Fault detection system and fault detection method for weighing equipment

Abstract

The invention provides a fault detection system for weighing equipment, which comprises the weighing equipment and a signal acquisition circuit, the signal acquisition circuit comprises an analog-to-digital converter, a power supply and a controller, and at least one strain sensor is connected to the signal acquisition circuit through a plurality of cables. The at least one strain sensor is configured to be connected to a power supply through a positive excitation line, grounded through a negative excitation line, connected to an input end of the analog-to-digital converter through a signal line, and connected to a reference end of the analog-to-digital converter through a feedback line; the power end of the analog-to-digital converter is connected with a power supply; a first diode is arranged between the strain sensor and the power supply, and the first diode is used for reducing the output voltage of the power supply, so that the voltage of the positive excitation line is smaller than the voltage of the power supply end of the analog-to-digital converter; and the controller is configured to judge the fault of the weighing equipment according to the positive excitation voltage of the positive excitation line, the positive excitation current of the positive excitation line and the feedback line voltage of the feedback line.

Description

Technical Field

[0001] The present application mainly relates to the technical field of diagnostic detection of instruments and equipment, and in particular to a fault detection system and a fault detection method for weighing equipment. Background Art

[0002] Industrial electronic scales or weighing systems typically include multiple load cells, each of which transmits weighing data to a terminal, which receives, processes, and displays the data. During operation, the system or terminal performs common fault diagnostics on the sensors, such as determining whether a sensor has a short circuit or other simple fault. The user can view the weighing data and diagnostic data on the terminal. However, current diagnostic methods are relatively simple, only able to determine whether a short circuit or open circuit has occurred. For complex weighing systems, such as those with multiple load cells or those using strain gauge sensors, it is impossible to determine specifically which sensor has failed, or which wire or strain gauge within the strain gauge sensor has failed, hindering accurate fault location. Being able to diagnose and locate specific fault information would help field technicians more accurately determine the fault type and more quickly identify solutions and resolve the problem. Summary of the Invention

[0003] The technical problem to be solved by the present application is to provide a fault detection system and a fault detection method for accurately locating faults in a weighing system.

[0004] To solve the above technical problems, the present application provides a fault detection system for a weighing device, comprising a weighing device and a signal acquisition circuit, wherein the weighing device comprises at least one strain gauge sensor, the signal acquisition circuit comprises an analog-to-digital converter, a power supply and a controller, the at least one strain gauge sensor is connected to the signal acquisition circuit via several cables, the several cables comprising a positive excitation line, a negative excitation line, a signal line and a feedback line, wherein the at least one strain gauge sensor is configured to: be connected to the power supply via a positive excitation line, be grounded via a negative excitation line, be connected to the input end of the analog-to-digital converter via a signal line, and be connected to the reference end of the analog-to-digital converter via a feedback line; the power supply end of the analog-to-digital converter is connected to the power supply; a first diode is arranged between the strain gauge sensor and the power supply, the first diode is used to step down the output voltage of the power supply so that the voltage of the positive excitation line is less than the voltage of the power supply end of the analog-to-digital converter; the controller is configured to: judge the fault of the weighing device based on the positive excitation voltage of the positive excitation line, the positive excitation current of the positive excitation line and the feedback line voltage of the feedback line.

[0005] In one embodiment of the present application, a second diode is provided between the negative excitation line and the internal ground, and the second diode is used to boost the voltage of the negative excitation line.

[0006] In one embodiment of the present application, a voltage detection unit and a current detection unit are further included, which are arranged between the first diode and the positive excitation line. The voltage detection unit is used to detect the positive excitation voltage of the positive excitation line and send the positive excitation voltage to the controller. The current detection unit is used to detect the positive excitation current of the positive excitation line and send the positive excitation current to the controller.

[0007] In one embodiment of the present application, the feedback line includes a positive feedback line and a negative feedback line, one end of the positive feedback line is short-circuited with the positive excitation line, and the other end of the positive feedback line is connected to the positive reference terminal REF+ of the analog-to-digital converter, one end of the negative feedback line is short-circuited with the negative excitation line, and the other end of the negative feedback line is connected to the negative reference terminal REF- of the analog-to-digital converter, and the analog-to-digital converter is configured such that: when the voltage difference between the positive reference terminal REF+ and the negative reference terminal REF- exceeds a preset value, the flag bit NOREF of the analog-to-digital converter is set to a preset bit, and the controller is configured to: obtain the flag bit NOREF.

[0008] In one embodiment of the present application, the signal line includes a positive signal line, which is connected to the positive input terminal of the analog-to-digital converter. The analog-to-digital converter is configured to: be set to a single-ended input mode, and set the amplification factor of the programmable gain amplifier of the analog-to-digital converter to 1. The controller is configured to: obtain the positive signal line voltage of the positive signal line according to the signal of the positive input terminal, and judge the fault of the weighing device in combination with the positive signal line voltage.

[0009] In one embodiment of the present application, the signal line includes a negative signal line, which is connected to the negative input terminal of the analog-to-digital converter. The analog-to-digital converter is configured to: be set to a single-ended input mode, and set the amplification factor of the programmable gain amplifier of the analog-to-digital converter to 1. The controller is configured to: obtain the negative signal line voltage of the negative signal line according to the signal of the negative input terminal, and judge the fault of the weighing device in combination with the negative signal line voltage.

[0010] In one embodiment of the present application, the signal line includes a positive signal line and a negative signal line, the positive signal line is connected to the positive input terminal of the analog-to-digital converter, and the negative signal line is connected to the negative input terminal of the analog-to-digital converter. The analog-to-digital converter is configured to: be set to a differential input mode, and set the amplification factor of the programmable gain amplifier of the analog-to-digital converter to a preset value not equal to 1. The controller is configured to: obtain the differential voltage between the positive signal line and the negative signal line, and determine the fault of the weighing device based on the differential voltage.

[0011] In an embodiment of the present application, the at least one strain sensor includes a plurality of bridge-connected strain gauges.

[0012] In order to solve the above-mentioned technical problems, the present application also proposes a fault detection method for weighing equipment, which is applied to the fault detection system as described above, including: obtaining the positive excitation voltage and positive excitation current of the positive excitation line of the at least one strain sensor, and obtaining the feedback line voltage of the feedback line of the at least one strain sensor; judging the fault of the weighing equipment according to the positive excitation voltage, positive excitation current and the feedback line voltage, the fault including cable line fault and strain gauge fault.

[0013] In one embodiment of the present application, the positive excitation voltage is equal to the supply voltage VDDA of the analog-to-digital converter minus the forward voltage drop of the first diode.

[0014] In one embodiment of the present application, the step of judging the fault of the strain gauge sensor according to the positive excitation voltage, the positive excitation current and the feedback line voltage includes: obtaining the flag NOREF of the analog-to-digital converter, the flag NOREF being related to the voltage difference between the positive feedback line and the negative feedback line; when the positive excitation voltage is abnormal, judging that the positive excitation line is short-circuited to the negative excitation line or the negative feedback line; when the positive excitation voltage is normal, the positive excitation current is 0, and the flag NOREF is abnormal, judging that the positive excitation line is open-circuited; when the positive excitation voltage is normal, the positive excitation current reaches the current limit value, and the flag NOREF is abnormal, judging that the positive feedback line or the negative feedback line is open-circuited, or that the positive feedback line is short-circuited to the negative feedback line or the negative excitation line.

[0015] In one embodiment of the present application, it also includes: when the analog-to-digital converter is in a single-ended input mode, respectively obtaining the positive signal line voltage of the positive signal line and the negative signal line voltage of the negative signal line; when the analog-to-digital converter is in a differential input mode, obtaining the differential voltage between the positive signal line and the negative signal line; judging the fault of the strain gauge sensor based on the positive excitation voltage, the positive excitation current, the feedback line voltage, the positive signal line voltage, the negative signal line voltage and the differential voltage.

[0016] In one embodiment of the present application, the step of judging the fault of the weighing device according to the positive excitation voltage, the positive excitation current, the feedback line voltage, the positive signal line voltage, the negative signal line voltage and the differential voltage includes: when the positive excitation voltage and the flag NOREF are both normal, when the positive signal line voltage and the negative signal line voltage are both fully loaded, and the differential voltage is no-load, judging that the positive feedback line is short-circuited to the positive signal line or the negative signal line; when the positive excitation voltage and the flag NOREF are both normal, when the positive signal line voltage, the negative signal line voltage and the differential voltage are all no-load, judging that the negative feedback line is short-circuited to the positive signal line or the negative signal line.

[0017] In one embodiment of the present application, the at least one strain sensor includes four bridged strain gauges, and the step of judging the fault of the weighing device according to the positive excitation voltage, the positive excitation current, the feedback line voltage, the positive signal line voltage, the negative signal line voltage and the differential voltage includes: when the positive excitation voltage and the flag NOREF are both normal, judging which strain gauge is disconnected or short-circuited according to the positive excitation current, the positive signal line voltage, the negative signal line voltage and the differential voltage.

[0018] In one embodiment of the present application, when a strain gauge fails, the differential voltage is positive full load or negative full load.

[0019] In one embodiment of the present application, when a cable fails, the positive excitation current is a first measurement value, and when a strain gauge fails, the positive excitation current is a second measurement value, and the first measurement value is different from the second measurement value.

[0020] The fault detection system and method of the present application sets a first diode between the strain gauge sensor and the power supply to reduce the positive excitation voltage of the strain gauge sensor relative to the power supply voltage, so that the actual excitation voltage range applied to the strain gauge sensor is lower than the power supply voltage of the analog-to-digital converter. Therefore, when the excitation line and the signal line are short-circuited, the analog-to-digital converter can still collect the signal on the signal line, which is conducive to continuous acquisition of signals and use for fault diagnosis. During the fault diagnosis process, the fault detection system and method of the present application can collect information of different states, including the positive signal line voltage and the negative signal line voltage and the differential voltage between the two, by setting the input end of the analog-to-digital converter to a single-ended input mode and a differential input mode respectively. Therefore, multiple different types of faults can be judged based on multiple signals, which is conducive to rapid and accurate fault location. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are included to provide a further understanding of the present application. They are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present application and, together with this specification, serve to explain the principles of the present application. In the accompanying drawings:

[0022] Figure 1 is an exemplary block diagram of a fault detection system for a weighing device according to a first embodiment of the present application;

[0023] Figure 2 This is a system block diagram of a fault detection system for a weighing device according to a second embodiment of the present application;

[0024] Figure 3 This is an exemplary flow chart of a fault detection method according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0026] As used herein, unless the context clearly indicates otherwise, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0027] Unless otherwise specified, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. Technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0028] Flowcharts are used in this application to illustrate the operations performed by systems according to embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the various steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0029] The weighing device of the present application may be any type of weighing device, including but not limited to industrial electronic scales, pallet scales, truck scales, etc. The weighing sensor used in the weighing device is a strain gauge sensor.

[0030] Figure 1 This is an exemplary block diagram of a fault detection system for a weighing device according to the first embodiment of the present application. Figure 1 As shown, the fault detection system 100 includes a weighing device 110 and a signal acquisition circuit 120, wherein the weighing device 110 includes at least one strain gauge sensor 111, the signal acquisition circuit 120 includes an analog-to-digital converter 121, a power supply 122 and a controller 130, and the at least one strain gauge sensor 111 is connected to the signal acquisition circuit 120 via a plurality of cables, the plurality of cables including a positive excitation line EXC+, a negative excitation line EXC-, a signal line SIG and a feedback line SEN, wherein the at least one strain gauge sensor 111 is configured as follows: connected to the power supply 122 via the positive excitation line EXC+, and connected to the power supply 122 via the negative excitation line EXC-. The excitation line EXC- is grounded, connected to the input terminal AIN of the analog-to-digital converter 121 through the signal line SIG, and connected to the reference terminal REF of the analog-to-digital converter 121 through the feedback line SEN; the power supply terminal VDDA of the analog-to-digital converter 121 is connected to the power supply 122; a first diode D1 is provided between the strain gauge sensor 111 and the power supply 122, and the first diode D1 is used to step down the output voltage Vs of the power supply 122, so that the voltage of the positive excitation line EXC+ is less than the voltage of the power supply terminal VDDA of the analog-to-digital converter 121; the controller 130 is configured to: according to the positive excitation voltage V EXC+ , positive excitation current I of positive excitation line EXC+ EXC+ and the feedback line voltage V of the feedback line SEN SEN A failure of the strain sensor 111 is determined.

[0031] like Figure 1 As shown, in Figure 1At least three types of cables are drawn from the strain gauge sensor 111, including an excitation line EXC, a signal line SIG, and a feedback line SEN. Each type of cable is paired, meaning that the strain gauge sensor 111 utilizes a six-wire wiring system. The signal line SIG includes a positive signal line SIG+ and a negative signal line SIG-. Accordingly, the input terminal AIN of the analog-to-digital converter 121 also includes a positive input terminal AIN+ and a negative input terminal AIN-. The feedback line SEN includes a positive feedback line SEN+ and a negative feedback line SEN-. Accordingly, the reference terminal REF of the analog-to-digital converter 121 also includes a positive reference terminal REF+ and a negative reference terminal REF-.

[0032] exist Figure 1 In the embodiment, the power supply 122 is electrically connected to the first diode D1, the analog-to-digital converter 121, and the controller 130 at the same time, and the power supply 122 is used to provide voltage Vs to other modules. The positive pole of the first diode D1 is close to the power supply 122, and the negative pole is close to the strain sensor 111. The power supply terminal VDDA of the analog-to-digital converter 121 is connected to the power supply 122, and is also connected to the positive pole of the first diode D1. The first diode D1 can provide a stable forward voltage drop to reduce the output voltage of the power supply 122. In some embodiments, the first diode D1 is a Schottky diode. Assuming that the forward voltage drop of the first diode D1 is Vf1 and the output voltage of the power supply 122 is Vs, then Vs≈V EXC+ +Vf1. The range of Vf1 can be 300mV≤Vf1<1V, and its specific value is related to the characteristics of the selected analog-to-digital converter 121, for example, it can be 500mV. Further, VDDA=Vs≈V EXC+ +Vf1. That is, by setting the first diode D1 so that V EXC+ Vf1 lower than VDDA.

[0033] Generally, the analog-to-digital converter 121 requires that the input voltage at the input terminal AIN should be smaller than VDDA. If the first diode D1 is not provided in the weighing system 100, that is, VDDA=V EXC+ , when the signal line SIG and the positive excitation line EXC+ are short-circuited, V SIG =VDDA, at this time, the input voltage of the input terminal AIN of the analog-to-digital converter 121 is equal to VDDA, which will cause the analog-to-digital converter 121 to be unable to normally collect the signal on the signal line SIG.

[0034] The weighing system 100 of the present application is provided with a first diode D1 so that when the signal line SIG and the positive excitation line EXC+ are short-circuited, V SIG =V EXC+=VDDA-Vf, the value of Vf is selected so that the input voltage of the input terminal AIN of the analog-to-digital converter 121 meets the input voltage requirement, so that the analog-to-digital converter 121 can normally collect the signal on the signal line SIG.

[0035] Example 1 How to obtain the positive excitation voltage V of the positive excitation line EXC+ EXC+ , positive excitation current I EXC+ and the feedback line voltage V SEN Detection devices such as voltmeters and ammeters can be placed at corresponding nodes in the circuit, or electrically connected to corresponding nodes, to obtain the required voltage and current values.

[0036] In some embodiments, the feedback line voltage V SEN Is the difference between the positive feedback line voltage and the negative feedback line voltage, that is, V SEN =V SEN+ -V SEN- .

[0037] In the weighing system 100, by setting the first diode D1, when the signal line SIG and the positive excitation line EXC+ are short-circuited, the analog-to-digital converter 121 can still normally collect the signal on the signal line SIG. Furthermore, combined with the positive excitation voltage V EXC+ , positive excitation current I EXC+ and the feedback line voltage V SEN , a detailed diagnosis of the specific fault of the strain sensor 111 can be made.

[0038] Figure 2 2 is a system block diagram of a fault detection system 200 according to the second embodiment of the present application. Compared with the first embodiment, the second embodiment also includes a weighing device 210 and a signal acquisition circuit 220. The specific structures of the two are slightly different, so different reference numerals are used. Figure 2 In addition to the first embodiment, the second embodiment further includes a voltage detection unit V and a current detection unit A, both of which are disposed between the first diode D1 and the positive excitation line EXC+. Specifically, one end of the voltage detection unit V is connected to the positive excitation line EXC+, and the other end is grounded; one end of the current detection unit A is connected to the positive excitation line EXC+, and the other end is connected to the cathode of the first diode D1. The voltage detection unit V is used to detect the positive excitation voltage V of the positive excitation line EXC+. EXC+ and the positive excitation voltage V EXC+ Sent to the controller 230, the current detection unit A is used to detect the positive excitation current I of the positive excitation line EXC+ EXC+ and the positive excitation current I EXC+ Sent to the controller 230. Positive excitation voltage V EXC+ and positive excitation current IEXC+ They respectively represent the excitation voltage and excitation current actually provided to the strain gauge sensor 211. It can be understood that after the excitation voltage is stepped down by the first diode D1, it is less than the output voltage of the power supply 222 and the VDDA of the analog-to-digital converter 221.

[0039] Specifically, the voltage detection unit V may be a voltmeter, and the current detection unit A may be an ammeter.

[0040] refer to Figure 2 As shown, in the embodiment of the present application, a second diode D2 is further included, which is arranged between the negative excitation line EXC- and the internal ground GND. The second diode D2 is used to boost the voltage of the negative excitation line EXC-, which has a similar function to the first diode D1. Figure 2 , the anode of the second diode D2 is connected to the negative excitation line EXC-, and the cathode is connected to the internal GND. Assuming that the forward voltage drop of the second diode D2 is Vf2, then V EXC- ≈GND+Vf2. Thus, when the signal line SIG is short-circuited with the negative excitation line EXC-, V SIG± ≈GND+Vf2, rather than 0V, so that the input voltage of the input terminal AIN of the analog-to-digital converter 121 meets the input voltage requirement, so that the analog-to-digital converter 121 can normally collect the signal on the signal line SIG.

[0041] In some embodiments, the second diode D2 is a Schottky diode. Vf1 and Vf2 can be equal, for example, both are 500 mV, or they can be different.

[0042] It should be noted that due to the existence of D1 and D2, there should be a relationship: V EXC+ =V S -V D1 =V S –Vf1, V EXC- =GND+V D2 =0+Vf2=Vf2.

[0043] refer to Figure 2The weighing device in this second embodiment includes a strain gauge sensor 211, which includes four bridged strain gauges RB1 to RB4, forming a Wheatstone bridge. The positive excitation line EXC+ and the positive feedback line SEN+ are simultaneously connected between RB1 and RB2, effectively short-circuiting the two at this end. The other end of the positive feedback line SEN+ is connected to the positive reference terminal REF+ of the analog-to-digital converter 221. The negative excitation line EXC- and the negative feedback line SEN- are simultaneously connected between RB3 and RB4, effectively short-circuiting the two at this end. The other end of the negative feedback line SEN- is connected to the negative reference terminal REF- of the analog-to-digital converter 211. One end of the positive signal line SIG+ is connected between RB1 and RB3, and one end of the negative signal line SIG- is connected between RB2 and RB4.

[0044] refer to Figure 2 In this embodiment, the analog-to-digital converter 211 is configured as follows: when the voltage difference (V REF+ -V REF- ) exceeds the preset value, the flag bit NOREF of the analog-to-digital converter 221 is set to the preset bit, and the controller 230 is configured to: obtain the flag bit NOREF. In these embodiments, the ADC chip of the analog-to-digital converter 221 has an internal register, and the internal register has a NOREF register flag bit. When V REF+ -V REF- When the difference between V REF+ -V REF- <0.1V, NOREF=1, indicating that the ADC chip is faulty; when V REF+ -V REF- >0.1V, for example, V REF+ -V REF- =5V, then NOREF=0, indicating no fault. According to these embodiments, the voltage difference V REF+ -V REF- Reflects the feedback line voltage V SEN =V SEN+ -V SEN- , that is, NOREF can reflect the feedback line voltage V SEN Size 。

[0045] In some embodiments, the analog-to-digital converter 221 is a chip such as AD7190, AD7194, or AD7195, all of which have the function of setting the flag NOREF according to the voltage difference between the positive reference terminal REF+ and the negative reference terminal REF-.

[0046] refer to Figure 2 In the second embodiment, the controller 230 can obtain the positive excitation voltage VEXC+ , positive excitation current I EXC+ and the feedback line voltage V SEN In addition, the voltage V of the positive signal line SIG+ can also be indirectly obtained through the analog-to-digital converter 211. SIG+ , the voltage V of the negative signal line SIG- SIG- , and the differential voltage V between the positive and negative signal lines SIG+ and SIG- SIG+ -V SIG- .

[0047] In some embodiments, the input terminal AIN of the analog-to-digital converter 221 of the present application can be set to a single-ended input mode or a differential input mode. In some embodiments, the controller 230 is an MCU, and software programming can be used to send commands from the controller 230 to the analog-to-digital converter 221 to set the input mode of its input terminal AIN. The analog-to-digital converter 221 chip can have two independent current sources, which output current from AIN+ and input current from AIN-, respectively, and the output current of AIN+ is equal to the input current of AIN-. The output current of the two independent current sources is, for example, 500nA.

[0048] refer to Figure 2 , in order to obtain the voltage V of the positive signal line SIG+ SIG+ , the analog-to-digital converter 221 can be configured for single-ended input mode. In this case, the reference ground AINCOM should be grounded GND. The analog-to-digital converter 221 has a configurable programmable gain amplifier PGA inside. In the single-ended input mode, the positive signal line SIG+ is connected to the positive input terminal AIN+ of the analog-to-digital converter 221. The amplification factor of the programmable gain amplifier of the analog-to-digital converter 221 is set to 1. The controller 230 is configured to: obtain the positive signal line voltage V of the positive signal line SIG+ based on the signal of the positive input terminal AIN+ SIG+ , combined with the positive signal line voltage V SIG+ Determine the fault of the weighing device. In this embodiment, in the single-ended input mode, the amplification factor of the programmable gain amplifier is set to 1, so that the analog-to-digital converter 221 can accurately collect the voltage on the positive signal line SIG+. When the positive signal line SIG+ is disconnected, that is, the AIN+ pin is floating, the voltage on the AIN+ input pin is the power supply voltage VDDA (ideally infinite). At this time, the internal error flag ERR of the analog-to-digital converter 221, such as AD7190, should report an error. The controller 230 can obtain the error information and combine it with the obtained positive signal line voltage V SIG+ The signals included are used for fault diagnosis.

[0049] In order to obtain the voltage V of the negative signal line SIG- SIG-, the analog-to-digital converter 221 can be configured for single-ended input mode, and the amplification factor of the programmable gain amplifier of the analog-to-digital converter 221 is set to 1 to detect the voltage of the negative signal line SIG-. When the negative signal line SIG- is disconnected, that is, the AIN- pin is floating, the voltage on the AIN- input pin is the supply voltage VDDA (ideally, infinite). At this time, the internal error flag ERR of the analog-to-digital converter 221, such as the AD7190, should be displayed. The controller 230 can then obtain this error information for fault diagnosis.

[0050] In order to obtain the differential voltage V between the positive and negative signal lines SIG+ and SIG- SIG+ -V SIG- The analog-to-digital converter 221 can be configured as a differential input mode, and the amplification factor of the programmable gain amplifier of the analog-to-digital converter 221 is set to a preset value not equal to 1, for example, set to 128. The controller 230 is configured to: obtain the differential voltage V between the positive signal line SIG+ and the negative signal line SIG- SIG+ -V SIG- , combined with the differential voltage V SIG+ -V SIG- Determining the Failure of the Strain Gauge Sensor It should be noted that during normal use of the weighing system 200 , the input mode of the analog-to-digital converter 221 is a differential input mode.

[0051] According to the embodiment shown in the second embodiment, the controller 230 can directly or indirectly obtain at least the following seven signals: the positive excitation voltage V EXC+ , negative excitation voltage V of negative excitation line EXC- EXC- , positive excitation current I of positive excitation line EXC+ EXC+ , the feedback line voltage V of the feedback line SEN SEN =V SEN+ -V SEN- , positive signal line voltage V SIG+ , negative signal line voltage V SIG- , and the differential voltage V between the positive and negative signal lines SIG+ and SIG- SIG+ -V SIG- .

[0052] The fault detection systems 100 and 200 can at least detect the positive excitation voltage V of the positive excitation line EXC+. EXC+ , positive excitation current I of positive excitation line EXC+ EXC+ , the feedback line voltage V of the feedback line SEN SEN =V SEN+ -V SEN- Detect the faults listed in Table 1 below:

[0053] Table 1:

[0054]

[0055] Table 1 shows three types of faults, all of which are related to short circuit or open circuit of the cable. These three faults can be detected based on the V EXC+ , I EXC+ 、V SEN+ -V SEN - Combine them to make a judgment.

[0056] Furthermore, Table 2 lists the results of fault diagnosis by combining all six signals mentioned above:

[0057] Table 2:

[0058]

[0059]

[0060]

[0061] As shown in Table 2, combining these six signals can detect 17 types of faults. Together with the three faults in Table 1, the fault detection system of this application can detect 20 types of faults. It can also specifically locate which cable is broken or shorted, and which strain gauge is disconnected or shorted, providing highly accurate diagnostic results that help on-site technicians quickly locate and resolve faults.

[0062] It should be noted that in Table 2, the fault types shown in rows 1 to 9 below the title row are cable faults, and the fault types shown in rows 10 to 17 are strain gauge faults. Figure 2 The strain gauge sensor 211 shown includes four strain gauges RB1 to RB4. Tables 1 and 2 are merely examples. For other types of strain gauge sensors 211, corresponding Tables 1 and 2 can be obtained based on settings and measurements.

[0063] In addition, in the sixth row under the title row of Table 2, when SIG+ is short-circuited to SIG-, regardless of whether the scale is loaded or not, V SIG+ and V SIG- The readings will change normally, but V SIG+ -V SIG-It will always maintain the no-load 0x0800 state. In Table 1 and Table 2, normal, half-load, no-load, positive full load, and negative full load are all for the weighing system, indicating the current state of the weighing system. Among them, in the positive full-load state, the input differential signal SIG+-SIG- is positive and the absolute value exceeds the maximum value allowed by the input analog-to-digital converter 221. The limit of the maximum allowable value is VDDA / (2*programmable gain amplifier amplification factor). At this time, the number collected by the acquisition system is 0x0FFF. In the negative full-load state, the input differential signal SIG-SIG- is negative and its absolute value exceeds the maximum value allowed by the input analog-to-digital converter 221. At this time, the number collected by the acquisition system is 0x0000. Under normal circumstances, a fixed weighing system will only experience positive loading under normal operation, that is, the strain gauge is subjected to positive pressure, SIG+>SIG-. However, in some abnormal circumstances, such as when the scale pan is dragged, negative loading may occur, that is, the strain gauge is subjected to negative pressure, SIG+ <SIG-。

[0064] Furthermore, in order to perform fault detection, the three signals mentioned in Table 1 can be obtained first, and then the other three signals mentioned in Table 2 can be obtained. This application does not limit the order in which the signals are obtained. Preferably, the fault detection system of this application can be used to detect the corresponding signals in the following order, which has good operability and timeliness:

[0065] (V EXC+ )≥(I EXC+ )>(V SEN+ -V SEN- )>(V SIG+ )≥(V SIG- )>(V SIG+ -V SIG- )

[0066] refer to Figure 3 As shown, the present application also proposes a fault detection method for weighing equipment, which can be performed by the fault detection system described above. Specifically, the fault detection method 300 includes:

[0067] Step S310: Obtain the positive excitation voltage V of the positive excitation line of at least one strain gauge sensor EXC+ and positive excitation current I EXC+ , and obtain the feedback line voltage V of the feedback line of at least one strain gauge sensor SEN ;

[0068] Step S320: According to the positive excitation voltage V EXC+ , positive excitation current I EXC+ and feedback line voltage V SEN Determine the fault of the weighing equipment, including cable fault and strain gauge fault.

[0069] It should be noted that the related descriptions of the fault detection systems 100 and 200 described above can be used to illustrate the fault detection method 300, and the same contents will not be repeated here.

[0070] In step S310, the positive excitation voltage V EXC+ =Equal to the power supply voltage VDDA of the analog-to-digital converter minus the first voltage drop Vf1, which is the forward voltage drop of the first diode D1. As shown in Table 1 and Table 2, taking the first voltage drop Vf1 = 500mV and VDDA = 5V as an example, V EXC+ The value is mainly 4.5V. When EXC+ is short-circuited to SEN- / EXC-, V EXC+ ≈0.5V, in this case, only according to V EXC+ If the voltage is ≈0.5V, it can be determined that EXC+ is shorted to SEN- / EXC-. The following explanation uses Vf1=Vf2=500mV and VDDA=5V as an example.

[0071] According to Table 1 and Table 2, some methods can be used to locate specific faults.

[0072] For example, in some embodiments, step S320 includes:

[0073] Step S321: Obtain the flag bit NOREF of the analog-to-digital converter, the flag bit NOREF and the voltage difference V between the positive feedback line and the negative feedback line SEN+ -V SEN- Related;

[0074] Step S322: When the positive excitation voltage V EXC+ In case of abnormality, the positive excitation line EXC+ is short-circuited to the negative excitation line EXC- or the negative feedback line SEN-;

[0075] The exception here can be V EXC+ When the voltage is less than a first preset value, for example, the first preset value is a value less than 4.5V, such as 4V. As shown in the second row below the title row in Table 1, EXC+ is short-circuited to SEN- / EXC-, which is V EXC+ ≈0.5V, at this time V EXC+ abnormal.

[0076] Step S323: As shown in the first row below the title row of Table 1, when the positive excitation voltage V EXC+ Under normal circumstances, when the positive excitation current is 0 and the flag NOREF is abnormal, that is, when NOREF=1, it is judged that the positive excitation line EXC+ is open. Here, normal can be V EXC+ When it is greater than a first preset value, for example, V EXC+ =4.5V, which is normal.

[0077] Step S324: As shown in the third row below the title row of Table 1, when the positive excitation voltage V EXC+ Normally, the positive excitation current I EXC+ When the current limit value of 100mA is reached and the flag NOREF is abnormal, it is determined that the positive feedback line SEN+ or the negative feedback line SEN- is open, or the positive feedback line SEN+ is short-circuited to the negative feedback line SEN- or the negative excitation line EXC-.

[0078] In some embodiments, the fault detection method 300 further includes:

[0079] Step S330: When the analog-to-digital converter is in single-ended input mode, the positive signal line voltage V of the positive signal line SIG+ is obtained. SIG+ and the negative signal line voltage V of the negative signal line SIG- SIG- ;

[0080] Step S331: When the analog-to-digital converter is in differential input mode, obtain the differential voltage V between the positive signal line SIG+ and the negative signal line SIG- SIG+ -V SIG- ;

[0081] Step S332: According to the positive excitation voltage V EXC+ , positive excitation current I EXC+ , feedback line voltage V SEN , positive signal line voltage V SIG+ , negative signal line voltage V SIG- and the differential voltage V SIG+ -V SIG- Determine the faults of the strain gauge sensor. These faults correspond to all the faults in Table 2, that is, they are determined by combining the six signals.

[0082] Furthermore, step S332 includes:

[0083] Step S3321: As shown in the third row below the title row of Table 2, when the positive excitation voltage V EXC+ When the positive signal line voltage V SIG+ and the negative signal line voltage V SIG- are fully loaded, and the differential voltage V SIG+ -V SIG- When it is no-load, it is determined that the positive feedback line SEN+ is short-circuited to the positive signal line SIG+ or the negative signal line SIG-;

[0084] Step S3322: When the positive excitation voltage V EXC+ When the positive signal line voltage V SIG+ , negative signal line voltage V SIG- and the differential voltage V SIG+ -VSIG- When both are unloaded, it is determined that the negative feedback line SEN- is short-circuited to the positive signal line SIG+ or the negative signal line SIG-.

[0085] exist Figure 2 In the illustrated embodiment, the strain gauge sensor 211 includes four bridged strain gauges, and step S332 includes:

[0086] Step S3323: When the positive excitation voltage and the flag NOREF are both normal, the positive excitation current I EXC+ , positive signal line voltage V SIG+ , negative signal line voltage V SIG- and the differential voltage V SIG+ -V SIG- Determine which strain gauge is disconnected or shorted. This step corresponds to rows 10 to 17 below the title row in Table 2, which all involve fault diagnosis of disconnected or shorted strain gauges.

[0087] Specifically, when a strain gauge fails, the differential voltage V SIG+ -V SIG- It is positive full load or negative full load.

[0088] Refer to Table 2. When a cable fails, the positive excitation current I EXC+ is the first measurement value. When a strain gauge fails, the positive excitation current I EXC+ is the second measurement value, and the first measurement value is different from the second measurement value. In Table 3, the first to ninth rows below the title row all represent cable faults, most of which are EXC+ The values ​​are all 11mA, and in rows 10 to 17, when the strain gauge fails, the EXC+ The value is 6mA or 17mA, which is obviously different from the cable fault. EXC+ The value can quickly determine whether the fault type is a cable fault or a strain gauge fault.

[0089] This fault detection method does not exhaustively list all fault diagnosis methods in Table 1 and Table 2. In other embodiments, a table lookup method can be used. The controller can directly query the specific fault type from Table 1 and Table 2 based on the obtained signal to quickly locate the fault.

[0090] The basic concepts have been described above. It will be apparent to those skilled in the art that the above disclosures are merely examples and do not limit the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and revisions to the present application. Such modifications, improvements, and revisions are suggested in the present application and remain within the spirit and scope of the exemplary embodiments of the present application.

[0091] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0092] Similarly, it should be noted that, in order to simplify the presentation of this disclosure and thereby facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this application sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not imply that the subject matter of this application requires more features than those mentioned. In fact, an embodiment may have fewer features than all of the features of a single embodiment disclosed above.

[0093] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in this application are all approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

Claims

1. A fault detection system for a weighing device, characterized in that: It includes a weighing device and a signal acquisition circuit, the weighing device includes at least one strain gauge sensor, the signal acquisition circuit includes an analog-to-digital converter, a power supply and a controller, the at least one strain gauge sensor is connected to the signal acquisition circuit via a number of cables, the number of cables include a positive excitation line, a negative excitation line, a signal line and a feedback line, wherein the at least one strain gauge sensor is configured to: be connected to the power supply via a positive excitation line, be grounded via a negative excitation line, be connected to the input end of the analog-to-digital converter via a signal line, and be connected to the reference end of the analog-to-digital converter via a feedback line; the power supply end of the analog-to-digital converter is connected to the power supply; a first diode is provided between the strain gauge sensor and the power supply, the first diode is used to step down the output voltage of the power supply so that the voltage of the positive excitation line is less than the voltage of the power supply end of the analog-to-digital converter; the controller is configured to: judge the fault of the weighing device based on the positive excitation voltage of the positive excitation line, the positive excitation current of the positive excitation line and the feedback line voltage of the feedback line.

2. The fault detection system according to claim 1, wherein: A second diode is provided between the negative excitation line and the internal ground, and the second diode is used to boost the voltage of the negative excitation line.

3. The fault detection system according to claim 2, wherein: It also includes a voltage detection unit and a current detection unit, which are arranged between the first diode and the positive excitation line. The voltage detection unit is used to detect the positive excitation voltage of the positive excitation line and send the positive excitation voltage to the controller. The current detection unit is used to detect the positive excitation current of the positive excitation line and send the positive excitation current to the controller.

4. The fault detection system according to claim 2, wherein: The feedback line includes a positive feedback line and a negative feedback line, one end of the positive feedback line is short-circuited with the positive excitation line, and the other end of the positive feedback line is connected to the positive reference terminal REF+ of the analog-to-digital converter, one end of the negative feedback line is short-circuited with the negative excitation line, and the other end of the negative feedback line is connected to the negative reference terminal REF- of the analog-to-digital converter, and the analog-to-digital converter is configured such that: when the voltage difference between the positive reference terminal REF+ and the negative reference terminal REF- exceeds a preset value, the flag bit NOREF of the analog-to-digital converter is set to a preset bit, and the controller is configured to: obtain the flag bit NOREF.

5. The fault detection system according to claim 2, wherein: The signal line includes a positive signal line, which is connected to the positive input terminal of the analog-to-digital converter. The analog-to-digital converter is configured to: be set to a single-ended input mode, and set the amplification factor of the programmable gain amplifier of the analog-to-digital converter to 1. The controller is configured to: obtain the positive signal line voltage of the positive signal line according to the signal of the positive input terminal, and judge the fault of the weighing equipment in combination with the positive signal line voltage.

6. The fault detection system according to claim 5, wherein: The signal line includes a negative signal line, which is connected to the negative input terminal of the analog-to-digital converter. The analog-to-digital converter is configured to: be set to a single-ended input mode, and set the amplification factor of the programmable gain amplifier of the analog-to-digital converter to 1. The controller is configured to: obtain the negative signal line voltage of the negative signal line according to the signal of the negative input terminal, and judge the fault of the weighing device in combination with the negative signal line voltage.

7. The fault detection system according to claim 2, wherein: The signal line includes a positive signal line and a negative signal line, the positive signal line is connected to the positive input terminal of the analog-to-digital converter, and the negative signal line is connected to the negative input terminal of the analog-to-digital converter. The analog-to-digital converter is configured to: be set to a differential input mode, and set the amplification factor of the programmable gain amplifier of the analog-to-digital converter to a preset value not equal to 1. The controller is configured to: obtain the differential voltage between the positive signal line and the negative signal line, and determine the fault of the weighing device based on the differential voltage.

8. The fault detection system according to claim 1, wherein: The at least one strain gauge sensor includes a plurality of bridge-connected strain gauges.

9. A method for fault detection of weighing equipment, applied to the fault detection system according to any one of claims 1 to 8, characterized in that: include: Acquire a positive excitation voltage and a positive excitation current of a positive excitation line of the at least one strain gauge sensor, and acquire a feedback line voltage of a feedback line of the at least one strain gauge sensor; The fault of the weighing device is determined according to the positive excitation voltage, the positive excitation current and the feedback line voltage, where the fault includes a cable fault and a strain gauge fault.

10. The fault detection method according to claim 9, wherein: The positive excitation voltage is equal to the power supply voltage VDDA of the analog-to-digital converter minus the forward voltage drop of the first diode.

11. The fault detection method according to claim 10, wherein: The step of determining a fault of the strain gauge sensor according to the positive excitation voltage, the positive excitation current, and the feedback line voltage includes: Obtaining a flag bit NOREF of the analog-to-digital converter, where the flag bit NOREF is related to a voltage difference between a positive feedback line and a negative feedback line; When the positive excitation voltage is abnormal, it is determined that the positive excitation line is short-circuited to the negative excitation line or the negative feedback line; When the positive excitation voltage is normal, the positive excitation current is 0, and the flag NOREF is abnormal, it is determined that the positive excitation line is open circuit; When the positive excitation voltage is normal, the positive excitation current reaches the current limit value, and the flag NOREF is abnormal, it is determined that the positive feedback line or the negative feedback line is open, or the positive feedback line is short-circuited to the negative feedback line or the negative excitation line.

12. The fault detection method according to claim 11, wherein: Also includes: When the analog-to-digital converter is in a single-ended input mode, the positive signal line voltage of the positive signal line and the negative signal line voltage of the negative signal line are respectively obtained; When the analog-to-digital converter is in a differential input mode, obtaining a differential voltage between the positive signal line and the negative signal line; A fault of the strain gauge sensor is determined according to the positive excitation voltage, the positive excitation current, the feedback line voltage, the positive signal line voltage, the negative signal line voltage, and the differential voltage.

13. The fault detection method according to claim 12, wherein: The step of judging a fault of the weighing device according to the positive excitation voltage, the positive excitation current, the feedback line voltage, the positive signal line voltage, the negative signal line voltage and the differential voltage comprises: When the positive excitation voltage and the flag NOREF are both normal, when the positive signal line voltage and the negative signal line voltage are both fully loaded, and the differential voltage is no-load, it is determined that the positive feedback line is short-circuited to the positive signal line or the negative signal line; When the positive excitation voltage and the flag NOREF are normal, and when the positive signal line voltage, the negative signal line voltage, and the differential voltage are all no-load, it is determined that the negative feedback line is short-circuited to the positive signal line or the negative signal line.

14. The fault detection method according to claim 12, wherein: The at least one strain gauge sensor includes four bridged strain gauges, and the step of determining a fault of the weighing device according to the positive excitation voltage, the positive excitation current, the feedback line voltage, the positive signal line voltage, the negative signal line voltage, and the differential voltage includes: When the positive excitation voltage and the flag NOREF are both normal, it is determined which strain gauge is disconnected or short-circuited based on the positive excitation current, the positive signal line voltage, the negative signal line voltage, and the differential voltage.

15. The fault detection method according to claim 14, wherein: When a strain gauge fails, the differential voltage is fully loaded in the positive direction or fully loaded in the negative direction.

16. The fault detection method according to claim 14, wherein: When a cable fails, the positive excitation current is a first measurement value. When a strain gauge fails, the positive excitation current is a second measurement value. The first measurement value is different from the second measurement value.

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