Intelligent water meter test circuit

Abstract

This utility model discloses a smart water meter testing circuit, including: a USB interface circuit, a TTL conversion circuit, a 485 bus circuit, an MBUS bus circuit, a first power supply circuit, a second power supply circuit, and a third power supply circuit. The USB interface circuit is used to connect to a host computer and is connected to the TTL conversion circuit and the first power supply circuit. The TTL conversion circuit is connected to the USB interface circuit, the 485 bus, and the MBUS bus. The 485 bus circuit is used to connect to a four-wire smart water meter and to feed back the test data of the four-wire smart water meter. The MBUS bus circuit is used to connect to a two-wire smart water meter and to feed back the test data of the two-wire smart water meter. This utility model can complete the testing of two-wire and four-wire smart water meters in one testing device without changing the testing device, which facilitates the testing of smart water meters by the staff and improves the testing efficiency of smart water meters.

Description

Technical Field

[0001] This utility model relates to the technical field of water meter testing, and in particular to a smart water meter testing circuit. Background Technology

[0002] A smart water meter is a new type of water meter that uses modern microelectronics technology, modern sensing technology, and smart IC card technology to measure water consumption and transmit and settle water consumption data. In addition to recording and electronically displaying water consumption, it can also automatically control water consumption according to the agreement, automatically calculate water fees for tiered water pricing, and store water consumption data.

[0003] Traditional meter reading methods require a significant manpower investment, with staff needing to visit each household to read meters, which is not only time-consuming and labor-intensive but also inefficient. Smart water meters can be read remotely and automatically, collecting users' water consumption data in real time and accurately, greatly reducing the cost and time of manual meter reading. However, before leaving the factory, smart water meters need to be tested for the accuracy of their water consumption data, specifically by comparing the data read from the smart water meter with the data from the smart water meter's mechanical technology. However, since existing smart water meters are generally two-wire or four-wire smart water meters, the data reading process on the host computer requires the use of testing devices with 485 or MBUS buses to read the data separately. Switching between testing devices increases the workload of staff and reduces the testing efficiency of smart water meters.

[0004] Therefore, existing technologies still need to be improved and developed. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a smart water meter test circuit, which integrates 485 bus and MBUS bus on the same test device to facilitate the testing of smart water meters by staff and improve the testing efficiency of smart water meters.

[0006] The technical solution of this utility model is as follows: A smart water meter testing circuit includes: a USB interface circuit, a TTL conversion circuit, a 485 bus circuit, an MBUS bus circuit, a first power supply circuit, a second power supply circuit, and a third power supply circuit; wherein, The USB interface circuit is used to connect to the host computer, and is also connected to the TTL conversion circuit and the first power supply circuit. The USB interface circuit is used to send control signals from the host computer and receive test signals from the smart water meter, and to provide a first power supply voltage to the first power supply circuit. The TTL conversion circuit is connected to the USB interface circuit, the 485 bus, and the MBUS bus respectively, and the TTL conversion circuit is used to realize the conversion between analog signals and digital signals. The 485 bus circuit is used to connect to a four-wire smart water meter and to provide feedback on the test data of the four-wire smart water meter. The MBUS bus circuit is used to connect to a two-wire smart water meter and to provide feedback on the test data of the two-wire smart water meter. The first power supply circuit is also connected to the TTL conversion circuit, the 485 bus circuit and the MBUS bus circuit respectively. The first power supply circuit is used to convert the first power supply voltage into a second power supply voltage to power the TTL conversion circuit, the 485 bus circuit and the MBUS bus circuit. The second power supply circuit is connected to the USB interface circuit and the 485 bus circuit respectively. The second power supply circuit is used to convert the first power supply voltage into a second power supply voltage to power the 485 bus circuit. The third power supply circuit is connected to the second power supply circuit and the MBUS bus circuit respectively. The third power supply circuit is used to convert the second power supply voltage into a third power supply voltage to power the MBUS bus circuit.

[0007] In a further embodiment of this invention, the 485 bus circuit includes: a high-speed transceiver, a first diode, a second diode, and an input / output interface; wherein, The signal receiving pin of the high-speed transceiver is connected to the signal receiving pin of the TTL conversion circuit, and the signal transmitting pin of the high-speed transceiver is connected to the signal transmitting pin of the TTL conversion circuit. The first signal input pin and the second signal input pin of the high-speed transceiver are connected to the input / output interface; The power pin of the high-speed transceiver is connected to the first power circuit. The cathode of the first diode is connected to the signal receiving pin of the high-speed transceiver, and the anode of the first diode is connected to the signal receiving pin of the TTL conversion circuit. The cathode of the second diode is connected to the signal transmit pin of the TTL conversion circuit, and the anode of the second diode is connected to the signal transmit pin of the high-speed transceiver.

[0008] In a further embodiment of this invention, the MBUS bus circuit includes: a third diode, a first resistor, a second resistor, a third resistor, a first transistor, a first amplifier, a second amplifier, a fourth diode, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second transistor, a third transistor, a power control chip, and an MBUS bus interface; wherein, The first amplifier is connected to the MBUS bus interface and is used to amplify the test signal fed back by the two-wire smart water meter. The second amplifier is connected to the first amplifier, and the second amplifier is used to perform secondary amplification processing on the test signal; The base of the first transistor is connected to one end of the third resistor, the collector of the first transistor is connected to one end of the first resistor and the cathode of the third diode, the emitter of the first transistor is grounded, the other end of the first resistor is connected to the first power supply voltage, and the other end of the third resistor is connected to the output terminal of the second amplifier. The anode of the third diode is connected to one end of the second resistor and the signal receiving end of the TTL conversion circuit, respectively, and the other end of the second resistor is connected to the first power supply voltage. The cathode of the fourth diode is connected to the signal transmitting pin of the TTL conversion circuit, the anode of the fourth diode is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the base of the second transistor. The emitter of the second transistor is connected to the first power supply voltage, the collector of the second transistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to one end of the sixth resistor and the base of the third transistor, and the other end of the sixth resistor is grounded. The collector of the third transistor is connected to one end of the seventh resistor, and the emitter of the third transistor is grounded. The other end of the seventh resistor is connected to the detection terminal of the power control chip; The input terminal of the power control chip is connected to a third power supply voltage, and the output terminal of the power control chip is connected to the MBUS bus interface.

[0009] In a further embodiment of this invention, the first transistor is an NPN transistor; the second transistor is a PNP transistor; and the third transistor is an NPN transistor.

[0010] In a further embodiment of this invention, the first power supply circuit includes a first power conversion chip, a first capacitor, and a second capacitor. The input terminal of the first power conversion chip is connected to the power output terminal of the USB interface circuit, and the output terminal of the first power conversion chip is connected to the TTL conversion circuit, the 485 bus circuit and the MBUS bus circuit respectively. The ground terminal of the first power conversion chip is grounded. One end of the first capacitor is connected to the input terminal of the first power conversion chip, and the other end of the first capacitor is grounded. One end of the second capacitor is connected to the output terminal of the first power conversion chip, and the other end of the second capacitor is grounded.

[0011] In a further embodiment of this invention, the second power supply circuit includes a second power conversion chip, a fifth diode, a sixth diode, and a third capacitor. The input terminal of the second power conversion chip is connected to the power supply terminal of the USB interface circuit, and the output terminal of the second power conversion chip is connected to the anode of the fifth diode. The cathode of the fifth diode is connected to the anode of the sixth diode, and the cathode of the sixth diode is connected to the power supply pin of the 485 bus circuit. One end of the third capacitor is connected to the cathode of the sixth diode, and the other end of the third capacitor is grounded.

[0012] In a further embodiment of this invention, the third power supply circuit includes: a third power conversion chip, a seventh diode, and a fourth capacitor; The power supply terminal of the third power conversion chip is connected to the output terminal of the second power conversion chip, and the output terminal of the third power conversion chip is connected to the anode of the seventh diode. The cathode of the seventh diode is connected to the MBUS bus circuit; One end of the fourth capacitor is connected to the cathode of the seventh diode, and the other end of the fourth capacitor is grounded.

[0013] In a further embodiment of this invention, the USB interface circuit includes a USB interface chip; the power supply terminal of the USB interface chip is connected to a power source; and the data pin of the USB interface chip is connected to the data pin of the TTL conversion circuit.

[0014] In a further embodiment of this invention, the TTL conversion circuit includes a TTL conversion chip and a TTL conversion interface; the data pin of the TTL conversion chip is connected to the data pin of the USB interface chip; the signal transmitting pin of the TTL conversion chip is connected to the signal transmitting pin of the high-speed transceiver and the signal transmitting terminal of the MBUS bus circuit respectively through the TTL conversion interface; the signal receiving pin of the TTL conversion chip is connected to the signal receiving pin of the high-speed transceiver and the signal receiving terminal of the MBUS bus circuit respectively through the TTL conversion interface.

[0015] A further feature of this invention is that the smart water meter testing circuit also includes a fourth power supply circuit, which comprises an external power supply connection interface, an eighth diode, a ninth diode, a tenth diode, an eighth resistor, a ninth resistor, and an LED indicator light; wherein, One end of the eighth resistor is connected to the output terminal of the external power supply interface, and the other end of the eighth resistor is connected to the anode of the eighth diode, the anode of the ninth diode, and one end of the ninth resistor, respectively. The cathode of the eighth diode is connected to the cathode of the tenth diode and the input terminal of the third power supply circuit, respectively. The cathode of the ninth diode is connected to the power supply terminal of the 485 bus circuit. The anode of the tenth diode is connected to the input terminal of the first power supply circuit.

[0016] This utility model provides a smart water meter testing circuit, comprising: a USB interface circuit, a TTL conversion circuit, a 485 bus circuit, an MBUS bus circuit, a first power supply circuit, a second power supply circuit, and a third power supply circuit. The USB interface circuit is used to connect to a host computer and is connected to the TTL conversion circuit and the first power supply circuit. The TTL conversion circuit is connected to the USB interface circuit, the 485 bus, and the MBUS bus. The 485 bus circuit is used to connect to a four-wire smart water meter and to provide feedback on the test data of the four-wire smart water meter. The MBUS bus circuit is used to connect to a two-wire smart water meter and to provide feedback on the test data of the two-wire smart water meter. The first power supply circuit is also connected to the TTL conversion circuit, the 485 bus circuit, and the MBUS bus circuit. The second power supply circuit is connected to the USB interface circuit and the 485 bus circuit. The third power supply circuit is connected to the second power supply circuit and the MBUS bus circuit. The smart water meter testing circuit provided by this utility model realizes the transmission of upper computer control signals and the feedback of smart water meter test data through USB interface circuit and TTL conversion circuit. The 485 bus circuit and MBUS bus circuit can both receive pulse signals from TTL conversion chip, and the TTL conversion circuit can also receive test signals fed back from 485 bus circuit and MBUS bus circuit respectively. Thus, the testing of two-wire and four-wire smart water meters can be completed in one testing device without changing the testing device, which facilitates the testing of smart water meters by the staff and improves the testing efficiency of smart water meters. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the smart water meter testing circuit in this utility model.

[0019] Figure 2 This is the circuit diagram of the USB interface circuit in this utility model.

[0020] Figure 3 This is the circuit diagram of the TTL conversion circuit in this utility model.

[0021] Figure 4 This is the interface circuit diagram of the TTL conversion circuit in this utility model.

[0022] Figure 5 This is the circuit schematic diagram of the 485 bus circuit in this utility model.

[0023] Figure 6 This is the schematic diagram of the interface circuit of the 485 bus circuit in this utility model.

[0024] Figure 7 This is the circuit schematic diagram of the MBUS bus circuit in this utility model.

[0025] Figure 8 This is the circuit diagram of the first power supply circuit in this utility model.

[0026] Figure 9 This is the circuit diagram of the second power supply circuit in this utility model.

[0027] Figure 10 This describes the circuit principle of the third power supply circuit in this utility model.

[0028] Figure 11 This is the circuit diagram of the fourth power supply circuit in this utility model.

[0029] The markings in the attached diagram are as follows: 100, USB interface circuit; 200, TTL conversion circuit; 300, 485 bus circuit; 400, MBUS bus circuit; 500, first power supply circuit; 600, second power supply circuit; 700, third power supply circuit; 800, fourth power supply circuit. Detailed Implementation

[0030] This utility model provides a smart water meter testing circuit. To make the purpose, technical solution, and effects of this utility model clearer and more explicit, the following detailed description is provided with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit it.

[0031] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of this utility model involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0032] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any of the units and all combinations thereof of one or more associatedly listed items.

[0033] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0034] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0035] Please also refer to Figures 1 to 11 This utility model provides a preferred embodiment of a smart water meter testing circuit.

[0036] In some embodiments, such as Figure 1As shown, this utility model provides a smart water meter testing circuit, which includes: a USB interface circuit 100, a TTL conversion circuit 200, a 485 bus circuit 300, an MBUS bus circuit 400, a first power supply circuit 500, a second power supply circuit 600, and a third power supply circuit 700. The USB interface circuit 100 is used to connect to a host computer and is also connected to the TTL conversion circuit 200 and the first power supply circuit 500. The USB interface circuit 100 sends control signals from the host computer and receives test signals from the smart water meter, and provides a first power supply voltage to the first power supply circuit 500. The TTL conversion circuit 200 is connected to the USB interface circuit 100, the 485 bus, and the MBUS bus, respectively, and is used to convert between analog and digital signals. The 485 bus circuit 300 is used to connect to a four-wire smart water meter and to provide feedback on the test data of the four-wire smart water meter. The MBUS bus circuit 400 is used to connect to a two-wire smart water meter and to provide feedback on the test data of the two-wire smart water meter. The first power supply circuit 500 is also connected to the... The TTL conversion circuit 200, the 485 bus circuit 300, and the MBUS bus circuit 400 are connected. The first power supply circuit 500 is used to convert the first power supply voltage into a second power supply voltage to power the TTL conversion circuit 200, the 485 bus circuit 300, and the MBUS bus circuit 400. The second power supply circuit 600 is connected to the USB interface circuit 100 and the 485 bus circuit 300, respectively. The second power supply circuit 600 is used to convert the first power supply voltage into a second power supply voltage to power the 485 bus circuit 300. The third power supply circuit 700 is connected to the second power supply circuit 600 and the MBUS bus circuit 400, respectively. The third power supply circuit 700 is used to convert the second power supply voltage into a third power supply voltage to power the MBUS bus circuit 400.

[0037] In this embodiment, the USB interface circuit 100 is used to connect to a host computer, enabling it to send control signals from the host computer to the smart water meter and upload test data from the smart water meter to the host computer. The host computer can be a computer terminal, mobile phone terminal, tablet computer, etc. The TTL conversion circuit 200 can convert the control signals (analog signals) sent by the USB interface circuit 100 into digital signals, and can also convert the test signals (digital signals) uploaded by the 485 bus circuit 300 and MBUS bus circuit 400 into analog signals.

[0038] Generally, smart water meters come in two-wire and four-wire versions. A two-wire smart water meter has one power line and one signal line, while a four-wire smart water meter has two power lines and two signal lines. Four-wire smart water meters require a 485 bus circuit 300 for data acquisition, while two-wire smart water meters require an MBUS bus circuit 400. Both the 485 bus circuit 300 and the MBUS bus circuit 400 are connected to the TTL conversion circuit 200 and can simultaneously receive control signals from the host computer. When testing a two-wire smart water meter, the MBUS bus circuit 400 is used to acquire data; when testing a four-wire smart water meter, the 485 bus circuit 300 is used.

[0039] The USB interface circuit 100 provides a first power supply voltage of 5V. The first power supply circuit 500 converts the 5V first power supply voltage into a second power supply voltage of 3.3V to power the TTL conversion circuit 200, the 485 bus circuit 300, and the MBUS bus circuit 400. The second power supply circuit 600 boosts the 5V first power supply voltage to 12V to power the 485 bus circuit 300. The third power supply circuit 700 boosts the 12V second power supply voltage to 32V to power the MBUS bus circuit 400.

[0040] As can be seen, the smart water meter testing circuit provided by this utility model realizes the transmission of upper computer control signals and the feedback of smart water meter test data through USB interface circuit 100 and TTL conversion circuit 200. Among them, 485 bus circuit 300 and MBUS bus circuit 400 can both receive pulse signals from TTL conversion chip, and TTL conversion circuit 200 can also receive test signals fed back from 485 bus circuit 300 and MBUS bus circuit 400 respectively. Thus, the testing of two-wire and four-wire smart water meters can be completed in one testing device without changing the testing device, which facilitates the staff to test smart water meters and improves the testing efficiency of smart water meters.

[0041] In some embodiments, such as Figure 2 As shown, the USB interface circuit 100 includes a USB interface chip U1; the power supply terminal of the USB interface chip U1 is connected to the power supply VBUS; the data pins (UD+, UD-) of the USB interface chip U1 are connected to the data pins of the TTL conversion circuit 200.

[0042] Furthermore, such as Figure 3 and Figure 4As shown, the TTL conversion circuit 200 includes a TTL conversion chip U2 and a TTL conversion interface J3; the data pins (UD+, UD-) of the TTL conversion chip U2 are connected to the data pins (UD+, UD-) of the USB interface chip U1; the signal transmitting pin TXD of the TTL conversion chip U2 is connected to the signal transmitting pin of the 485 bus circuit 300 and the signal transmitting terminal of the MBUS bus circuit 400 through the TTL conversion interface J3; the signal transmitting pin TXD of the TTL conversion chip is connected to the signal receiving pin RXD of the 485 bus circuit 300 and the signal receiving terminal RXD of the MBUS bus circuit 400 through the TTL conversion interface J3.

[0043] In this embodiment, the USB interface chip U1 and the TTL conversion chip U2 are used to send control signals and upload test signals. In one implementation, the USB interface chip U1 can be a TYPE-C-31-M12 type USB interface chip, and the TTL conversion chip U2 can be a CH340T type TTL conversion chip.

[0044] In some embodiments, such as Figure 5 As shown, the 485 bus circuit 300 includes: a high-speed transceiver U3, a first diode D1, a second diode D2, and input / output interfaces (P8 and P9). Specifically, the signal receiving pin RXD of the high-speed transceiver U3 is connected to the signal receiving pin RXD of the TTL conversion circuit 200, and the signal transmitting pin TXD of the high-speed transceiver U3 is also connected to the signal transmitting pin TXD of the TTL conversion circuit 200. The first signal input pin B and the second signal input pin A of the high-speed transceiver U3 are connected to the input / output interfaces. The power supply pin VDD of the high-speed transceiver U3 is connected to the first power supply circuit 500. The cathode of the first diode D1 is connected to the signal receiving pin (pin 1) of the high-speed transceiver U3, and the anode of the first diode D1 is connected to the signal receiving pin of the TTL conversion circuit 200. The cathode of the second diode D2 is connected to the signal transmitting pin of the TTL conversion circuit 200, and the anode of the second diode D2 is connected to the signal transmitting pin (pin 4) of the high-speed transceiver U3.

[0045] In this embodiment, the signal receiving and signal transmitting pins of the high-speed transceiver U3 are connected to the corresponding signal receiving and signal transmitting pins of the TTL conversion circuit 200. The two signal input pins (A and B) of the high-speed transceiver U3 are connected to the input / output ports (P8 and P9), which are then connected to a four-wire smart water meter to enable signal transmission and transmission. Specifically, the first diode D1 is connected to the signal receiving pin of the high-speed transceiver U3, and the second diode D2 is connected to the signal transmitting pin of the high-speed transceiver U3, preventing crosstalk from the MBUS bus circuit 400 to the 485 bus circuit 300.

[0046] In some embodiments, such as Figure 7As shown, the MBUS bus circuit 400 includes: a third diode D3, a first resistor R1, a second resistor R2, a third resistor R3, a first transistor Q1, a first amplifier U5, a second amplifier U6, a fourth diode D4, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a second transistor Q2, a third transistor Q3, a power control chip U4, and an MBUS bus interface J1. The first amplifier U5 is connected to the MBUS bus interface J1 and is used to amplify the test signal fed back from the two-wire smart water meter. The second amplifier U6 is connected to the first amplifier U5 and is used to amplify the test signal. The base of the first transistor Q1 is connected to one end of the third resistor R3. The collector of the first transistor Q1 is connected to one end of the first resistor R1 and the cathode of the third diode D3. The emitter of the first transistor Q1 is grounded. The other end of the first resistor R1 is connected to the first power supply voltage. The other end of the third resistor R3 is connected to the output terminal of the second amplifier U6. The anode of the third diode D3 is connected to one end of the second resistor R2 and the signal receiving terminal RXD of the TTL conversion circuit 200. The other end of the second resistor R2 is connected to the first power supply voltage. The cathode of the fourth diode D4 is connected to the signal transmitting pin TXD of the TTL conversion circuit 200. The anode of the fourth diode D4 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the base of the second transistor Q2. The emitter of the second transistor Q2 is connected to a first power supply voltage. The collector of the second transistor Q2 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to one end of the sixth resistor R6 and the base of the third transistor Q3. The other end of the sixth resistor R6 is grounded. The collector of the third transistor Q3 is connected to one end of the seventh resistor R7, and the emitter of the third transistor Q3 is grounded. The other end of the seventh resistor R7 is connected to the detection terminal of the power control chip U4. The input terminal of the power control chip U4 is connected to a third power supply voltage, and the output terminal of the power control chip U4 is connected to the MBUS bus interface J1.

[0047] In this embodiment, the first resistor R1, the second resistor R2, and the second transistor Q2 are connected to a 3.3V voltage, and the power control chip U4 is connected to a 32V voltage. The first transistor Q1 is an NPN transistor; the second transistor Q2 is a PNP transistor; and the third transistor Q3 is an NPN transistor.

[0048] In the signal sending operation, when no signal is sent, the second transistor Q2 and the third transistor Q3 are disconnected, and the power control chip U4 detects the voltage status of node F. At this time, the power control chip U4 outputs a voltage of 30V. When a signal is sent, the second transistor Q2 and the third transistor Q3 are turned on, and the power control chip U4 detects the voltage of node F and outputs a voltage of 20V, thereby sending the control signal to the smart water meter in a pulse manner.

[0049] In the signal uploading operation, when no test signal is uploaded, the first transistor Q1 is turned off, and the signal receiving terminal RXD of the MBUS bus circuit 400 is at a high level. When a test signal is uploaded, the test signal is amplified by the first amplifier U5 and the second amplifier U6 and then input to the base of the first transistor Q1 through the third resistor R3. The first transistor Q1 is turned on, and the signal receiving terminal RXD of the MBUS bus circuit 400 is at a low level, thereby realizing the feedback of the test signal to the host computer in the form of a pulse signal.

[0050] The third diode D3 is connected to the signal receiving end of the MBUS bus circuit 400, and the fourth diode D4 is connected to the signal transmitting end of the MBUS bus circuit 400, which can prevent the signal of the 485 bus circuit 300 from being transmitted to the MBUS bus circuit 400.

[0051] In some embodiments, such as Figure 8 As shown, the first power supply circuit 500 includes a first power conversion chip U7, a first capacitor C1, and a second capacitor C2. The input terminal of the first power conversion chip U7 is connected to the power output terminal of the USB interface circuit 100, and the output terminal of the first power conversion chip U7 is connected to the TTL conversion circuit 200, the 485 bus circuit 300, and the MBUS bus circuit 400, respectively. The ground terminal of the first power conversion chip U7 is grounded. One end of the first capacitor C1 is connected to the input terminal of the first power conversion chip U7, and the other end of the first capacitor C1 is grounded. One end of the second capacitor C2 is connected to the output terminal of the first power conversion chip U7, and the other end of the second capacitor C2 is grounded.

[0052] In this embodiment, the input terminal of the first power conversion chip U7 is connected to the 5V voltage provided by the USB interface circuit 100, converting the 5V voltage to 3.3V to power the TTL conversion circuit 200, the 485 bus circuit 300, and the MBUS bus circuit 400. In one implementation, the first power conversion chip U7 can be an HT7533-1_SOT-89 model power conversion chip.

[0053] In some embodiments, such as Figure 9 As shown, the second power supply circuit 600 includes a second power conversion chip U8, a fifth diode D5, a sixth diode D6, and a third capacitor C3. The input terminal of the second power conversion chip U8 is connected to the power supply terminal of the USB interface circuit 100, and the output terminal of the second power conversion chip U8 is connected to the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the anode of the sixth diode D6, and the cathode of the sixth diode D6 is connected to the power supply pin of the 485 bus circuit 300; one end of the third capacitor C3 is connected to the cathode of the sixth diode D6, and the other end of the third capacitor C3 is grounded.

[0054] In this embodiment, the input terminal of the second power conversion chip U8 is connected to the 5V power supply provided by the USB interface circuit 100, and outputs the 12V voltage 485VDD required by the 485 bus circuit 300 via the fifth diode D5 and the sixth diode D6, where 485VDD is a 12V voltage. The third capacitor C3 is a filter capacitor. In one implementation, the second power conversion chip U8 can be an AP3012 power chip.

[0055] In some embodiments, the third power supply circuit 700 includes: a third power conversion chip U9, a seventh diode D7, and a fourth capacitor C4; the power supply terminal of the third power conversion chip U9 is connected to the output terminal of the second power conversion chip U8, and the output terminal of the third power conversion chip U9 is connected to the anode of the seventh diode D7; the cathode of the seventh diode D7 is connected to the MBUS bus circuit 400; one end of the fourth capacitor C4 is connected to the cathode of the seventh diode D7, and the other end of the fourth capacitor C4 is grounded.

[0056] In this embodiment, the third power conversion chip U9 is connected to the output terminal of the second power circuit 600, and can boost the 12V voltage to 32V to power the power control chip U4. The fourth capacitor C4 is a filter capacitor. In one implementation, the third power conversion chip U9 can be an AX5201ESA model power conversion chip.

[0057] In some embodiments, such as Figure 11As shown, the smart water meter test circuit also includes a fourth power supply circuit 800, which includes an external power connection interface JK, an eighth diode D8, a ninth diode D9, a tenth diode D10, an eighth resistor R8, a ninth resistor R9, and an LED indicator LED1. One end of the eighth resistor R8 is connected to the output terminal of the external power connection interface JK, and the other end of the eighth resistor R8 is connected to the anode of the eighth diode D8, the anode of the ninth diode D9, and one end of the ninth resistor R9. The cathode of the eighth diode D8 is connected to the cathode of the tenth diode D10 and the input terminal of the third power supply circuit 700. The cathode of the ninth diode D9 is connected to the power supply terminal of the 485 bus circuit 300. The anode of the tenth diode D10 is connected to the input terminal of the first power supply circuit 500.

[0058] In this embodiment, the external power connection interface JK can be connected to an external power source. The external power source, after passing through the eighth resistor R8, the eighth diode D8, the ninth diode D9, and the tenth diode D10, can output 5V, 12V, and the 485VDD power supply voltage required by the 485 bus circuit. Additionally, the external power source, after passing through the eighth resistor R8, flows through the ninth resistor R9 and the LED indicator LED1. When an external power source is connected, the LED indicator LED1 illuminates to indicate to the operator that an external power source is currently available.

[0059] In summary, the intelligent water meter testing circuit provided by this utility model has the following beneficial effects: The smart water meter testing circuit provided by this utility model realizes the transmission of upper computer control signals and the feedback of smart water meter test data through USB interface circuit and TTL conversion circuit. The 485 bus circuit and MBUS bus circuit can both receive pulse signals from TTL conversion chip, and the TTL conversion circuit can also receive test signals fed back from 485 bus circuit and MBUS bus circuit respectively. Thus, the testing of two-wire and four-wire smart water meters can be completed in one testing device without changing the testing device, which facilitates the testing of smart water meters by the staff and improves the testing efficiency of smart water meters.

[0060] It should be understood that the application of this utility model is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A smart water meter testing circuit, characterized in that, include: The circuit includes a USB interface circuit, a TTL conversion circuit, a 485 bus circuit, an MBUS bus circuit, a first power supply circuit, a second power supply circuit, and a third power supply circuit; among which... The USB interface circuit is used to connect to the host computer, and is also connected to the TTL conversion circuit and the first power supply circuit. The USB interface circuit is used to send control signals from the host computer and receive test signals from the smart water meter, and to provide a first power supply voltage to the first power supply circuit. The TTL conversion circuit is connected to the USB interface circuit, the 485 bus, and the MBUS bus respectively, and the TTL conversion circuit is used to realize the conversion between analog signals and digital signals. The 485 bus circuit is used to connect to a four-wire smart water meter and to provide feedback on the test data of the four-wire smart water meter. The MBUS bus circuit is used to connect to a two-wire smart water meter and to provide feedback on the test data of the two-wire smart water meter. The first power supply circuit is also connected to the TTL conversion circuit, the 485 bus circuit and the MBUS bus circuit respectively. The first power supply circuit is used to convert the first power supply voltage into a second power supply voltage to power the TTL conversion circuit, the 485 bus circuit and the MBUS bus circuit. The second power supply circuit is connected to the USB interface circuit and the 485 bus circuit respectively. The second power supply circuit is used to convert the first power supply voltage into a second power supply voltage to power the 485 bus circuit. The third power supply circuit is connected to the second power supply circuit and the MBUS bus circuit respectively. The third power supply circuit is used to convert the second power supply voltage into a third power supply voltage to power the MBUS bus circuit.

2. The smart water meter testing circuit according to claim 1, characterized in that, The 485 bus circuit includes: a high-speed transceiver, a first diode, a second diode, and an input / output interface; wherein... The signal receiving pin of the high-speed transceiver is connected to the signal receiving pin of the TTL conversion circuit, and the signal transmitting pin of the high-speed transceiver is connected to the signal transmitting pin of the TTL conversion circuit. The first signal input pin and the second signal input pin of the high-speed transceiver are connected to the input / output interface; The power pin of the high-speed transceiver is connected to the first power circuit. The cathode of the first diode is connected to the signal receiving pin of the high-speed transceiver, and the anode of the first diode is connected to the signal receiving pin of the TTL conversion circuit. The cathode of the second diode is connected to the signal transmit pin of the TTL conversion circuit, and the anode of the second diode is connected to the signal transmit pin of the high-speed transceiver.

3. The smart water meter testing circuit according to claim 2, characterized in that, The MBUS bus circuit includes: a third diode, a first resistor, a second resistor, a third resistor, a first transistor, a first amplifier, a second amplifier, a fourth diode, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second transistor, a third transistor, a power control chip, and an MBUS bus interface; wherein, The first amplifier is connected to the MBUS bus interface and is used to amplify the test signal fed back by the two-wire smart water meter. The second amplifier is connected to the first amplifier, and the second amplifier is used to perform secondary amplification processing on the test signal; The base of the first transistor is connected to one end of the third resistor, the collector of the first transistor is connected to one end of the first resistor and the cathode of the third diode, the emitter of the first transistor is grounded, the other end of the first resistor is connected to the first power supply voltage, and the other end of the third resistor is connected to the output terminal of the second amplifier. The anode of the third diode is connected to one end of the second resistor and the signal receiving end of the TTL conversion circuit, respectively, and the other end of the second resistor is connected to the first power supply voltage. The cathode of the fourth diode is connected to the signal transmitting pin of the TTL conversion circuit, the anode of the fourth diode is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the base of the second transistor. The emitter of the second transistor is connected to the first power supply voltage, the collector of the second transistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to one end of the sixth resistor and the base of the third transistor, and the other end of the sixth resistor is grounded. The collector of the third transistor is connected to one end of the seventh resistor, and the emitter of the third transistor is grounded. The other end of the seventh resistor is connected to the detection terminal of the power control chip; The input terminal of the power control chip is connected to a third power supply voltage, and the output terminal of the power control chip is connected to the MBUS bus interface.

4. The smart water meter testing circuit according to claim 3, characterized in that, The first transistor is an NPN transistor; the second transistor is a PNP transistor; and the third transistor is an NPN transistor.

5. The smart water meter testing circuit according to claim 1, characterized in that, The first power supply circuit includes a first power conversion chip, a first capacitor, and a second capacitor; The input terminal of the first power conversion chip is connected to the power output terminal of the USB interface circuit, and the output terminal of the first power conversion chip is connected to the TTL conversion circuit, the 485 bus circuit and the MBUS bus circuit respectively. The ground terminal of the first power conversion chip is grounded. One end of the first capacitor is connected to the input terminal of the first power conversion chip, and the other end of the first capacitor is grounded. One end of the second capacitor is connected to the output terminal of the first power conversion chip, and the other end of the second capacitor is grounded.

6. The smart water meter testing circuit according to claim 1, characterized in that, The second power supply circuit includes a second power conversion chip, a fifth diode, a sixth diode, and a third capacitor; The input terminal of the second power conversion chip is connected to the power supply terminal of the USB interface circuit, and the output terminal of the second power conversion chip is connected to the anode of the fifth diode. The cathode of the fifth diode is connected to the anode of the sixth diode, and the cathode of the sixth diode is connected to the power supply pin of the 485 bus circuit. One end of the third capacitor is connected to the cathode of the sixth diode, and the other end of the third capacitor is grounded.

7. The smart water meter testing circuit according to claim 6, characterized in that, The third power supply circuit includes: a third power conversion chip, a seventh diode, and a fourth capacitor; The power supply terminal of the third power conversion chip is connected to the output terminal of the second power conversion chip, and the output terminal of the third power conversion chip is connected to the anode of the seventh diode. The cathode of the seventh diode is connected to the MBUS bus circuit; One end of the fourth capacitor is connected to the cathode of the seventh diode, and the other end of the fourth capacitor is grounded.

8. The smart water meter testing circuit according to claim 3, characterized in that, The USB interface circuit includes a USB interface chip; the power supply terminal of the USB interface chip is connected to a power source; and the data pin of the USB interface chip is connected to the data pin of the TTL conversion circuit.

9. The smart water meter testing circuit according to claim 8, characterized in that, The TTL conversion circuit includes a TTL conversion chip and a TTL conversion interface; the data pin of the TTL conversion chip is connected to the data pin of the USB interface chip; the signal transmission pin of the TTL conversion chip is connected to the signal transmission pin of the high-speed transceiver and the signal transmission terminal of the MBUS bus circuit through the TTL conversion interface; the signal reception pin of the TTL conversion chip is connected to the signal reception pin of the high-speed transceiver and the signal reception terminal of the MBUS bus circuit through the TTL conversion interface.

10. The smart water meter testing circuit according to claim 1, characterized in that, Also includes: The fourth power supply circuit includes: an external power connection interface, an eighth diode, a ninth diode, a tenth diode, an eighth resistor, a ninth resistor, and an LED indicator; wherein, One end of the eighth resistor is connected to the output terminal of the external power supply interface, and the other end of the eighth resistor is connected to the anode of the eighth diode, the anode of the ninth diode, and one end of the ninth resistor, respectively. The cathode of the eighth diode is connected to the cathode of the tenth diode and the input terminal of the third power supply circuit, respectively. The cathode of the ninth diode is connected to the power supply terminal of the 485 bus circuit. The anode of the tenth diode is connected to the input terminal of the first power supply circuit.

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