Multi-channel isolated thermocouple acquisition system

Abstract

The invention provides a multichannel isolated thermocouple acquisition system, which relates to the technical field of thermocouple temperature detection and comprises a control board card and a thermocouple acquisition board card. The control board card comprises a microcontroller unit, an FPGA unit and a power supply unit, the FPGA unit is in communication connection with an external controller, and the power supply unit is used for supplying power; an analog switch circuit in the thermocouple acquisition board card is respectively connected with a cold junction compensation channel and a plurality of independent thermocouple acquisition channels, the analog switch circuit is in communication connection with a microcontroller unit through an SPI bus, and the thermocouple acquisition channels are used for acquiring thermocouple signals of various different types; the microcontroller unit is used for processing thermocouple signals and sending the thermocouple signals to an external controller through the FPGA unit. The system supports multi-point temperature acquisition and electrical isolation between acquisition channels, is compatible with various thermocouple types, meets industrial requirements, improves system reliability, separates system control and communication functions, and improves the overall performance of the system.

Description

Technical Field

[0001] This invention relates to the field of thermocouple temperature detection technology, and in particular to a multi-channel isolated thermocouple acquisition system. Background Technology

[0002] Temperature detection is crucial in modern industrial production, especially for processes requiring high-precision control. The stability and reliability of temperature control systems directly affect product quality and production efficiency. Thermocouples, as a common sensor, are widely used in various temperature control systems due to their advantages such as fast response speed, high stability, and wide applicability.

[0003] In the existing technology, considering that multiple temperature points often need to be detected in the production environment, the common single-channel thermocouple acquisition module cannot meet the needs of multi-point detection. In addition, in the common multi-channel thermocouple acquisition module, there are usually electrical connections between the channels. Therefore, when one channel has a problem, the entire multi-channel thermocouple acquisition module will malfunction, which will cause the data acquired by other channels to also have problems, affecting the accuracy of data acquisition.

[0004] Therefore, a thermocouple acquisition module capable of high-precision acquisition of multi-channel thermocouple signals urgently needs to be studied. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a multi-channel isolated thermocouple acquisition system, which solves the technical problem that existing thermocouple acquisition systems cannot achieve high-precision acquisition of multi-channel thermocouple signals.

[0006] This invention provides a multi-channel isolated thermocouple acquisition system, including a control board and a thermocouple acquisition board;

[0007] The control board includes a microcontroller unit, an FPGA unit, and a power supply unit. The FPGA unit is communicatively connected to an external controller, and the power supply unit is connected to both the microcontroller unit and the FPGA unit to provide power.

[0008] The thermocouple acquisition board includes an analog switch circuit, a cold junction compensation channel, and multiple independent thermocouple acquisition channels. The analog switch circuit is connected to the cold junction compensation channel and the multiple thermocouple acquisition channels respectively. The analog switch circuit is connected to the microcontroller unit via an SPI bus. The thermocouple acquisition channels are used to acquire various types of thermocouple signals.

[0009] The microcontroller unit is used to acquire and process the thermocouple signals acquired by the thermocouple acquisition board, and send the processed signals to the external controller through the FPGA unit.

[0010] Optionally, the thermocouple acquisition channel includes a resettable fuse, a filter capacitor, a first operational amplifier, a first analog-to-digital converter, a first digital isolation unit, and a first power management unit; the thermocouple signal acquisition terminal of the thermocouple acquisition channel is connected to the analog switch circuit in sequence through the first operational amplifier, the first analog-to-digital converter, and the first digital isolation unit; the resettable fuse is connected between the thermocouple signal acquisition terminal and the first operational amplifier, and the filter capacitor is connected in parallel with the thermocouple signal acquisition terminal; the first power management unit is used to supply power to the thermocouple acquisition channel.

[0011] Optionally, the thermocouple acquisition channel supports K-type, J-type, T-type, E-type, N-type, S-type, and R-type thermocouples.

[0012] Optionally, the cold junction compensation channel includes a temperature measurement unit, a second operational amplifier, a second analog-to-digital converter, a second digital isolation unit, and a second power management unit. The temperature measurement unit is connected to the analog switching circuit in sequence through the second operational amplifier, the second analog-to-digital converter, and the second digital isolation unit. The temperature measurement unit includes a resistance temperature detector (RTD), a current source, and a reference resistor. The first end of the RTD is connected to the positive input terminal of the second operational amplifier, the second end of the RTD is connected to the negative input terminal of the second operational amplifier, and the third end of the RTD is also connected to ground through the reference resistor. The current source is connected to both ends of the RTD. The second power management unit is used to supply power to the cold junction compensation channel.

[0013] Optionally, the system further includes a watchdog unit and a crystal oscillator unit; the watchdog unit is connected between the microcontroller unit and the FPGA unit, the microcontroller unit sends a feed signal to the watchdog unit based on a preset time interval, the watchdog unit determines the working state of the microcontroller unit based on the feed signal, and sends a reset signal to the microcontroller unit through the FPGA unit according to the working state; the crystal oscillator unit is connected between the microcontroller unit and the FPGA unit, and the crystal oscillator unit is used to provide a clock signal to the microcontroller unit and the FPGA unit to maintain the synchronization of data communication between the microcontroller unit and the FPGA unit in real time.

[0014] Optionally, the system further includes multiple RS485 communication units, each RS485 communication unit including a first RS485 communication module and a second RS485 communication module; the FPGA unit is configured with multiple redundant HDLC channels, each HDLC channel being connected to the RS485 communication unit for transmitting clock signals and data signals through the RS485 communication unit, wherein each HDLC channel receives clock signals unidirectionally through the first RS485 communication module, and each HDLC channel transmits data signals bidirectionally through the second RS485 communication module.

[0015] Optionally, the power supply unit includes a connected DC / DC converter and a low-dropout linear regulator; the power supply unit connects to multiple system power supplies through a power interface, and after the multiple system power supplies are combined into a single total power supply, the DC / DC converter and the low-dropout linear regulator are used to convert the total power supply into a working power supply, and the microcontroller unit and the FPGA unit are powered based on the working power supply.

[0016] Optionally, a power detection unit is connected between the microcontroller unit and the power interface. The power detection unit is used to detect the operating status of the multi-system power supply. When the power detection unit detects that the operating status of the multi-system power supply is abnormal, it sends an alarm message to the external controller through the FPGA unit.

[0017] Optionally, the microcontroller unit is provided with an SPI communication interface, which is connected to the thermocouple acquisition board via an expansion interface board; the expansion interface board also integrates multiple bus transceivers.

[0018] Optionally, the microcontroller unit is provided with a serial communication interface, which is connected to external devices via an RS232 communication module.

[0019] The multi-channel isolated thermocouple acquisition system provided by this invention supports simultaneous continuous acquisition of multiple temperature points by setting up multiple thermocouple acquisition channels and analog switching circuits, thereby improving the system's data acquisition capability and meeting the needs of complex industrial scenarios. Each acquisition channel is independent and has electrical isolation characteristics, effectively preventing interference and fault propagation between channels. When one channel malfunctions, the other channels can still operate normally, ensuring the stable operation of the system. Furthermore, the thermocouple acquisition channels are compatible with various thermocouple types, enhancing the system's versatility. The cold junction compensation channel monitors the temperature of the thermocouple cold junction for the microcontroller unit to perform compensation calculations, eliminating measurement errors caused by cold junction temperature changes and ensuring the accuracy and reliability of data processing. The control board has a microcontroller unit responsible for data acquisition and processing, and an FPGA unit responsible for communication with external controllers, realizing functional division of labor and improving system response speed and communication reliability.

[0020] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 A schematic diagram of the overall structure of a multi-channel isolated thermocouple acquisition system provided in one embodiment of this application;

[0024] Figure 2 A schematic diagram of the specific structure of the thermocouple acquisition board in a multi-channel isolated thermocouple acquisition system provided in this application;

[0025] Figure 3 This is a schematic diagram of the specific structure of the control board in a multi-channel isolated thermocouple acquisition system provided in one embodiment of this application.

[0026] In the picture:

[0027] R1, resettable fuse; R2, RTD; R3, reference resistor; C1, filter capacitor; U1, first operational amplifier; U2, second operational amplifier; AD1, first analog-to-digital converter; AD2, second analog-to-digital converter; Vin+1~7, Vin-1~7, thermocouple signal acquisition terminals; DC / DC converter; LDO, low-voltage linear regulator. Detailed Implementation

[0028] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0029] This invention provides a multi-channel isolated thermocouple acquisition system, such as... Figure 1 As shown, the system includes a control board and a thermocouple acquisition board. The control board includes a microcontroller unit, an FPGA unit, and a power supply unit. The FPGA unit communicates with an external controller, and the power supply unit is connected to both the microcontroller unit and the FPGA unit for power supply. The thermocouple acquisition board includes an analog switch circuit, a cold junction compensation channel, and multiple independent thermocouple acquisition channels. The analog switch circuit is connected to both the cold junction compensation channel and the multiple thermocouple acquisition channels. The analog switch circuit communicates with the microcontroller unit via an SPI bus. The thermocouple acquisition channels are used to acquire various types of thermocouple signals. The microcontroller unit acquires and processes the thermocouple signals acquired by the thermocouple acquisition board and sends the processed signals to the external controller via the FPGA unit.

[0030] The multi-channel isolated thermocouple acquisition system provided by this invention supports simultaneous continuous acquisition of multiple temperature points by setting up multiple thermocouple acquisition channels and analog switching circuits, thereby improving the system's data acquisition capability and meeting the needs of complex industrial scenarios. Each acquisition channel is independent and has electrical isolation characteristics, effectively preventing interference and fault propagation between channels. When one channel malfunctions, the other channels can still operate normally, ensuring the stable operation of the system. Furthermore, the thermocouple acquisition channels are compatible with various thermocouple types, enhancing the system's versatility. The cold junction compensation channel monitors the temperature of the thermocouple cold junction for the microcontroller unit to perform compensation calculations, eliminating measurement errors caused by cold junction temperature changes and ensuring the accuracy and reliability of data processing. The control board has a microcontroller unit responsible for data acquisition and processing, and an FPGA unit responsible for communication with external controllers, realizing functional division of labor and improving system response speed and communication reliability.

[0031] Specifically, the external controller (DPU, Distributed Processing Unit) provided in this application is the core controller of the Distributed Control System (DCS), responsible for performing local data acquisition, logic operation, closed-loop control, and equipment control tasks. As an embedded industrial controller, it is typically used in more complex and larger-scale continuous process control scenarios. Specifically, it achieves real-time data acquisition, control algorithm execution, communication, and integration functions with the multi-channel isolated thermocouple acquisition system provided in this application.

[0032] Specifically, in the above embodiment, the thermocouple acquisition channel includes a resettable fuse R1, a filter capacitor C1, a first operational amplifier U1, a first analog-to-digital converter AD1, a first digital isolation unit, and a first power management unit; the thermocouple signal acquisition terminal of the thermocouple acquisition channel is connected to the analog switch circuit in sequence through the first operational amplifier U1, the first analog-to-digital converter AD1, and the first digital isolation unit; the resettable fuse R1 is connected between the thermocouple signal acquisition terminal and the first operational amplifier U1, and the filter capacitor is connected in parallel with the thermocouple signal acquisition terminal; the first power management unit is used to supply power to the thermocouple acquisition channel.

[0033] In this embodiment, such as Figure 2 As shown, a total of 7 thermocouple acquisition channels are set up. Each thermocouple acquisition channel has a thermocouple signal acquisition terminal, namely Vin+ and Vin-, for receiving differential analog signals. A filter capacitor C1 is set before the first operational amplifier U1 to remove high-frequency noise in the input signal and ensure signal purity. In addition, each thermocouple acquisition channel is equipped with a self-resetting fuse R1, which can protect against abnormal external signals and resume normal data acquisition after the abnormal signal is removed. The input signal received by the thermocouple signal acquisition terminal is first processed by the first operational amplifier U1 to improve signal quality and adapt to subsequent analog-to-digital conversion. The conditioned analog signal is then sent to the first analog-to-digital converter AD1 for digital processing, converting the analog signal into a digital signal. After passing through the first digital isolation unit, it is transmitted to the analog switching circuit. The first digital isolation unit can use components such as optocouplers and transformers to achieve electrical isolation and prevent mutual interference between different acquisition channels. Under the control of the microcontroller unit, the analog switching circuit selects different thermocouple acquisition channels for data acquisition and transmission.

[0034] In addition, each thermocouple acquisition channel is equipped with a first power management unit for power supply. Specifically, the first power management unit includes a DC / DC converter and a connected low-dropout linear regulator. The DC / DC converter is used to provide a stable power supply voltage, while the low-dropout linear regulator is used to further stabilize the power supply voltage and ensure that the thermocouple acquisition channel works normally.

[0035] Specifically, in the above embodiments, the thermocouple acquisition channel supports K-type, J-type, T-type, E-type, N-type, S-type, and R-type thermocouples.

[0036] The thermocouple acquisition channel is compatible with various types of thermocouple sensors. Specifically, it can connect to and accurately process signals from the following seven common industrial standard thermocouples: Type K thermocouples (NiCr-NiSi), with a wide temperature range (approximately -200℃ to +1350℃), good stability, and low cost, making them one of the most commonly used thermocouples; Type J thermocouples (Fe-Constantan), with a medium temperature range (approximately -40℃ to +750℃), high sensitivity, and suitable for reducing atmospheres; Type T thermocouples (Cu-Constantan), with good low-temperature performance (approximately -200℃ to +350℃), commonly used for low-temperature measurements, and high accuracy; and Type E thermocouples (NiCr-Constantan). Type K thermocouples have high thermoelectric potential output and high sensitivity, suitable for low and medium temperature ranges (approximately -200℃ to +900℃); Type N thermocouples are made of Nicrosil-Nisil, with better stability than Type K and strong oxidation resistance, suitable for long-term high-temperature measurements (approximately -200℃ to +1300℃); Type S thermocouples are made of platinum-rhodium 10-platinum (PtRh10-Pt), a precious metal thermocouple with extremely high stability, used for high-temperature precision measurements (approximately 0℃ to +1600℃), often used for standard temperature measurement or calibration; Type R thermocouples are made of platinum-rhodium 13-platinum (PtRh13-Pt), similar to Type S, also a precious metal thermocouple with a similar temperature range (approximately 0℃ to +1600℃), but with slightly higher sensitivity than Type S.

[0037] In this embodiment, the thermocouple acquisition channel provided by this application is not designed for only one type of thermocouple, but can be adapted to a variety of commonly used industrial thermocouple types. Users can flexibly select the appropriate thermocouple sensor according to actual temperature measurement needs, thereby adapting to a variety of different application scenarios.

[0038] Specifically, in the above embodiment, the cold junction compensation channel includes a temperature measurement unit, a second operational amplifier U2, a second analog-to-digital converter AD2, a second digital isolation unit, and a second power management unit. The temperature measurement unit is connected to the analog switch circuit in sequence through the second operational amplifier U2, the second analog-to-digital converter AD2, and the second digital isolation unit. The temperature measurement unit includes a thermistor R2, a current source, and a reference resistor R3. The first end of the thermistor R2 is connected to the positive input terminal of the second operational amplifier U2, the second end of the thermistor R2 is connected to the negative input terminal of the second operational amplifier U2, and the third end of the thermistor R2 is connected to the ground terminal through the reference resistor R3. The current source is connected to both ends of the thermistor R2, wherein the third end of the thermistor R2 is short-circuited. The second power management unit is used to supply power to the cold junction compensation channel.

[0039] In this embodiment, the overall structure of the cold junction compensation channel is similar to that of the thermocouple acquisition channel, and will not be elaborated further here. The difference lies in the temperature measurement unit set in the cold junction compensation channel. Specifically, the resistance temperature detector (RTD) R2 adopts a three-wire connection, including three terminals. The three-wire connection method is suitable for industrial applications requiring high temperature measurement accuracy. The RTD R2 is specifically a PT100 platinum resistance thermometer used to measure ambient temperature as the basis for cold junction compensation. It is excited by two current sources: one current source flows into the RTD R2 from node A, and the other current source... Thermistor R2 flows out from node B and is grounded. The current source provides a constant excitation current to thermistor R2, causing it to generate a voltage drop proportional to temperature. Reference resistor R3 is mainly used to provide a stable reference potential for node B. When current flows through thermistor R2, a voltage drop will be generated between nodes A and B. In order to accurately measure the voltage drop, it is necessary to ensure that node B has a fixed potential, which is usually grounded. However, directly grounding node B may introduce additional noise or interference. Therefore, using a reference resistor R3 as a grounding path can effectively filter out these interferences while maintaining the potential stability of node B.

[0040] Specifically, in the above embodiments, such as Figure 3 As shown, the system also includes a watchdog unit and a crystal oscillator unit. The watchdog unit is connected between the microcontroller unit and the FPGA unit. The microcontroller unit sends a feed signal to the watchdog unit at a preset time interval. The watchdog unit determines the working state of the microcontroller unit based on the feed signal and sends a reset signal to the microcontroller unit through the FPGA unit according to the working state. The crystal oscillator unit is connected between the microcontroller unit and the FPGA unit. The crystal oscillator unit is used to provide clock signals to the microcontroller unit and the FPGA unit to maintain the synchronization of data communication between the microcontroller unit and the FPGA unit in real time.

[0041] In this embodiment, the microcontroller unit sends a feed signal to the watchdog chip in the watchdog unit at a preset time interval, such as 500 milliseconds. The purpose is to reset the timer in the watchdog chip to indicate that the microcontroller unit is operating normally. If the watchdog chip does not receive the feed signal from the microcontroller unit within the preset time interval, it can be determined that the microcontroller unit may have malfunctioned or the program may have crashed. Once a timeout is detected, the watchdog chip will immediately generate a reset signal and pass it to the FPGA unit. After receiving the reset signal from the watchdog chip, the FPGA unit will process it accordingly and pass it back to the microcontroller unit, so that the microcontroller unit will perform a reset operation upon receiving the reset signal, reinitialize its internal state and registers, and thus restore it to the initial working state.

[0042] In addition, the crystal oscillator unit, as a high-precision frequency source, provides a stable clock signal for the microcontroller unit and the FPGA unit to ensure the correctness and real-time performance of data transmission between the microcontroller unit and the FPGA unit. In this application, the frequency of the crystal oscillator unit is 16MHz.

[0043] Specifically, in the above embodiments, the system further includes multiple RS485 communication units, each RS485 communication unit including a first RS485 communication module and a second RS485 communication module; the FPGA unit is configured with multiple redundant HDLC channels, which are connected to the RS485 communication units for transmitting clock signals and data signals through the RS485 communication units. The HDLC channels receive clock signals unidirectionally through the first RS485 communication module and transmit data signals bidirectionally through the second RS485 communication module.

[0044] In this embodiment, with Figure 3For example, the FPGA unit has two HDLC (Advanced Data Link Control) channels, labeled as channel A and channel B. Each channel contains two information streams: an HDLC clock signal and an HDLC data signal. The HDLC clock signal is used to synchronize data transmission, ensuring that the receiving end can correctly decode the data from the sending end. The HDLC data signal includes the actual data content to be transmitted, encapsulated according to the HDLC protocol. Channel A and channel B are respectively connected to the first RS485 communication module and the second RS485 communication module. The RS485 communication module is a communication module based on the RS-485 standard, which has strong anti-interference capabilities and a long transmission distance, making it suitable for data transmission in industrial environments. Specifically, the first RS485 communication module receives the RS485 clock signal sent by the external controller and converts it into an HDLC clock signal for transmission to channel A or channel B, realizing unidirectional transmission of the clock signal. The second RS485 communication module transmits HDLC data signals bidirectionally with the HDLC channel and RS485 data signals bidirectionally with the external controller, thereby realizing bidirectional data signal transmission between the HDLC and the external controller.

[0045] Based on this, the RS485 communication unit provided in this application improves the redundancy and fault tolerance of the system by transmitting the clock signal and data signal separately, and each channel is connected to an independent RS485 communication module. Furthermore, the number of channels and module configuration can be adjusted according to actual needs to flexibly cope with different application scenarios.

[0046] It should be noted that the connector used in this application is a 48-pin European connector, which is used to realize the electrical connection between the system and external devices.

[0047] Specifically, in the above embodiments, the power supply unit includes a DC / DC converter and a low-dropout linear regulator connected to each other; the power supply unit connects to multiple system power supplies through a power interface, and after the multiple system power supplies are combined into a single total power supply, the DC / DC converter and the low-dropout linear regulator are used to convert the total power supply into a working power supply, and the microcontroller unit and FPGA unit are powered based on the working power supply.

[0048] In this embodiment, such as Figure 3As shown, two independent 24V system power supplies are used as inputs and connected to the power supply unit through a power interface. This power interface can also use a 48-pin European connector. The two 24V system power supplies are then combined into one 24V system power supply to ensure that if one power supply fails, the other can continue to supply power, improving system reliability. The combined 24V power supply is converted to 5V by a DC / DC converter. The 5V power supply obtained by the DC / DC converter is then converted to 3.3V operating power by a low-dropout linear regulator. The 3.3V operating power supply is mainly used to power the microcontroller unit and the FPGA unit. To meet the lower voltage requirements of the FPGA unit's core logic, another low-dropout linear regulator is used to convert the 3.3V operating power supply to 1.2V operating power for dedicated use by the FPGA unit.

[0049] In addition, the system power supply output via the 48-pin European connector, the 5V power supply output via the DC / DC converter, and the 3.3V power supply output via the low dropout linear regulator can all be connected to the 2×7-pin connector sub-board to connect to other boards and increase the system's expandability.

[0050] Furthermore, a power detection unit is connected between the microcontroller unit and the power interface. The power detection unit is used to detect the operating status of the multi-system power supply. When the power detection unit detects an abnormal operating status of the multi-system power supply, it sends an alarm message to the external controller through the FPGA unit.

[0051] In this embodiment, the microcontroller unit monitors the voltage, current, and other parameters of the two 24V system power supplies in real time to determine whether the power supply is operating normally. If an abnormality is detected in one of the power supplies, such as low voltage, high voltage, or complete power failure, the microcontroller unit can immediately identify and take corresponding measures, such as switching to the other system power supply to ensure uninterrupted power supply. At the same time, the microcontroller unit generates alarm information and sends it to the external controller through the FPGA unit to remotely notify the staff. In addition, the microcontroller unit can also issue alarm signals through other alarm devices, such as status indicator lights, buzzers, or communication interfaces connected to the microcontroller unit, to promptly warn the staff on site.

[0052] Specifically, in the above embodiments, the microcontroller unit is provided with an SPI communication interface, which is connected to the thermocouple acquisition board through an expansion interface board; the expansion interface board also integrates multiple bus transceivers.

[0053] In this embodiment, the thermocouple acquisition board is connected to the expansion interface board and communicates with the microcontroller unit via the SPI bus. The microcontroller unit has two independent SPI interfaces, namely SPI1 and SPI2, which are used to communicate with different peripherals or sub-boards respectively. Through full-duplex mode, it can send and receive data simultaneously. In addition, the expansion interface board also integrates multiple bus transceivers as backups to support the access and level conversion of multiple communication protocols when the system is upgraded or the function is expanded, thereby improving the system's flexibility and scalability and meeting the future needs of connecting to different peripherals or subsystems.

[0054] Specifically, in the above embodiments, the microcontroller unit is provided with a serial communication interface, which is connected to external devices through an RS232 communication module.

[0055] In this embodiment, the microcontroller unit is equipped with a serial communication interface (UART interface) for full-duplex serial communication. The RS232 communication module is used to convert TTL level to RS-232 standard level to meet the communication needs between different devices. The RS232 module is connected to the microcontroller unit through the UART interface and is responsible for level conversion and signal driving. Then, the RS232 communication module is connected to the physical connection port of the external device to access the external device. The physical connection port can be an RJ11 interface, which is commonly used for connecting devices such as analog telephones and modems. Based on this, data transmission and reception between the microcontroller unit and the external device are realized. The specific serial communication interface is reserved for debugging.

[0056] In addition, such as Figure 3As shown, considering that a multi-channel thermocouple acquisition system may require the connection of multiple expansion cards with different functions (such as analog input, digital input / output, etc.), a card address line is connected between the FPGA unit and the 48-pin European connector. The card address line is used to assign a unique address identifier to the inserted expansion card. Through different combinations of card address line states, the location and identity of each card can be uniquely determined, enabling the system to identify and correctly access different expansion modules and perform corresponding data read and write operations. The FPGA unit also has a debug download interface for programming, debugging, and updating the internal logic of the FPGA. Simultaneously, to ensure efficient and reliable data communication between the FPGA unit and the microcontroller unit, the FPGA unit has an HDLC interface. HDLC is a bit-oriented synchronous data link layer protocol with powerful error detection and correction capabilities. When the FPGA unit and the microcontroller unit exchange data through the HDLC interface, the integrity and reliability of data transmission can be guaranteed. The FPGA unit also has a storage unit for storing data output by the microcontroller unit. The microcontroller unit has an SWD (Serial Line Debug) download interface for programming, debugging, and updating the internal program of the microcontroller unit.

[0057] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing this application. Those skilled in the art will understand that the modules in the apparatus of the embodiment can be distributed within the apparatus of the embodiment as described, or can be modified to be located in one or more apparatuses different from this embodiment. The modules of the above-described embodiment can be combined into one module, or further divided into multiple sub-modules.

[0058] The serial numbers in this application are for descriptive purposes only and do not represent the superiority or inferiority of any particular implementation scenario. The above disclosures are merely a few specific implementation scenarios of this application; however, this application is not limited thereto, and any variations conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A multi-channel isolated thermocouple acquisition system, characterized in that, include: Control board and thermocouple acquisition board; The control board includes a microcontroller unit, an FPGA unit, and a power supply unit. The FPGA unit is communicatively connected to an external controller, and the power supply unit is connected to both the microcontroller unit and the FPGA unit to provide power. The thermocouple acquisition board includes an analog switch circuit, a cold junction compensation channel, and multiple independent thermocouple acquisition channels. The analog switch circuit is connected to the cold junction compensation channel and the multiple thermocouple acquisition channels respectively. The analog switch circuit is connected to the microcontroller unit via an SPI bus. The thermocouple acquisition channels are used to acquire various types of thermocouple signals. The microcontroller unit is used to acquire and process the thermocouple signals acquired by the thermocouple acquisition board, and send the processed signals to the external controller through the FPGA unit.

2. The multi-channel isolated thermocouple acquisition system according to claim 1, characterized in that, The thermocouple acquisition channel includes a resettable fuse, a filter capacitor, a first operational amplifier, a first analog-to-digital converter, a first digital isolation unit, and a first power management unit; The thermocouple signal acquisition terminal of the thermocouple acquisition channel is connected to the analog switch circuit in sequence through the first operational amplifier, the first analog-to-digital converter and the first digital isolation unit; The self-resetting fuse is connected between the thermocouple signal acquisition terminal and the first operational amplifier, and the filter capacitor is connected in parallel with the thermocouple signal acquisition terminal; The first power management unit is used to supply power to the thermocouple acquisition channel.

3. The multi-channel isolated thermocouple acquisition system according to claim 1 or 2, characterized in that, The thermocouple acquisition channel supports K-type, J-type, T-type, E-type, N-type, S-type, and R-type thermocouples.

4. The multi-channel isolated thermocouple acquisition system according to claim 1, characterized in that, The cold junction compensation channel includes a temperature measurement unit, a second operational amplifier, a second analog-to-digital converter, a second digital isolation unit, and a second power management unit. The temperature measurement unit is connected to the analog switch circuit in sequence through the second operational amplifier, the second analog-to-digital converter, and the second digital isolation unit; The temperature measurement unit includes a resistance temperature detector (RTD), a current source, and a reference resistor. The first end of the RTD is connected to the positive input terminal of the second operational amplifier, the second end of the RTD is connected to the negative input terminal of the second operational amplifier, and the third end of the RTD is connected to the ground terminal through the reference resistor. The current source is connected to both ends of the RTD, wherein the second end and the third end of the RTD are short-circuited. The second power management unit is used to supply power to the cold junction compensation channel.

5. The multi-channel isolated thermocouple acquisition system according to claim 1, characterized in that, The system also includes a watchdog unit and a crystal oscillator unit; The watchdog unit is connected between the microcontroller unit and the FPGA unit. The microcontroller unit sends a feed signal to the watchdog unit at a preset time interval. The watchdog unit determines the working state of the microcontroller unit based on the feed signal and sends a reset signal to the microcontroller unit through the FPGA unit according to the working state. The crystal oscillator unit is connected between the microcontroller unit and the FPGA unit. The crystal oscillator unit is used to provide clock signals to the microcontroller unit and the FPGA unit to maintain the synchronization of data communication between the microcontroller unit and the FPGA unit in real time.

6. The multi-channel isolated thermocouple acquisition system according to claim 1, characterized in that, The system also includes multiple RS485 communication units, each RS485 communication unit including a first RS485 communication module and a second RS485 communication module; The FPGA unit is configured with multiple redundant HDLC channels. The HDLC channels are connected to the RS485 communication unit and are used to transmit clock signals and data signals through the RS485 communication unit. The HDLC channels receive clock signals unidirectionally through the first RS485 communication module and transmit data signals bidirectionally through the second RS485 communication module.

7. The multi-channel isolated thermocouple acquisition system according to claim 1, characterized in that, The power supply unit includes a DC / DC converter and a low-dropout linear regulator connected in series; The power supply unit connects to multiple system power supplies through a power interface. After the multiple system power supplies are combined into a single total power supply, the DC / DC converter and the low-dropout linear regulator are used to convert the total power supply into a working power supply, which then powers the microcontroller unit and the FPGA unit.

8. The multi-channel isolated thermocouple acquisition system according to claim 7, characterized in that, A power detection unit is connected between the microcontroller unit and the power interface. The power detection unit is used to detect the operating status of the multi-channel system power supply. When the power detection unit detects an abnormal operating state of the multi-system power supply, it sends an alarm message to the external controller through the FPGA unit.

9. The multi-channel isolated thermocouple acquisition system according to claim 1, characterized in that, The microcontroller unit is equipped with an SPI communication interface, which is connected to the thermocouple acquisition board via an expansion interface board. The expansion interface board also integrates multiple bus transceivers.

10. The multi-channel isolated thermocouple acquisition system according to claim 1, characterized in that, The microcontroller unit is equipped with a serial communication interface, which is connected to external devices via an RS232 communication module.

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