Self-detection calibration circuit for analog quantity input board and analog quantity input board

Abstract

The present application relates to the technical field of detection circuits, and discloses a self-detection calibration circuit for an analog input board and an analog input board, wherein the self-detection calibration circuit comprises: the output end of the signal generation unit is configured as a self-detection AO port, and a first standard signal is output through the self-detection AO port; the channel selection unit is configured to connect the AI ​​port and the self-detection AO port to send the first standard signal to the AI ​​port; the signal acquisition unit is configured to sample the signal on the AI ​​port to obtain a first sampling signal; the controller is configured to generate a first standard signal, and compare the first standard signal with the first sampling signal, and detect whether an abnormality occurs in the AI ​​port according to the comparison result. The present application can timely detect whether the function of the analog input board is normal and calibrate it through the internally integrated self-detection calibration circuit, and reduce the difficulty of detection and calibration, and improve the reliability of the analog input board.

Description

Technical Field

[0001] The present application relates to the technical field of detection circuits, and in particular to a self-detection and calibration circuit for an analog input card and an analog input card. Background Art

[0002] As an important interface in industrial control systems, analog input interfaces are mainly used to receive analog signals corresponding to physical quantities of industrial equipment during operation, thereby providing a data basis for condition monitoring of industrial control systems. Therefore, the accuracy, stability and reliability of analog input interfaces are crucial to the normal operation of the entire industrial control system.

[0003] In the related art, the analog input interface is usually tested and calibrated for its analog input function through external testing and calibration equipment. However, such external testing and calibration equipment not only increases the equipment and labor generation, but may also increase the difficulty of detecting the analog input interface in harsh industrial environments. For example, external environmental factors such as electromagnetic interference, high temperature or high humidity may affect the signal transmission effect between the external testing and calibration equipment and the analog input interface, thereby affecting the detection and calibration effect of the analog input interface. Summary of the invention

[0004] The present application provides a self-detection and calibration circuit for an analog input board and an analog input board, which solves the current problem in a relatively harsh industrial environment. By integrating a self-detection and calibration circuit inside the analog input board to realize self-detection of the AI ​​(analog input) port, it is possible to timely detect whether the function of the analog input board is normal and perform calibration, thereby reducing the difficulty of detecting and calibrating the function of the analog input board in a harsh industrial environment and improving the reliability of the analog input board.

[0005] In order to achieve the above objectives, the main technical solutions adopted in this application include:

[0006] In a first aspect, an embodiment of the present application provides a self-detection calibration circuit for an analog input card, wherein the analog input card is provided with multiple groups of mutually independent AI ports, and the self-detection calibration circuit comprises:

[0007] A signal generating unit, wherein the output end of the signal generating unit is configured as a self-detection AO port, and outputs a first standard signal through the self-detection AO port;

[0008] a channel selection unit, the channel selection unit being configured to connect the AI ​​port and the self-detection AO port to send a first standard signal to the AI ​​port;

[0009] A signal acquisition unit, wherein the signal acquisition unit is configured to sample the signal on the AI ​​port to obtain a first sampling signal;

[0010] A controller is configured to generate the first standard signal, compare the first standard signal with the first sampling signal, and detect whether an abnormality occurs in the AI ​​port according to the comparison result.

[0011] The self-detection calibration circuit proposed in the embodiment of the present application sends a first standard signal to the AI ​​port through a signal generation unit and a channel selection unit, and obtains a first sampling signal for the AI ​​port through a signal acquisition unit, so as to compare the first sampling signal with the original first standard signal through a controller, thereby timely detecting whether an abnormality occurs in the AI ​​port. Therefore, the embodiment of the present application forms a self-detection feedback mechanism inside the analog input board by integrating a self-detection calibration circuit in the analog input board, which can effectively avoid the problem of difficulty in AI port detection caused by interference from external environmental factors in harsh environments, and effectively suppresses the interference of external environmental changes on AI port detection, ensuring the accuracy and real-time nature of the detection results, and can also reduce the time cost and labor cost of detection in harsh environments, greatly improving the detectability and reliability of the AI ​​port.

[0012] Optionally, in some embodiments of the present application, the channel selection unit is configured to cut off the connection between the AI ​​port and the external signal source and connect the AI ​​port to the self-detection AO port when the analog input board is in self-detection mode.

[0013] Optionally, in some embodiments of the present application, the AI ​​ports adopt a redundant design, wherein each group of the AI ​​ports includes a primary AI port and a backup AI port;

[0014] The controller is also configured to drive the channel selection unit to simultaneously connect the main AI port and the backup AI port to the external signal source based on a preset cycle when the main AI port is connected to the external signal source, compare the analog quantities on the main AI port and the backup AI port, and determine that the analog input board enters the self-detection mode based on the comparison result.

[0015] The embodiment of the present application performs redundant design on the AI ​​port, and through the comparison mechanism between the redundant ports, possible abnormalities or errors in the main AI port can be detected. Once the detection result shows that the signal difference between the main AI port and the backup AI port exceeds the allowable range, it is automatically determined whether the analog input board enters the self-detection mode based on the comparison result to further calibrate the accuracy and stability of the port. Therefore, on the one hand, it can enhance the reliability and fault tolerance of the AI ​​port, and on the other hand, it can realize the function of entering the self-detection mode, reduce human intervention and detection time, and improve the self-detection efficiency and reliability of the analog input board.

[0016] Optionally, in some embodiments of the present application, the signal generating unit includes:

[0017] A digital-to-analog conversion chip, the digital-to-analog conversion chip being configured to be connected to an internal signal source of the controller and to convert a standard digital signal generated by the internal signal source into a standard analog signal;

[0018] The first amplifying circuit is configured to amplify the standard analog signal to obtain a first standard signal, and send the first standard signal to the self-detection AO port.

[0019] The embodiment of the present application utilizes the internal signal source of the controller to provide a stable standard digital signal, and processes it into a standard analog signal through the digital-to-analog conversion chip, and then obtains the first standard signal through the signal amplification processing of the first amplifier circuit. Therefore, the signal generation unit in the embodiment of the present application can ensure the stability and accuracy of the first standard signal, and then the effective output of the first standard signal is realized through the above-mentioned self-detection AO port.

[0020] Optionally, in some embodiments of the present application, the first amplification circuit includes:

[0021] A first amplifier, wherein a positive input terminal of the first amplifier is connected to an output terminal of the digital-to-analog conversion chip;

[0022] A switch tube, wherein the gate of the switch tube is connected to the output end of the first amplifier via a current limiting resistor, the source of the switch tube is connected to the negative input end of the first amplifier, and the drain of the switch tube is connected to the self-detection AO port via a co-coupled inductor.

[0023] The embodiment of the present application performs signal amplification processing through a first amplifier, and provides signal isolation and protection for the transmission of the first standard signal by setting a co-coupled inductor between the switch tube and the self-detection AO port.

[0024] Optionally, in some embodiments of the present application, the channel selection unit includes a multiplexer, wherein an input end of the multiplexer is connected to the self-detection AO port, a first output end of the multiplexer is connected to a first relay switch between the AI ​​port and the self-detection AO port, and a second output end of the multiplexer is connected to the AI ​​port and a second relay switch of an external signal source.

[0025] The embodiment of the present application realizes free switching of the AI ​​port between the external signal source and the self-detection AO port inside the board by setting a channel selection unit. Therefore, the setting of the above-mentioned self-detection calibration circuit will not affect the normal function of the AI ​​port to receive the external signal source. At the same time, it can cut off the connection between the AI ​​port and the external signal source in the self-detection mode to avoid external interference, and connect the AI ​​port to the self-detection AO port, so that the AI ​​port can perform internal self-detection, which helps the AI ​​port to quickly switch between normal working mode and self-detection mode.

[0026] Optionally, in some embodiments of the present application, the signal acquisition unit includes:

[0027] A second amplifying circuit, wherein the second amplifying circuit is configured to collect an analog quantity on the AI ​​port and perform differential amplification on the analog quantity;

[0028] The analog-to-digital conversion circuit is configured to perform analog-to-digital conversion on the analog quantity after differential amplification by the second amplification circuit to obtain the first sampling signal, and send the first sampling signal to the controller through the I2C bus.

[0029] The embodiment of the present application realizes high-precision acquisition of the analog quantity on the AI ​​port through the signal acquisition unit to facilitate subsequent signal comparison and abnormal state detection, and suppresses external noise interference through the differential amplification of the second amplifier circuit, thereby improving the signal acquisition accuracy and anti-interference ability.

[0030] Optionally, in some embodiments of the present application, the self-detection calibration circuit further includes a signal calibration unit, and the signal calibration unit is configured to determine a calibration coefficient according to a ratio of the first standard signal to the first sampling signal when an abnormality occurs in the AI ​​port.

[0031] Optionally, in some embodiments of the present application, the signal calibration unit is further configured to send the calibration coefficient to the controller and drive the signal calibration program of the controller to calibrate the analog quantity on the AI ​​port based on the calibration coefficient.

[0032] The embodiment of the present application realizes automatic calibration of the AI ​​port through a signal calibration unit. If an abnormality occurs in the AI ​​port, the signal calibration unit will determine the calibration coefficient based on the ratio of the first standard signal to the first sampling signal to reflect the deviation between the signal input through the AI ​​port and the actual input signal, thereby providing a basis for the calibration of the AI ​​port and greatly improving the stability of the AI ​​port.

[0033] In a second aspect, an embodiment of the present application provides an analog quantity input board, the analog quantity input board comprising:

[0034] A plurality of mutually independent AI signal input units, wherein the input end of each of the AI ​​signal input units is configured as a group of AI ports;

[0035] According to the self-detection calibration circuit described in the above embodiment, the self-detection calibration circuit configures the circuit corresponding to the AI ​​port.

[0036] The analog input card proposed in the embodiment of the present application detects the analog receiving function of the AI ​​port through the above-mentioned self-detection calibration circuit, so as to promptly find out whether the AI ​​port has any abnormality. Therefore, the embodiment of the present application forms a self-detection feedback mechanism inside the analog input card by integrating the self-detection calibration circuit in the analog input card, which can effectively avoid the problem of difficulty in AI port detection caused by interference from external environmental factors in harsh environments. It not only effectively suppresses the interference of external environmental changes on AI port detection, and ensures the accuracy and real-time nature of the detection results, but also can reduce the time cost and labor cost of detection in harsh environments, greatly improving the detectability and reliability of the AI ​​port. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A structural block diagram of a self-detection and calibration circuit for an analog input card proposed in an embodiment of the present application;

[0039] Figure 2 A circuit structure diagram of a signal generating unit proposed in an embodiment of the present application;

[0040] Figure 3 A schematic diagram of the structure of the AI ​​port redundancy design proposed in the embodiment of the present application;

[0041] Figure 4This is a circuit structure diagram of the signal acquisition unit proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0043] As an important component of industrial control systems, analog input interfaces are mainly used to receive analog signals from sensors, actuators and other industrial equipment during operation, such as physical quantities such as equipment operating current, equipment operating voltage, and equipment operating temperature collected by sensors. With the expansion of the scale and increase of complexity of automation control systems, higher requirements are placed on the reliability and detectability of analog input interfaces.

[0044] In the related art, the analog input interface usually uses external detection equipment to detect the input function of the analog input interface. This detection method has many shortcomings. First, relying on external detection equipment requires adding additional hardware modules, which increases equipment and labor costs, and reduces the real-time detection of the working status of the analog input interface, resulting in low detection efficiency.

[0045] In addition, in outdoor industrial environments such as ship systems, there are external factors such as high temperature and humidity, salt spray, mold, impact, vibration, electromagnetic interference, etc., which increase the difficulty of detecting the analog input interface and may affect the effective detection of the analog input interface by external detection equipment, thereby reducing the stability, reliability and detectability of the analog input interface.

[0046] In this embodiment, a self-detection calibration circuit for an analog output card is provided, which can be used in industrial control systems, such as programmable logic controllers (PLCs) such as ship systems and electrical equipment control systems.

[0047] like Figure 1 As shown, the analog input board is provided with multiple groups of mutually independent AI ports 10, and the self-detection calibration circuit 20 includes a signal generating unit 100, a channel selecting unit 200, a signal collecting unit 300 and a controller 400;

[0048] Among them, the output end of the signal generating unit 100 is configured as a self-detection AO port, and outputs a first standard signal through the self-detection AO port, the channel selecting unit 200 is configured to connect the AI ​​port 10 and the self-detection AO port to send the first standard signal to the AI ​​port 10, the signal acquisition unit 300 is configured to sample the signal on the AI ​​port 10 to obtain a first sampling signal, the controller 400 is configured to generate the above-mentioned first standard signal, and compare the above-mentioned first standard signal with the above-mentioned first sampling signal, and detect whether an abnormality occurs in the AI ​​port 10 according to the comparison result.

[0049] The self-detection calibration circuit 20 provided in this embodiment sends a first standard signal to the AI ​​port 10 through the signal generation unit 100 and the channel selection unit 200, and obtains a first sampling signal of the AI ​​port 10 through the signal acquisition unit 300, so as to compare the first sampling signal with the original first standard signal through the controller 400, thereby timely detecting whether an abnormality occurs in the AI ​​port 10. Therefore, the embodiment of the present application forms a self-detection feedback mechanism inside the analog input board by integrating the self-detection calibration circuit 20 in the analog input board, which can effectively avoid the problem of difficulty in detecting the AI ​​port 10 caused by interference from external environmental factors in harsh environments, and effectively suppresses the interference of external environmental changes on the detection of the AI ​​port 10, ensuring the accuracy and real-time nature of the detection results, and can also reduce the time cost and labor cost of detection in harsh environments, greatly improving the detectability and reliability of the AI ​​port 10.

[0050] In order to realize self-detection of the AI ​​port, the embodiment of the present application sets another set of self-detection AO ports (including AO+ port and AO- port) on the analog input board. The controller 400 outputs the first standard signal to the AI ​​port 10 through the signal generation unit 100, and switches the AI ​​port to the only self-detection AO port on the analog input board through the channel selection unit 200, so as to transfer the above-mentioned first standard signal to the signal acquisition unit 300 and generate the corresponding first sampling signal, which can truly reflect the signal input status on the AI ​​port 10. Finally, the self-detection signal feedback mechanism inside the analog input board is realized by feeding the first sampling signal back to the controller 400.

[0051] Specifically, if Figure 2As shown, in the embodiment of the present application, the signal generating unit 100 includes a digital-to-analog conversion chip 110 and a first amplifying circuit 120, wherein the digital-to-analog conversion chip 110 is configured to access the internal signal source of the controller 400, and convert the standard digital signal generated by the internal signal source into a standard analog signal. The first amplifying circuit 120 is configured to amplify the standard analog signal to obtain a first standard signal, and send the first standard signal to the self-detection AO port.

[0052] Furthermore, if Figure 2 As shown, the first amplifier circuit 120 includes a first amplifier U1 and a switch tube Q1, wherein the positive input terminal of the first amplifier U1 is connected to the output terminal DA_AO of the digital-to-analog conversion chip 120, the gate of the switch tube Q1 is connected to the output terminal of the first amplifier U1 via a current limiting resistor R1, the source of the Q1 switch tube is connected to the negative input terminal of the first amplifier U1, and the drain of the Q1 switch tube is connected to the self-detection AO port via a co-coupled inductor L1, wherein the self-detection AO port includes an AO+ port and an AO- port.

[0053] Specifically, the controller 400 drives its internal signal source to generate a standard digital signal, and obtains a standard analog signal after the digital-to-analog conversion processing of the digital-to-analog conversion chip 120. The positive input terminal of the first amplifier U1 receives the standard analog signal for signal amplification processing, thereby turning on the switch tube Q1 to transmit the amplified standard analog signal to the AO+ port and the AO- port. In addition, a filter circuit is formed by capacitors C1 and C2 to reduce the influence of power supply fluctuations and noise on the first amplifier U1, and current protection is provided to the switch tube Q1 through the current limiting resistor R1 and the resistors R2 and R3 in the peripheral circuit. In some embodiments of the present application, the model of the above-mentioned first amplifier U1 is SGM8249-1, and the model of the switch tube Q1 is 2N7002.

[0054] In the embodiment of the present application, since the internal signal source of the controller 400 generates a high-precision standard digital signal based on preset standard parameters, and compared with the external signal source that may be affected by interference or noise in the transmission environment, the internal signal source can avoid these uncertain factors, thereby ensuring that the above-mentioned first standard signal has high consistency and reliability, and can directly use the internal signal source of the controller 400 to reduce hardware costs, thereby greatly improving the accuracy of the AI ​​port self-detection results and reducing the difficulty of AI port self-detection.

[0055] In the embodiment of the present application, a co-coupling inductor L1 is set between the switch tube Q1 and the self-detection AO port to provide signal isolation and protection for the transmission of the first standard signal, wherein the inductance value of the co-coupling inductor L1 is 470uH, and the input end of the co-coupling inductor L1 is also connected to the 24V power supply through the diode D1 and the fuse F2 in sequence to protect the power supply end. The other end of the co-coupling inductor L1 is respectively set as the AO+ port and the AO- port to form a group of self-detection AO ports, and a filter capacitor C3 is connected between the AO+ port and the AO- port.

[0056] The embodiment of the present application utilizes the internal signal source of the controller 400 to provide a stable standard digital signal, and processes it into a standard analog signal through the digital-to-analog conversion chip 110, and then obtains the first standard signal through the signal amplification processing of the first amplifier circuit 120. Therefore, the signal generation unit 100 in the embodiment of the present application can ensure the stability and accuracy of the first standard signal, and then the effective output of the first standard signal is realized through the above-mentioned self-detection AO port.

[0057] In an embodiment of the present application, the channel selection unit 200 is configured to cut off the connection between the AI ​​port 10 and the external signal source and connect the AI ​​port 10 to the self-detection AO port when the analog input board is in self-detection mode, thereby realizing AI port self-detection inside the analog input board.

[0058] Furthermore, the channel selection unit 200 includes a multiplexer (MUX), wherein an input end of the multiplexer is connected to the self-detection AO port, a first output end of the multiplexer is connected to a first relay switch K1 between the AI ​​port 10 and the self-detection AO port, and a second output end of the multiplexer is connected to the AI ​​port 10 and a second relay switch K2 of an external signal source.

[0059] Specifically, when the signal generating unit 100 outputs the first standard signal, the input end of the multiplexer receives the first standard signal, indicating that the AI ​​port needs to be self-tested. At this time, the multiplexer drives the first relay switch K1 to close and drives the second relay switch K2 to open, thereby switching the first standard signal to the AI ​​port. When the signal generating unit 100 does not output the first standard signal, it means that the AI ​​port does not need to be self-tested at present. At this time, the multiplexer drives the first relay switch K1 to open and drives the second relay switch K2 to close, thereby allowing the AI ​​port to normally receive the analog quantity sent by the external signal source.

[0060] Therefore, the embodiment of the present application realizes free switching of the AI ​​port between the external signal source and the AO port inside the board through the channel selection unit 200. The setting of the above-mentioned self-detection calibration circuit will not affect the normal function of the AI ​​port to receive the external signal source. At the same time, it can cut off the connection between the AI ​​port and the external signal source in the self-detection mode to avoid external interference, and connect the AI ​​port to the self-detection AO port, so that the AI ​​port can perform internal self-detection, which helps the AI ​​port to quickly switch between the normal working mode and the self-detection mode.

[0061] In the embodiment of the present application, the AI ​​ports 10 adopt a redundant design, wherein each group of AI ports 10 includes an active AI port 11 and a standby AI port 12 .

[0062] On this basis, the controller 400 is also configured to drive the channel selection unit 200 to simultaneously connect the main AI port and the backup AI port to the external signal source based on a preset cycle when the main AI port 11 is connected to the external signal source 30, and compare the analog quantities on the main AI port and the backup AI port, and determine whether the analog input board enters the self-detection mode based on the comparison result.

[0063] Figure 3 The schematic diagram of the redundant design is shown. When the signal generating unit 100 does not output the first standard signal, the multiplexer drives the second relay switch K2 to close, so that the main AI port 11 normally receives the analog quantity sent by the external signal source 30, and drives the third relay switch K3 between the backup AI port 12 and the external signal source 30 based on a preset cycle, so that the main AI port 11 and the backup AI port 12 simultaneously receive the analog quantity sent by the external signal source 30. In some embodiments of the present application, the preset cycle is 1000ms.

[0064] The controller 400 compares whether the analog quantities on the active AI port 11 and the standby AI port 12 are consistent. If the error between the analog quantities on the active AI port 11 and the standby AI port 12 exceeds a preset threshold, it indicates that at least one of the active AI port 11 and the standby AI port 12 is abnormal, so it is necessary to perform self-detection on the AI ​​port 10, that is, enter the self-detection mode. If the error between the analog quantities on the active AI port 11 and the standby AI port 12 does not exceed the preset threshold, it indicates that the active AI port 11 and the standby AI port 12 are currently functioning normally. At this time, the controller 400 sends a feedback signal to the multiplexer to confirm that the function is normal, so as to drive the multiplexer to disconnect the third relay switch K3 and keep the second relay switch K2 closed.

[0065] Therefore, the embodiment of the present application performs redundant design for the AI ​​port, and determines the trigger condition for entering the self-detection mode through a comparison mechanism between the redundant ports based on a preset period, so as to detect possible abnormalities or errors in the main AI port. Once the detection result shows that the signal difference between the main AI port and the backup AI port exceeds the allowable range, it is automatically determined whether the analog input board enters the self-detection mode based on the comparison result to further calibrate the accuracy and stability of the port. On the one hand, it can enhance the reliability and fault tolerance of the AI ​​port, and on the other hand, it can realize the function of entering the self-detection mode, reduce human intervention and detection time, and improve the self-detection efficiency and reliability of the analog input board.

[0066] Further, in some embodiments of the present application, multiple groups of independent AI ports 10 are provided on the analog input board, and different preset periods can be set for different AI ports 10. Specifically, the self-detection calibration circuit 20 further includes a signal fluctuation detection unit, which is used to monitor the fluctuation of the analog quantity received by each main AI port in real time, and adjust the preset period according to the fluctuation.

[0067] Specifically, the signal fluctuation detection unit is configured to obtain the historical sampling signal of the AI ​​port 10 by the signal acquisition unit 300, and when the fluctuation amplitude of the historical sampling signal obtained by multiple consecutive samplings is maintained within the preset range and the consecutive number of times reaches a preset value, it is determined that the corresponding AI port 10 is in a low fluctuation state and the above-mentioned preset period is reduced. In an example of an embodiment of the present application, the signal acquisition unit 300 obtains the historical sampling signal of the AI ​​port 10 at a preset sampling period, and the product obtained by multiplying the above-mentioned preset value, the preset adjustment coefficient and the sampling period of the signal acquisition unit 300 can be used as the preset period after reduction.

[0068] When the analog quantity continuously received by the AI ​​port fluctuates greatly, the possibility of damage to the AI ​​port due to sudden changes in input is greatly increased, so it is necessary to reasonably set the above preset period to trigger the start of the self-detection mode in a timely manner. On the contrary, if a group of AI ports 10 of the analog input board is in a low fluctuation state, it means that the analog quantity currently input to this group of AI ports 10 changes relatively smoothly, and a stable input signal is generally less likely to damage the AI ​​port, so the above preset period may be appropriately reduced, effectively avoiding the controller from switching the connection status of the main AI port and the backup AI port with the external signal source too frequently, thereby adaptively reducing the power consumption of the self-detection calibration circuit.

[0069] like Figure 4As shown, in the embodiment of the present application, the signal acquisition unit 300 includes a second amplifier circuit 310 and an analog-to-digital conversion circuit 320, wherein the second amplifier circuit 310 is configured to acquire an analog quantity on the AI ​​port 10 and perform differential amplification on the analog quantity, and the analog-to-digital conversion circuit 320 is configured to perform analog-to-digital conversion on the analog quantity after differential amplification by the second amplifier circuit 310 to obtain a first sampling signal, and send the first sampling signal to the controller 400 through the I2C bus.

[0070] Specifically, in the second amplifier circuit 310, the positive input terminal of the second amplifier U2A collects the analog quantity on the AI+ port through the resistors R4 to R6 and the diode D2 to amplify the analog quantity on the AI+ port, and inputs it to the negative input terminal of the third amplifier U2B through the current limiting resistor R7. In addition, the positive power supply terminal of the second amplifier U2A is connected to the power supply AV_5V, the negative power supply terminal of the second amplifier U2A is connected to the power supply AV_-5V, and a filter circuit composed of capacitors C4 and C5 is provided between the positive power supply terminal and the ground terminal AGND.

[0071] The positive input terminal of the fourth amplifier U3A collects the analog quantity on the AI-port through the resistor R8 to amplify the analog quantity on the AI-port and inputs it to the positive input terminal of the third amplifier U2B through the current limiting resistor R9. In addition, the positive power supply terminal of the fourth amplifier U3A is connected to the power supply AV_5V, the negative power supply terminal of the fourth amplifier U3A is connected to the power supply AV_-5V, and a filter circuit composed of a resistor R10, a capacitor C6 and a capacitor C7 is provided between the negative power supply terminal and the ground terminal AGND.

[0072] In addition, a protection circuit consisting of a resistor R11 and a TVS tube D3 connected in parallel is provided between the AI+ port and the AI- port.

[0073] The third amplifier U2B further performs differential amplification on the analog quantity after amplification by the second amplifier U2A and the fourth amplifier U3A through a feedback circuit composed of a resistor R12 and a resistor R13, so as to improve the signal accuracy and its anti-interference ability. At the same time, the positive power supply terminal of the third amplifier U2B is connected to the power supply AV_5V, and the negative power supply terminal of the third amplifier U2B is connected to the power supply AV_-5V.

[0074] The circuit composed of the fifth amplifier U3B, resistor R14, resistor R15 and capacitor C8 is used to generate a reference voltage Vref_2.2V and send it to the positive input terminal of the third amplifier U2B. At the same time, the positive power supply terminal of the fifth amplifier U3B is connected to the power supply AV_5V, and the negative power supply terminal of the fifth amplifier U3B is connected to the power supply AV_-5V.

[0075] The embodiment of the present application realizes high-precision acquisition of the analog quantity on the AI ​​port through the signal acquisition unit to facilitate subsequent signal comparison and abnormal state detection, and suppresses external noise interference through the differential amplification of the second amplifier circuit, thereby improving the signal acquisition accuracy and anti-interference ability.

[0076] The third amplifier U2B outputs the analog quantity after differential amplification to the IN-pin and IN+pin of the analog-to-digital conversion chip U4 in the analog-to-digital conversion circuit 320, wherein the analog-to-digital conversion circuit 320 also includes a peripheral circuit of the analog-to-digital conversion chip U4 composed of resistors R16 to R19 and capacitors C9 to C12. The analog quantity output by the third amplifier U2B is converted into a digital signal by the analog-to-digital conversion chip U4, and then sent to the controller 400 through the SDA pin and the SCL pin in the form of I2C bus transmission.

[0077] The embodiment of the present application realizes high-precision acquisition of the analog quantity on the AI ​​port 10 through the signal acquisition unit 300, so that the controller 400 can subsequently compare the first standard signal and the first sampling signal and detect abnormal conditions, and through the differential amplification of the second amplifier circuit 310, external noise interference is suppressed, thereby improving the signal acquisition accuracy and anti-interference ability.

[0078] In the embodiment of the present application, the self-detection calibration circuit 20 also includes a signal calibration unit 500, wherein the signal calibration unit 500 is configured to determine a calibration coefficient according to a ratio of a first standard signal to a first sampling signal when an abnormality occurs in the AI ​​port 10.

[0079] Furthermore, the signal calibration unit 500 is also configured to send the calibration coefficient to the controller 400 and drive the signal calibration program of the controller 400 to calibrate the analog quantity on the AI ​​port 10 based on the calibration coefficient.

[0080] For example, assuming that the current analog quantity corresponding to the first standard signal outputted through the self-detection AO port is 4mA, and the current analog quantity corresponding to the first sampled signal collected on the AI ​​port is 3mA, the calibration coefficient k is determined to be 4 / 3. In the subsequent analog quantity input process, the analog quantity input to the AI ​​port is always multiplied by the calibration coefficient k through the signal calibration program of the controller 400, that is, the AI ​​port is soft-compensated through the signal calibration program of the controller 400 until the calibration coefficient is updated again in the next self-detection process.

[0081] Therefore, the embodiment of the present application realizes automatic calibration of the AI ​​port 10 through the signal calibration unit 400. If an abnormality occurs in the AI ​​port 10, the signal calibration unit 400 will determine the calibration coefficient k based on the ratio of the first standard signal to the first sampling signal to reflect the deviation between the signal input through the AI ​​port 10 and the actual input signal, thereby providing a basis for the calibration of the AI ​​port 10 and greatly improving the stability of the AI ​​port 10.

[0082] Accordingly, an embodiment of the present application provides an analog input board, comprising a plurality of independent AI signal input units and a self-detection calibration circuit 20, wherein the input end of each AI signal input unit is configured as a group of AI ports 10, and the self-detection calibration circuit 20 configures the circuit corresponding to the AI ​​port 10.

[0083] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0084] In an embodiment of the present application, the above-mentioned analog input board also includes a health management unit, which includes a voltage detection circuit, a current detection circuit, a temperature detection circuit and a co-controller. The voltage detection circuit is configured to collect the working voltage of the analog input board, the current detection circuit is configured to collect the working current of the analog input board, the temperature detection circuit is configured to detect the working temperature of the analog input board, and the co-controller is configured to receive the working voltage, working current and working temperature, and to alarm when the working voltage, working current and working temperature exceed the preset rated range.

[0085] In some embodiments of the present application, the model of the above-mentioned co-controller is QJ32F103CBT6. The processor provides 128KB internal FLASH, 20KB internal SRAM, 3 UART interfaces, 2 I2C interfaces, 2 SPI interfaces, 37 GPIO interfaces, 2 12-bit precision 2MSPS ADC first controllers with a total of 10 channels, 1 USB interface and 1 CAN interface, etc., to meet the functional requirements of the health management unit. In addition, the co-controller communicates with the controller 400 through the UART bus, which is used to cut off the connection between the AI ​​port 10 and the external signal source through the controller 400 when an alarm occurs in the co-controller.

[0086] Specifically, the voltage detection circuit collects voltages through the 12-bit precision ADC of the co-controller. The voltage detection circuit can collect up to 10 voltages at the same time. The built-in 12-bit ADC with an accuracy of 1% is used to measure each input and compare the result with the overvoltage threshold, undervoltage threshold, and the warning threshold configured as undervoltage or overvoltage. When the measured voltage exceeds the set threshold, a fault alarm signal is issued, and it can communicate with the host computer or management chip through the I²C bus interface to achieve multiple modes of alarm. The ADC integrated in the co-controller collects voltages in the range of 0-3.6V, so voltages exceeding 3.6V need to be divided, and then the real voltage value is restored on the voltage value through the internal calculation formula. The current detection circuit first converts the current to voltage through the op amp, then adjusts the output impedance through the voltage follower, and finally enters the MCU for AD acquisition. The temperature detection circuit uses a temperature sensor model NST175H-QMSR, which is an integrated digital temperature sensor with a 12-bit analog-to-digital converter that can be powered by a 2.7V to 5.5V power supply. It can read the temperature with a resolution of 0.0625°C and is rated to operate in the temperature range of -55°C to +125°C. It has a digital output with a two-wire I2C interface, which can communicate with the host computer or a dedicated management chip through the I2C bus to achieve real-time monitoring and management functions.

[0087] The embodiment of the present application detects the voltage, current and temperature of the analog input board through the voltage detection circuit, current detection circuit and temperature detection circuit in the health management unit, and alarms abnormal detection results through the auxiliary controller, which helps to ensure the normal operation of the analog input board and improve the reliability and stability of the analog input board.

[0088] The analog input card proposed in the embodiment of the present application detects the analog receiving function of the AI ​​port through the above-mentioned self-detection calibration circuit 20, so as to timely discover whether the AI ​​port has any abnormality. Therefore, the embodiment of the present application forms a self-detection feedback mechanism inside the analog input card by integrating the self-detection calibration circuit in the analog input card, which can effectively avoid the problem of difficulty in AI port detection caused by interference from external environmental factors in harsh environments. It not only effectively suppresses the interference of external environmental changes on AI port detection, ensures the accuracy and real-time nature of the detection results, but also can reduce the time cost and labor cost of detection in harsh environments, greatly improving the detectability and reliability of the AI ​​port.

[0089] Although the embodiments of the present application are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

[0090] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0091] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0092] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0093] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

[0094] Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A self-detection and calibration circuit for an analog input card, characterized in that: The analog input board is provided with a plurality of mutually independent AI ports, and the self-detection calibration circuit comprises: A signal generating unit, wherein the output end of the signal generating unit is configured as a self-detection AO port, and outputs a first standard signal through the self-detection AO port; a channel selection unit, the channel selection unit being configured to connect the AI ​​port and the self-detection AO port to send a first standard signal to the AI ​​port; A signal acquisition unit, wherein the signal acquisition unit is configured to sample the signal on the AI ​​port to obtain a first sampling signal; a controller configured to generate the first standard signal, compare the first standard signal with the first sampling signal, and detect whether an abnormality occurs in the AI ​​port according to the comparison result; Wherein, the AI ​​port is an analog input port, and the AO port is an analog output port; The channel selection unit is configured to cut off the connection between the AI ​​port and the external signal source and connect the AI ​​port to the self-detection AO port when the analog input board is in the self-detection mode; The AI ​​ports adopt a redundant design, wherein each group of the AI ​​ports includes a primary AI port and a backup AI port; The controller is further configured to, when the main AI port is connected to an external signal source, drive the channel selection unit to simultaneously connect the main AI port and the standby AI port to the external signal source based on a preset cycle, compare the analog quantities on the main AI port and the standby AI port, and determine that the analog quantity input board enters the self-detection mode according to the comparison result; Among them, the self-detection calibration circuit also includes a signal fluctuation detection unit, which is configured to obtain the historical sampling signal of the AI ​​port by the signal acquisition unit. When the fluctuation amplitude of the historical sampling signal obtained by multiple consecutive samplings remains within a preset range and the consecutive number of times reaches a preset value, it is determined that the AI ​​port is in a low fluctuation state, and the preset period is reduced according to the product obtained by multiplying the preset value, the preset adjustment coefficient and the sampling period of the signal acquisition unit.

2. The self-detection calibration circuit according to claim 1, characterized in that: The signal generating unit comprises: A digital-to-analog conversion chip, the digital-to-analog conversion chip being configured to be connected to an internal signal source of the controller and to convert a standard digital signal generated by the internal signal source into a standard analog signal; The first amplifying circuit is configured to amplify the standard analog signal to obtain a first standard signal, and send the first standard signal to the self-detection AO port.

3. The self-detection calibration circuit according to claim 2, characterized in that: The first amplifying circuit comprises: A first amplifier, wherein a positive input terminal of the first amplifier is connected to an output terminal of the digital-to-analog conversion chip; A switch tube, wherein the gate of the switch tube is connected to the output end of the first amplifier via a current limiting resistor, the source of the switch tube is connected to the negative input end of the first amplifier, and the drain of the switch tube is connected to the self-detection AO port via a co-coupled inductor.

4. The self-detection calibration circuit according to claim 1, characterized in that: The channel selection unit includes a multiplexer, wherein an input end of the multiplexer is connected to the self-detection AO port, a first output end of the multiplexer is connected to a first relay switch between the AI ​​port and the self-detection AO port, and a second output end of the multiplexer is connected to the AI ​​port and a second relay switch of the external signal source.

5. The self-detection calibration circuit according to claim 1, characterized in that: The signal acquisition unit comprises: A second amplifying circuit, wherein the second amplifying circuit is configured to collect an analog quantity on the AI ​​port and perform differential amplification on the analog quantity; The analog-to-digital conversion circuit is configured to perform analog-to-digital conversion on the analog quantity after differential amplification by the second amplification circuit to obtain the first sampling signal, and send the first sampling signal to the controller through the I2C bus.

6. The self-detection calibration circuit according to claim 1, characterized in that: The self-detection calibration circuit further includes a signal calibration unit, which is configured to determine a calibration coefficient according to a ratio of the first standard signal to the first sampling signal when an abnormality occurs in the AI ​​port.

7. The self-detection calibration circuit according to claim 6, characterized in that: The signal calibration unit is further configured to send the calibration coefficient to the controller and drive a signal calibration program of the controller to calibrate the analog quantity on the AI ​​port based on the calibration coefficient.

8. An analog input board, characterized in that: The analog input board comprises: A plurality of mutually independent AI signal input units, wherein the input end of each of the AI ​​signal input units is configured as an AI port; According to any one of claims 1 to 7, the self-detection calibration circuit configures the circuit corresponding to the AI ​​port.

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