PLC analog quantity + / -10V output device

Abstract

The utility model discloses a PLC analog quantity + / -10V output device. The PLC analog quantity + / -10V output device comprises a signal processing unit, a digital signal isolation unit, a D / A conversion unit and a plurality of voltage analog quantity output units mounted on the D / A conversion unit, each voltage analog quantity output unit comprises an analog signal input interface, an amplifying / processing circuit and an analog signal output interface; the amplifying / processing circuit comprises a differential amplifier, a first-order RC passive low-pass filter, a voltage follower, an inverting amplifier with a push-pull circuit, a loop compensation network, an output dummy load / 0V holding resistor, an optocoupler relay switching circuit and an anti-interference and protection circuit. According to the voltage analog quantity output circuit provided by the utility model, by introducing a loop compensation theory and a multi-protection control circuit, the problems of insufficient stability and poorer anti-interference capability of voltage analog quantity output are effectively solved, and meanwhile, the protection function for a core device operational amplifier is enhanced.

Description

Technical Field

[0001] The utility model relates to the field of industrial automation and control, and in particular to a PLC analog quantity ±10V output device. Background Art

[0002] A Programmable Logic Controller (PLC) is a microprocessor-based digital computing controller. Because it can automatically control external expansion components, it is widely and importantly used in control systems for various devices.

[0003] PLC analog outputs play a key role in industrial automation, providing precise, continuous signal control, enabling fine-tuning and closed-loop feedback control of various devices. This functionality not only improves system control accuracy and stability, but also enables seamless integration and flexible application between devices, creating a safe, efficient, and reliable operating environment for industrial production.

[0004] Traditional standard voltage analog output ranges typically range from 0 to 10V and 0 to 5V, primarily used to provide standard signal sources for precise control of industrial equipment. However, this conventional voltage analog output range cannot meet current industrial control requirements, necessitating a wider voltage output range. Furthermore, while existing voltage analog output circuits perform well in various industrial control applications, their stability and anti-interference capabilities remain insufficient, often resulting in poor performance in harsh industrial environments.

[0005] From the above analysis, it can be seen that improving the performance and reliability of voltage analog output circuits to adapt to various complex and harsh industrial environments is an urgent problem that needs to be solved. Summary of the Invention

[0006] The purpose of the utility model is to solve the defects in the prior art and provide a PLC analog ±10V output circuit device, which can effectively eliminate interference signals caused by external harsh environments and working conditions, and solve the problems of insufficient stability and anti-interference ability of voltage analog output.

[0007] In order to achieve the above purpose, the technical solution provided by the present utility model is as follows:

[0008] A ±10V analog output device for a programmable logic controller (PLC) comprises a signal processing unit, a digital signal isolation unit, a D / A conversion unit, and a plurality of voltage analog output units mounted on the D / A conversion unit; each voltage analog output unit comprises an analog signal input interface, an amplification / processing circuit, and an analog signal output interface; the amplification / processing circuit comprises a differential amplifier, a first-order RC passive low-pass filter, a voltage follower, an inverting amplifier with a push-pull circuit, a loop compensation network, an output dummy load / 0V holding resistor, an optocoupler relay switching circuit, and an anti-interference and protection circuit; a digital signal received by the signal processing unit is transmitted to the D / A conversion unit via the digital signal isolation unit for conversion into an analog signal, and then the voltage analog signal is amplified to ±10V by the differential amplifier, the first-order RC passive low-pass filter, and the voltage follower, and then processed by the inverting amplifier with a push-pull circuit, the loop compensation network, the output dummy load / 0V holding resistor, the optocoupler relay switching circuit, and the anti-interference and protection circuit before output.

[0009] The utility model amplifies the voltage analog quantity to ±10V through a differential amplifier, a first-order RC passive low-pass filter and a voltage follower; and processes the initially modulated ±10V voltage analog quantity through an inverting amplifier with a push-pull circuit, a loop compensation network, an output dummy load / 0V holding resistor, an optocoupler relay switching circuit, an anti-interference and protection circuit, thereby outputting a ±10V voltage analog quantity with high stability.

[0010] Among them, the inverting amplifier with a push-pull circuit not only improves the output circuit driving capability, but also protects the operational amplifier; the loop compensation network is used to improve the phase margin of the operational amplifier loop and improve the stability of the operational amplifier; the output dummy load / 0V holding resistor acts as an output dummy load when the optocoupler relay is turned on, used to protect the inverting amplifier of the push-pull circuit, improve stability and release residual current when power is off. When the optocoupler relay is turned off, it acts as a 0V holding resistor and is in a pull-down state, so that the voltage output port remains at 0V; the optocoupler relay switching circuit is used to control whether the voltage analog quantity is output; the anti-interference and protection circuit can provide protection functions such as static electricity and overcurrent.

[0011] Furthermore, the differential amplifier is composed of an operational amplifier U1A, resistors R1, R2, R3, R4 and capacitors C1, C2 and C3; the first-order RC passive low-pass filter is composed of a resistor R5 and a capacitor C4; the voltage follower is composed of an operational amplifier U1B and resistors R6 and R7; the inverting amplifier with a push-pull circuit is composed of an operational amplifier U2A, transistors Q1, Q2, diodes D1, D2, D3, D4, resistors R8, R9, R10, R11, R12 and capacitors C5 and C6; the output dummy load / 0V holding resistor uses resistor R14; the loop compensation network is composed of resistor R13 and capacitor C6; the optocoupler relay switching circuit is composed of an optocoupler relay U3, transistor Q3, resistors R15, R16, R17 and capacitor C8; the anti-interference and protection circuit is composed of a bidirectional transient suppressor VD1, a resettable fuse FU1 and capacitor C7.

[0012] The specific connections are as follows:

[0013] One end of the resistor R1 is connected to AOUT_IN of the analog signal input interface, the other end of the resistor R1 is connected to one end of the resistor R2, one end of the capacitor C2, and the non-inverting input terminal of the operational amplifier, the other end of the resistor R2 and the capacitor C2 are connected to the power supply GND, one end of the resistor R3 is connected to the analog signal input interface VOUT_REF, the other end of the resistor R3 is connected to one end of the capacitor C1, one end of the resistor R4, and the inverting input terminal of the operational amplifier, the other end of the capacitor C1 is connected to the power supply GND, the output terminal of the operational amplifier U1A is connected to the capacitor C3, the other end of the resistor R4 and one end of R5, the non-inverting input terminal of the operational amplifier U1B, one end of the capacitor C4 and the other end of R5 The other end of capacitor C4 is connected to the power supply GND, the inverting input of the operational amplifier U1B is connected to one end of the resistor R6, the other end of the resistor R6 is connected to one end of the resistors R7 and R8, the output of the operational amplifier U1B is connected to the other end of R7, the other end of R8 is connected to the inverting input of the operational amplifier U2A, one end of the resistor R11, and one end of the capacitor C6, the non-inverting input of the operational amplifier U2A is connected to one end of the resistor R9, the other end of the resistor R9 is connected to the power supply GND, the output of the operational amplifier U2A is connected to the resistor R10 and one end of the capacitor C5, the other end of the capacitor C5 is connected to the power supply GND, and the other end of the resistor R10 is connected to the positive electrode of the diode D1 , the cathode of diode D2 is connected to the base of transistor Q1, the anode of diode D2 is connected to the base of transistor Q2, the collector of transistor Q1 is connected to the power supply V+ and the cathode of diode D3, the emitter of transistor Q1 is connected to the emitter of transistor Q2, the anode of diode D3, the cathode of diode D4, and one end of resistor R12, the collector of transistor Q2 is connected to the power supply V- and the anode of diode D4, pin 4 of the optocoupler relay is connected to the other end of resistors R11, R12, and capacitor C6, pin 1 of the optocoupler relay is connected to one end of resistor R15, the other end of resistor R15 is connected to the power supply V1+, and pin 2 of the optocoupler relay is connected to the The collector is connected, the emitter of the transistor Q3 is connected to the power supply GND, the base of the transistor Q3 is connected to one end of the capacitor C8, resistors R16, and R17, the other end of the capacitor C8 and resistor R16 is connected to the power supply GND, the other end of R17 is connected to the enable control interface OV_EN, pin 3 of the optocoupler relay is connected to the capacitor C7, bidirectional transient voltage suppressor VD1, self-recovery fuse FU1, one end of the resistor R13, and R14, the other end of the resistor R13 is connected to the capacitor C6, the resistor R14, bidirectional transient voltage suppressor VD1, the other end of the capacitor C6, and C7 are connected to the power supply GND, and the other end of the self-recovery fuse FU1 is connected to AOUT of the analog signal output interface.

[0014] Furthermore, the signal processing unit includes an MCU microprocessor chip and a digital signal communication interface; the MCU microprocessor chip is connected to the digital signal isolation unit through the digital signal communication interface; the digital signal isolation unit includes a multi-channel digital isolation chip and a digital signal communication interface; the multi-channel digital isolation chip is connected to the signal processing unit and the D / A conversion unit respectively through the digital signal communication interface; the D / A conversion unit includes a DAC integrated circuit chip, an analog signal input interface and an analog signal output interface; the DAC integrated circuit chip is connected to the D / A conversion unit through the analog signal input interface, and is connected to the industrial equipment through the analog signal output interface.

[0015] Furthermore, the multi-channel digital isolation chip includes but is not limited to NSi8240, TPT7742 and other chips.

[0016] Furthermore, the digital signal communication interface of the signal processing unit is a conventional digital signal communication interface such as SPI, I2C, CAN or USART built into the MCU microprocessor chip.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The utility model provides a PLC analog ±10V output circuit device, which improves the direct output scheme of the operational amplifier in the traditional technical solution: the technical solution of the simple operational amplifier directly outputting the voltage analog quantity is replaced by a combined amplification and conditioning solution of a differential amplifier, a first-order RC passive low-pass filter, a voltage follower, and an inverting amplifier with a push-pull circuit, which can effectively eliminate interference signals caused by external harsh environments and working conditions, and solve the problems of insufficient stability and insufficient anti-interference ability of the voltage analog quantity output; in addition, a loop compensation network, an output dummy load / 0V holding resistor, an optocoupler relay switching circuit, and an anti-interference and protection circuit are added to the voltage analog quantity output port of the traditional technical solution, which can effectively reduce the influence of external interference on the voltage analog quantity output, solve the problem that the operational amplifier is easily damaged by faults, and thus improve the reliability of industrial control.

[0019] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, to the extent such concepts are not mutually inconsistent, can be considered to be part of the inventive subject matter of this disclosure.

[0020] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will become apparent from the following description or through practice of specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the structural block diagram of the PLC analog ±10V output device of the utility model;

[0022] Figure 2 for Figure 1 Circuit diagram of a medium voltage analog output unit. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should have the common meaning understood by people with ordinary skills in the field to which the utility model belongs.

[0024] The terms "first," "second," and similar words used in the specification and claims of this utility model application do not indicate any order, quantity, or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a," "an," "the," and similar words do not indicate a limitation on quantity, but rather indicate the presence of at least one. Words such as "include" or "comprise" mean that the elements or objects preceding "include" or "comprise" include the features, wholes, steps, operations, elements, and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their collections.

[0025] "Up", "down", "left", "right", etc. are only used to express relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0026] This utility model provides a ±10V analog output circuit device for PLCs. This PLC voltage analog output circuit device effectively eliminates interference signals caused by harsh external environments and operating conditions, addressing issues with the stability and anti-interference capabilities of the voltage analog output. Furthermore, this PLC voltage analog output circuit device protects the operational amplifier in the output circuit. In practical industrial applications, this device significantly improves the reliability of PLC control systems for automated equipment. The following describes the PLC voltage analog output device disclosed in this utility model in more detail, with reference to the embodiments shown in the accompanying drawings.

[0027] The voltage analog output disclosed in the present invention will be further specifically described below in conjunction with the embodiments shown in the accompanying drawings.

[0028] like Figure 1 As shown, a PLC analog ±10V output circuit device includes a signal processing unit, a digital signal isolation unit, a D / A conversion unit, and a plurality of voltage analog output units mounted on the D / A conversion unit.

[0029] Among them, the signal processing unit includes an MCU microprocessor chip and a digital signal communication interface;

[0030] The digital signal isolation unit includes a multi-channel digital isolation chip and a digital signal communication interface;

[0031] Furthermore, the multi-channel digital isolation chip of the digital signal isolation unit may be, but is not limited to, NSi8240, TPT7742 and other chips;

[0032] The D / A conversion unit includes a high-precision DAC integrated circuit chip, a digital signal communication interface, and an analog signal output interface;

[0033] The voltage analog output unit includes an amplification / processing circuit composed of components such as an operational amplifier, a transistor, a diode, an optocoupler relay, a resistor, and a capacitor, an analog signal input interface, and an analog signal output interface;

[0034] Furthermore, the analog signal amplification / processing circuit of the voltage analog output unit is a differential amplifier, a first-order RC passive low-pass filter, a voltage follower, an inverting amplifier with a push-pull circuit, a loop compensation network, an output dummy load / 0V holding resistor, an optocoupler relay switching circuit, and an anti-interference and protection circuit.

[0035] Among them, the differential amplifier circuit, the first-order RC passive low-pass filter, and the voltage follower are used to realize the preliminary modulation of the ±10V voltage analog quantity; the inverting amplifier with a push-pull circuit not only improves the output circuit driving capability, but also realizes the protection of the operational amplifier; the loop compensation network is used to improve the phase margin of the operational amplifier loop and improve the stability of the operational amplifier; the output dummy load / 0V holding resistor acts as an output dummy load when the optocoupler relay is turned on, and is used to protect the inverting amplifier of the push-pull circuit, improve stability and release residual current when power is off. When the optocoupler relay is turned off, it acts as a 0V holding resistor, which is in a pull-down state, so that the voltage output port remains at 0V; the optocoupler relay switching circuit is used to control whether the voltage analog quantity is output; the anti-interference and protection circuit can provide static electricity, overcurrent and other protection functions.

[0036] More specifically, the analog signal amplification / processing circuit of the voltage analog output unit is as follows: Figure 2As shown, it includes operational amplifiers U1A, U1B, U2A, resistors R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, capacitors C1, C2, C3, C4, C5, C6, C7, C8, diodes D1, D2, D3, D4, transistors Q1, Q2, Q3, optocoupler relay U3, bidirectional transient voltage suppressor VD1, and resettable fuse FU1.

[0037] Among them, the operational amplifier U1A, resistors R1, R2, R3, R4 and capacitors C1, C2, C3 constitute a differential amplifier; resistor R5 and capacitor C4 constitute a first-order RC passive low-pass filter; operational amplifier U1B and resistors R6, R7 constitute a voltage follower; operational amplifier U2A, transistors Q1, Q2, diodes D1, D2, D3, D4, resistors R8, R9, R10, R11, R12 and capacitors C5, C6 constitute an inverting amplifier with a push-pull circuit; resistor R13 and capacitor C6 constitute a loop compensation network; resistor R14 also acts as an output dummy load / 0V holding resistor; optocoupler relay U3, transistor Q3, resistors R15, R16, R17 and capacitor C8 constitute an optocoupler relay switching circuit; bidirectional transient suppressor VD1, resettable fuse FU1 and capacitor C7 constitute an anti-interference and protection circuit.

[0038] The specific connections are as follows:

[0039] One end of the resistor R1 is connected to AOUT_IN of the analog signal input interface, the other end of the resistor R1 is connected to one end of the resistor R2, one end of the capacitor C2, and the non-inverting input terminal of the operational amplifier, the other end of the resistor R2 and the capacitor C2 are connected to the power supply GND, one end of the resistor R3 is connected to the analog signal input interface VOUT_REF, the other end of the resistor R3 is connected to one end of the capacitor C1, one end of the resistor R4, and the inverting input terminal of the operational amplifier, the other end of the capacitor C1 is connected to the power supply GND, the output terminal of the operational amplifier U1A is connected to the capacitor C3, the other end of the resistor R4 and one end of R5, the non-inverting input terminal of the operational amplifier U1B, one end of the capacitor C4 and the other end of R5 The other end of capacitor C4 is connected to the power supply GND, the inverting input of the operational amplifier U1B is connected to one end of the resistor R6, the other end of the resistor R6 is connected to one end of the resistors R7 and R8, the output of the operational amplifier U1B is connected to the other end of R7, the other end of R8 is connected to the inverting input of the operational amplifier U2A, one end of the resistor R11, and one end of the capacitor C6, the non-inverting input of the operational amplifier U2A is connected to one end of the resistor R9, the other end of the resistor R9 is connected to the power supply GND, the output of the operational amplifier U2A is connected to the resistor R10 and one end of the capacitor C5, the other end of the capacitor C5 is connected to the power supply GND, and the other end of the resistor R10 is connected to the positive electrode of the diode D1 , the cathode of diode D2 is connected to the base of transistor Q1, the anode of diode D2 is connected to the base of transistor Q2, the collector of transistor Q1 is connected to the power supply V+ and the cathode of diode D3, the emitter of transistor Q1 is connected to the emitter of transistor Q2, the anode of diode D3, the cathode of diode D4, and one end of resistor R12, the collector of transistor Q2 is connected to the power supply V- and the anode of diode D4, pin 4 of the optocoupler relay is connected to the other end of resistors R11, R12, and capacitor C6, pin 1 of the optocoupler relay is connected to one end of resistor R15, the other end of resistor R15 is connected to the power supply V1+, and pin 2 of the optocoupler relay is connected to the The collector is connected, the emitter of the transistor Q3 is connected to the power supply GND, the base of the transistor Q3 is connected to one end of the capacitor C8, resistors R16, and R17, the other end of the capacitor C8 and resistor R16 is connected to the power supply GND, the other end of R17 is connected to the enable control interface OV_EN, pin 3 of the optocoupler relay is connected to the capacitor C7, bidirectional transient voltage suppressor VD1, self-recovery fuse FU1, one end of the resistor R13, and R14, the other end of the resistor R13 is connected to the capacitor C6, the resistor R14, bidirectional transient voltage suppressor VD1, the other end of the capacitor C6, and C7 are connected to the power supply GND, and the other end of the self-recovery fuse FU1 is connected to AOUT of the analog signal output interface.

[0040] In this embodiment, the number of voltage analog output units corresponds to the number of channels of the high-precision DAC integrated circuit chip. When the number of voltage analog output units increases, the number of high-precision DAC integrated circuit chips will also increase accordingly.

[0041] Furthermore, the digital signal communication interface of the signal processing unit may be a conventional digital signal communication interface such as SPI, I2C, CAN or USART built into the MCU microprocessor chip;

[0042] The digital communication interface of the signal processing unit is connected to the digital signal communication interface of the digital signal isolation unit, and the digital signal communication interface of the digital signal isolation unit is connected to the digital signal communication interface of the D / A conversion unit;

[0043] The analog signal output interface of the D / A conversion unit is connected to the analog signal input interfaces of the plurality of voltage analog output units, and the analog signal output interfaces of the plurality of voltage analog output units are connected to industrial equipment;

[0044] The voltage analog output range can be -10V to +10V, but is not limited to conventional output ranges such as 0V to 5V and 0V to 10V.

[0045] The following is combined with Figure 1 The voltage output process of a PLC analog ±10V output circuit device disclosed in the present invention is further specifically introduced. The process includes the following steps:

[0046] S1, after the signal processing unit receives the configured voltage range configuration and the required output voltage, it transmits it to the D / A conversion unit through the digital signal communication interface of the signal processing unit and the digital signal isolation unit, and after analog-to-digital conversion by the D / A conversion unit, it transmits it to the voltage analog output unit through the analog signal output interface;

[0047] S2. The plurality of voltage analog output units amplify and process the input analog signals to modulate the input voltage analog quantity to the required voltage. The amplification / processing circuit amplifies the voltage analog quantity to ±10V based on VOUT_REF and AOUT_IN of the analog signal input interface through a differential amplifier, a first-order RC passive low-pass filter, and a voltage follower.

[0048] S3. The several voltage analog output units process the initially modulated ±10V voltage analog through an inverting amplifier with a push-pull circuit, a loop compensation network, an output dummy load / 0V holding resistor, an optocoupler relay switching circuit, an anti-interference and protection circuit, and then output a ±10V voltage analog with high stability.

[0049] While the present invention has been described above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations may be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A PLC analog ±10V output device, characterized in that: The system comprises a signal processing unit, a digital signal isolation unit, a D / A conversion unit and a plurality of voltage analog output units mounted on the D / A conversion unit; each voltage analog output unit comprises an analog signal input interface, an amplification / processing circuit and an analog signal output interface; the amplification / processing circuit comprises a differential amplifier, a first-order RC passive low-pass filter, a voltage follower, an inverting amplifier with a push-pull circuit, a loop compensation network, an output dummy load / 0V holding resistor, an optocoupler relay switching circuit, and an anti-interference and protection circuit; the digital signal received by the signal processing unit is transmitted to the D / A conversion unit via the digital signal isolation unit and converted into an analog signal, and then the voltage analog quantity is amplified to ±10V by the differential amplifier, the first-order RC passive low-pass filter and the voltage follower, and then processed by the inverting amplifier with a push-pull circuit, the loop compensation network, the output dummy load / 0V holding resistor, the optocoupler relay switching circuit, and the anti-interference and protection circuit before output.

2. The PLC analog ±10V output device according to claim 1, characterized in that: The differential amplifier is composed of an operational amplifier U1A, resistors R1, R2, R3, R4 and capacitors C1, C2 and C3; the first-order RC passive low-pass filter is composed of a resistor R5 and a capacitor C4; the voltage follower is composed of an operational amplifier U1B and resistors R6 and R7; the inverting amplifier with a push-pull circuit is composed of an operational amplifier U2A, transistors Q1, Q2, diodes D1, D2, D3, D4, resistors R8, R9, R10, R11, R12 and capacitors C5 and C6; the output dummy load / 0V holding resistor uses a resistor R14; the loop compensation network is composed of a resistor R13 and a capacitor C6; the optocoupler relay switching circuit is composed of an optocoupler relay U3, a transistor Q3, resistors R15, R16, R17 and a capacitor C8; the anti-interference and protection circuit is composed of a bidirectional transient suppressor VD11, a resettable fuse FU1 and a capacitor C7.

3. The PLC analog ±10V output device according to claim 2, characterized in that: The signal processing unit includes an MCU microprocessor chip and a digital signal communication interface; the MCU microprocessor chip is connected to the digital signal isolation unit through the digital signal communication interface; the digital signal isolation unit includes a multi-channel digital isolation chip and a digital signal communication interface; the multi-channel digital isolation chip is connected to the signal processing unit and the D / A conversion unit respectively through the digital signal communication interface; the D / A conversion unit includes a DAC integrated circuit chip, an analog signal input interface and an analog signal output interface; the DAC integrated circuit chip is connected to the D / A conversion unit through the analog signal input interface and is connected to the industrial equipment through the analog signal output interface.

4. The PLC analog ±10V output device according to claim 3, characterized in that: The multi-channel digital isolation chip adopts NSi8240 or TPT7742 chip.

5. The PLC analog ±10V output device according to claim 4, characterized in that: The digital signal communication interface of the signal processing unit is a built-in digital signal communication interface of the MCU microprocessor chip.

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