A frequency-to-analog safety barrier

Abstract

This invention provides a frequency-to-analog safety barrier, comprising a voltage conversion circuit, a transformer coil drive circuit, a transformer, a first AC voltage rectification and filtering circuit, a frequency signal processing circuit, a NAMUR signal processing circuit, an NPNPNP signal processing circuit, a frequency processing circuit, an MCU control circuit, a TTL output interface, an isolation chip, a square wave processing circuit, a filtering circuit, a DC output circuit, and an alarm relay. The voltage conversion circuit is connected to the transformer via the transformer coil drive circuit. The transformer supplies power to the hazardous and safe zones via the first AC voltage rectification and filtering circuit. Multiple intrinsically safe terminals in the hazardous zone are connected to the frequency processing circuit via three signal processing circuits. The frequency processing circuit outputs to the MCU control circuit. The MCU output sequentially passes through the TTL interface, the isolation chip, the square wave processing circuit, and the filtering circuit to the DC output circuit. This invention achieves frequency signal to analog quantity conversion and safety isolation, increasing system stability.

Description

Technical Field

[0001] This utility model belongs to the field of safety barrier technology, and in particular relates to a frequency-to-analog safety barrier. Background Technology

[0002] A safety barrier is a device installed between intrinsically safe and non-intrinsically safe circuits to limit the voltage and current supplied to the intrinsically safe circuit within a certain safe range. Also known as a safety retainer, it is a safety interface for intrinsically safe circuits. It can transmit electrical signals bidirectionally between the safe area (intrinsically safe) and the hazardous area (non-intrinsically safe), and can limit the transfer of energy from the hazardous area to the safe area due to a fault.

[0003] The existing frequency-type safety barriers have the following disadvantages: traditional frequency-type safety barriers are mainly based on frequency input and frequency output, and the safety barrier only serves the purpose of isolating field interference. Secondly, the input range of existing safety barriers is difficult to take into account both large-scale and small-scale measurements. In addition, the front-end input of existing safety barriers can often only be connected to one type of frequency sensor, and the output anti-interference capability of existing frequency-type safety barrier products is not strong. Utility Model Content

[0004] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a frequency-to-analog safety barrier.

[0005] This utility model provides a frequency-to-analog safety barrier, comprising:

[0006] Voltage conversion circuit, transformer coil drive circuit, transformer, first AC voltage rectification and filtering circuit, frequency signal processing circuit, NAMUR signal processing circuit, NPNPNP signal processing circuit, frequency processing circuit, MCU control circuit, TTL output interface, isolation chip, square wave processing circuit, filtering circuit, DC output circuit and alarm relay;

[0007] The input terminal of the voltage conversion circuit is used to receive external DC voltage signals, and the output terminal of the voltage conversion circuit is connected to the input terminal of the transformer through the transformer coil drive circuit.

[0008] The output terminal of the transformer is connected to the first AC voltage rectifier and filter circuit, and the output terminal of the first AC voltage rectifier and filter circuit supplies power to the dangerous area and the safe area respectively.

[0009] The hazardous area is equipped with an intrinsically safe terminal, which is connected to multiple frequency processing circuits through at least one of a frequency signal processing circuit, a NAMUR signal processing circuit, and an NPNPNP signal processing circuit.

[0010] The output terminal of the frequency processing circuit is connected to the input terminal of the MCU control circuit, and the output terminal of the MCU control circuit is connected to the DC output circuit in sequence through the TTL output interface, the isolation chip, the square wave processing circuit, and the filtering processing circuit.

[0011] The MCU control circuit is also connected to the alarm relay.

[0012] According to the present invention, a frequency-to-analog safety barrier is provided, wherein multiple intrinsically safe terminals are provided, including proximity switch terminals, frequency signal terminals, and NPNPNP transistor terminals.

[0013] According to the present invention, a frequency-to-analog safety barrier is provided, wherein the proximity switch terminal includes a NAMUR proximity switch terminal and a dry contact switch terminal, and the NPNPNP transistor terminal includes a three-wire NPNPNP terminal, an NPNPNP transistor terminal, and an encoder terminal.

[0014] According to the frequency-to-analog safety barrier provided by this utility model, it further includes:

[0015] Second AC voltage rectifier and filter circuit;

[0016] The second AC voltage rectifier and filter circuit is connected to the transformer, and the output of the second AC voltage rectifier and filter circuit supplies power to the communication circuit.

[0017] According to the present invention, a frequency-to-analog safety barrier is provided, wherein the NAMUR signal processing circuit is provided with a first power supply output terminal for powering the front-end sensor, and the NPNPNP signal processing circuit is provided with a second power supply output terminal for powering the front-end sensor.

[0018] According to the frequency-to-analog safety barrier provided by this utility model, it further includes:

[0019] Loop current identification circuit;

[0020] The loop current identification circuit is connected to the NAMUR signal processing circuit and is used to measure the loop power supply current and determine open circuit and short circuit faults.

[0021] According to the present invention, a frequency-to-analog safety barrier is provided, wherein the alarm relay supports 3000V isolation capability, and the output terminal of the alarm relay is configured as a short-circuit switch.

[0022] According to the present invention, a frequency-to-analog safety barrier is provided, wherein the MCU control circuit is further provided with a configuration line connection port for connecting to an external computer for parameter setting and alarm setting.

[0023] According to the present invention, a frequency-to-analog safety barrier is provided, wherein the frequency processing circuit supports a frequency reduction function, which is used to reduce the frequency of the input frequency signal and output a square wave signal to the MCU control circuit.

[0024] According to the present invention, a frequency-to-analog safety barrier is provided, wherein the output signal of the DC output circuit is a current signal or a voltage signal, which is used to connect to a PLC system.

[0025] This invention provides a frequency-to-analog safety barrier that, through a combination of a voltage conversion circuit, a transformer coil drive circuit, and a transformer, achieves stable conversion of a wide range of input voltages and multi-channel isolated power supply. This effectively improves the system's power supply stability and safety, avoiding equipment damage and measurement errors caused by voltage fluctuations. Secondly, the design of multiple intrinsically safe terminals allows the same device to be compatible with various types of sensors, such as proximity switches, frequency signals, and NP-NP-NP transistors, significantly improving the product's versatility and applicability, reducing users' inventory pressure and equipment investment costs, and simplifying on-site installation and maintenance. Furthermore, the NAMUR signal processing circuit and NPN... The PNP signal processing circuit provides two power supply outputs, ensuring reliable operation of the front-end sensor, eliminating signal instability caused by insufficient power supply, and improving the reliability of the entire measurement system. Furthermore, the loop current identification circuit enables real-time monitoring of the loop status, allowing for timely detection of faults such as open circuits and short circuits, preventing production accidents and economic losses due to undetected faults. The frequency reduction function of the frequency processing circuit effectively reduces the system's processing load, improving signal processing accuracy and stability. This invention also achieves high-precision conversion of frequency signals to analog signals through a series structure of MCU control circuit, TTL output interface, isolation chip, square wave processing circuit, and filter processing circuit. Simultaneously, the isolation chip provides excellent electrical isolation, enhancing the system's anti-interference capability and safety. The DC output circuit of this invention outputs standard current or voltage signals, which can be directly connected to the PLC system, avoiding signal conversion steps, reducing transmission loss and interference, and improving the reliability and accuracy of signal transmission.

[0026] Overall, this invention improves system stability and security, enhances product versatility and applicability, ensures power supply reliability, improves signal processing accuracy and anti-interference capabilities, maintains compatibility with existing systems, and ensures ease of maintenance and operation. Attached Figure Description

[0027] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Throughout the drawings, the same reference numerals denote the same components. Obviously, the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings.

[0028] Figure 1 A circuit connection diagram of a frequency-to-analog safety barrier provided for an embodiment of this utility model;

[0029] Figure 2 This is a wiring diagram of a frequency-to-analog safety barrier provided for an embodiment of the present invention.

[0030] Reference numerals: 11. Voltage conversion circuit; 12. Transformer coil drive circuit; 13. Transformer; 14. First AC voltage rectification and filtering circuit; 15. Frequency signal processing circuit; 16. NAMUR signal processing circuit; 17. NPNPNP signal processing circuit; 18. Frequency processing circuit; 19. MCU control circuit; 20. TTL output interface; 21. Isolation chip; 22. Square wave processing circuit; 23. Filtering circuit; 24. DC output circuit; 25. Alarm relay; 26. Second AC voltage rectification and filtering circuit; 27. Loop current identification circuit. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions in the embodiments of this utility model, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0032] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this utility model.

[0033] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "installed," "connected," and "joined" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this invention. Rather, they are merely examples of methods and systems consistent with some aspects of this invention as detailed in the appended claims.

[0035] The embodiments of this utility model are described below with reference to the accompanying drawings.

[0036] like Figure 1 As shown, this utility model provides a frequency-to-analog safety barrier, comprising:

[0037] Voltage conversion circuit 11, transformer coil drive circuit 12, transformer 13, first AC voltage rectification and filtering circuit 14, frequency signal processing circuit 15, NAMUR signal processing circuit 16, NPNPNP signal processing circuit 17, frequency processing circuit 18, MCU control circuit 19, TTL output interface 20, isolation chip 21, square wave processing circuit 22, filtering processing circuit 23, DC output circuit 24, and alarm relay 25.

[0038] Furthermore, the frequency-to-analog safety barrier provided by this utility model is an integrated signal processing device that achieves high-precision conversion and safe isolation of frequency signals to analog signals through the coordinated operation of multiple functional modules.

[0039] Specifically, the entire system of this utility model adopts a modular design, with the components connected to form a complete signal processing link. The voltage conversion circuit, as the power supply front end of the system, is responsible for stabilizing unstable external DC voltage signals, providing a stable and reliable power foundation for subsequent circuits. The transformer coil drive circuit works in conjunction with the transformer to achieve electrical isolation and multi-channel power output, ensuring electrical safety between hazardous and safe areas. The first AC voltage rectification and filtering circuit converts the AC signal output from the transformer into a DC signal, supplying power to different areas of the system. The frequency signal processing circuit, NAMUR signal processing circuit, and NPNPNP signal processing circuit constitute diverse input interfaces, adaptable to different types of frequency sensors. The frequency processing circuit is responsible for preprocessing and conditioning the input frequency signals. The MCU control circuit, as the core processing unit of the system, realizes the digital processing of signals and control logic. The TTL output interface, isolation chip, square wave processing circuit, filtering circuit, and DC output circuit constitute a complete output processing link, ensuring the quality and stability of the final output signal. The alarm relay provides fault alarm and protection functions, enhancing the reliability and safety of the system.

[0040] The input terminal of the voltage conversion circuit 11 is used to receive external DC voltage signals, and the output terminal of the voltage conversion circuit 11 is connected to the input terminal of the transformer 13 through the transformer coil drive circuit 12.

[0041] Furthermore, the voltage conversion circuit undertakes the fundamental power supply function of the entire system. Its input terminal is designed to receive external DC voltage signals and stabilize the input voltage signal within the required operating voltage range through an internal voltage regulation mechanism. This circuit employs high-efficiency switching power supply technology, enabling it to maintain output voltage stability over a wide input voltage range and effectively resist the impact of power grid fluctuations on system operation. The output terminal of the voltage conversion circuit is connected to the input terminal of the transformer via a transformer coil drive circuit, achieving not only further voltage regulation but also laying the foundation for subsequent electrical isolation. The transformer coil drive circuit uses PWM control technology, precisely controlling the duty cycle and frequency of the drive signal to accurately adjust the transformer's operating state, ensuring stable operation under different load conditions. The voltage conversion circuit of this invention not only improves the system's power supply efficiency and reduces power consumption but also enhances the system's adaptability to input voltage fluctuations, providing a reliable power guarantee for the stable operation of the entire safety barrier and effectively avoiding measurement errors and equipment damage caused by power instability.

[0042] The output terminal of the transformer 13 is connected to the first AC voltage rectifier and filter circuit 14, and the output terminal of the first AC voltage rectifier and filter circuit 14 supplies power to the dangerous area and the safe area respectively.

[0043] Furthermore, the connection between the transformer and the first AC voltage rectifier and filter circuit constitutes the core of the power distribution of this utility model. The transformer achieves electrical isolation and voltage transformation through the principle of electromagnetic induction, and its multiple output windings provide the required voltage levels for different parts of the system. The first AC voltage rectifier and filter circuit receives the AC signal output from the transformer, converts the AC signal into a pulsating DC signal through rectifier diodes, and then smooths it through filter capacitors, finally outputting a stable DC voltage.

[0044] The power supply in the hazardous area primarily provides power to the sensors and signal processing circuits on site, while the power supply in the safe area provides power to the control and output circuits. The electrical isolation achieved through the transformer effectively blocks the transfer of fault energy from the hazardous area to the safe area. Even if a short circuit or other fault occurs in the hazardous area, it will not affect the normal operation of the safe area. This not only significantly improves the safety and reliability of the system, but also effectively prevents the spread of faults from the hazardous area to the safe area. At the same time, through reasonable power distribution, it ensures that each functional module can obtain a stable and reliable power supply, thereby improving the overall stability of the system.

[0045] The hazardous area is provided with an intrinsically safe terminal, which is connected to multiple frequency processing circuits 18 through at least one of the frequency signal processing circuits 15, NAMUR signal processing circuit 16, and NPNPNP signal processing circuit 17.

[0046] Furthermore, the intrinsically safe terminals located in the hazardous area are connected to the frequency processing circuit through three different signal processing circuits. This diverse interface design reflects the system's versatility and flexibility. Specifically, the frequency signal processing circuit is dedicated to processing standard frequency signal inputs and can receive signals from various frequency generators. The NAMUR signal processing circuit is designed according to the NAMUR standard and is specifically designed to process signals from NAMUR type sensors. The NPNPNP signal processing circuit can process three-wire and two-wire transistor output signals. The outputs of all these processing circuits are connected to the frequency processing circuit to achieve unified signal processing.

[0047] As the core of signal preprocessing, the frequency processing circuit is responsible for standardizing frequency signals from different sources, including signal amplitude normalization, frequency range adjustment, and waveform shaping. This setting allows users to select the most suitable sensor type based on the actual site conditions without replacing the entire set of equipment, greatly improving the applicability of the system, significantly reducing the user's equipment investment costs, reducing inventory pressure, simplifying on-site installation and maintenance, and improving the system's compatibility and scalability.

[0048] The output terminal of the frequency processing circuit 18 is connected to the input terminal of the MCU control circuit 19. The output terminal of the MCU control circuit 19 is connected to the DC output circuit 24 in sequence through the TTL output interface 20, the isolation chip 21, the square wave processing circuit 22, and the filter processing circuit 23.

[0049] Furthermore, the connection between the frequency processing circuit and the MCU control circuit constitutes the core signal processing link of the system. The frequency processing circuit outputs the pre-processed frequency signal to the MCU control circuit for further digital processing.

[0050] The MCU control circuit uses a high-performance microcontroller as its core processor, which has powerful signal processing capabilities and rich peripheral interfaces. After receiving the frequency signal, the MCU performs precise frequency measurement and analysis of the signal through its built-in timer and counter functions. Then, it converts the frequency value into the corresponding digital quantity according to the preset conversion algorithm. The MCU's output is connected to the DC output circuit in sequence through the TTL output interface, isolation chip, square wave processing circuit, and filter processing circuit to form a complete output processing link.

[0051] The TTL output interface converts the digital signals inside the MCU into standard TTL level signals. The isolation chip provides electrical isolation for the digital signals. The square wave processing circuit converts the digital signals into PWM square wave signals. The filtering circuit performs low-pass filtering on the PWM signals. Finally, the DC output circuit outputs a stable analog signal. The above multi-stage processing design ensures high accuracy and high stability of signal conversion.

[0052] The frequency processing circuit of this invention is connected to the MCU control circuit, realizing high-precision conversion of frequency signals to analog signals. The conversion accuracy can meet the high requirements of industrial control. At the same time, through multi-level isolation and filtering, noise and interference in the signal transmission process are effectively suppressed, improving the quality and reliability of the output signal.

[0053] The MCU control circuit 19 is also connected to the alarm relay 25.

[0054] Furthermore, the connection between the MCU control circuit and the alarm relay provides the system with comprehensive fault detection and alarm functions. The MCU monitors the system's working status in real time through its built-in monitoring algorithm, including the validity of the input signal, the rationality of the frequency range, and the working status of the circuit. When the MCU detects that the input frequency signal exceeds the preset acquisition range or that a fault such as a disconnection or short circuit occurs, it will immediately activate the alarm relay.

[0055] The alarm relay adopts an electromagnetic relay structure, which features reliable operation and fast response. Its contacts can be configured as normally open or normally closed to adapt to different alarm system requirements. The relay output can be connected to external alarm indication devices, control systems or safety interlock devices to realize timely transmission and processing of fault information.

[0056] In addition, the MCU also has fault recording and diagnostic functions, which can store the time, type and parameter information of the fault occurrence, which facilitates subsequent fault analysis and system maintenance. The intelligent fault detection and alarm mechanism set up by this utility model greatly improves the reliability and safety of the system. It can issue an alarm at the first time a fault occurs, avoiding production accidents and economic losses caused by the failure to detect faults in time. At the same time, it provides maintenance personnel with detailed fault diagnosis information, improving the efficiency of fault handling.

[0057] The intrinsically safe terminals are provided in multiple ways, including proximity switch terminals, frequency signal terminals, and NPNPNP transistor terminals.

[0058] Furthermore, the proximity switch terminal is specifically designed to connect various types of proximity switch sensors, which are used in automated control systems for position detection, object detection, and other applications; the frequency signal terminal is used to receive standard frequency signal input and can be connected to various frequency generators, encoders, and other devices; the NPNPNP transistor terminal is designed to connect three-wire NPN or PNP type sensors, which are used to detect switching signals or pulse signals.

[0059] It should be noted that although the system of this utility model provides multiple types of terminals, only one type can be selected for connection in actual use, in order to avoid mutual interference between signals and ensure the accuracy of signal processing.

[0060] The proximity switch terminals include NAMUR proximity switch terminals and dry contact switch terminals, and the NPNPNP transistor terminals include three-wire NPNPNP terminals, NPNPNP transistor terminals, and encoder terminals.

[0061] Furthermore, the proximity switch terminals of this invention are further subdivided into two types: NAMUR proximity switch terminals and dry contact switch terminals. NAMUR proximity switch terminals are designed according to the NAMUR international standard and can connect to proximity switch sensors conforming to this standard. Dry contact switch terminals are used to connect to various dry contact output switching devices, such as limit switches, push-button switches, and relay contacts. The NPNPNP transistor terminals are subdivided into three-wire NPNPNP terminals, NPNPNP transistor terminals, and encoder terminals. Three-wire NPNPNP terminals are used to connect to three-wire NPN or PNP output sensors, which require an independent power supply line. NPNPNP transistor terminals are suitable for various transistor output sensor devices. Encoder terminals connect to rotary encoders or linear encoders and can process high-frequency pulse signals output by the encoder. Each type of terminal is equipped with corresponding signal processing circuitry to ensure correct identification and processing of the signal characteristics of the corresponding sensor. The refined terminal classification design provided by this invention allows the system to adapt to most types of frequency sensors on the market, greatly expanding the application range of the equipment and improving user flexibility.

[0062] It also includes: a second AC voltage rectifier and filter circuit 26; the second AC voltage rectifier and filter circuit 26 is connected to the transformer 13, and the output terminal of the second AC voltage rectifier and filter circuit 26 supplies power to the communication circuit.

[0063] Furthermore, the addition of a second AC voltage rectifier and filter circuit provides the system with additional power supply capability. This circuit is connected to another set of output windings of the transformer and operates independently of the first AC voltage rectifier and filter circuit. The second AC voltage rectifier and filter circuit adopts a similar rectification and filtering principle as the first circuit, but its output voltage and current specifications are specially designed according to the requirements of the communication circuit. The communication circuit typically includes communication interfaces such as RS485, RS232, and Ethernet. These interfaces require a stable power supply to ensure the reliability of communication, and they are powered by an independent power supply circuit, avoiding power interference between the communication circuit and the main signal processing circuit, thus improving communication quality and the overall stability of the system.

[0064] In addition, the output of the second AC voltage rectifier and filter circuit is also equipped with overcurrent protection and short-circuit protection functions. It can automatically cut off the power supply when the communication circuit fails, protecting other circuits from being affected. When the communication function has a problem, the communication circuit can be repaired independently without affecting the main signal processing function. This not only improves the reliability and stability of the system's communication function and ensures the accuracy of data transmission, but also reduces mutual interference between different functional modules through power isolation, thereby improving the electromagnetic compatibility performance of the entire system.

[0065] The NAMUR signal processing circuit 16 is provided with a first power supply output terminal for powering the front-end sensor, and the NPNPNP signal processing circuit 17 is provided with a second power supply output terminal for powering the front-end sensor.

[0066] Furthermore, the power supply output terminals of the NAMUR signal processing circuit and the NPNPNP signal processing circuit respectively provide the necessary operating power for the front-end sensor, ensuring the integrity and practicality of the system.

[0067] Specifically, the first power supply output terminal of the NAMUR signal processing circuit provides a standard operating voltage of 8.2V DC for NAMUR type sensors. This voltage value strictly conforms to the NAMUR standard, ensuring that the sensor can work normally and output a standard signal. The first power supply output terminal also has a current limiting protection function, which can automatically limit the output current and protect the power supply circuit from damage when the sensor experiences a short circuit or overload. The second power supply output terminal of the NPNPNP signal processing circuit mainly provides operating power for three-wire NPN or PNP type sensors. The output voltage is usually 24V or 12V. This embodiment selects 12V, which can meet the power supply requirements of most industrial sensors. The second power supply output terminal is also equipped with overcurrent protection and short circuit protection functions to ensure the safety and reliability of the power supply.

[0068] The integrated power supply design described above eliminates the need for users to equip the sensors with separate power supply equipment, simplifying system installation and wiring, reducing system complexity and cost. At the same time, the power supply inside the safety barrier ensures the quality of the sensor's power supply, avoiding the impact of unstable external power supply on sensor operation, and improving the accuracy of signal acquisition and the overall reliability of the system.

[0069] It also includes: a loop current identification circuit 27; the loop current identification circuit 27 is connected to the NAMUR signal processing circuit 16 and is used to measure the loop power supply current and determine open circuit and short circuit faults.

[0070] Furthermore, the loop current identification circuit of this invention aims to provide advanced fault diagnosis functions for monitoring the operating current of the NAMUR loop and determining the operating status of the sensor and connecting lines by analyzing changes in the loop current.

[0071] The NAMUR sensor works by transmitting signal information by changing the loop current. During normal operation, the loop current varies within a specific range. When the sensor detects a target, the loop current changes accordingly. This invention incorporates a loop current identification circuit that uses a high-precision current detection chip to monitor the loop current in real time and converts the current signal into a digital signal for analysis and processing by the MCU. When a circuit break occurs, the loop current drops to near zero; when a short circuit occurs, the loop current exceeds the normal range. By analyzing the characteristics of the current signal, the MCU can accurately determine the loop's operating status and promptly detect faults such as breakage and short circuits. Furthermore, this circuit can also detect the sensor's operating status. When an internal fault occurs in the sensor, its loop current characteristics also change. Current analysis allows for early detection of sensor faults, enabling the detection of abnormalities at the moment of occurrence, thus saving valuable time for timely fault handling and effectively preventing production accidents and equipment damage caused by delayed fault detection.

[0072] The alarm relay 25 supports 3000V isolation capability, and the output terminal of the alarm relay 25 is set as a short-circuit switch.

[0073] Furthermore, the alarm relay of this invention supports 3000V isolation capability, ensuring complete electrical isolation between the alarm signal and the main circuit. The alarm relay of this invention adopts the principle of electromagnetic isolation, with no direct electrical connection between the input side and the output side. Even if a high-voltage fault occurs, it will not affect the operation of the output side. The relay output terminal is designed as a short-circuit switch. Under normal conditions, the contacts are open, and under fault conditions, the contacts are closed, which has fault-safe characteristics. In addition, the high isolation capability design greatly improves the system safety level, ensures the reliability of the alarm function, and provides reliable safety protection for operators and equipment.

[0074] The MCU control circuit 19 is also provided with a configuration line connection port for connecting to an external computer to set parameters and alarms.

[0075] Furthermore, the MCU control circuit is equipped with a configuration line connection port to establish a communication connection with an external computer, enabling parameter setting and alarm setting functions. The configuration line connection port adopts standard interfaces such as RS232, RS485, or USB, which has good compatibility. Moreover, parameters such as frequency acquisition range, output range, and alarm threshold can be set through dedicated configuration software, allowing the same device to adapt to different application scenarios.

[0076] The frequency processing circuit 18 supports a frequency reduction function, which is used to reduce the frequency of the input frequency signal and output a square wave signal to the MCU control circuit 19.

[0077] Furthermore, the frequency processing circuit supports frequency reduction, which reduces the high-frequency input signal to a range that the MCU can effectively process. The frequency processing circuit uses digital or analog frequency division technology to process the signal according to a preset division ratio, reducing the performance requirements of the MCU and improving signal stability and anti-interference ability. In addition, the frequency processing circuit adopts high-precision clock synchronization technology to ensure that the signal after frequency reduction maintains a strict frequency ratio with the original signal. The frequency reduction function expands the frequency measurement range of the system and improves measurement accuracy and stability.

[0078] The output signal of the DC output circuit 24 is a current signal or a voltage signal, which is used to connect to the PLC system.

[0079] Furthermore, the DC output circuit outputs industrial standard signals such as 4-20mA current signals or 0-10V voltage signals. The 4-20mA signal has advantages such as strong anti-interference ability, long transmission distance, and high accuracy. The DC output circuit of this utility model adopts high-precision digital-to-analog conversion technology, with a conversion accuracy of over 0.1%. It is equipped with linearity correction function. In addition, the output terminal is designed with short-circuit protection and overload protection functions. It can be directly connected to the analog input module of the PLC system. The standardized output design ensures good compatibility with various PLC systems, simplifies system integration work, and improves the degree of automation and control accuracy.

[0080] like Figure 2 The diagram shows the system connection of the frequency-to-analog safety barrier of this invention, illustrating the electrical isolation and signal transmission path between the hazardous area and the safe area. The blue hazardous area on the left contains various types of frequency signal input sources, including switch contact inputs, proximity switch inputs, frequency signal generators, and PNP / NPN transistor sensors. These input signals are conditioned by corresponding signal processing circuits before being transmitted to the safe area. The safe area on the right contains the core circuitry for signal processing and conversion of this invention. Electrical isolation is achieved through an isolation amplifier, safely transmitting the frequency signals from the hazardous area to the safe area for processing, ultimately outputting standard analog signals such as relay alarms or current signals.

[0081] Figure 2 The power supply modules (B-, A+) provide isolated power to the entire system, ensuring that both hazardous and safe areas have independent and reliable power supplies. Figure 2 As can be seen, the diverse input interface design provided by this utility model enables the device to be compatible with different types of frequency sensors. Through electrical isolation technology, it ensures that faults in the hazardous area will not affect the normal operation of the safe area. At the same time, it realizes the accurate conversion of frequency signals to analog signals, demonstrating the important role of safety barriers in signal isolation, conversion and safety protection in industrial automation systems.

[0082] This invention provides a frequency-to-analog safety barrier and proposes an intrinsically safe intelligent I / O module. This invention uses current output to convert field frequency signals into current signals, reducing errors caused by environmental interference during data transmission and increasing system stability and anti-interference capabilities. Secondly, this invention can be installed on any of various frequency sensors, increasing equipment versatility and reducing inventory pressure. Furthermore, this invention features high precision, strong isolation and withstand voltage capabilities, and high EMC rating in its channel range setting. This invention also includes dual-color alarm lights and alarm relays, providing different display logics and selections for different error conditions, facilitating timely problem detection on-site.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model, and not to limit it. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present utility model. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A frequency-to-analog safety barrier, characterized in that, include: Voltage conversion circuit, transformer coil drive circuit, transformer, first AC voltage rectification and filtering circuit, frequency signal processing circuit, NAMUR signal processing circuit, NPNPNP signal processing circuit, frequency processing circuit, MCU control circuit, TTL output interface, isolation chip, square wave processing circuit, filtering circuit, DC output circuit and alarm relay; The input terminal of the voltage conversion circuit is used to receive external DC voltage signals, and the output terminal of the voltage conversion circuit is connected to the input terminal of the transformer through the transformer coil drive circuit. The output terminal of the transformer is connected to the first AC voltage rectifier and filter circuit, and the output terminal of the first AC voltage rectifier and filter circuit supplies power to the dangerous area and the safe area respectively. The hazardous area is equipped with an intrinsically safe terminal, which is connected to multiple frequency processing circuits through at least one of a frequency signal processing circuit, a NAMUR signal processing circuit, and an NPNPNP signal processing circuit. The output terminal of the frequency processing circuit is connected to the input terminal of the MCU control circuit, and the output terminal of the MCU control circuit is connected to the DC output circuit in sequence through the TTL output interface, the isolation chip, the square wave processing circuit, and the filtering processing circuit. The MCU control circuit is also connected to the alarm relay.

2. The frequency-to-analog safety barrier according to claim 1, characterized in that, Multiple intrinsically safe terminals are provided, including proximity switch terminals, frequency signal terminals, and NPNPNP transistor terminals.

3. A frequency-to-analog safety barrier according to claim 2, characterized in that, The proximity switch terminals include NAMUR proximity switch terminals and dry contact switch terminals, and the NPNPNP transistor terminals include three-wire NPNPNP terminals, NPNPNP transistor terminals, and encoder terminals.

4. A frequency-to-analog safety barrier according to claim 1, characterized in that, Also includes: Second AC voltage rectifier and filter circuit; The second AC voltage rectifier and filter circuit is connected to the transformer, and the output of the second AC voltage rectifier and filter circuit supplies power to the communication circuit.

5. A frequency-to-analog safety barrier according to claim 1, characterized in that, The NAMUR signal processing circuit is provided with a first power supply output terminal for powering the front-end sensor, and the NPNPNP signal processing circuit is provided with a second power supply output terminal for powering the front-end sensor.

6. A frequency-to-analog safety barrier according to claim 1, characterized in that, Also includes: Loop current identification circuit; The loop current identification circuit is connected to the NAMUR signal processing circuit and is used to measure the loop power supply current and determine open circuit and short circuit faults.

7. A frequency-to-analog safety barrier according to claim 1, characterized in that, The alarm relay supports 3000V isolation capability, and the output terminal of the alarm relay is set as a short-circuit switch.

8. A frequency-to-analog safety barrier according to claim 1, characterized in that, The MCU control circuit is also equipped with a configuration line connection port for connecting to an external computer to set parameters and alarms.

9. A frequency-to-analog safety barrier according to claim 1, characterized in that, The frequency processing circuit supports frequency reduction, which is used to reduce the frequency of the input frequency signal and output a square wave signal to the MCU control circuit.

10. A frequency-to-analog safety barrier according to claim 1, characterized in that, The output signal of the DC output circuit is a current signal or a voltage signal, which is used to connect to the PLC system.

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