, characterized in that: The master station sending circuit includes a first switch circuit, a second switch circuit, a power supply control circuit and a step-down circuit; The first switch circuit is connected to the processor and the input end of the second switch circuit; the second switch circuit is connected to the first power supply end of the power supply control circuit and the input end of the overload detection circuit; the second power supply end of the power supply control circuit is connected to the input end of the overload detection circuit through the step-down circuit.

3. The MBus master station device with overload detection and overload protection functions according to claim 2, characterized in that: The first switch circuit includes a first voltage-dividing resistor, a second voltage-dividing resistor and a first switch tube; one end of the second voltage-dividing resistor is connected to the processor, and the other end is grounded through the first voltage-dividing resistor; a first electrode of the first switch tube is connected between the first voltage-dividing resistor and the second voltage-dividing resistor, a second electrode is grounded, and a third electrode is connected to the second switch circuit; The step-down circuit is composed of a first step-down tube, a first thermistor, a second step-down tube, a third step-down tube, a second thermistor and a bypass capacitor, which are connected by wires; The second switch circuit includes a first current limiting resistor, a first voltage regulator tube, a first shunt resistor and a second switch tube; One end of the first current limiting resistor is connected to the first switch circuit, and the other end is connected to between the first electrode and the second electrode of the second switch tube through the first voltage regulator tube and the first shunt resistor; the third electrode of the second switch tube is connected between the second buck tube and the third buck tube; One end of the second current limiting resistor is connected to the output end of the overload protection circuit, and the other end is connected between the first electrode and the second electrode of the third switch tube through the second voltage regulator tube and the second shunt resistor; the third electrode of the third switch tube is connected to the negative electrode of the MBus bus.

4. The MBus master station device with overload detection and overload protection functions according to claim 1, characterized in that: The input end of the dual-channel filter circuit is connected to the remote instrument, and the output end is connected to the processor through the comparison amplifier circuit and the time base circuit.

5. The MBus master station device with overload detection and overload protection functions according to claim 4, characterized in that: The dual-channel filter circuit comprises a third voltage-dividing resistor, a fourth voltage-dividing resistor and two second-order high-pass filter circuits; the two second-order high-pass filter circuits are each composed of two resistors and two capacitors, which are connected by wires; the third voltage-dividing resistor is connected between the two second-order high-pass filter circuits and is grounded through the fourth voltage-dividing resistor; The comparison amplifier circuit includes a dual operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a first feedback resistor; the first pin of the dual operational amplifier is connected to the second pin of the dual operational amplifier through the first feedback resistor; the second pin of the dual operational amplifier is connected to the first second-order high-pass filter circuit through the first resistor; the third pin of the dual operational amplifier is connected to the second second-order high-pass filter circuit through the third resistor, and is grounded through the fourth resistor; the fourth pin of the dual operational amplifier is connected to a voltage divider circuit through the fifth resistor and the sixth resistor; the fifth pin of the dual operational amplifier is grounded; the sixth pin of the dual operational amplifier is connected to the first pin of the dual operational amplifier through the second resistor, and is connected between the fifth resistor and the sixth resistor; The timing circuit includes a timer, a third current limiting resistor, a fourth current limiting resistor and a first clamping diode; the first pin of the timer is connected to the comparison amplifier circuit through the third current limiting resistor and is grounded through the first clamping diode; the second pin of the timer is connected to the first pin; the third pin of the timer is connected to the processor through the fourth current limiting resistor.

6. The MBus master station device with overload detection and overload protection functions according to claim 1, characterized in that: One end of the fifth voltage-dividing resistor is connected to the second output end of the main station sending circuit, and the other end is grounded through the sixth voltage-dividing resistor; one end of the seventh voltage-dividing resistor is connected to the power supply, and the other end is grounded through the eighth voltage-dividing resistor; the first pin of the operational comparator is connected between the fifth voltage-dividing resistor and the sixth voltage-dividing resistor, the second pin is connected between the seventh voltage-dividing resistor and the eighth voltage-dividing resistor, and the third pin is connected to the processor through the level conversion circuit.

7. The MBus master station device with overload detection and overload protection functions according to claim 6, characterized in that: The level conversion circuit includes a low-high level conversion circuit and a high-low level conversion circuit; the low-high level conversion circuit is composed of a fourth switch tube, a seventh resistor, a fifth current limiting resistor, and an eighth resistor, which are connected by wires and are used to convert the low level output by the third pin of the operational comparator into a high level; The high-low level conversion circuit is composed of a fifth switch tube, a ninth resistor, a tenth resistor and an eleventh resistor, which are connected by wires and are used to convert the high level output by the third pin of the operational comparator into a low level.

8. The MBus master station device with overload detection and overload protection functions according to claim 1, characterized in that: The first electrode of the sixth switch tube is connected to the processor through the twelfth resistor and the sixth current-limiting resistor, the second electrode is connected to the second input end of the master station sending circuit, and the third electrode is grounded.

9. The MBus master station device with overload detection and overload protection functions according to claim 1, characterized in that: It also includes a power supply circuit, which is respectively connected to the processor, the master station sending circuit, the master station receiving circuit, the overload detection circuit and the overload protection circuit for providing working power.

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