Encoder broken line detection device and method

Abstract

The invention discloses an encoder broken line detection device and method. The encoder broken line detection device comprises a sampling unit, a detection module, an MCU and an encoder. The detection module is used for pulling up the voltage of the input end of the sampling unit to the voltage of the power supply end and controlling connection and disconnection of a pull-up loop and a ground loop; a pull-up resistor and a pull-up switch are connected in series between the input end and the power supply end of the sampling unit; a grounding end of the sampling unit is connected with a grounding signal end of the encoder to form a ground loop, and the ground loop is connected in series with a ground loop switch; and the output end of the sampling unit is connected with the MCU. According to the invention, motor rotation and pulse detection are not needed, broken line detection of the encoder with open-circuit output of the collector is realized, the problem of detecting broken line of the encoder in a scene that the motor is static and has no pulse output is solved, and the safety risk caused by starting the motor for detection is avoided.

Description

Technical Field

[0001] This invention relates to the field of encoder signal detection, and more particularly to an encoder wire breakage detection device and method. Background Technology

[0002] Currently, encoders detect the speed and direction of the lifting or traveling motor of a forklift in real time, helping the controller to accurately control lifting, tilting or moving actions. There are many reasons for encoder wire breakage, among which contact failure caused by loose interface is more common. Encoder wire breakage will cause inaccurate readings and large errors.

[0003] The existing solution, patent application number CN201210592058.0 entitled "An Incremental Encoder Disconnection Detection Circuit," includes a rectifier unit and an optocoupler detection module. When any phase differential signal transmission line output by the encoder is uninterrupted, the secondary sides of the three optocouplers are turned on, pulling the output levels of the three optocouplers low. When any phase or multiple phase differential signal transmission line is disconnected, the optocoupler in that circuit is not turned on, the secondary side of the optocoupler is cut off, and the output level of the optocoupler is set high. When one or more phase detection circuits detect that the optocoupler output level is high, the system reports an encoder disconnection error.

[0004] The above technical solution relies on the differential signal output by the encoder (i.e., the motor needs to rotate to generate pulses). There must be a differential signal input from the encoder; otherwise, the rectifier bridge will have no signal, the optocoupler status cannot be determined, and the detection will fail.

[0005] For encoder disconnection detection, pulse changes can be used to determine the connection when the controller is in motion. However, in some special cases, such as when the controller is stationary, the power-on self-test of the encoder wiring requires pulse-free detection. For encoders whose output signal is open collector (OC gate), the open OC gate state and disconnection are both high impedances for the electronic control input circuit and cannot be distinguished. Summary of the Invention

[0006] The purpose of this invention is to provide an encoder disconnection detection device and method that can actively change the circuit state through dual-switch control, without relying on the encoder's pulse signal, and achieve disconnection detection in pulseless scenarios by actively controlling the circuit state.

[0007] The present invention adopts the following technical solution: An encoder disconnection detection device includes a sampling unit, a detection module, an MCU, and an encoder; The sampling unit is used to receive the voltage signal output by the encoder, divide the received voltage signal, and then transmit it to the MCU. The sampling unit uses the input terminal consisting of the first terminal, the second terminal, and the third terminal to connect to the A, B, and Z phase signal output terminals of the encoder. The sampling unit uses the output terminal to connect to the MCU. The sampling unit also uses the ground terminal and the power supply terminal to ground and connect to the power supply terminal respectively. The encoder's ground signal terminal and power signal terminal are respectively connected to the ground terminal and power terminal of the sampling unit; The detection module includes a pull-up circuit, a pull-up circuit on / off controller, and a ground circuit on / off controller. The two ends of the pull-up circuit are connected to the input terminal of the sampling unit and the power supply terminal, respectively. The pull-up circuit is used to pull up the voltage at the input terminal of the sampling unit to the voltage at the power supply terminal. The pull-up circuit on / off controller is connected in series between the input terminal of the sampling unit and the power supply terminal, and the ground circuit on / off controller is connected in series between the ground terminal of the sampling unit and the ground signal terminal of the encoder. The MCU controls the pull-up circuit on / off controller and the ground circuit on / off controller respectively, thereby controlling the connection and disconnection of the pull-up circuit and the ground circuit; the MCU is used to receive the voltage signal output by the sampling unit and output the truth table, and also to determine the encoder's disconnection status based on the on / off status of the pull-up circuit on / off controller and the ground circuit on / off controller combined with the truth table.

[0008] Furthermore, the encoder disconnection detection device also includes a conditioning circuit; the output terminal of the sampling unit is connected to the input port of the conditioning circuit, and the output terminal of the conditioning circuit is connected to the MCU; the conditioning circuit is used to optimize the quality of the A, B, and Z signals input by the encoder.

[0009] Furthermore, the pull-up circuit on / off controller and the ground circuit on / off controller are configured as switching devices using MOSFETs, transistors, and / or relays.

[0010] An encoder disconnection detection method, applicable to the encoder disconnection detection device described above, wherein the pull-up circuit continuity controller is implemented using a pull-up switch, and the ground circuit continuity controller is implemented using a ground circuit switch; the detection method includes the following steps: S1: The MCU controls the closing of the pull-up switch and the ground loop switch; S2: The input of the sampling unit is divided and transmitted to the MCU. The MCU receives the level output from the sampling unit and outputs a truth table. When the input of the sampling unit is low, the truth table shows that the input of the sampling unit is 0; When the input of the sampling unit is high, the truth table shows that the input of the sampling unit is 1; S3: The MCU controls the pull-up switch to open; at the same time, it controls the ground loop switch to open, entering the fault detection stage; S4: During the fault detection phase When the MCU output truth table shows that the sampling unit input is 1, that is, the sampling unit input is at a high level, it indicates that the connection between the controller and the encoder is good. When the MCU output truth table shows that the sampling unit input is 0, that is, the sampling unit input is at a low level, it indicates that there is a disconnection between the controller and the encoder.

[0011] Furthermore, the detection methods also include: S5: When a disconnection is detected between the controller and the encoder, the MCU controls the ground loop switch to close. If the MCU output truth table shows that the sampling unit input port is 0, that is, the first terminal, the second terminal and the third terminal are low level, it indicates that the ground connection is normal and the encoder power signal terminal is disconnected. If the MCU output truth table shows that the sampling unit input port is 1, that is, the first terminal, the second terminal and the third terminal are at a high level, it indicates that the encoder's ground signal terminal is disconnected.

[0012] Furthermore, step S2 is as follows: S2: After the input of the sampling unit is divided, it is transmitted to the MCU through the conditioning circuit. The MCU receives the level output of the sampling unit and outputs the truth table. If the input of the sampling unit is low, the output of the conditioning circuit is low, and the truth table shows that the input of the sampling unit is 0. If the input of the sampling unit is high, the output of the conditioning circuit is high, and the truth table shows that the input of the sampling unit is 1.

[0013] This invention enables open-circuit detection of encoders with open collector outputs in scenarios where the motor is stationary and there is no pulse output (such as forklift parking on a slope or equipment power-on self-test). It eliminates the need for motor rotation and pulse detection. By disconnecting the ground loop, the encoder becomes an equipotential body. In the absence of pulses, a high-level condition is established as normal, and a low-level condition as a criterion for open circuit is defined. By actively controlling the ground loop and pull-up voltage, the electrical characteristics of the open-circuit gate are altered, changing from high impedance to a high-potential VCC level, clearly distinguishing it from the low level of the open-circuit state. This eliminates misjudgments and solves the problem of inaccurate or large errors caused by encoder open circuits, while also avoiding the safety risks associated with starting the motor for detection. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of a specific embodiment of an encoder wire breakage detection device according to the present invention; Figure 2 This is a schematic diagram of yet another specific embodiment of the encoder wire breakage detection device of the present invention; Figure 3 This is a flowchart illustrating a specific embodiment of the encoder disconnection detection method of the present invention; Figure 4 This is a flowchart illustrating another specific embodiment of the encoder disconnection detection method of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments described herein clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments described herein, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are within the scope of protection of this document. It should be noted that, unless otherwise specified, the embodiments and features described herein can be arbitrarily combined with each other.

[0017] The following is in conjunction with the appendix Figures 1 to 4 The present invention will be described in detail with reference to the embodiments: This invention applies to encoders whose output signal is output from an open collector, such as incremental photoelectric encoders. Incremental photoelectric encoders output signals from an open collector (OC gate), and the angle is determined by pulse counting. The A, B, and Z phase signal outputs of the encoder are respectively connected to the input terminals of the controller. The power supply line is connected to the forklift controller or an external power supply, and the shielding wire is grounded to reduce interference.

[0018] An encoder disconnection detection device is provided. The present invention provides a specific embodiment one. The encoder disconnection detection device includes a sampling unit, a detection module, an MCU and an encoder.

[0019] In this invention, the sampling unit, detection module, and MCU can be integrated into the forklift controller.

[0020] The sampling unit is used to receive the voltage signal output by the encoder and divide the received voltage signal before transmitting it to the MCU. The sampling unit uses the input terminal consisting of the first terminal ENC_A, the second terminal ENC_B, and the third terminal ENC_Z to connect to the A, B, and Z phase signal output terminals of the encoder. The sampling unit uses the output terminal to connect to the MCU. The sampling unit also uses the ground terminal GND2 and the power supply terminal VCC2 to ground and connect to the power supply terminal, respectively.

[0021] The encoder's ground signal terminal GND1 and power signal terminal VCC1 are connected to the sampling unit's ground terminal GND2 and power terminal VCC2, respectively.

[0022] The detection module includes a pull-up circuit, a pull-up circuit on / off controller, and a ground circuit on / off controller. The two ends of the pull-up circuit are connected to the input terminal of the sampling unit and the power supply terminal VCC2, respectively. The pull-up circuit is used to pull up the voltage of the input terminal of the sampling unit to match the voltage of the power supply terminal VCC2. The pull-up circuit on / off controller is connected in series between the input terminal of the sampling unit and the power supply terminal VCC2, and the ground circuit on / off controller is connected in series between the ground terminal GND2 of the sampling unit and the ground signal terminal GND1 of the encoder.

[0023] The MCU controls the pull-up circuit on / off controller and the ground circuit on / off controller respectively, thereby controlling the connection and disconnection of the pull-up circuit and the ground circuit; the MCU is used to receive the voltage signal output by the sampling unit and output the truth table, and also to determine the encoder disconnection status based on the opening and closing status of the ground circuit switch and the pull-up switch combined with the truth table.

[0024] In this embodiment, The pull-up circuit on / off controller is implemented using pull-up switch S1, and the ground circuit on / off controller is implemented using ground circuit switch S2.

[0025] The first terminal ENC_A, the second terminal ENC_B, and the third terminal ENC_Z of the sampling unit are respectively connected to the signal output terminals A, B, and Z of the encoder. The power supply terminal VCC2 of the sampling unit is electrically connected to the power signal terminal VCC1 of the encoder; A pull-up resistor R and a pull-up switch S1 are connected in series between the input terminal of the sampling unit and the power supply terminal VCC2; The grounding terminal GND2 of the sampling unit, the ground loop switch S2, and the grounding signal terminal GND1 of the encoder are connected in series to form a ground loop, and the ground loop switch S2 is connected in series in the ground loop. The output port of the sampling unit is connected to the MCU.

[0026] In this embodiment, the pull-up switch S1 and the ground loop switch S2 can be switching devices such as MOSFETs, transistors, and / or relays.

[0027] In this invention, in scenarios where the motor is stationary and there is no pulse output (such as forklift parking on a slope or equipment power-on self-test), there is no need for the motor to rotate or for pulse detection. This invention enables the detection of open-collector output encoder disconnection, solving the problem of inaccurate readings or large errors caused by encoder disconnection and avoiding the safety risks caused by starting the motor for detection.

[0028] An encoder disconnection detection device is provided. The present invention provides a second specific embodiment. The encoder disconnection detection device includes a sampling unit, a detection module, a conditioning circuit, an MCU, and an encoder. In this invention, the sampling unit, conditioning circuit, detection module, and MCU are integrated on the forklift controller; The sampling unit is used to receive the voltage signal output by the encoder and divide the received voltage signal, which is then transmitted to the MCU after passing through the conditioning circuit. The sampling unit uses the input terminal composed of the first terminal ENC_A, the second terminal ENC_B, and the third terminal ENC_Z to connect to the A, B, and Z phase signal output terminals of the encoder respectively. The sampling unit uses the output terminal to connect to the input terminal of the conditioning circuit, and the output terminal of the conditioning circuit is connected to the MCU. The sampling unit also uses the ground terminal GND2 and the power supply terminal VCC2 to ground and connect to the power supply terminal respectively.

[0029] The conditioning circuit is used to optimize the quality of the A, B, and Z signals input from the encoder, making the signals more suitable for MCU acquisition and processing; The encoder's ground signal terminal GND1 and power signal terminal VCC1 are connected to the sampling unit's ground terminal GND2 and power terminal VCC2, respectively.

[0030] The detection module includes a pull-up circuit, a pull-up circuit on / off controller, and a ground circuit on / off controller. The two ends of the pull-up circuit are connected to the input terminal of the sampling unit and the power supply terminal VCC2, respectively. The pull-up circuit is used to pull up the voltage of the input terminal of the sampling unit to match the voltage of the power supply terminal VCC2. The pull-up circuit on / off controller is connected in series between the input terminal of the sampling unit and the power supply terminal VCC2, and the ground circuit on / off controller is connected in series between the ground terminal GND2 of the sampling unit and the ground signal terminal GND1 of the encoder.

[0031] The MCU controls the pull-up circuit on / off controller and the ground circuit on / off controller respectively, thereby controlling the connection and disconnection of the pull-up circuit and the ground circuit; the MCU is used to receive the voltage signal output by the conditioning circuit and output the truth table, and also to determine the encoder disconnection status based on the opening and closing status of the ground circuit switch and the pull-up switch combined with the truth table.

[0032] In this embodiment, The pull-up circuit on / off controller is implemented using pull-up switch S1, and the ground circuit on / off controller is implemented using ground circuit switch S2.

[0033] The first terminal ENC_A, the second terminal ENC_B, and the third terminal ENC_Z of the sampling unit are respectively connected to the A phase, B phase, and Z phase of the encoder's output port. A pull-up resistor R and a pull-up switch S1 are connected in series between the input terminal of the sampling unit and the power supply terminal VCC2; The power supply terminal VCC2 of the sampling unit is electrically connected to the power signal terminal VCC1 of the encoder; The grounding terminal GND2 of the sampling unit, the ground loop switch S2, and the grounding signal terminal GND1 of the encoder are connected in series to form a ground loop, and the ground loop switch S2 is connected in series in the ground loop. The output port of the sampling unit is connected to the input port of the conditioning circuit, and the output port of the conditioning circuit is connected to the MCU.

[0034] In this embodiment, the pull-up switch and ground loop switch can be switching devices such as MOSFETs, transistors, and / or relays.

[0035] In this invention, in scenarios where the motor is stationary and there is no pulse output (such as forklift parking on a slope or equipment power-on self-test), there is no need for the motor to rotate or for pulse detection. This invention enables the detection of open-collector output encoder disconnection, solving the problem of inaccurate readings or large errors caused by encoder disconnection and avoiding the safety risks caused by starting the motor for detection.

[0036] An encoder wire breakage detection method, specifically embodiment three, applicable to the encoder wire breakage detection device of embodiment one above, includes the following steps: S1: The MCU controls the closing of the pull-up switch and the ground loop switch; S2: The input of the sampling unit is divided and transmitted to the MCU. The MCU receives the level output from the sampling unit and outputs a truth table. Dividing the input is a standard technique in this field and will not be elaborated further. When the input of the sampling unit is low, the truth table shows that the input of the sampling unit is 0; When the input of the sampling unit is high, the truth table shows that the input of the sampling unit is 1; S3: The MCU controls the pull-up switch to open; at the same time, it controls the ground loop switch to open, entering the fault detection stage; S4: During the fault detection phase When the MCU output truth table shows that the sampling unit input is 1, that is, the sampling unit input is at a high level, it indicates that the connection between the controller and the encoder is good. When the MCU output truth table shows that the sampling unit input is 0, that is, the sampling unit input is low, it indicates that there is a disconnection between the controller and the encoder. S5: When a disconnection is detected between the controller and the encoder, the MCU controls the ground loop switch to close. If the MCU output truth table shows that the sampling unit input port is 0, that is, the first terminal ENC_A, the second terminal ENC_B and the third terminal ENC_Z are at low level, it indicates that the ground connection is normal and the encoder power signal terminal is disconnected. If the MCU output truth table shows that the sampling unit input port is 1, that is, the first terminal ENC_A, the second terminal ENC_B and the third terminal ENC_Z are at high level, it indicates that the encoder's ground signal terminal GND1 is disconnected.

[0037] Pull-up resistors are used to pull the input voltage to the power supply voltage; pull-up switches are used to connect or disconnect the loop from the pull-up resistor to the power supply voltage, and the MCU controls the opening and closing of the pull-up switch; ground loop switches are used to control the connection or disconnection of the ground loop, and the MCU controls the opening and closing of the ground loop switch.

[0038] This method achieves pulse-free open circuit detection by disconnecting the ground loop to make the encoder an equipotential body. It establishes a judgment standard of high level for normal operation and low level for open circuit when there is no pulse, enabling effective detection in static, pulse-free output scenarios (such as forklift parking on a slope, equipment power-on self-test, etc.). By actively controlling the ground loop and pull-up voltage, the electrical characteristics of the OC gate when it is open are changed from high impedance to VCC equipotential high level, which is clearly distinguished from the low level of the open circuit state, eliminating false judgments.

[0039] An encoder wire breakage detection method, specifically embodiment four of the present invention, is applicable to the encoder wire breakage detection device of embodiment two above, and includes the following steps in sequence: S1: The MCU controls the closing of the pull-up switch and the ground loop switch; S2: The input of the sampling unit is divided and transmitted to the MCU. The MCU receives the level output from the sampling unit and outputs a truth table. Dividing the input is a standard technique in this field and will not be elaborated further. When the input of the sampling unit is low, the output of the conditioning circuit is low, and the truth table shows that the input of the sampling unit is 0. When the input of the sampling unit is high, the output of the conditioning circuit is high, and the truth table shows that the input of the sampling unit is 1. S3: The MCU controls the pull-up switch to open; at the same time, it controls the ground loop switch to open, entering the fault detection stage; S4: During the fault detection phase When the MCU output truth table shows that the sampling unit input is 1, that is, the sampling unit input port is at a high level, it indicates that the connection between the controller and the encoder is good; When the MCU output truth table shows that the sampling unit input port is 0, that is, the sampling unit input port is at a low level, it indicates that there is a disconnection between the controller and the encoder. S5: When a disconnection is detected between the controller and the encoder, the MCU controls the ground loop switch to close. If the MCU output truth table shows that the sampling unit input port is 0, that is, the first terminal ENC_A, the second terminal ENC_B and the third terminal ENC_Z are at low level, it indicates that the ground connection is normal and the encoder power signal terminal is disconnected. If the MCU output truth table shows that the sampling unit input port is 1, that is, the first terminal ENC_A, the second terminal ENC_B and the third terminal ENC_Z are at high level, it indicates that the encoder's ground signal terminal GND1 is disconnected.

[0040] In this invention, during ground wire detection, the controller controls the pull-up switch to open, disconnecting the pull-up circuit, and simultaneously controls the ground circuit switch to close, connecting the ground circuit. Since the pull-up voltage is disconnected, the sampling unit input port should be at a low level, and the MCU output truth table shows that the sampling unit input port is 0. However, if the encoder's ground signal terminal GND1 is disconnected, even if the S2 ground circuit is closed, it will still be in an open state. The monitoring result is the same as in step 4, with the first terminal ENC_A, the second terminal ENC_B, and the third terminal ENC_Z outputting at a high level, and the MCU output truth table showing that the sampling unit input port is 1.

[0041] This method designs a detection method based on the detection circuit to distinguish the disconnection state when the OC gate is open, realizing pulse-free disconnection detection. By disconnecting the ground loop to make the encoder an equipotential body, a judgment standard of high level is established when there is no pulse, and low level is used to distinguish between normal and disconnection. This enables effective detection in static pulse-free output scenarios (such as forklift parking on a slope, equipment power-on self-test, etc.). By actively controlling the ground loop and pull-up voltage, the electrical characteristics when the OC gate is open are changed from high impedance to VCC equipotential high level, which is clearly distinguished from the low level in the disconnection state, eliminating false judgments.

[0042] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An encoder wire breakage detection device, characterized in that: Includes a sampling unit, a detection module, an MCU, and an encoder; The sampling unit is used to receive the voltage signal output by the encoder, divide the received voltage signal, and then transmit it to the MCU. The sampling unit uses the input terminal consisting of the first terminal, the second terminal, and the third terminal to connect to the A, B, and Z phase signal output terminals of the encoder. The sampling unit uses the output terminal to connect to the MCU. The sampling unit also uses the ground terminal and the power supply terminal to ground and connect to the power supply terminal respectively. The encoder's ground signal terminal and power signal terminal are respectively connected to the ground terminal and power terminal of the sampling unit; The detection module includes a pull-up circuit, a pull-up circuit on / off controller, and a ground circuit on / off controller. The two ends of the pull-up circuit are connected to the input terminal of the sampling unit and the power supply terminal, respectively. The pull-up circuit is used to pull up the voltage at the input terminal of the sampling unit to the voltage at the power supply terminal. The pull-up circuit on / off controller is connected in series between the input terminal of the sampling unit and the power supply terminal, and the ground circuit on / off controller is connected in series between the ground terminal of the sampling unit and the ground signal terminal of the encoder. The MCU controls the pull-up circuit on / off controller and the ground circuit on / off controller respectively, thereby controlling the connection and disconnection of the pull-up circuit and the ground circuit; the MCU is used to receive the voltage signal output by the sampling unit and output the truth table, and also to determine the encoder's disconnection status based on the opening and closing status of the pull-up circuit on / off controller and the ground circuit on / off controller combined with the truth table.

2. The encoder wire breakage detection device according to claim 1, characterized in that: The encoder disconnection detection device further includes a conditioning circuit; the output terminal of the sampling unit is connected to the input port of the conditioning circuit, and the output terminal of the conditioning circuit is connected to the MCU; the conditioning circuit is used to optimize the quality of the A, B, and Z signals input by the encoder.

3. The encoder wire breakage detection device according to claim 1, characterized in that: The pull-up circuit on / off controller and the ground circuit on / off controller are used as switching devices, which employ MOSFETs, transistors and / or relays.

4. A method for detecting encoder wire breakage, applicable to the encoder wire breakage detection device according to any one of claims 1 to 3, characterized in that, The pull-up circuit on / off controller utilizes a pull-up switch, and the ground circuit on / off controller utilizes a ground circuit switch; the detection method includes the following steps: S1: The MCU controls the closing of the pull-up switch and the ground loop switch; S2: The input of the sampling unit is divided and transmitted to the MCU. The MCU receives the level output from the sampling unit and outputs a truth table. When the input of the sampling unit is low, the truth table shows that the input of the sampling unit is 0; When the input of the sampling unit is high, the truth table shows that the input of the sampling unit is 1; S3: The MCU controls the pull-up switch to open; at the same time, it controls the ground loop switch to open, entering the fault detection stage; S4: During the fault detection phase When the MCU output truth table shows that the sampling unit input is 1, that is, the sampling unit input is at a high level, it indicates that the connection between the controller and the encoder is good. When the MCU output truth table shows that the sampling unit input is 0, that is, the sampling unit input is at a low level, it indicates that there is a disconnection between the controller and the encoder.

5. The encoder wire breakage detection method according to claim 4, characterized in that, The detection methods also include: S5: When a disconnection is detected between the controller and the encoder, the MCU controls the ground loop switch to close. If the MCU output truth table shows that the sampling unit input port is 0, that is, the first terminal, the second terminal and the third terminal are low level, it indicates that the ground connection is normal and the encoder power signal terminal is disconnected. If the MCU output truth table shows that the sampling unit input port is 1, that is, the first terminal, the second terminal and the third terminal are at a high level, it indicates that the encoder's ground signal terminal is disconnected.

6. The encoder wire breakage detection method according to claim 4, characterized in that: Step S2 is as follows: S2: After the input of the sampling unit is divided, it is transmitted to the MCU through the conditioning circuit. The MCU receives the level output of the sampling unit and outputs the truth table. If the input of the sampling unit is low, the output of the conditioning circuit is low, and the truth table shows that the input of the sampling unit is 0. If the input of the sampling unit is high, the output of the conditioning circuit is high, and the truth table shows that the input of the sampling unit is 1.

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