Input detection circuit

Abstract

The utility model relates to an input detection circuit. The input detection circuit comprises a disconnection detection circuit, the disconnection detection circuit is connected between a digital quantity sensor and a controller in an industrial network, the digital quantity sensor is connected with a disconnection resistor in parallel, the disconnection detection circuit comprises a voltage division circuit, and the voltage division circuit is connected with the digital quantity sensor. The voltage division circuit is used for performing voltage division on an input signal of the digital quantity sensor to obtain a divided voltage; and the comparison circuit is connected with the voltage division circuit and the controller, the comparison circuit is used for outputting a level signal to the controller according to the divided voltage and the reference voltage, and the level signal is used for indicating whether a cable between the input detection circuit and the digital quantity sensor is disconnected or not. According to the technical scheme provided by the invention, the cable connection condition between the digital quantity sensor and the input detection circuit can be effectively diagnosed, and the reliability of an industrial network is improved.

Description

Technical Field

[0001] This application relates to the field of industrial network technology, and in particular to an input detection circuit. Background Technology

[0002] In the field of industrial networks, digital sensors can convert physical quantity signals into electrical signals, which are then input into the detection circuit and converted into signals that can be processed by the controller.

[0003] Currently, the distance between digital sensors and input detection circuits can be as long as several kilometers. In dense application scenarios, thousands or even tens of thousands of digital sensors may be deployed. Once the communication between the digital sensor and the input detection circuit is abnormal, it becomes extremely difficult to troubleshoot, which seriously affects the reliability of industrial networks. Utility Model Content

[0004] Based on this, embodiments of this application provide an input detection circuit that can effectively diagnose the cable connection status between the digital sensor and the input detection circuit, thereby improving the reliability of industrial networks.

[0005] This application provides an input detection circuit. The input detection circuit includes a disconnection detection circuit, which is connected between a digital sensor and a controller in an industrial network. The digital sensor has a disconnection resistor connected in parallel. The disconnection detection circuit includes:

[0006] A voltage divider circuit is connected to the digital sensor and is used to divide the input signal of the digital sensor to obtain a voltage divider voltage.

[0007] A comparator circuit is connected to the voltage divider circuit and the controller. The comparator circuit is used to output a level signal to the controller based on the voltage divider voltage and the reference voltage. The level signal is used to indicate whether the cable between the input detection circuit and the digital sensor is disconnected.

[0008] In one embodiment, the digital sensor is a high-side digital sensor, the comparison circuit includes a first comparator, the voltage divider circuit includes a first voltage divider circuit and a second voltage divider circuit, a first terminal of the first voltage divider circuit is connected to a reference voltage source, a second terminal of the first voltage divider circuit is connected to a common power supply terminal, a first terminal of the second voltage divider circuit is connected to the digital sensor, and a second terminal of the second voltage divider circuit is connected to a common power supply terminal.

[0009] Wherein, the voltage dividing point of the first voltage divider circuit is connected to the inverting terminal of the first comparator, and the voltage dividing point of the second voltage divider circuit is connected to the non-inverting terminal of the first comparator; or,

[0010] The voltage dividing point of the first voltage divider circuit is connected to the non-inverting terminal of the first comparator, and the voltage dividing point of the second voltage divider circuit is connected to the inverting terminal of the first comparator.

[0011] In one embodiment, the voltage divider circuit further includes:

[0012] A voltage divider resistor, wherein the first end of the voltage divider resistor is connected to the reference voltage source, and the second end of the voltage divider resistor is connected to the voltage division point of the second voltage divider circuit.

[0013] In one embodiment, the disconnection detection circuit further includes:

[0014] A first isolation circuit, the primary side of which is connected to the output of the first comparator and the first detection power supply, and the secondary side of which is connected to the controller, the second detection power supply and ground.

[0015] In one embodiment, the input detection circuit further includes a first low-power detection circuit, the first low-power detection circuit comprising:

[0016] A first current limiting circuit is used to limit the current magnitude of the signal input from the digital sensor to the first current limiting circuit. The first terminal of the first current limiting circuit is connected to the digital sensor, and the second terminal of the first current limiting circuit is connected to the controller.

[0017] In one embodiment, the first current limiting circuit includes:

[0018] A first series resistor, the first end of which is connected to the digital sensor, and the second end of which is connected to the controller;

[0019] The first voltage regulator has a first terminal connected to a first detection power supply and a second terminal connected to a common power supply terminal.

[0020] A first current-limiting resistor, the first end of which is connected to the third end of the first voltage regulator, and the second end of which is connected to the second end of the first voltage regulator;

[0021] The first transistor has its base connected to the first detection power supply, its emitter connected to the first end of the first current-limiting resistor and the third end of the first voltage regulator, and its collector connected to the second end of the first series resistor.

[0022] In one embodiment, the first low-power detection circuit further includes:

[0023] The second isolation circuit has its primary side connected to the second terminal of the first series resistor and the collector of the first transistor, and its secondary side connected to the second detection power supply, the controller, and ground.

[0024] In one embodiment, the digital sensor is a low-side digital sensor, and the voltage divider circuit includes:

[0025] The third voltage divider circuit has its first terminal connected to the common power supply terminal, its voltage division point connected to the digital sensor, and its second terminal connected to the comparator circuit.

[0026] The fourth voltage divider circuit has its first terminal connected to the first detection power supply, its second terminal connected to the common power supply terminal, and its voltage division point connected to the comparator circuit.

[0027] In one embodiment, the comparison circuit includes:

[0028] The second comparator is connected to the inverting terminal of the third voltage divider circuit, and the voltage dividing point of the fourth voltage divider circuit is connected to the non-inverting terminal of the second comparator.

[0029] The third comparator has its output terminal connected to the non-inverting terminal of the second comparator, its inverting terminal connected to a reference voltage source, and its output terminal connected to the controller.

[0030] In one embodiment, the disconnection detection circuit further includes:

[0031] The third isolation circuit has its primary side connected to the output of the third comparator and the first detection power supply, and its secondary side connected to the controller, the second detection power supply, and ground.

[0032] In one embodiment, the input detection circuit further includes a second low-power detection circuit, the second low-power detection circuit comprising:

[0033] The second current limiting circuit has a first terminal connected to the digital sensor and a second terminal connected to the controller. The second current limiting circuit is used to limit the current magnitude of the signal input to the digital sensor.

[0034] In one embodiment, the second current limiting circuit includes:

[0035] A second series resistor, the first end of which is connected to the digital sensor, and the second end of which is connected to the controller;

[0036] The second voltage regulator has its first terminal connected to the second terminal of the second series resistor.

[0037] The second current-limiting resistor has its first end connected to the second end of the second voltage regulator.

[0038] The base of the second transistor is connected to the third terminal of the second voltage regulator, and the emitter of the second transistor is connected to the first terminal of the second current-limiting resistor and the second terminal of the second voltage regulator.

[0039] The base of the third transistor is connected to the collector of the second transistor and the first detection power supply. The collector of the third transistor is connected to the base of the second transistor and the third terminal of the second voltage regulator. The emitter of the third transistor is connected to the first detection power supply.

[0040] In one embodiment, the second low-power detection circuit further includes:

[0041] The fourth isolation circuit has its primary side connected to the second terminal of the second series resistor and the second terminal of the second current-limiting resistor, and its secondary side connected to the second detection power supply, the controller, and ground.

[0042] The aforementioned input detection circuit includes a disconnection detection circuit connected between a digital sensor and a controller in the industrial network. The digital sensor has a disconnection resistor connected in parallel. This disconnection detection circuit includes a voltage divider circuit and a comparator circuit. The voltage divider circuit is connected to the digital sensor and is used to divide the input signal of the digital sensor to obtain a divided voltage. The comparator circuit is connected to the voltage divider circuit and the controller and is used to output a level signal to the controller based on the divided voltage and a reference voltage. This level signal is used to indicate whether the cable between the input detection circuit and the digital sensor is disconnected. For example, if the cable between the input detection circuit and the digital sensor is not disconnected, the input signal of the digital sensor... The current is relatively large. Even when the cable between the input detection circuit and the digital sensor is disconnected, the disconnection detection circuit can still detect the current of the digital sensor's input signal because the digital sensor has a disconnection resistor connected in parallel. However, this current is much smaller than the current when the cable between the input detection circuit and the digital sensor is not disconnected. Therefore, after the voltage divider circuit divides the input signal of the digital sensor, the comparator circuit uses the reference voltage as a reference to detect the voltage (current) change of the digital sensor's input signal. This allows the circuit to determine whether the cable between the input detection circuit and the digital sensor is disconnected, quickly identify communication abnormalities between the digital sensor and the input detection circuit, and improve the reliability of the industrial network. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a connection diagram of an input detection circuit in one embodiment of this application;

[0045] Figure 2 This is a connection diagram of a wire breakage detection circuit in another embodiment of this application;

[0046] Figure 3 This is a connection diagram of a wire breakage detection circuit in another embodiment of this application;

[0047] Figure 4 This is a connection diagram of a wire breakage detection circuit in another embodiment of this application;

[0048] Figure 5 This is a schematic diagram of a wire breakage detection circuit in another embodiment of this application;

[0049] Figure 6 This is a schematic diagram of a voltage reference circuit in another embodiment of this application;

[0050] Figure 7 This is a schematic diagram of a wire breakage detection circuit in another embodiment of this application;

[0051] Figure 8 This is a connection diagram of an input detection circuit in another embodiment of this application;

[0052] Figure 9 This is a schematic diagram of a first low-power detection circuit in another embodiment of this application;

[0053] Figure 10 This is a schematic diagram of a wire breakage detection circuit in another embodiment of this application;

[0054] Figure 11 This is a schematic diagram of a wire breakage detection circuit in another embodiment of this application;

[0055] Figure 12 This is a connection diagram of an input detection circuit in another embodiment of this application;

[0056] Figure 13 This is a schematic diagram of a second low-power detection circuit in another embodiment of this application.

[0057] Explanation of reference numerals in the attached figures:

[0058] Wire breakage detection circuit - 10; Comparison circuit - 101; Voltage divider circuit - 102; First voltage divider circuit - 1021; Second voltage divider circuit - 1022; First isolation circuit - 1023; Third voltage divider circuit - 1024; Fourth voltage divider circuit - 1025; Third isolation circuit - 1026; First low power consumption detection circuit - 20; First current limiting circuit - 201; Second isolation circuit - 202; Second low power consumption detection circuit - 30; Second current limiting circuit - 301; Fourth isolation circuit - 302; Digital sensor - 40; Wire breakage resistor - 401; Controller - 50. Detailed Implementation

[0059] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0061] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0062] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0063] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0064] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0065] In the field of industrial networks, digital sensors can convert physical quantity signals into electrical signals, which are then input into the detection circuit and converted into signals that can be processed by the controller.

[0066] Currently, the distance between digital sensors and input detection circuits can be several kilometers. In dense application scenarios, thousands or even tens of thousands of digital sensors may be deployed. Once the communication between the digital sensor and the input detection circuit is abnormal, such as if the cable between the input detection circuit and the digital sensor is broken, it will become extremely difficult to troubleshoot, thus seriously affecting the reliability of industrial networks.

[0067] To address the aforementioned technical problems, embodiments of this application provide an input detection circuit. The technical solutions and beneficial effects provided by these embodiments will be described exemplarily below with reference to the accompanying drawings.

[0068] Please see Figure 1 This application provides an input detection circuit, which includes a disconnection detection circuit 10. The disconnection detection circuit 10 is connected between a digital sensor 40 and a controller 50 in an industrial network, and the digital sensor 40 is connected in parallel with a disconnection resistor 401.

[0069] When the cable between the input detection circuit and the digital sensor 40 is not disconnected, the current of the input signal of the digital sensor 40 is relatively large. When the cable between the input detection circuit and the digital sensor 40 is disconnected, since the digital sensor 40 is connected in parallel with the disconnection resistor 401, the disconnection detection circuit 10 can also detect the current of the input signal of the digital sensor 40. However, this current will be much smaller than the current when the cable between the input detection circuit and the digital sensor 40 is not disconnected. Based on this current change, it can be determined whether the cable between the input detection circuit and the digital sensor 40 is disconnected.

[0070] The circuit structure of the open circuit detection circuit 10 in the embodiments of this application will be described exemplarily below.

[0071] Please see Figure 2 The open circuit detection circuit 10 includes a voltage divider circuit 102 and a comparator circuit 101.

[0072] The voltage divider circuit 102 is connected to the digital sensor 40, and the comparator circuit 101 is connected to the voltage divider circuit 102 and the controller 50. The voltage divider circuit 102 is used to divide the input signal of the digital sensor 40 to obtain a divided voltage. The comparator circuit 101 is used to output a level signal to the controller 50 based on the divided voltage and the reference voltage. This level signal is used to indicate whether the cable between the input detection circuit and the digital sensor 40 is disconnected.

[0073] For example, if the voltage of the input signal of the digital sensor 40 is large (i.e., the current is large), then the cable between the input detection circuit and the digital sensor 40 is not disconnected. If the voltage of the input signal of the digital sensor 40 is small (i.e., the current is small), then the cable between the input detection circuit and the digital sensor 40 is disconnected.

[0074] In industrial networks, digital sensors 40 are typically divided into high-side digital sensors and low-side digital sensors, see [link to relevant documentation]. Figure 3 and Figure 4 , Figure 3 The digital sensor shown is a high-side digital sensor, which is connected to an external power supply Vin. Figure 4 The digital sensor shown is a low-side digital sensor, which is connected to the common power terminal COM.

[0075] The circuit structure of the input detection circuit will be described below by way of example, distinguishing between the two types of digital sensors 40.

[0076] 1) Using digital sensor 40 as an example Figure 3 Taking the high-side digital sensor shown as an example, the circuit structure of the disconnection detection circuit 10 included in the input detection circuit will be described first as an example.

[0077] In the case where the digital sensor 40 is a high-side digital sensor, please refer to Figure 5 The comparator circuit 101 includes a first comparator U1, and the voltage divider circuit 102 includes a first voltage divider circuit 1021 and a second voltage divider circuit 1022.

[0078] The first terminal of the first voltage divider circuit 1021 is used to connect to the reference voltage source. Figure 5 The first terminal of the first voltage divider circuit 1021 shown is connected to the VREF_COMP terminal of the reference voltage source, and the second terminal of the first voltage divider circuit 1021 is connected to the common terminal of the power supply (e.g., Figure 5 The COM connection is shown.

[0079] The voltage divider point of the first voltage divider circuit 1021 is the same as the inverting terminal of the first comparator (e.g., Figure 5 The "-" terminal of the first comparator U1 shown is connected, or, in other possible embodiments, the voltage dividing point of the first voltage divider circuit 1021 is connected to the non-inverting terminal of the first comparator (e.g., the "-" terminal). Figure 5 The "+" terminal of the first comparator U1 shown is connected. In the following embodiments, the voltage divider point of the first voltage divider circuit 1021 is connected to the inverting terminal of the first comparator as an example.

[0080] The first voltage divider circuit 1021 may include Figure 5 The voltage divider resistors R9 and R11 are shown. The first end of the voltage divider resistor R9 is connected to the reference voltage source, the second end of the voltage divider resistor R9 is connected to the first end of the voltage divider resistor R11, the second end of the voltage divider resistor R11 is connected to the common power supply terminal, and the voltage divider point between the voltage divider resistors R9 and R11 is connected to the inverting terminal of the first comparator.

[0081] In this embodiment of the application, the reference voltage source can be a voltage reference circuit, as exemplarily seen in [reference 1]. Figure 6 This is a schematic diagram of a voltage reference circuit. The voltage reference circuit can be part of the open circuit detection circuit 10 in the embodiments of this application, or it can be an external circuit; no specific limitation is made here.

[0082] Figure 6In the voltage reference circuit shown, the first terminal of the voltage regulator U5 is connected to the first detection power supply V1 through resistor R6 and diode D2. The first detection power supply V1 supplies power to the voltage reference circuit. The first terminal of the voltage regulator U5 is also connected to the second terminal of the voltage regulator U5 and the open circuit detection circuit 10. The third terminal of the voltage regulator U5 is connected to the common terminal of the power supply. A capacitor C6 is connected in parallel between the second terminal and the third terminal of the voltage regulator U5. Since the voltage between the second terminal and the third terminal of the voltage regulator U5 is constant, a constant reference voltage can be provided to the open circuit detection circuit 10 through the VREF_COMP terminal of the voltage reference circuit.

[0083] The first voltage divider circuit 1021, included in the voltage divider circuit 102, has been described above. The second voltage divider circuit 1022, also included in the voltage divider circuit 102, will be described below. Please continue reading... Figure 5 The first terminal of the second voltage divider circuit 1022 is connected to the digital sensor 40. Figure 5 Not shown, Figure 5 The PDI (Parallel Digital Interface) terminal shown is connected to the digital sensor 40, and the second terminal of the second voltage divider circuit 1022 is connected to the common power supply terminal.

[0084] When the voltage dividing point of the first voltage divider circuit 1021 is connected to the inverting terminal of the first comparator, the voltage dividing point of the second voltage divider circuit 1022 is connected to the non-inverting terminal of the first comparator; when the voltage dividing point of the first voltage divider circuit 1021 is connected to the non-inverting terminal of the first comparator, the voltage dividing point of the second voltage divider circuit 1022 is connected to the inverting terminal of the first comparator. No specific restrictions are imposed here. The following embodiments will be described using the example of the first voltage divider circuit 1021 being connected to the inverting terminal of the first comparator and the second voltage divider circuit 1022 being connected to the non-inverting terminal of the first comparator.

[0085] A capacitor C1 is connected in parallel between the non-inverting terminal and the inverting terminal of the first comparator.

[0086] The second voltage divider circuit 1022 may include Figure 5 The voltage divider resistors R7 and R10 are shown. The first end of the voltage divider resistor R7 is connected to the digital sensor 40, and the second end of the voltage divider resistor R7 is connected to the first end of the voltage divider resistor R10. The second end of the voltage divider resistor R10 is connected to the common power supply terminal. The voltage divider point between the voltage divider resistors R7 and R10 is connected to the non-inverting terminal of the first comparator.

[0087] Please continue reading Figure 5 The voltage divider circuit 102 also includes voltage divider resistors (such as...). Figure 5The voltage divider resistor R12 (shown) has its first end connected to a reference voltage source, and its second end connected to the voltage division point of the second voltage divider circuit 1022, i.e., the second end of R12 is connected between voltage divider resistors R7 and R10. Since the level of the first comparator is unstable when the cable between the input detection circuit and the digital sensor 40 is disconnected, the first comparator may make incorrect judgments. Adding voltage divider resistor R12 can stabilize the level of the first comparator, thereby improving the accuracy of the disconnection detection.

[0088] In this way, the reference voltage generated by the reference voltage source is divided by the first voltage divider circuit 1021 and then sent to the inverting input terminal of the first comparator. The input signal of the digital sensor 40 is divided by the second voltage divider circuit 1022 and then sent to the non-inverting input terminal of the first comparator. The first comparator compares the signals at the non-inverting input terminal and the inverting input terminal, which can determine whether the cable between the input detection circuit and the digital sensor 40 is disconnected.

[0089] Specifically, the cable between the input detection circuit and the digital sensor 40 is disconnected (equivalent to...). Figure 3 Even with the switch in the digital sensor 40 shown open, the disconnection resistor 401 will still provide a path to the disconnection detection circuit 10, and the non-inverting terminal of the first comparator can still detect voltage, indicating that the cable between the input detection circuit and the digital sensor 40 is normally connected (equivalent to...). Figure 3 When the switch in the digital sensor 40 shown is closed, the input signal of the digital sensor 40 can be provided by its own path.

[0090] In this embodiment of the application, if the cable between the input detection circuit and the digital sensor 40 is not disconnected, the circuit design can ensure that the voltage divided at the non-inverting input terminal of the digital sensor 40 is greater than the voltage divided at the inverting terminal of the reference voltage of the first comparator. The first comparator is not grounded internally, so the first comparator outputs a high-level signal.

[0091] When the cable between the input detection circuit and the digital sensor 40 is disconnected, the current of the input signal of the digital sensor 40 is very small, which is equivalent to no voltage input to the input signal. The voltage of the non-inverting terminal of the first comparator is completely determined by the voltage division of the reference voltage. Through circuit design, the voltage of the non-inverting terminal is made to be less than the voltage of the inverting terminal. The first comparator is internally grounded, and the first comparator outputs a low-level signal.

[0092] In one embodiment, based on Figure 5 In the embodiment shown, the disconnection detection circuit 10 further includes a first isolation circuit.

[0093] The primary side of the first isolation circuit is connected to the output of the first comparator and the first detection power supply, and the secondary side of the first isolation circuit is connected to the controller 50, the second detection power supply and ground.

[0094] For example, see Figure 7 The first isolation circuit 1023 includes an optocoupler U4, and the first pin of the optocoupler U4 is connected to... Figure 7 The voltage divider circuit formed by resistors R2 and R14 is connected to the first detection power supply V1. The second pin of optocoupler U4 is connected to the output of the first comparator, the third pin of optocoupler U4 is grounded, and the fourth pin of optocoupler U4 is connected via… Figure 7 The voltage divider circuit formed by resistors R16 and R3 shown is connected to the detection power supply V2. Figure 7 The PDI_OL terminal shown is connected to controller 50.

[0095] In this embodiment, the open circuit detection circuit 10 has built-in isolation. The external power supply VIN of the digital sensor 40 can share the same power supply as the first detection power supply V1, or two independent power supplies can be used, as long as the two independent power supplies share a common ground. The second detection power supply V2 and the first detection power supply V1 can be isolated power supplies.

[0096] When the cable between the input detection circuit and the digital sensor 40 is not disconnected, as described above, the voltage divider of the input signal of the digital sensor 40 at the non-inverting input terminal of the first comparator is greater than the voltage divider of the reference voltage at the inverting terminal of the first comparator. The first comparator is not grounded internally, the primary side of the first isolation circuit 1023 is not conducting, that is, the primary side of the optocoupler U4 is not conducting, and the first isolation circuit 1023 does not generate power consumption.

[0097] When the cable between the input detection circuit and the digital sensor 40 is disconnected, as mentioned above, the voltage at the non-inverting end of the first comparator is less than the voltage at the inverting end, the first comparator is grounded internally, the primary side of the first isolation circuit 1023 is turned on, that is, the primary side of the optocoupler U4 is turned on, the secondary side level of the optocoupler U4 flips, and power consumption is generated.

[0098] In this embodiment, by designing a first isolation circuit in the disconnection detection circuit 10, in actual implementation, due to the complex and changeable on-site environment, signal interference may occur to the normal operation of the input detection circuit in this embodiment. The first isolation circuit can isolate the interference signal and ensure the reliable and stable operation of the input detection circuit.

[0099] In this embodiment, digital sensor 40 is used as an example of a high-side digital sensor. Figure 8 As shown, the input detection circuit also includes a first low-power detection circuit 20.

[0100] The circuit structure of the first low-power detection circuit 20 included in the input detection circuit will be described below as an example.

[0101] In this embodiment of the application, the first low-power detection circuit 20 may include a first current limiting circuit 201. The first end of the first current limiting circuit 201 is connected to the digital sensor 40, and the second end of the first current limiting circuit 201 is connected to the controller 50. The first current limiting circuit 201 is used to limit the current magnitude of the signal input from the digital sensor 40 to the first current limiting circuit 201.

[0102] In the case where the digital sensor 40 is a high-side digital sensor, such as Figure 3 As shown, the digital sensor 40 is connected to an external power supply VIN. When the signal is output from the digital sensor 40, it passes through the first low-power detection circuit 20 before reaching the controller 50. Since the voltage of the signal output by the digital sensor 40 is relatively high, it will consume a significant amount of power. In this embodiment, the first low-power detection circuit 20 includes a first current-limiting circuit 201. This first current-limiting circuit 201 can limit the current input to the digital sensor 40, thus reducing power consumption.

[0103] In one embodiment, see Figure 9 The first current limiting circuit 201 includes a first series resistor, a first voltage regulator, a first current limiting resistor, and a first transistor.

[0104] First series resistor (e.g.) Figure 9 The first end of the resistor R4 (shown) is connected to the digital sensor 40 (PDI terminal), and the second end of the first series resistor is connected to the controller 50. A diode D1 can also be connected between the first series resistor and the digital sensor 40. A first voltage regulator (such as...) Figure 9 The first terminal of the voltage regulator U2 shown is connected to the first detection power supply V1, and the second terminal of the first voltage regulator is connected to the power supply common terminal COM. The first current-limiting resistor (e.g.) Figure 9 The first terminal of the resistor R5 (as shown) is connected to the third terminal of the first voltage regulator, and the second terminal of the first current-limiting resistor is connected to the second terminal of the first voltage regulator. The first transistor (such as...) Figure 9 The base of Q1 is connected to the first detection power supply, the emitter of the first transistor is connected to the first end of the first current limiting resistor and the third end of the first voltage regulator, and the collector of the first transistor is connected to the second end of the first series resistor.

[0105] In this embodiment of the application, in the first current limiting circuit 201, the voltage between the second and third terminals of the first voltage regulator is constant. This constant voltage is applied to the first current limiting resistor, and the reference current value generated on the first current limiting resistor is the maximum input current. Since the first series resistor and the first current limiting resistor are connected in series, the current magnitude of the signal input to the first current limiting circuit 201 by the digital sensor 40 is limited. By limiting the maximum input current, power consumption can be reduced.

[0106] Please continue reading Figure 9 In this embodiment, the first low-power detection circuit 20 further includes a second isolation circuit 202. The primary side of the second isolation circuit 202 is connected to the second terminal of the first series resistor and the collector of the first transistor, and the secondary side of the second isolation circuit 202 is connected to the second detection power supply, the controller 50, and ground.

[0107] The second isolation circuit 202 may include Figure 9 The optocoupler U3 shown has its first pin connected to the second terminal of the first series resistor, its second pin connected to the collector of the first transistor, and a resistor R13 and a capacitor C2 connected between the first and second pins. The third pin of the optocoupler U3 is connected via... Figure 9 The voltage divider circuit formed by resistors R15 and R1 is connected to the second detection power supply V2. The fourth pin of optocoupler U3 is grounded, and capacitor C3 is connected between the third and fourth pins of optocoupler U3. Figure 7 The PDI_DE terminal shown is connected to the controller 50. Whether the primary side of the second isolation circuit 202 is turned on or off can achieve signal isolation.

[0108] In this embodiment of the application, the logical relationship between the disconnection detection circuit 10 and the first low-power detection circuit 20 for the high-side digital sensor can be shown in Table 1:

[0109] Table 1

[0110]

[0111] In Table 1, a state value of "0" indicates that the circuit is responding normally, and a state value of "1" indicates that the circuit is not responding.

[0112] For high-side digital sensors, when the input detection circuit is working normally (the cable between the input detection circuit and the digital sensor is not disconnected), i.e., in the "ON" state shown in Table 1, the first low-power detection circuit 20 responds normally, while the disconnection detection circuit 10 does not respond. When the input detection circuit is disconnected (the cable between the input detection circuit and the digital sensor is disconnected), i.e., in the "disconnection" state shown in Table 1, the first low-power detection circuit 20 does not respond, while the disconnection detection circuit 10 responds normally. After the input detection circuit is powered off, i.e., in the "OFF" state shown in Table 1, both the first low-power detection circuit 20 and the disconnection detection circuit 10 do not respond. It can be understood that there is no situation where both the disconnection detection circuit 10 and the first low-power detection circuit 20 respond.

[0113] In this way, Table 1 can be used to distinguish all states of the disconnection detection circuit 10 and the first low-power detection circuit 20 in real time.

[0114] 2) Using digital sensor 40 as an example Figure 4 Taking the low-side digital sensor shown as an example, the circuit structure of the disconnection detection circuit 10 included in the input detection circuit will be described first as an example.

[0115] In the case where the digital sensor 40 is a low-side digital sensor, please refer to Figure 10 The voltage divider circuit 102 includes a third voltage divider circuit 1024 and a fourth voltage divider circuit 1025.

[0116] The first terminal of the third voltage divider circuit 1024 is connected to the common power supply terminal, and the voltage division point of the third voltage divider circuit 1024 is connected to the digital sensor 40. Figure 10 The voltage dividing point of the third voltage divider circuit 1024 shown is connected to the NDI_OL_IN terminal of the digital sensor 40. The second terminal of the third voltage divider circuit 1024 is connected to the comparator circuit 101.

[0117] The third voltage divider circuit 1024 may include Figure 10 The voltage divider resistors R16 and R10 are shown. The first end of the voltage divider resistor R16 is connected to the common power supply terminal, and the second end of the voltage divider resistor R16 is connected to the first end of the voltage divider resistor R10. The second end of the voltage divider resistor R10 is connected to the comparator circuit 101, and the voltage division point between the voltage divider resistors R16 and R10 is connected to the digital sensor 40.

[0118] The first terminal of the fourth voltage divider circuit 1025 is connected to the first detection power supply V1, the second terminal of the fourth voltage divider circuit 1025 is connected to the common terminal of the power supply, and the voltage division point of the fourth voltage divider circuit 1025 is connected to the comparator circuit 101.

[0119] Please continue reading Figure 10 The fourth voltage divider circuit 1025 includes Figure 10 The voltage divider resistors R12 and R13 shown are connected as follows: the first end of voltage divider resistor R12 is connected to the first detection power supply V1; the second end of voltage divider resistor R12 is connected to the first end of voltage divider resistor R13; the second end of voltage divider resistor R13 is connected to the common power supply terminal; and the voltage division point between voltage divider resistors R12 and R13 is connected to comparator circuit 101.

[0120] Please continue reading Figure 10 In this embodiment of the application, the comparison circuit 101 includes a second comparator (such as...). Figure 10 Comparator U4 shown) and third comparator (as shown) Figure 10 The comparator U6 shown), the second terminal of the third voltage divider circuit 1024 (as shown) Figure 10 The second terminal of the voltage divider resistor R10 shown is connected to the inverting terminal of the second comparator, and the voltage division point of the fourth voltage divider circuit 1025 is (as shown in the figure). Figure 10 The voltage divider point between the voltage divider resistors R12 and R13 shown is connected to the non-inverting terminal of the second comparator.

[0121] The output of the second comparator is connected to the non-inverting terminal of the third comparator, the inverting terminal of the third comparator is connected to the reference voltage source, and the output of the third comparator is connected to the controller 50.

[0122] Thus, for the low-side digital sensor, the input signal of the digital sensor 40 is divided by the third voltage divider circuit 1024 and applied to the inverting terminal of the second comparator U4 (or subtractor). The voltage provided by the first detection power supply is divided by the fourth voltage divider circuit 1025 and applied to the non-inverting terminal of the second comparator. The input signal is first compared with the voltage difference of V1 (the voltage difference after voltage division) by the second comparator, and then compared with the reference voltage provided by the reference voltage source (VREF_COMP) by the third comparator U6.

[0123] In this embodiment, if the cable between the input detection circuit and the digital sensor 40 is not disconnected, the circuit design can ensure that the third comparator outputs a high-level signal.

[0124] When the cable between the input detection circuit and the digital sensor 40 is disconnected, the current of the input signal of the digital sensor 40 is very small, which is equivalent to no voltage input to the input signal. Through circuit design, the third comparator outputs a low-level signal.

[0125] In this way, the high-level or low-level signal output by the third comparator can characterize the voltage (current) change of the input signal of the digital sensor 40, thereby determining whether the cable between the input detection circuit and the digital sensor 40 is broken, quickly identifying communication abnormalities between the digital sensor 40 and the input detection circuit, and improving the reliability of the industrial network.

[0126] In one embodiment, based on Figure 10 In the embodiment shown, the disconnection detection circuit 10 further includes a third isolation circuit.

[0127] The primary side of the third isolation circuit is connected to the output of the third comparator and the first detection power supply, and the secondary side of the third isolation circuit is connected to the controller 50, the second detection power supply and ground.

[0128] For example, see Figure 11 The third isolation circuit 1026 includes an optocoupler U3, and the first pin of the optocoupler U3 is connected to... Figure 11 The voltage divider circuit formed by resistors R4 and R7 is connected to the first detection power supply V1. The second pin of optocoupler U4 is connected to the output of the third comparator U6. The third pin of optocoupler U4 is grounded, and the fourth pin of optocoupler U4 is connected via… Figure 11 The voltage divider circuit formed by resistors R19 and R5 shown is connected to the second detection power supply V2. Figure 11 The NDI0_OL terminal shown is connected to controller 50.

[0129] In this embodiment, the open circuit detection circuit 10 has built-in isolation. The external power supply VIN of the digital sensor 40 can share the same power supply as the first detection power supply V1, or two independent power supplies can be used, as long as the two independent power supplies share a common ground. The second detection power supply V2 and the first detection power supply V1 can be isolated power supplies.

[0130] If the cable between the input detection circuit and the digital sensor 40 is not disconnected, as mentioned above, the third comparator outputs a high-level signal, the primary side of the third isolation circuit 1026 is not conducting, that is, the primary side of the optocoupler 3 is not conducting, and the third isolation circuit 1026 does not generate power consumption.

[0131] When the cable between the input detection circuit and the digital sensor 40 is disconnected, as mentioned above, the third comparator is internally grounded, the primary side of the third isolation circuit 1026 is turned on, that is, the primary side of the optocoupler U3 is turned on, the secondary side level of the optocoupler U3 is flipped, and power consumption is generated.

[0132] In this embodiment, digital sensor 40 is still used as an example of a low-side digital sensor, such as... Figure 12 As shown, the input detection circuit also includes a second low-power detection circuit 30.

[0133] In this embodiment, by setting a third isolation circuit in the disconnection detection circuit 10, in actual implementation, due to the complex and changeable on-site environment, signal interference may occur to the normal operation of the input detection circuit in this embodiment. The third isolation circuit can isolate the interference signal and ensure the reliable and stable operation of the input detection circuit.

[0134] The circuit structure of the second low-power detection circuit 30 included in the input detection circuit will be described below as an example.

[0135] In this embodiment of the application, the second low-power detection circuit 30 includes a second current limiting circuit 301. The first end of the second current limiting circuit 301 is connected to the digital sensor 40, and the second end of the second current limiting circuit 301 is connected to the controller 50. The second current limiting circuit 301 is used to limit the current magnitude of the signal input to the digital sensor 40.

[0136] In the case where the digital sensor 40 is a low-side digital sensor, such as Figure 4 As shown, the digital sensor 40 is grounded. At this time, after the signal is output by the controller 50, it can pass through the second low-power detection circuit 30 and then reach the digital sensor 40. The second low-power detection circuit 30 includes a second current limiting circuit 301, which can limit the current of the signal input to the digital sensor 40, thus helping to reduce signal power consumption.

[0137] In one embodiment, see Figure 13 The second current limiting circuit 301 includes a second series resistor, a second voltage regulator, a second current limiting resistor, a second transistor, and a third transistor.

[0138] Second series resistor (such as) Figure 13 The first terminal of the resistor R8 (shown) is connected to the digital sensor 40, the second terminal of the second series resistor is connected to the controller 50, and the second voltage regulator (such as...) Figure 13 The first terminal of U1 (as shown) is connected to the second terminal of the second series resistor, and the second current-limiting resistor (such as...) Figure 13 The first terminal of the resistor R15 (as shown) is connected to the second terminal of the second voltage regulator, the second terminal of the second current-limiting resistor is connected to the first terminal of the second voltage regulator, and the second transistor (such as...) Figure 13 The base of the second transistor (Q2) is connected to the third terminal of the second regulator, and the emitter of the second transistor is connected to the first terminal of the first current-limiting resistor and the second terminal of the second regulator. The third transistor (as shown) Figure 13 The base of Q1 is connected to the collector of the second transistor and the first detection power supply. The collector of the third transistor is connected to the base of the second transistor and the third terminal of the second voltage regulator. The emitter of the third transistor is connected to the first detection power supply.

[0139] In this embodiment of the application, in the second current-limiting circuit 301, the voltage between the first and second terminals of the second voltage regulator is constant, and this constant voltage is applied across the second current-limiting resistor, such as... Figure 13 As shown, the currents of R2, Q2, and R15 are equal. Since the BE junction of Q1 plus R1 and D3 plus R2 are connected in parallel, and the voltage of the BE junction of D3 is approximately equal to that of D1, the voltages across R1 and R2 are also equal. Therefore, the currents in the left and right columns of the second current limiting circuit 301 are the same, resulting in a total output current that is twice the current-limiting current provided by U1 and R15. Because the second series resistor is connected in series with the second current-limiting resistor, the current magnitude of the signal input to the digital sensor 40 of the second current limiting circuit 301 is limited, resulting in a constant current output. By limiting the maximum input current, power consumption can be reduced. Before the branch current is less than the operating current of U1, the second current limiting circuit 301 can provide a constant current, and the output current will not increase as the closing impedance of the digital sensor 40 decreases.

[0140] Please continue reading Figure 13 In this embodiment, the first low-power detection circuit 20 further includes a fourth isolation circuit 302. The primary side of the fourth isolation circuit 302 is connected to the second terminal of the second series resistor and the second terminal of the second current-limiting resistor, and the secondary side of the fourth isolation circuit 302 is connected to the second detection power supply, the controller 50, and ground.

[0141] The fourth isolation circuit 302 may include Figure 13 The optocoupler U2 shown has its first pin connected to the second terminal of the second series resistor, and its second pin connected to the second terminal of the second current-limiting resistor. A resistor R9 and a capacitor C4 are also connected between the first and second pins of the optocoupler U2. The third pin of the optocoupler U2 is connected via... Figure 13 The voltage divider circuit formed by resistors R18 and R3 is connected to the second detection power supply V2. The fourth pin of optocoupler U2 is grounded, and capacitor C5 is connected between the third and fourth pins of optocoupler U2. Figure 13 The NDI_DE terminal shown is connected to the controller 50. Whether the primary side of the fourth isolation circuit 302 is turned on or off can achieve signal isolation.

[0142] In this embodiment of the application, for a low-side digital sensor, the logical relationship between the disconnection detection circuit 10 and the first low-power detection circuit 20 can be as shown in Table 1 above. The two detection signals can distinguish all states of the input signal in real time.

[0143] Overall, the embodiments of this application design a low-power detection circuit and a disconnection detection circuit 10 built with discrete components for the digital sensor 40. This solution can perform real-time disconnection diagnosis on the connecting cable between the digital sensor 40 and the input detection circuit, and can locate cable connection faults in a timely and accurate manner in complex industrial environments.

[0144] Furthermore, the embodiments of this application can cover all types of digital sensors 40 in the field. The low-power detection circuit can greatly reduce the power consumption of the detection system and increase the circuit point density. The design of low-power input detection circuit further promotes product miniaturization and density. Real-time disconnection detection can detect disconnection faults in the field, which can help to troubleshoot faults in a timely manner. High real-time performance can expose faults that occur in the field in the first instance, provide timely warnings, ensure that faults do not spread, and ensure stable and safe production.

[0145] The implementation methods and beneficial effects of the power supply circuit in this application, as well as the implementation methods and beneficial effects of the input detection circuit described above, can be found in the relevant descriptions above, and will not be repeated here.

[0146] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0147] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0148] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An input detection circuit, characterized in that, The input detection circuit includes a disconnection detection circuit, which is connected between a digital sensor and a controller in the industrial network. The digital sensor has a disconnection resistor connected in parallel. The disconnection detection circuit includes: A voltage divider circuit is connected to the digital sensor and is used to divide the input signal of the digital sensor to obtain a voltage divider. A comparator circuit is connected to the voltage divider circuit and the controller. The comparator circuit is used to output a level signal to the controller based on the voltage divider voltage and the reference voltage. The level signal is used to indicate whether the cable between the input detection circuit and the digital sensor is disconnected.

2. The input detection circuit according to claim 1, characterized in that, The digital sensor is a high-side digital sensor. The comparison circuit includes a first comparator. The voltage divider circuit includes a first voltage divider circuit and a second voltage divider circuit. The first terminal of the first voltage divider circuit is connected to a reference voltage source. The second terminal of the first voltage divider circuit is connected to a common power supply terminal. The first terminal of the second voltage divider circuit is connected to the digital sensor. The second terminal of the second voltage divider circuit is connected to a common power supply terminal. Wherein, the voltage dividing point of the first voltage divider circuit is connected to the inverting terminal of the first comparator, and the voltage dividing point of the second voltage divider circuit is connected to the non-inverting terminal of the first comparator; or, The voltage dividing point of the first voltage divider circuit is connected to the non-inverting terminal of the first comparator, and the voltage dividing point of the second voltage divider circuit is connected to the inverting terminal of the first comparator.

3. The input detection circuit according to claim 2, characterized in that, The voltage divider circuit also includes: A voltage divider resistor, wherein the first end of the voltage divider resistor is connected to the reference voltage source, and the second end of the voltage divider resistor is connected to the voltage dividing point of the second voltage divider circuit.

4. The input detection circuit according to claim 2, characterized in that, The disconnection detection circuit also includes: A first isolation circuit, the primary side of which is connected to the output of the first comparator and the first detection power supply, and the secondary side of which is connected to the controller, the second detection power supply and ground.

5. The input detection circuit according to any one of claims 2-4, characterized in that, The input detection circuit further includes a first low-power detection circuit, which includes: A first current limiting circuit is used to limit the current magnitude of the signal input from the digital sensor to the first current limiting circuit. The first terminal of the first current limiting circuit is connected to the digital sensor, and the second terminal of the first current limiting circuit is connected to the controller.

6. The input detection circuit according to claim 5, characterized in that, The first current limiting circuit includes: A first series resistor, the first end of which is connected to the digital sensor, and the second end of which is connected to the controller; The first voltage regulator has a first terminal connected to a first detection power supply and a second terminal connected to a common power supply terminal. A first current-limiting resistor, the first end of which is connected to the third end of the first voltage regulator, and the second end of which is connected to the second end of the first voltage regulator; The first transistor has its base connected to the first detection power supply, its emitter connected to the first end of the first current-limiting resistor and the third end of the first voltage regulator, and its collector connected to the second end of the first series resistor.

7. The input detection circuit according to claim 6, characterized in that, The first low-power detection circuit further includes: The second isolation circuit has its primary side connected to the second terminal of the first series resistor and the collector of the first transistor, and its secondary side connected to the second detection power supply, the controller, and ground.

8. The input detection circuit according to claim 1, characterized in that, The digital sensor is a low-side digital sensor, and the voltage divider circuit includes: The third voltage divider circuit has its first terminal connected to the common power supply terminal, its voltage division point connected to the digital sensor, and its second terminal connected to the comparator circuit. The fourth voltage divider circuit has its first terminal connected to the first detection power supply, its second terminal connected to the common power supply terminal, and its voltage division point connected to the comparator circuit.

9. The input detection circuit according to claim 8, characterized in that, The comparison circuit includes: The second comparator is connected to the inverting terminal of the third voltage divider circuit, and the voltage dividing point of the fourth voltage divider circuit is connected to the non-inverting terminal of the second comparator. The third comparator has its output terminal connected to the non-inverting terminal of the second comparator, its inverting terminal connected to a reference voltage source, and its output terminal connected to the controller.

10. The input detection circuit according to claim 9, characterized in that, The disconnection detection circuit also includes: The third isolation circuit has its primary side connected to the output of the third comparator and the first detection power supply, and its secondary side connected to the controller, the second detection power supply, and ground.

11. The input detection circuit according to any one of claims 8-10, characterized in that, The input detection circuit further includes a second low-power detection circuit, which includes: The second current limiting circuit has a first terminal connected to the digital sensor and a second terminal connected to the controller. The second current limiting circuit is used to limit the current magnitude of the signal input to the digital sensor.

12. The input detection circuit according to claim 11, characterized in that, The second current limiting circuit includes: A second series resistor, the first end of which is connected to the digital sensor, and the second end of which is connected to the controller; The second voltage regulator has its first terminal connected to the second terminal of the second series resistor. The second current-limiting resistor has its first end connected to the second end of the second voltage regulator. The base of the second transistor is connected to the third terminal of the second voltage regulator, and the emitter of the second transistor is connected to the first terminal of the second current-limiting resistor and the second terminal of the second voltage regulator. The base of the third transistor is connected to the collector of the second transistor and the first detection power supply. The collector of the third transistor is connected to the base of the second transistor and the third terminal of the second voltage regulator. The emitter of the third transistor is connected to the first detection power supply.

13. The input detection circuit according to claim 12, characterized in that, The second low-power detection circuit also includes: The fourth isolation circuit has its primary side connected to the second terminal of the second series resistor and the second terminal of the second current-limiting resistor, and its secondary side connected to the second detection power supply, the controller, and ground.

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