Current acquisition device

Abstract

The application provides a current acquisition device, and relates to the technical field of current measurement. The current acquisition device comprises a first state acquisition module on a first circuit board, a current acquisition module comprising a plurality of 4-20 mA current acquisition circuits which are electrically isolated from each other, a control module and a second state acquisition module on a second circuit board, and the second circuit board is arranged on a controller. The first state acquisition module is used for acquiring the power supply state of a power supply which supplies power to the current acquisition module. The second state acquisition module is used for acquiring the power supply state of a power supply which supplies power to the control module and transmitting the power supply state to the control module. A plurality of types of interfaces are arranged on the first circuit board. Signals acquired by the first state acquisition module and the current acquisition module are transmitted to the control module through the plurality of interfaces. The control module is connected with a main controller bus. The current acquisition device is improved in reliability, flexibility of on-site arrangement, acquisition precision and maintenance convenience.

Description

Technical Field

[0001] This application relates to the field of current measurement technology, and particularly to the acquisition of 4-20mA current in the field of industrial control. Specifically, a current acquisition device is provided. Background Technology

[0002] In industrial automation control, 4-20mA current is a common instrument current. Therefore, the acquisition of 4-20mA current is particularly important, especially for processes requiring high-precision control, as the accuracy of data acquisition directly affects the reliable operation of the industrial site. The main approach to 4-20mA current acquisition is to convert the current into voltage using a sampling resistor, and then convert the analog signal into a digital signal using an analog-to-digital converter (AD converter) for further processing. In practical applications, 4-20mA current acquisition devices are mostly single-channel, multi-channel non-isolated, or multi-channel isolated types. Single-channel current acquisition devices cannot meet the needs of multi-point current acquisition. In multi-channel non-isolated current acquisition devices, there are electrical connections between channels. If the acquisition of one channel fails, it may cause the entire current acquisition device to malfunction, leading to problems with the data acquired from other channels. Furthermore, multi-channel isolated current acquisition devices used in practical applications suffer from limited functionality, low accuracy, poor reliability, and limited flexibility in local deployment. Summary of the Invention

[0003] The purpose of this application is to provide a current acquisition device to overcome one or more defects existing in the prior art, such as single-channel current acquisition devices, multi-channel non-isolated current acquisition devices, and multi-channel isolated current acquisition devices.

[0004] To achieve the above objectives, the first aspect of this application provides a current acquisition device for use in an industrial control system. The industrial control system includes a main controller and a locally deployed slave controller. The device includes a first status acquisition module located on a first circuit board and a current acquisition module including multiple electrically isolated 4-20mA current acquisition circuits, as well as a control module and a second status acquisition module located on a second circuit board. The second circuit board is disposed on the slave controller.

[0005] The first status acquisition module is used to acquire the power supply status of the power supply that powers the current acquisition module;

[0006] The second status acquisition module is used to acquire the power supply status of the power supply that powers the control module and transmit it to the control module;

[0007] The first circuit board is provided with multiple types of interfaces, including multiple types of serial ports. The signals collected by the first status acquisition module and the current acquisition module are transmitted to the control module through multiple interfaces. The control module is connected to the main controller through a bus.

[0008] In one specific embodiment of this application, the control module includes an MCU unit and an FPGA unit. The signals acquired by the first state acquisition module and the current acquisition module are transmitted to the MCU unit through multiple interfaces. The MCU unit is connected to the FPGA unit, and the FPGA unit is connected to the main controller via a bus.

[0009] In one specific embodiment of this application, the device further includes a plurality of RS485 communication modules disposed on a second circuit board and connected to the FPGA unit, each of the RS485 communication modules being connected to the bus.

[0010] In one specific embodiment of this application, the current acquisition module further includes an analog switch. The 4~20mA current acquisition circuit includes a sampling resistor, an amplifier, an AD converter, and a digital isolator for converting the 4~20mA current signal into a voltage signal. The amplifier is connected to the sampling resistor and the AD converter respectively. The AD converter is connected to the amplifier and the digital isolator respectively. The analog switch is used to select and connect one digital isolator to the control module and disconnect the remaining digital isolators from the control module.

[0011] In one specific embodiment of this application, the power supply for the current acquisition module has a positive power output terminal and a negative power output terminal. The 4~20mA current acquisition circuit includes a sampling resistor that converts the 4~20mA current signal output by the external transmitter into a voltage signal. When the transmitter is not powered by the power supply for the current acquisition module, the negative terminal of the transmitter is connected to the first terminal of the sampling resistor, and the positive terminal of the transmitter is connected to the second terminal of the sampling resistor. When the transmitter is powered by the power supply for the current acquisition module, the positive terminal of the transmitter is connected to the positive power output terminal, the negative terminal of the transmitter is connected to the first terminal of the sampling resistor, and the second terminal of the sampling resistor is connected to the negative power output terminal.

[0012] In one specific embodiment of this application, the 4~20mA current acquisition circuit further includes a first protection component connected to the positive terminal of the power output, a second protection component connected to the negative terminal of the power output, a third protection component connected to the first terminal of the sampling resistor, and a fourth protection component connected to the second terminal of the sampling resistor.

[0013] The second protection component is used to disconnect the connection between the negative terminal of the power output and the reference ground in the event of overcurrent or overvoltage.

[0014] The third protection component is used to disconnect the connection between the negative terminal of the transmitter and the first terminal of the sampling resistor in the event of overcurrent or overvoltage.

[0015] When the transmitter is powered by the same power supply that powers the current acquisition module, the first protection component is used to disconnect the connection between the positive terminal of the power supply output and the positive terminal of the transmitter in case of overcurrent or overvoltage, and the fourth protection component is used to disconnect the connection between the negative terminal of the power supply output and the second terminal of the sampling resistor in case of overcurrent or overvoltage.

[0016] When the transmitter is not powered by the same power supply that powers the current acquisition module, the fourth protection component is used to disconnect the connection between the positive terminal of the transmitter and the second terminal of the sampling resistor in the event of overcurrent or overvoltage.

[0017] In one specific embodiment of this application, the first protection component, the second protection component, the third protection component, and the fourth protection component are all resettable fuses.

[0018] In one specific embodiment of this application, the device further includes a first power conversion module disposed on a second circuit board. The power input terminal of the first power conversion module is used to connect to the first power output terminal of the system power supply that supplies power to the main controller via an external first switch and to the second power output terminal of the system power supply via an external second switch. The first power conversion module is used to convert the output voltage of the first power output terminal or the second power output terminal into the operating voltage of the control module and the second status acquisition module. The second status acquisition module is used to collect the on / off status of the circuit between the first power output terminal and the first power conversion module, and the circuit between the second power output terminal and the first power conversion module, respectively, and transmit them to the control module.

[0019] In one specific embodiment of this application, the device further includes a plurality of isolated second power conversion modules disposed on a first circuit board. The power input terminal of each second power conversion module is used to connect to the power input terminal of the first power conversion module. The power output terminal of each second power conversion module outputs the operating voltage required by each 4~20mA current acquisition circuit. The first status acquisition module is used to acquire the on / off state of the circuit between the power input terminal of the second power conversion module and the end of the first switch connected to the power input terminal of the first power conversion module, and transmit it to the control module.

[0020] In one specific embodiment of this application, the device further includes multiple bus transceiver modules disposed on a second circuit board. Multiple GPIO ports of the MCU unit are respectively connected to the first end of each of the bus transceiver modules. The signals acquired by the current acquisition module and the first status acquisition module are transmitted to the MCU unit through multiple of the GPIO ports of the MCU unit, the SPI interface of the MCU unit, and the second ends of each of the bus transceiver modules.

[0021] The above technical solution, based on the principles of board separation, multiple interface types, and functional expansion, improves the reliability, acquisition accuracy, and on-site deployment flexibility of the 4~20mA current acquisition device, and facilitates maintenance. The aforementioned functional expansion specifically refers to the acquisition of the power supply status of the power source supplying the current acquisition module and the control module.

[0022] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0024] Figure 1 The diagram shown is a block diagram of the current acquisition device provided in an embodiment of this application;

[0025] Figure 2 The diagram shown is a functional block diagram of the mainboard of the current acquisition device provided in an embodiment of this application;

[0026] Figure 3 The diagram shown is a functional block diagram of the sub-board of the current acquisition device provided in an embodiment of this application;

[0027] Figure 4 The diagram shown is a schematic of the external power supply mode;

[0028] Figure 5 The diagram shown is a schematic of the internal power supply mode. Detailed Implementation

[0029] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the embodiments of this application.

[0030] If the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0031] See Figure 1 This application provides a current acquisition device applied to an industrial control system, which includes a main controller and locally deployed slave controllers. The current acquisition device includes a first status acquisition module on a first circuit board, a current acquisition module comprising multiple electrically isolated 4-20mA current acquisition circuits, and a control module and a second status acquisition module on a second circuit board, wherein the second circuit board is located on the slave controller. The first circuit board has multiple types of interfaces, including multiple types of serial ports. Signals acquired by the first status acquisition module and the current acquisition module are transmitted to the control module via the multiple interfaces described above. The control module is connected to the main controller via a bus. The first status acquisition module is used to acquire the power supply status of the power supply to the current acquisition module. The second status acquisition module is used to acquire the power supply status of the power supply to the control module and transmit it to the control module.

[0032] In the above embodiments, the existing multi-channel isolated 4~20mA current acquisition device is improved based on the technical concept of board separation, multiple types of interfaces, and functional expansion. First, a board separation design is adopted, with the first state acquisition module and the current acquisition module located on the first circuit board, and the control module and the second state acquisition module located on the second circuit board. Second, communication between the first circuit board and the control module is realized through multiple types of interfaces, including multiple types of serial ports. Third, the functions of the existing current acquisition device that only performs 4~20mA current acquisition are expanded through the first state acquisition module and the second state acquisition module. Based on this, firstly, the channel isolation between different 4~20mA current acquisition circuits reduces the electrical interference experienced by the 4~20mA current acquired at different points, thereby improving the current acquisition accuracy. Secondly, the current acquisition module implemented in the above embodiment has greater flexibility in local deployment, mainly reflected in the design of the circuit board, multiple types of interfaces, and multiple types of serial ports. For example, when one control module controls multiple current acquisition modules and other types of data acquisition modules, one or more first circuit boards can be flexibly set to connect to the control module according to the actual location's multi-point 4~20mA current acquisition requirements. In addition, the distance between different acquisition points and the slave controller varies, and the design of multiple types of interfaces and multiple types of serial ports makes the configuration of the first circuit board in different locations more flexible. Furthermore, based on the design of the circuit board, multiple types of interfaces, and multiple types of serial ports, the current acquisition module implemented in the above embodiment is easy to maintain. Finally, the acquisition of power supply status enables the fault status of the current acquisition device to be detected in a timely manner, improving the reliability of the current acquisition device.

[0033] In summary, the embodiments described above improve the acquisition accuracy, reliability, and on-site deployment flexibility of the 4~20mA current acquisition device, and facilitate maintenance.

[0034] Specifically, in one embodiment of this application, the current acquisition module further includes an analog switch. The 4-20mA current acquisition circuit includes a sampling resistor, an amplifier, an AD converter, and a digital isolator for converting the 4-20mA current signal output from an external transmitter into a voltage signal. The amplifier is connected to the sampling resistor and the AD converter, and the AD converter is connected to the amplifier and the digital isolator. The analog switch is used to selectively connect one digital isolator to the control module and disconnect the remaining digital isolators from the control module. In a pair of ratios, the three discrete components—amplifier, AD converter, and digital isolator—are replaced by an integrated component. The integrated component is a precision fixed-gain amplifier or precision amplifier that integrates an isolated DC / DC converter. However, discrete components are easier to maintain and have a cost advantage. Simultaneously, the combined use of the isolation functions of the amplifier, the digital isolator, and the analog switch reduces electrical interference affecting the 4-20mA current data acquired at each point, thereby improving the current acquisition accuracy of the current acquisition device.

[0035] In the following embodiments, the first circuit board is referred to as the sub-board, and the second circuit board is referred to as the main board. Figure 3 The diagram shown is a functional block diagram of a sub-board. Figure 3 Eight 4~20mA current acquisition circuits are shown, numbered 1 through 8. Taking channel 1 as an example, AD in the 4~20mA current acquisition circuit in the figure represents an AD converter. Figure 3 The analog switches used are 8-to-1 analog switches, and the digital isolators are four-channel digital isolators.

[0036] In one specific embodiment of this application, the current acquisition device supports two power supply modes for the transmitter: an external power supply mode and an internal power supply mode. That is, by different wiring methods, the internal or external power supply mode can be selected and switched for a single channel according to the on-site deployment requirements of the current acquisition device. Specifically, the power supply to the current acquisition module has a positive output terminal and a negative output terminal. When the transmitter is not powered by the power supply to the current acquisition module, the negative terminal of the transmitter is connected to the first terminal of the sampling resistor, and the positive terminal of the transmitter is connected to the second terminal of the sampling resistor. When the transmitter is powered by the power supply to the current acquisition module, the positive terminal of the transmitter is connected to the positive output terminal of the power supply as described above, the negative terminal of the transmitter is connected to the first terminal of the sampling resistor, and the second terminal of the sampling resistor is connected to the negative output terminal of the power supply as described above. The wiring method when the transmitter is not powered by the power supply to the current acquisition module is the external power supply mode, as described above. Figure 4As shown. When the transmitter is powered by the same power supply that powers the current acquisition module, the wiring method is the internal power supply mode described above, as follows: Figure 5 As shown. Figure 4 and Figure 5 In the diagram, the 4~20mA current acquisition circuit has four external terminals: "Iin+", "Iin-", "24V+", and "24V-". The "Iin+" terminal connects to the first end of the sampling resistor, and the "Iin-" terminal connects to the second end of the sampling resistor. "24V+" and "24V-" indicate that the current acquisition module uses a 24V power supply. However, a non-24V power supply can also be used depending on the specific application. Figure 3 In the circuit, the first end of the sampling resistor is connected to the positive input terminal of the amplifier, and the second end of the sampling resistor is connected to the negative input terminal of the amplifier.

[0037] Based on the above specific embodiments, in an improved embodiment, the 4~20mA current acquisition circuit has four external terminals connected to components for overcurrent / overvoltage protection, namely: a first protection component connected to the positive power output terminal of the power supply powering the current acquisition module, a second protection component connected to the negative power output terminal of the power supply powering the current acquisition module, a third protection component connected to the first terminal of the sampling resistor, and a fourth protection component connected to the second terminal of the sampling resistor. Specifically, when the transmitter uses internal power supply mode, the first protection component is used to disconnect the connection between the positive power output terminal and the positive terminal of the transmitter in case of overcurrent or overvoltage. The second protection component is used to disconnect the connection between the negative power output terminal and the reference ground in case of overcurrent or overvoltage. The third protection component is used to disconnect the connection between the negative terminal of the transmitter and the first terminal of the sampling resistor in case of overcurrent or overvoltage. When the transmitter uses external power supply mode, the fourth protection component is used to disconnect the connection between the positive terminal of the transmitter and the second terminal of the sampling resistor in case of overcurrent or overvoltage. When the transmitter is in internal power supply mode, the fourth protection component is used to disconnect the connection between the negative terminal of the power output and the second terminal of the sampling resistor in case of overcurrent or overvoltage.

[0038] like Figure 3 As shown, the first, second, third, and fourth protection components are all resettable fuses. Each of the four external terminals in channels 1 through 8 is equipped with a resettable fuse. The first, second, third, and fourth protection components can also utilize devices such as TVS diodes that provide overcurrent / overvoltage protection. By installing the first, second, third, and fourth protection components at the four external terminals respectively, overcurrent / overvoltage protection is achieved, thereby improving the reliability of the current acquisition device.

[0039] In one example, a 4-20mA current is collected by a sampling resistor and then sequentially sent to a rail-to-rail operational amplifier via a resettable fuse, a common-mode inductor, a TVS diode, and an RC filter circuit.

[0040] In one specific implementation, the control module includes an MCU unit and an FPGA unit. The data acquired by the first state acquisition module and the current acquisition module are connected to the MCU unit via multiple of the aforementioned multi-type interfaces. The MCU unit is connected to the FPGA unit, and the FPGA unit is connected to the main controller via a bus. For example, the MCU unit can be an STM32 microcontroller. The FPGA unit expands the data processing capabilities and bus communication capabilities of the MCU unit, enabling the control module to acquire 4-20mA current from more channels and, in some applications, data from more non-current boards. This meets the diverse needs of locally deployed current acquisition devices, especially supporting a wider range of 4-20mA current acquisition channels.

[0041] In one specific embodiment, the current acquisition device further includes multiple RS485 communication modules connected to the FPGA unit on a second circuit board, each RS485 communication module being connected to a bus. This redundancy of the RS485 communication modules improves the reliability of the current acquisition device.

[0042] Figure 2The diagram shown is a functional block diagram of the motherboard in a specific embodiment of this application. The control module includes an STM32-type MCU unit and an FPGA unit. Furthermore, the MCU unit and the FPGA unit communicate via an interface logic module within the FPGA unit to implement HDLC interface logic transmission. The MCU unit transmits data to be stored to the storage unit within the FPGA unit. An external watchdog chip from STMicroelectronics is used. The STM32-type MCU unit feeds the watchdog every 500ms to ensure reliable microcontroller reset in case of program crashes. The STM32-type MCU unit is also connected to a 16MHz crystal oscillator and an RS232 module. The RS232 module is also connected to an RJ11 interface. The STM32-type MCU unit is also connected to an SWD download interface and status indicator lights. The FPGA unit is connected to an A-channel RS485 communication module and a B-channel RS485 communication module. The FPGA unit implements the parsing of the A-channel HDLC protocol and the B-channel HDLC protocol. The A-channel RS485 communication module includes a first RS485 module and a second RS485 module. The first RS485 module transmits RS485 clock signals, and the second RS485 module transmits RS485 data signals. The B-channel RS485 communication module includes a third RS485 module and a fourth RS485 module. The third RS485 module transmits RS485 clock signals, and the fourth RS485 module transmits RS485 data signals. The FPGA unit is also connected to a debug download interface and has an address detection module. The address detection module detects the card's address information in real time and then sends the collected address information to the MCU unit.

[0043] In one specific embodiment, the main controller is powered by the system power supply, and the control module and the second status acquisition module are also powered by the system power supply. Preferably, the system power supply provides two power supply lines to the control module and the second status acquisition module to ensure that if one power supply line is lost, the other power supply can be used, thereby ensuring the normal power supply to the motherboard. Specifically, the current acquisition device also includes a first power conversion module disposed on the second circuit board. The power input terminal of the first power conversion module is connected to the first power output terminal of the system power supply via a first switch and to the second power output terminal of the system power supply via a second switch. The first power conversion module is used to convert the output voltage of the first or second power output terminal of the system power supply into the operating voltage of the control module and the second status acquisition module. The second status acquisition module is used to collect the on / off status of the circuit between the first power output terminal of the system power supply and the first power conversion module, and the circuit between the second power output terminal of the system power supply and the first power conversion module, respectively, and transmit them to the control module. Two power supply lines are designed between the first power conversion module and the system power supply. This redundant design improves the reliability of the current acquisition device. As we know, the on / off state refers to the state of a circuit being connected or disconnected, and the state of connection or disconnection can be fed back through voltage or current signals.

[0044] For example, such as Figure 2 As shown in the diagram, the motherboard is powered by two 24V system power supplies, connected to the motherboard via a single 48-pin European connector, designated as channel A and channel B. The redundant two 24V power supplies are combined into one, converted to 5V by the first DC / DC module, then to 3.3V by the first LDO power module, and finally to 1.2V by the second LDO power module. The first power conversion module comprises a first DC / DC module, a first LDO power module, and a second LDO power module. The redundant 24V power detection module shown in the diagram is the second status acquisition module, which includes voltage sensors located on the line between the first power conversion module and the first power output terminal of the system power supply, as well as voltage sensors located on the line between the first power conversion module and the second power output terminal of the system power supply. For example, under the control of the main controller, the first switch is turned on and the second switch is kept in the off state. At this time, 24V power is connected through the first power output terminal of the system power supply to power the motherboard. If the MCU unit determines that there is an abnormality in the power supply line from the first power output terminal of the system power supply to the motherboard based on the voltage collected by the second state acquisition module, it reports to the main controller. The main controller turns on the second switch according to the information reported by the MCU unit, so that the motherboard is connected to 24V power through the second power output terminal of the system power supply to maintain normal power supply to the motherboard and ensure that the entire current acquisition device works normally.

[0045] In one specific embodiment, the current acquisition device further includes a plurality of isolated second power conversion modules disposed on the first circuit board. The power input terminal of each second power conversion module is used to connect to the power input terminal of the first power conversion module. The power output terminal of each second power conversion module outputs the working voltage required by each 4~20mA current acquisition circuit. The first state acquisition module is used to acquire the on / off state of the circuit between the power input terminal of the second power conversion module and the end of the first switch connected to the power input terminal of the first power conversion module, and transmit it to the control module.

[0046] For example, such as Figure 2 As shown in the diagram, after the two 24V system power supplies are connected through a 48-pin European connector on the motherboard, the redundant two 24V power supplies are combined into one 24V power supply. This one 24V power supply has two 24V voltage output branches. The first 24V voltage output branch powers the motherboard, and the second 24V voltage output branch powers the sub-board. The second 24V voltage output branch is introduced to the sub-board through a 2*7-pin connector on the motherboard. The 24V voltage introduced through this output branch is connected to the power input terminal of the second power conversion module. The second power conversion module includes an isolated second DC / DC module (…). Figure 3 The DC / DC converter shown) and the fourth LDO power module ( Figure 3 The LDO shown in the diagram), the second DC / DC module implements isolated 24V to 24V conversion, and the fourth LDO power module implements 24V to 5V conversion. The generated 5V voltage is used as the reference power supply shown in the diagram. The reference power supply powers the amplifier, AD converter, etc. Figure 3 The second power conversion module comprises eight modules. From top to bottom, the first module provides reference power to channel 1, the second to channel 2, the third to channel 3, the fourth to channel 4, the fifth to channel 5, the sixth to channel 6, the seventh to channel 7, and the eighth to channel 8. The field power detection module shown in the diagram is the first status acquisition module, which can be a voltage sensor installed in the circuit between the 24V voltage introduced to the sub-board via 2*7-pin connectors and the second power conversion module.

[0047] In one specific implementation, the multiple types of serial ports set on the first circuit board include SPI serial ports, other bus type serial ports, etc.

[0048] In one specific embodiment, the current acquisition device further includes multiple bus transceiver modules disposed on a second circuit board. Multiple GPIO ports of the MCU unit are respectively connected to the first terminals of each of the bus transceiver modules. Signals acquired by the current acquisition module and the first state acquisition module are transmitted to the MCU unit through multiple of the GPIO ports of the MCU unit, the SPI interface of the MCU unit, and the second terminals of each bus transceiver module. The isolation effect of the bus transceiver modules improves the acquisition accuracy of the current acquisition device.

[0049] like Figure 2 As shown, the motherboard is connected to the sub-board via a 2*28PIN header, and the bus transceiver module is a bus transceiver.

[0050] In a specific application, to acquire 8 channels of 4~20mA current, the MCU unit outputs a signal via the SPI1 serial port to control the analog switch to perform the selection function. This signal reaches the analog switch after passing through the aforementioned 2*28 pin connector. The analog switch also outputs a signal acquired by one of the current acquisition circuits. This signal reaches the SPI1 serial port of the MCU unit after passing through the aforementioned 2*28 pin connector. The signal acquired by the first state acquisition module reaches a GPIO port of the MCU unit after passing through the aforementioned 2*28 pin connector.

[0051] In another specific application, to acquire 16 channels of 4~20mA current, for 8 of these 4~20mA currents, the MCU unit outputs a signal via the SPI1 serial port to control the analog switch to perform the selection function. This signal reaches the analog switch after passing through the aforementioned 2*28-pin connector. The analog switch also outputs a signal acquired by one of the current acquisition circuits. This signal reaches the MCU unit's SPI1 serial port after passing through the aforementioned 2*28-pin connector. The signal acquired by the first state acquisition module reaches a GPIO port of the MCU unit after passing through the aforementioned 2*28-pin connector. For the other 8 channels of 4~20mA current, the MCU unit outputs a signal via the bus transceiver to control the analog switch to perform the selection function, receives the signal acquired by the current acquisition circuit, and receives the signal acquired by the first state acquisition module.

[0052] application Figure 2 The motherboard shown and Figure 3The process of the sub-board acquiring 8 channels of 4~20mA current is as follows. First, the sub-board is connected via 2*28PIN and 2*7PIN pins on the main board, and a bus is connected via a 48PIN European pin. The A-channel 24V system power supply and the B-channel 24V system power supply are connected to the main board via the aforementioned 48PIN European pin, and are combined into one 24V power supply. This 24V power supply is introduced into the sub-board via the 2*7PIN pin. This 24V power supply is also connected to the first DC / DC module. The first DC / DC module converts the 24V power supply to 5V. The generated 5V voltage powers the MCU unit. The 5V voltage is also converted to 3.3V by the first LDO module. The generated 3.3V voltage is further converted to 1.2V by the second LDO module. Both the 3.3V and 1.2V voltages are used as the power supply voltage for the FPGA unit. The 5V voltage generated by the first DC / DC module and the 3.3V voltage generated by the first LDO power supply module are both connected to the sub-board via the aforementioned 2*7PIN pin. Each transmitter to be acquired for current signal is connected to the external terminals of the respective current acquisition circuit in a corresponding manner, either through external power supply mode or internal power supply mode. The "24V+" terminal is connected to the second DC / DC module via a resettable fuse. In internal power supply mode, for channel 1, terminal A1 is connected to the negative terminal of the first transmitter, terminal B1 is connected to 24V-, and the positive terminal of that transmitter is connected to 24V+. For channel 2, terminal A2 is connected to the negative terminal of the second transmitter, terminal B2 is connected to 24V-, and the positive terminal of that transmitter is connected to 24V+. For channel 8, terminal A8 is connected to the negative terminal of the eighth transmitter, terminal B8 is connected to 24V-, and the positive terminal of that transmitter is connected to 24V+. In external power supply mode, for channel 1, terminal A1 is connected to the negative terminal of the first transmitter, and terminal B1 is connected to the positive terminal of that transmitter. For channel 2, terminal A2 is connected to the negative terminal of the second transmitter, and terminal B2 is connected to the positive terminal of that transmitter. For channel 8, terminal A8 is connected to the negative terminal of the eighth transmitter, and terminal B8 is connected to the positive terminal of that transmitter. After completing the above connections, the MCU unit acquires the 4~20mA current signal output from each transmitter, the power supply status of the sub-board, and the power supply status of the main board. The acquired data is then transmitted to the main controller via the FPGA unit. The main controller uses this acquired data to implement alarms for redundant 485 communication faults, over-measurement limit faults, AD converter faults, redundant system power supply faults, and field power supply faults.

[0053] It should also be noted that this application does not involve improvements to the method. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such 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 this application.

Claims

1. A current acquisition device, applied in an industrial control system, the industrial control system comprising a main controller and locally deployed slave controllers, characterized in that, The device includes a first status acquisition module located on a first circuit board and a current acquisition module including multiple electrically isolated 4~20mA current acquisition circuits, as well as a control module and a second status acquisition module located on a second circuit board, the second circuit board being disposed on the slave controller; The first status acquisition module is used to acquire the power supply status of the power supply that powers the current acquisition module; The second status acquisition module is used to acquire the power supply status of the power supply that powers the control module and transmit it to the control module; The first circuit board is provided with multiple types of interfaces, including multiple types of serial ports. The signals collected by the first status acquisition module and the current acquisition module are transmitted to the control module through multiple interfaces. The control module is connected to the main controller through a bus.

2. The current acquisition device according to claim 1, characterized in that, The control module includes an MCU unit and an FPGA unit. The signals acquired by the first status acquisition module and the current acquisition module are transmitted to the MCU unit through multiple interfaces. The MCU unit is connected to the FPGA unit, and the FPGA unit is connected to the main controller via a bus.

3. The current acquisition device according to claim 2, characterized in that, The device also includes a plurality of RS485 communication modules connected to the FPGA unit on a second circuit board, each of the RS485 communication modules being connected to the bus.

4. The current acquisition device according to claim 1, characterized in that, The current acquisition module also includes an analog switch. The 4~20mA current acquisition circuit includes a sampling resistor, an amplifier, an AD converter, and a digital isolator for converting the 4~20mA current signal into a voltage signal. The amplifier is connected to the sampling resistor and the AD converter respectively. The AD converter is connected to the amplifier and the digital isolator respectively. The analog switch is used to select and connect one digital isolator to the control module and disconnect the remaining digital isolators from the control module.

5. The current acquisition device according to claim 1, characterized in that, The power supply for the current acquisition module has a positive output terminal and a negative output terminal. The 4~20mA current acquisition circuit includes a sampling resistor that converts the 4~20mA current signal output by the external transmitter into a voltage signal. When the transmitter is not powered by the power supply for the current acquisition module, the negative terminal of the transmitter is connected to the first terminal of the sampling resistor, and the positive terminal of the transmitter is connected to the second terminal of the sampling resistor. When the transmitter is powered by the power supply for the current acquisition module, the positive terminal of the transmitter is connected to the positive output terminal of the power supply, the negative terminal of the transmitter is connected to the first terminal of the sampling resistor, and the second terminal of the sampling resistor is connected to the negative output terminal of the power supply.

6. The current acquisition device according to claim 5, characterized in that, The 4~20mA current acquisition circuit further includes a first protection component connected to the positive terminal of the power output, a second protection component connected to the negative terminal of the power output, a third protection component connected to the first terminal of the sampling resistor, and a fourth protection component connected to the second terminal of the sampling resistor. The second protection component is used to disconnect the connection between the negative terminal of the power output and the reference ground in the event of overcurrent or overvoltage. The third protection component is used to disconnect the connection between the negative terminal of the transmitter and the first terminal of the sampling resistor in the event of overcurrent or overvoltage. When the transmitter is powered by the same power supply that powers the current acquisition module, the first protection component is used to disconnect the connection between the positive terminal of the power supply output and the positive terminal of the transmitter in case of overcurrent or overvoltage, and the fourth protection component is used to disconnect the connection between the negative terminal of the power supply output and the second terminal of the sampling resistor in case of overcurrent or overvoltage. When the transmitter is not powered by the same power supply that powers the current acquisition module, the fourth protection component is used to disconnect the connection between the positive terminal of the transmitter and the second terminal of the sampling resistor in the event of overcurrent or overvoltage.

7. The current acquisition device according to claim 6, characterized in that, The first protection component, the second protection component, the third protection component, and the fourth protection component are all resettable fuses.

8. The current acquisition device according to claim 1, characterized in that, The device further includes a first power conversion module disposed on a second circuit board. The power input terminal of the first power conversion module is used to connect to the first power output terminal of the system power supply that supplies power to the main controller via an external first switch and to the second power output terminal of the system power supply via an external second switch. The first power conversion module is used to convert the output voltage of the first power output terminal or the second power output terminal into the operating voltage of the control module and the second status acquisition module. The second status acquisition module is used to collect the on / off status of the circuit between the first power output terminal and the first power conversion module, and the circuit between the second power output terminal and the first power conversion module, respectively, and transmit them to the control module.

9. The current acquisition device according to claim 8, characterized in that, The device further includes multiple isolated second power conversion modules disposed on the first circuit board. The power input terminal of each second power conversion module is used to connect to the power input terminal of the first power conversion module. The power output terminal of each second power conversion module outputs the operating voltage required by each 4~20mA current acquisition circuit. The first status acquisition module is used to acquire the on / off state of the circuit between the power input terminal of the second power conversion module and the end of the first switch connected to the power input terminal of the first power conversion module, and transmit it to the control module.

10. The current acquisition device according to claim 2, characterized in that, The device also includes multiple bus transceiver modules disposed on a second circuit board. Multiple GPIO ports of the MCU unit are respectively connected to the first end of each of the bus transceiver modules. The signals acquired by the current acquisition module and the first status acquisition module are transmitted to the MCU unit through multiple of the GPIO ports of the MCU unit, the SPI interface of the MCU unit, and the second ends of each of the bus transceiver modules.

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