Slave station capacitance film vacuum gauge reading device based on EtherCAT bus

Abstract

The invention belongs to the technical field of vacuum metering, and particularly relates to a slave station capacitance film vacuum gauge reading device based on an EtherCAT bus. The slave station capacitance film vacuum gauge reading device based on the EtherCAT bus comprises an excitation signal generation module, a sensor interface module, a current-voltage conversion module, a band-pass filtering module, a precision rectification and filtering module, an analog quantity output interface module, an analog-to-digital conversion module, a control circuit module, an EtherCAT bus module and a power supply module. The slave station capacitance film vacuum gauge based on the EtherCAT bus can be conveniently connected to the EtherCAT industrial Ethernet bus, and has the characteristics of accurate data acquisition, high transmission efficiency, simple wiring and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum measurement, and in particular relates to a slave capacitance film vacuum gauge readout device based on an EtherCAT bus. Background Art

[0002] Traditional capacitance film vacuum gauge data acquisition devices usually rely on analog signal transmission, which can no longer meet the growing requirements of modern industrial control systems in terms of transmission efficiency, real-time response capability, and expansion convenience. Integrating EtherCAT industrial Ethernet bus technology into capacitance film vacuum gauges and making full use of its superior data transmission characteristics to significantly improve the performance of data acquisition systems is of great significance for promoting the upgrade and optimization of industrial control systems. Summary of the invention

[0003] In view of this, for application scenarios such as multi-channel vacuum acquisition systems and high-reliability vacuum acquisition, combined with the characteristics of easy networking of the EtherCAT industrial Ethernet bus and its strong anti-interference advantage, the present application provides a slave capacitance film vacuum gauge readout device based on the EtherCAT bus. The slave capacitance film vacuum gauge based on the EtherCAT bus can be easily connected to the EtherCAT industrial Ethernet bus, and has the characteristics of accurate data acquisition, high transmission efficiency, simple wiring, etc. It can be widely used in the field of industrial vacuum measurement and has good application prospects.

[0004] The technical solution for implementing the present invention is as follows:

[0005] A slave capacitance film vacuum gauge readout device based on EtherCAT bus, comprising: an excitation signal generating module, a sensor interface module, a current-voltage conversion module, a bandpass filtering module, a precision rectification and filtering module, an analog output interface module, an analog-to-digital conversion module, a control circuit module, an EtherCAT bus module and a power supply module; wherein,

[0006] The excitation signal generating module is used to generate a sinusoidal wave excitation signal;

[0007] The sensor interface module is used to send the excitation signal generated by the excitation signal generating module to the capacitance film vacuum gauge, and receive the current signal sent back by the capacitance film vacuum gauge;

[0008] The current-voltage conversion module is used to convert the current signal sent back by the sensor received by the sensor interface module into a voltage signal and output it;

[0009] The bandpass filter module is used to filter out the harmonic components in the output signal of the current-voltage conversion module;

[0010] The precision rectification and filtering module is used to rectify and filter the voltage signal output by the current-voltage conversion module;

[0011] The analog-to-digital conversion module is used to perform analog-to-digital conversion processing on the signal output by the precision rectification and filtering module;

[0012] The control circuit module is used to receive and process the signal output by the analog-to-digital conversion module;

[0013] The EtherCAT bus module is used to convert the signal processed by the control circuit module into an EtherCAT bus data signal and output it to the network interface;

[0014] The power supply module is used to provide power to each component unit of the entire system.

[0015] Furthermore, the excitation signal generating module of the present invention comprises a Wien bridge oscillator circuit, a gain adjustment circuit and a rectifier and filter circuit; wherein the Wien bridge oscillator circuit is composed of an operational amplifier and a precision resistor and capacitor circuit, and is used to generate a sinusoidal wave signal; the gain adjustment circuit is composed of a JFET and a resistor, and the JFET is connected in series in the feedback loop of the Wien bridge oscillator circuit, and is used for sinusoidal wave gain adjustment; the rectifier and filter circuit is composed of a filter composed of a diode and an active integrator, and is used to rectify and process the signal into a relatively smooth DC signal; the positive electrode of the diode is connected to the output end of the Wien bridge oscillator circuit, and the output is connected to the gate of the JFET in the gain adjustment circuit.

[0016] Furthermore, the Wien bridge oscillator circuit of the present invention is mainly composed of an operational amplifier U 1.1 and by the resistor R 1 , R 2 , R 3 , R 4 With capacitor C 1 , C 3 The precision resistor-capacitor circuit is composed of 1 and capacitor C 1 After being connected in series, it is connected in parallel to the operational amplifier U 1.1 Between the same-direction input and output terminals, the resistor R 2 and capacitor C 3 Connect in parallel to the operational amplifier U 1.1 Between the same-direction input terminal and ground, the resistor R 3 Connected in parallel to the operational amplifier U 1.1 Between the inverting input and output of the operational amplifier U 1.1 Through the resistor R 4 Connect the gain adjustment circuit;

[0017] The gain adjustment circuit consists of a JFET and a resistor R6 , R 7 The resistance R of the Wien bridge oscillator circuit is 4 Series resistance R 6 After grounding, the field effect transistor Q 1 The drain and source are connected in parallel with the resistor R 6 At both ends of the field effect transistor Q 1 The gate is connected through the resistor R 7 Connect the rectifier and filter circuit;

[0018] The rectifier and filter circuit is composed of a diode D 1 , Active Integrator U 1.2 , resistor R 5 And the capacitor C 2 , C 4 The gain adjustment circuit is composed of a resistor R 7 Connect active integrator U 1.2 The output terminal, the capacitor C 4 and resistor R 5 Connected in parallel to the active integrator U 1.2 Between the inverting input and output terminals of the Wien bridge oscillator circuit operational amplifier U 1.1 The output terminal of the diode D 1 The positive pole is connected to the cathode of the diode and the active integrator U 1.2 The inverting input terminal.

[0019] Furthermore, the current-voltage conversion module of the present invention is used to convert the current signal into a voltage signal, mainly composed of an operational amplifier U 2 , feedback resistor R f And the zero adjustment resistor PR 1 The feedback resistor is connected in series in the feedback loop of the operational amplifier, the center tap of the zero adjustment resistor is connected to the inverting input terminal of the operational amplifier, and the two ends are connected to +VREF and -VREF respectively; the current-voltage conversion module, its input end is the signal input terminal in the sensor interface module.

[0020] Furthermore, the bandpass filter module of the present invention is used to select the frequency of the useful signal and filter out the harmonic components. 1 The feedback network is composed of resistor R 1 , R 2 , R 3 The operational amplifier is composed of capacitors, the in-phase terminal is connected to the negative pole of the power supply, and the inverting terminal is connected to the feedback network; the input end of the bandpass filter module is connected to the output end of the current-voltage conversion module.

[0021] Furthermore, the precision rectification and filtering module of the present invention is mainly composed of a buffer, a precision rectification circuit and an RC low-pass filter; the buffer is composed of an operational amplifier U 2.1 The operational amplifier is connected to the output end of the bandpass filter module at the same phase end, and the inverting end is short-circuited with the output end of the operational amplifier; the precision rectifier circuit is composed of an operational amplifier U 2.2 , resistor R 14 , R 12 , R 13 , R 17 , and diode D 2 , D 3 The RC low-pass filter is composed of a resistor R 15 With capacitor C 8 Composition, resistance R 15 One end is connected to the output end of the precision rectifier circuit, and the other end is used as the output end of the precision rectifier and filter module and connected to the capacitor C 8 One end is connected and the other end of the capacitor is connected to the power ground.

[0022] Furthermore, the analog output interface module of the present invention has one end J1 connected to the C in the precision rectification and filtering module. 8 The other end J2 is connected to the power ground and is used to output a 0~10V vacuum degree analog signal.

[0023] Furthermore, the analog-to-digital conversion module of the present invention is composed of a high-precision 24-bit ADC chip and its peripheral circuits, and the input end of the ADC chip is connected to the output end of the precision rectification and filtering module.

[0024] Furthermore, the control circuit module of the present invention is composed of a single-chip microcomputer and its peripheral circuits; the single-chip microcomputer is connected to the IO port of the ADC chip and is used for register initialization configuration of the ADC chip.

[0025] Furthermore, the EtherCAT bus module described in the present invention is composed of an EtherCAT control chip and its peripheral circuits, and an Ethernet RJ45 interface; its IO port is connected to the single-chip microcomputer in the control circuit module to receive control and data from the single-chip microcomputer; the Ethernet RJ45 interface is used to connect to the industrial Internet to complete data output.

[0026] Beneficial effects:

[0027] The circuit scheme of the present invention is simple. Compared with the previous vacuum metering equipment, the output result is a digital signal, which has strong anti-interference ability, long transmission distance and high reliability.

[0028] Using EtherCAT network bus as the output interface, it can be easily connected to the EtherCAT industrial Ethernet bus. It has the characteristics of accurate data collection, high transmission efficiency, simple wiring, etc., and can be widely used in the field of industrial vacuum measurement.

[0029] A 0-10V analog output interface is designed, which is backward compatible with the existing analog acquisition interfaces in industrial sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a circuit implementation module diagram of the present invention;

[0031] Figure 2 It is an excitation signal generating module circuit;

[0032] Figure 3 It is a sensor interface module;

[0033] Figure 4 It is a current-voltage conversion module circuit;

[0034] Figure 5 It is a bandpass filter module circuit;

[0035] Figure 6 It is a precision rectification and filtering module circuit;

[0036] Figure 7 It is the analog output interface module circuit;

[0037] Figure 8 It is the relationship between the analog-to-digital conversion module, the control circuit module, the EtherCAT bus module, and the power supply module. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0039] It should be noted that the following embodiments and features in the embodiments may be combined with each other in the absence of conflict; and, based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making any creative work are within the scope of protection of the present disclosure.

[0040] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0041] like Figure 1 As shown, a slave capacitance film vacuum gauge readout method and circuit based on EtherCAT bus, including: an excitation signal generating module, a sensor interface module, a current-voltage conversion module, a bandpass filtering module, a precision rectification and filtering module, an analog output interface module, an analog-to-digital conversion module, a control circuit module, an EtherCAT bus module and a power supply module;

[0042] The excitation signal generating module is used to generate a sinusoidal wave excitation signal; the sensor interface module is used to send the excitation signal generated by the excitation signal generating module to the capacitance film vacuum gauge and receive the current signal sent back by the capacitance film vacuum gauge; the current-voltage conversion module is used to convert the current signal sent back by the sensor received by the sensor interface module into a voltage signal and output it; the bandpass filtering module is used to filter out the harmonic components in the output signal of the current-voltage conversion module; the precision rectification and filtering module is used to rectify and filter the voltage signal output by the current-voltage conversion module; the analog-to-digital conversion module is used to perform analog-to-digital conversion on the signal output by the precision rectification and filtering module; the control circuit module is used to receive the signal output by the analog-to-digital conversion module for processing; the EtherCAT bus module is used to convert the signal processed by the control circuit module into an EtherCAT bus data signal and output it to the network interface; the power supply module is used to provide power to each component unit of the entire system.

[0043] The excitation signal generation module is used to generate a sinusoidal excitation signal. The sinusoidal excitation signal generated by this high-precision signal source is sent to the sensor, and the sensor will output a signal containing its own capacitance information. The principle is that capacitors with different capacitance have different capacitive reactances under the same excitation signal, so the signal current after passing through the sensor is related to its capacitance. The signal output by the sensor is converted from current to voltage, and the converted signal is conditioned, and the harmonic components are filtered out and then precisely rectified to obtain a DC signal with an amplitude linearly related to the sensor capacitance. Then, this signal is collected and converted into vacuum degree by a digital-to-analog converter, and sent out by the EtherCAT bus, thus completing the entire detection process. This part of the circuit from the excitation signal to the analog-to-digital conversion mainly realizes the conversion of capacitance to voltage, which is called capacitance-voltage conversion.

[0044] like Figure 2 As shown, in the embodiment of the present application, the stability of the detection result is directly related to the amplitude stability of the sinusoidal signal used. In view of this, a Wien bridge oscillator circuit including an automatic gain control mechanism is designed to generate a sinusoidal signal to ensure the stability of the excitation signal amplitude. It includes a Wien bridge oscillator circuit, a gain adjustment circuit and a rectifier filter circuit; wherein the Wien bridge oscillator circuit is composed of an operational amplifier and a precision resistor-capacitor circuit, and is used to generate a sinusoidal wave signal; the gain adjustment circuit is composed of a JFET (junction field effect transistor) and a resistor, and the JFET is connected in series in the feedback loop of the Wien bridge oscillator circuit for sinusoidal wave gain adjustment; the rectifier filter circuit is composed of a filter composed of a diode and an active integrator, and is used to rectify and process the signal into a relatively smooth DC signal; the positive pole of the diode is connected to the output end of the Wien bridge oscillator circuit, and the output is connected to the gate of the JFET in the gain adjustment circuit. The circuit is specifically as follows:

[0045] The Wien bridge oscillator circuit is mainly composed of an operational amplifier U 1.1 and by the resistor R 1 , R 2 , R 3 , R 4 With capacitor C 1 , C 3 The precision resistor-capacitor circuit is composed of 1 and capacitor C 1 After being connected in series, it is connected in parallel to the operational amplifier U 1.1 Between the same-direction input and output terminals, the resistor R 2 and capacitor C 3 Connect in parallel to the operational amplifier U 1.1 Between the same-direction input terminal and ground, the resistor R 3 Connected in parallel to the operational amplifier U 1.1 Between the inverting input and output of the operational amplifier U 1.1 Through the resistor R4 Connect the gain adjustment circuit;

[0046] The gain adjustment circuit consists of a JFET (junction field effect transistor) and a resistor R 6 , R 7 The resistance R of the Wien bridge oscillator circuit is 4 Series resistance R 6 After grounding, the field effect transistor Q 1 The drain and source are connected in parallel with the resistor R 6 At both ends of the field effect transistor Q 1 The gate is connected through the resistor R 7 Connect the rectifier and filter circuit;

[0047] The rectifier and filter circuit is composed of a diode D 1 , Active Integrator U 1.2 , resistor R 5 And the capacitor C 2 , C 4 The gain adjustment circuit is composed of a resistor R 7 Connect active integrator U 1.2 The output terminal, the capacitor C 4 and resistor R 5 Connected in parallel to the active integrator U 1.2 Between the inverting input and output terminals of the Wien bridge oscillator circuit operational amplifier U 1.1 The output terminal of the diode D 1 The positive pole is connected to the cathode of the diode and the active integrator U 1.2 The inverting input terminal.

[0048] The schematic diagram of the excitation signal generation is as follows: Figure 2 As shown, Q 1 The diode in the traditional Wien bridge oscillator solution is replaced by a junction field effect transistor with a zero temperature coefficient, and connected to the feedback circuit as a gain adjustment element. This design can greatly enhance the adaptability of the sinusoidal signal output to ambient temperature changes, thereby achieving higher temperature stability and improving the reliability of the results of the entire detection process. 1 The signal output is sampled and rectified and sent to C 4 , R 5 With operational amplifier U 1.2 The low-pass filter outputs a smooth DC signal to control Q 1 The gate of 1 Series in U 1.1 In the feedback loop, by adjusting Q 1 The gate voltage controls the output signal amplitude and can achieve the purpose of amplitude stabilization. 1.2 The reference voltage VREF The size of R can change the output amplitude of the oscillation circuit. 1 , C 1 , R 2 , C 2 The frequency of the Wien bridge oscillator circuit is determined together, and the capacitive reactance X of the capacitor being measured c It is also related to the excitation signal frequency f, so R 1 , C 1 , R 2 , C 2 Select high-precision and low-temperature drift devices.

[0049] like Figure 3 As shown, the analog output interface module of the embodiment of the present application has one end J 1 Connect C in the precision rectification and filtering module 8 , the other end J 2 Connected to the power ground, used to output 0~10V vacuum degree analog signal.

[0050] Figure 4 As shown, the current-voltage conversion module in the embodiment of the present application is used to convert the current signal into a voltage signal, which is converted by the operational amplifier U 2 , feedback resistor R f 、Zero adjustment resistor PR 1 And the capacitor C X The feedback resistor is connected in series in the feedback loop of the operational amplifier, the center tap of the zero adjustment resistor is connected to the same-direction input terminal of the operational amplifier, and the two ends are connected to +VREF and -VREF respectively; the input terminal of the current-voltage conversion module is connected in series with a capacitor C X Connect to the signal input terminal J in the sensor interface module 2 .

[0051] The basic principle of current-voltage conversion is that the excitation signal is sent to one end of the capacitor to be measured, and the current signal output from the other end is composed of U 2 With R f The current-voltage conversion circuit composed of the above circuits is converted into voltage and then output. x The capacitance to be measured is connected to C x Location.PR 1 It is a zero adjustment potentiometer, used to adjust the output zero point.

[0052] like Figure 5 As shown, the bandpass filter module of the embodiment of the present application is used to select the frequency of the useful signal and filter out the harmonic components. 1 The feedback network is composed of resistor R 1 , R 2 , R 3And the capacitor C 1 , C 2 The operational amplifier has a common-phase terminal connected to the negative pole of the power supply and a negative-phase terminal connected to the feedback network; the input terminal of the bandpass filter module is connected to the output terminal of the current-voltage conversion module. 1 The same-direction input terminal is grounded, and the reverse input terminal is connected in series with a capacitor C 2 and resistor R 1 Then connect to the output end of the current-voltage conversion module, resistor R 1 and capacitor C 2 Through the resistor R 2 Ground, through capacitor C 1 Connect to amplifier U 1 The output terminal, resistor R 3 Connect to amplifier U 1 between the inverting input and output terminals.

[0053] The voltage signal output by the current-voltage conversion circuit is essentially an amplitude modulated signal. Figure 4 The AM signal output by the circuit contains a large number of harmonic components in addition to the base frequency. In order to make the subsequent processing easier, it is necessary to extract the base frequency component containing useful information. Figure 2 The frequency of the generated excitation signal is known, so we can design a bandpass filter that only allows the known frequency to pass. Figure 5 The schematic diagram of the active bandpass filter used in this design is shown. 1 =C 2 = C, the size of the capacitor C does not affect the gain H (jf 0 ) and quality factor Q, so its capacitance is usually determined by engineering experience, such as the selection range of 10kHz-100kHz frequency is 1000pF-100pF, and C is selected in the present invention. 1 =C 2 =470pF.

[0054] like Figure 6 As shown, the precision rectification and filtering module of the embodiment of the present application is composed of a buffer, a precision rectification circuit and an RC low-pass filter; the buffer is composed of an operational amplifier U 2.1 The operational amplifier is connected to the output end of the bandpass filter module at the same phase end, and the inverting end is short-circuited with the output end of the operational amplifier; the precision rectifier circuit is composed of an operational amplifier U 2.2 , resistor R 12 , R 13 , R 14 , R 17 And diode D 2 , D3; the operational amplifier U2.2 The inverting input terminal is connected through the resistor R 14 Connect to operational amplifier U 2.1 The output of the operational amplifier U 2.2 The non-inverting input terminal is connected through the resistor R 17 Ground, operational amplifier U 2.2 The output end is connected in series with a diode D 2 As the output end of the precision rectifier circuit, the resistor R 13 and diode D 3 After being connected in series, it is connected in parallel to the operational amplifier U 2.2 Between the inverting input and output terminals, the resistor R 12 Connected in parallel to the operational amplifier U 2.2 The RC low-pass filter is composed of a resistor R 15 With capacitor C 8 Composition, resistance R 15 One end is connected to the output end of the precision rectifier circuit, and the other end is used as the output end of the precision rectifier and filter module and connected to the capacitor C 8 One end is connected and the other end of the capacitor is connected to the power ground.

[0055] The signal output by the active filter is an amplitude modulated signal with the same frequency as the excitation signal, and its amplitude value is related to the capacitance being measured. When the vacuum sensor is working, the vacuum degree of the measured environment changes relatively slowly, and its capacitance also changes relatively slowly. Moreover, the output capacitance is usually a monotonic function within the effective range. Therefore, it is only necessary to extract the amplitude of the amplitude modulated signal. The present invention uses a precision rectifier circuit to complete the extraction of the amplitude signal, such as Figure 6 As shown in the figure, the input signal first passes through U 2.1 Isolation buffer to eliminate the mutual influence between the previous and next stages as much as possible. 15 With C 8 A low-pass filter is formed to filter the signal output by the rectifier circuit, and the output end will be directly connected to the input end of the ADC acquisition circuit. 15 =1kΩ, C 8 =10uF, select 24-bit AD7732 for analog-to-digital conversion, its input range can reach ±10V, and the ADC acquisition circuit uses the application circuit recommended in the AD7732 manual to meet the needs of this design.

[0056] like Figure 7 As shown, the analog output interface module has one end J1 connected to C8 in the precision rectification and filtering module, and the other end J2 connected to the power ground, for outputting 0-10V vacuum analog signal.

[0057] like Figure 8As shown, the control circuit module described in the embodiment of the present application is composed of a single-chip microcomputer and its peripheral circuits; the single-chip microcomputer is connected to the IO port of the ADC chip and is used for register initialization configuration of the ADC chip.

[0058] This embodiment uses LAN9252 as the EtherCAT slave controller. The designed EtherCAT slave circuit block diagram is as follows: Figure 8 LAN9252 sets up a slave station by reading the configuration information in the external EEPROM. After the configuration is completed, the microcontroller can communicate with LAN9252 through the SPI serial or parallel mode PD I interface.

[0059] The single chip microcomputer is the core of the entire capacitance film vacuum gauge control part, and it has three main functions: first, it configures the ADC register, completes the hardware layer control of ADC data conversion, and pre-processes the obtained data, such as digital filtering; second, it calculates the collected data, such as parameter fitting and vacuum degree conversion; third, as the control core of the EtherCAT slave station, it uses its own hardware SPI interface module to complete the communication with LAN9252.

[0060] The power supply part provides power for the whole machine, with one DC24V input and three sets of DC3.3V, DC5V, and DC±12V output power.

[0061] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A slave capacitance film vacuum gauge readout device based on EtherCAT bus, characterized in that: include: Excitation signal generation module, sensor interface module, current-voltage conversion module, bandpass filter module, precision rectification and filtering module, analog output interface module, analog-to-digital conversion module, control circuit module, EtherCAT bus module and power supply module; among them, The excitation signal generating module is used to generate a sinusoidal wave excitation signal; The sensor interface module is used to send the excitation signal generated by the excitation signal generating module to the capacitance film vacuum gauge, and receive the current signal sent back by the capacitance film vacuum gauge; The current-voltage conversion module is used to convert the current signal sent back by the sensor received by the sensor interface module into a voltage signal and output it; The bandpass filter module is used to filter out the harmonic components in the output signal of the current-voltage conversion module; The precision rectification and filtering module is used to rectify and filter the voltage signal output by the current-voltage conversion module; The analog-to-digital conversion module is used to perform analog-to-digital conversion processing on the signal output by the precision rectification and filtering module; The control circuit module is used to receive and process the signal output by the analog-to-digital conversion module; The EtherCAT bus module is used to convert the signal processed by the control circuit module into an EtherCAT bus data signal and output it to the network interface; The power supply module is used to provide power to each component unit of the entire system.

2. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 1, characterized in that: The excitation signal generating module comprises a Wien bridge oscillator circuit, a gain adjustment circuit and a rectifier filter circuit; wherein the Wien bridge oscillator circuit is composed of an operational amplifier and a precision resistor-capacitor circuit, and is used to generate a sinusoidal wave signal; the gain adjustment circuit is composed of a JFET and a resistor, and the JFET is connected in series in the feedback loop of the Wien bridge oscillator circuit, and is used to adjust the sinusoidal wave gain; the rectifier filter circuit is composed of a filter composed of a diode and an active integrator, and is used to rectify and process the signal into a relatively smooth DC signal; the anode of the diode is connected to the output end of the Wien bridge oscillator circuit, and the output is connected to the gate of the JFET in the gain adjustment circuit.

3. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 2, characterized in that: The Wien bridge oscillator circuit is mainly composed of an operational amplifier U 1.1 It is composed of a precision resistor-capacitor circuit consisting of resistors R1, R2, R3, R4 and capacitors C1 and C3, wherein resistor R1 and capacitor C1 are connected in series and then in parallel to the operational amplifier U 1.1 Between the same-direction input and output terminals, resistor R2 and capacitor C3 are connected in parallel and then connected to the operational amplifier U 1.1 The resistor R3 is connected in parallel to the operational amplifier U 1.1 Between the inverting input and output of the operational amplifier U 1.1 Connect the gain adjustment circuit through resistor R4; The gain adjustment circuit is composed of a JFET and resistors R6 and R7. The resistor R4 of the Wien bridge oscillator circuit is connected in series with the resistor R6 and then grounded. The drain and source of the field effect transistor Q1 are connected in parallel to the two ends of the resistor R6. The gate of the field effect transistor Q1 is connected to the rectifier filter circuit through the resistor R7. The rectifier and filter circuit is composed of a diode D1, an active integrator U 1.2 , resistor R5 and capacitors C2 and C4, and the gain adjustment circuit is connected to the active integrator U through the resistor R7. 1.2 The output end, the capacitor C4 and the resistor R5 are connected in parallel to the active integrator U 1.2 Between the inverting input and output terminals of the Wien bridge oscillator circuit operational amplifier U 1.1 The output end is connected to the positive electrode of diode D1, and the negative electrode of the diode is connected to the active integrator U 1.2 The inverting input terminal.

4. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 1, characterized in that: The current-voltage conversion module is used to convert the current signal into a voltage signal, and is mainly composed of an operational amplifier U2, a feedback resistor R f and a zero adjustment resistor PR1; the feedback resistor is connected in series in the feedback loop of the operational amplifier, the center tap of the zero adjustment resistor is connected to the inverting input terminal of the operational amplifier, and the two ends are respectively connected to +VREF and -VREF; the current-voltage conversion module, its input end is the signal input terminal in the sensor interface module.

5. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 1, characterized in that: The bandpass filter module is used to select the frequency of useful signals and filter out harmonic components, and is composed of a feedback network and an operational amplifier U1; the feedback network is composed of resistors R1, R2, and R3 capacitors, and the operational amplifier has a common-phase terminal connected to the negative pole of the power supply and an anti-phase terminal connected to the feedback network; the input end of the bandpass filter module is connected to the output end of the current-voltage conversion module.

6. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 1, characterized in that: The precision rectification and filtering module is mainly composed of a buffer, a precision rectification circuit and an RC low-pass filter; the buffer is composed of an operational amplifier U 2.1 The operational amplifier is connected to the output end of the bandpass filter module, and the inverting end is short-circuited with the output end of the operational amplifier; the precision rectifier circuit is composed of an operational amplifier U 2.2 , resistor R 14 , R 12 , R 13 , R 17 , and diodes D2 and D3; the RC low-pass filter is composed of a resistor R 15 Together with capacitor C8, resistor R 15 One end is connected to the output end of the precision rectification circuit, and the other end is used as the output end of the precision rectification and filtering module and is connected to one end of the capacitor C8, and the other end of the capacitor is connected to the power ground.

7. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 6, characterized in that: The analog output interface module has one end J1 connected to C8 in the precision rectification and filtering module, and the other end J2 connected to the power ground, and is used to output a 0-10V vacuum degree analog signal.

8. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 1, characterized in that: The analog-to-digital conversion module is composed of a high-precision 24-bit ADC chip and its peripheral circuits, and the input end of the ADC chip is connected to the output end of the precision rectification and filtering module.

9. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 1, characterized in that: The control circuit module is composed of a single-chip microcomputer and its peripheral circuits; the single-chip microcomputer is connected to the IO port of the ADC chip and is used for initializing the register configuration of the ADC chip.

10. The EtherCAT bus-based slave capacitance film vacuum gauge readout device according to claim 1, characterized in that: The EtherCAT bus module is composed of an EtherCAT control chip and its peripheral circuits, and an Ethernet RJ45 interface; its IO port is connected to the single-chip microcomputer in the control circuit module to receive control and data from the single-chip microcomputer; the Ethernet RJ45 interface is used to connect to the industrial Internet to complete data output.

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