Controller Device Supporting Simultaneous 4-20mA Current Loop Signal and RS-485 Communication Based on a Two-Wire Structure

Abstract

The present invention relates to a controller device that simultaneously supports 2-wire current loop-based communication, which can be applied to level gauge systems used in various fields such as industrial facilities, environmental management facilities, and various storage facilities, and particularly in environments where wiring between the sensor and the controller is limited or additional wiring work is difficult, and which can simultaneously support 4-20mA signals and RS-485 communication based on a single 2-wire current loop. In a water level measuring device, the water level measuring device is equipped with a field installation unit installed at the site to supply power to the water level measuring device using a DC component through a two-wire transmission line, and to transmit a 4-20mA current loop signal by modulating the DC component, and to simultaneously transmit and receive a digital communication signal in the RS-485 format using a differential signal line AB, which is an AC component of the same two-wire transmission line, and a controller device equipped with a control receiving unit capable of receiving and controlling the signal. Accordingly, the present invention has the advantage that a controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication can supply power with a DC component through the same 2-wire transmission line, transmit a 4-20mA loop signal by modulating the DC component, and simultaneously transmit and receive RS-485 digital communication signals using a differential signal line which is an AC component.

Description

Technology Field

[0001] The present invention relates to an industrial water level gauge and sensor control system, and more specifically, to a controller device that simultaneously supports 2-wire current loop-based communication, which can be applied to water level gauge systems used in various fields such as industrial facilities, environmental management facilities, and various storage facilities, and particularly in environments where wiring between a sensor and a controller is limited or additional wiring work is difficult, and which can simultaneously support a 4-20mA signal and RS-485 communication based on a single 2-wire current loop. Background Technology

[0002] Conventional water level gauge systems widely adopt a two-wire method to simultaneously perform power supply and current signal transmission. This method has a structure that supplies power to the sensor through two wires while simultaneously transmitting the measurement signal generated by the sensor through the same path. Generally, a 4-20mA current loop is used, and the current value output from the sensor is converted in proportion to the measured water level and transmitted to the controller.

[0003] The above existing controller is a two-wire structure that interprets this current value to obtain water level information and performs control operations based on it. It is designed to minimize the number of wires while simultaneously supplying power and transmitting signals, and has been utilized as a basic water level measurement method in various fields, such as industrial facilities and environmental management facilities.

[0004] Existing 2-wire communication methods have been widely used in a structure that performs power supply and current signal transmission through the same wiring, but they have inherent limitations in that they cannot include communication functions. Measurement signals generated by such sensors are simply converted into 4-20mA current values ​​and transmitted to the controller, making bidirectional data exchange—such as changing sensor settings or controlling their status—impossible. Consequently, users cannot remotely control or diagnose the operation of the sensor, and face the inconvenience of having to physically access the site to change settings when necessary, as well as the risk of safety accidents. In particular, for sensors installed in dangerous or hard-to-access locations, these structural constraints pose significant problems for worker safety and system operational efficiency.

[0005] To solve these conventional problems, technology has been applied to configure two additional separate RS-485 communication lines for changing sensor settings or controlling the state. As a result, the entire system has a 4-wire structure, and configuring 4-20mA and RS-485 separately has been widely used as a general communication method.

[0006] In this field, various prior art related to industrial water level gauges and sensor control systems is already known.

[0008] For example, in Korean Registered Patent Publication No. 10-0995677 (Publication Date: Nov. 19, 2010), “a measuring unit (100) equipped with a plurality of measuring sensors (101~105) to measure information related to the water quality of water; a data receiving unit (200) individually connected to the plurality of measuring sensors (101~105) to receive information related to the water quality of water and process the received information through computation; a data collecting unit (400) that integrally collects and simultaneously processes the information related to the water quality of water processed from the data receiving unit (200); a controller unit (500) that controls the operation of the measuring unit (100) and the data collecting unit (400) and transmits the information processed from the data collecting unit (400) through data communication with an external device; and a controller unit (500) that performs communication with the controller unit (500) and uses the transmitted information to control the measuring unit (100), the data collecting unit (400), and the An automation control unit (600) that transmits control commands via a PLC to a controller unit (500); and a data display unit (700) that displays information transmitted through the controller unit (500) are included in a multi-item multi-water quality measurement system, wherein the water quality information of the water includes at least one of hydrogen ion concentration (pH), oxidation-reduction potential (ORP), dissolved oxygen (DO), electrical conductivity, activated sludge suspended solids concentration (MLSS), suspended solids concentration (SS), turbidity, sodium, and silica, and the data receiving unit (200) includes a switch unit (220) that turns the power supply on and off; a cycle display unit (221) that displays the collection cycle of the water quality information of the water set by the controller unit (500); a transmission / reception display unit (222, 223) that displays whether data is transmitted or received with the data collection unit (400); and the plurality of A sensor connection rack (200a) is provided, which includes sensor connection terminals (224, 225) that are directly connected to measurement sensors (101~105), and the controller unit (500) comprises a switch unit (501) for turning power supply on and off;A multi-item multi-water quality measurement system is provided, comprising: a period display unit (502) for displaying a collection cycle of water quality-related information that is preset; a transmission / reception display unit (503, 504) for displaying whether data is transmitted or received with the data collection unit (400); and a data communication rack (500a) having signal receiving terminals (505, 506) such that if the water quality-related information received from the data receiving unit (200) or the data collection unit (400) is an analog signal, it is received via an analog terminal of 4~20mA, and if it is a digital signal, it is received via a digital terminal of RS232 or RS485; wherein the data display unit (700) is provided with a correction unit (C) in which the transmitted information can be independently corrected;

[0010] In addition, Korean Registered Patent Publication No. 10-2175898 (Publication Date: Nov. 06, 2020) describes a “communication method enabling communication between a DC power source and digital data by connecting a master device and a plurality of slave devices in a two-wire non-polar manner; wherein the master device uses voltage fluctuations of the line as a data generation signal, and the slave device is the master device

[0011] Communicate by increasing or decreasing the consumption of the current supplied from and using it as a data generation signal.

[0012] The master device acquires data by inputting a communication pulse of a certain width into the receiver of the built-in communication device, wherein two comparators embedded in the master MCU interrupt the pulse generated by the current consumption at the rising edge; the slave device acquires data by inputting the communication pulse of a certain width into the receiver of the built-in communication device, wherein the voltage fluctuation signal received from the master device generates an interrupt at the rising edge by two comparators embedded in the slave MCU, which are wired to operate in opposite directions; the MCU acquires data by inputting the communication pulse of a certain width into the receiver of the built-in communication device, wherein the master device detects the rising edge of the transformer and uses it for communication as a signal that generates the start and end of a square wave;The above-mentioned slave device uses signals to generate the start and end of a square wave, and the above-mentioned two-wire digital data communication method capable of DC power supply uses two different voltage sources for voltage fluctuation; the transmission of the above-mentioned master device uses two different voltage sources for voltage fluctuation and utilizes voltage fluctuation, while the transmission of the slave device uses current fluctuation to retransmit data received by the master device to the slave; when the above-mentioned master device sends data to the slave device, it utilizes voltage fluctuation of the line, and when the above-mentioned slave device sends data to the master device, it adds or subtracts its own current consumption from the power supplied by the master to implement both DC power supply and digital data communication; when transmitting data from the master device to the slave device, the two power supplies are switched to change the voltage level, a timer is activated using voltage fluctuation of the line as a signal, and the output of the timer is used as data; a certain delay is given between the call and response of the master device and the slave device to indicate that the transmission of the communication packet has ended, and since the response data of the slave device can only be received by the master, data transfer between slave devices is slave There is a “2-wire digital data communication method capable of supplying DC power,” characterized in that a master device receiving data from a device retransmits data from a slave device to share data between slave devices, slave calls are time-divided in a round-robin manner, and when the master retransmits to another slave after receiving a slave response signal, a constant current circuit composed of a fixed resistor of a slave constant voltage circuit is used;

[0014] In addition, Korean Registered Patent Publication No. 10-2611816 (Publication Date: Dec. 07, 2023) describes a “control system for a three-phase four-wire inverter for compensating for voltage imbalance in four phases (a, b, c, N) by controlling a three-phase four-wire voltage-type inverter, comprising: a voltage control unit that calculates a command value for an inductor current of an output filter from the capacitor voltage of the output filter of the three-phase four-wire inverter for each of the four phases; and a current control unit that generates four phase voltage command values ​​for controlling a switch of the three-phase four-wire inverter using the command value for the inductor current, characterized by comprising a three-phase four-wire inverter control system.”

[0016] In addition, Korean Registered Patent Publication No. 10-2616885 (Publication Date: Dec. 21, 2023) describes a “powerless digital indicator that displays a sensing value detected by a transmitter operating by receiving 4~20mA DC from a power source through a two-wire loop wiring, wherein the indicator operates by receiving a portion of the output current of the transmitter without a separate power supply, and comprises: a comparison unit that compares the current sensing value, which is the output current of the transmitter, with a previous sensing value, outputs a first signal if they are the same, and outputs a second signal if they are different; a switch unit that selects a first path to cut off power consumption when the first signal from the comparison unit is input, and selects a second path to transmit the output current of the transmitter to display the current sensing value when the second signal is input; a power generation unit that receives and converts the output current of the transmitter by the switch unit that receives the second signal and outputs power; a microcontroller that receives the power output from the power generation unit and calculates the current sensing value; and the micro A “powerless digital indicator” is known, characterized by including a digital paper display that digitally displays a current sensing value calculated from a controller, and maintains the display without consuming power after display.

[0018] As described above, Korean registered patent publication No. 10-0995677 (publication date: Nov. 19, 2010) aims to provide a multi-item multi-water quality measurement system that allows for maintenance and repair without affecting each measurement channel through multiple measurement sensors by constructing and controlling multiple measurement sensors that measure water quality-related information of multiple items into a single integrated system. However, by separately providing an analog terminal of 4~20mA and a signal receiving terminal that receives via a digital terminal of RS232 or RS485, the structure of the overall data communication rack becomes a 4-wire structure, which causes the structure of the equipment wiring to increase excessively. Consequently, there are problems such as increased construction costs for production facilities, increased maintenance costs and repair time, and structural problems that make it difficult to apply to existing facilities.

[0020] In addition, Korean Registered Patent Publication No. 10-2175898 (Publication Date: Nov. 06, 2020) describes a communication method in which a master device and a plurality of slave devices are connected in a two-wire non-polar manner to enable communication between a DC power source and digital data; The purpose is to provide a two-wire digital data communication method capable of DC power supply, characterized in that the master device uses voltage fluctuations of the line as a data generation signal, and the slave device communicates by increasing or decreasing the consumption of the current supplied from the master device as a data generation signal. However, since the focus is on the data transmission and reception interface, there is a problem in that it cannot directly process the 4~20mA analog loop signal commonly used in sensors. Additionally, although a process is required to convert the current value output by the water level sensor into voltage or digitize it through an ADC, there is a problem in that this function is not included in the circuit. Furthermore, in a significant number of water level sensors, power and signals flow through the same line in a two-wire loop power structure, but this circuit has a structure that receives +3.3V and +12V separately, so there is a problem in that it is not compatible with the loop method, and therefore, there is a problem in that the power structure is not suitable for direct connection to the sensor.

[0022] In addition, Korean registered patent publication No. 10-2611816 (Date of publication: Dec. 07, 2023) aims to provide a 3-phase 4-wire inverter control system that can reduce computational load and complexity by reducing the number of compensators for unbalanced load voltage compensation and simplifying the modulation technique. However, this circuit has structural problems in that it cannot directly process the 4~20mA analog loop or RS485 digital communication signal output by the water level sensor, and it has problems in that it does not include a function to receive, convert, or transmit sensor data. Furthermore, since it operates centered on voltage and current control loops, the control objective is different from the purpose of measuring physical quantities such as water level measurement. It simply converts physical height into current or digital data and transmits it, but since this circuit is a control structure for the stable operation of a power conversion device, the purpose itself is not suitable. Moreover, it is used in environments with high humidity, temperature changes, and electrical noise, but this circuit has problems in that it does not consider insulation, waterproofing, and surge protection functions required for industrial sensor environments, resulting in low reliability.

[0024] Furthermore, Korean Registered Patent Publication No. 10-2616885 (Publication Date: Dec. 21, 2023) aims to provide a power-free digital indicator that minimizes power consumption by using a two-wire loop current that is selectively supplied to the transmitter only when necessary without a separate power source. However, first, the 4~20mA signal is an analog method based on a current loop, expressing the physical quantity of the sensor as the current value itself. Since this structure allows power and the signal to flow through the same two wires, it has strengths in long-distance transmission and noise immunity. On the other hand, RS485 is a digital communication method based on differential voltage that requires separate transmit and receive lines to transmit data frames. Therefore, the two methods differ in their physical transmission principles and requirements, leading to the problem that they cannot be carried simultaneously on the same two wires.

[0025] In addition, the 2-wire loop is essentially a structure that integrates power supply and signal transmission into a single path, but RS485 requires an independent communication line. Because of this, if the two signals are run in parallel, a collision occurs, and neither can operate normally. Furthermore, RS485 requires a higher-level protocol such as Modbus RTU, but since the analog loop does not have this concept, there is a problem that the two signals cannot be interpreted simultaneously on the same line.

[0027] As mentioned above, this necessitated the additional configuration of a separate RS-485 communication line to change the sensor's setting values ​​or control its status; consequently, this resulted in the entire system becoming complex with a 4-wire structure, leading to increased installation costs and time.

[0028] In particular, since most existing sites are equipped with only two-wire wiring, additional wiring work is often physically difficult or impossible. Consequently, applying communication functions requires users to visit dangerous or hard-to-access sites in person to perform setup and inspection, which adds to the inconvenience and safety issues.

[0029] In addition, conventional controllers have the terminal block and control board configured as a single unit in industrial settings, which presents a problem where maintenance or after-sales service is difficult because all wiring must be disconnected in the event of a failure.

[0030] This poses a problem by increasing work inconvenience and halting system operations, thereby significantly reducing on-site efficiency, and thus, improvement measures are currently required. Prior art literature

[0031] · Korean Registered Patent Publication No. 10-0995677 (Publication Date: Nov. 19, 2010) · Korean Registered Patent Publication No. 10-2175898 (Publication Date: Nov. 06, 2020) · Korean Registered Patent Publication No. 10-2611816 (Publication Date: Dec. 07, 2023) · Korean Registered Patent Publication No. 10-2616885 (Publication Date: Dec. 21, 2023)

[0032] doesn't exist The problem to be solved

[0033] Accordingly, the present invention was devised to solve the aforementioned problems and provides a controller device capable of supplying power with a DC component through the same two-wire transmission line, transmitting a 4-20mA loop signal by modulating the DC component, and simultaneously transmitting and receiving RS-485 digital communication signals using differential signal line AB, which is an AC component. This enables the simultaneous processing of power supply, analog loop signals, and digital communication on a single two-wire transmission line, thereby simplifying the wiring structure and facilitating installation and maintenance.

[0034] In addition, a current loop driver, a loop receiver, an RS-485 transmitter, and a receiver are each independently provided to enable parallel processing of analog and digital signals, and resistors, capacitors, and inductors are placed at the loop terminals to stably separate and combine DC and AC components, thereby ensuring communication stability.

[0035] In addition, the objective is to provide a controller device that simultaneously supports 2-wire current loop-based 4-20mA signals and RS-485 communication, which can significantly improve field maintainability by adopting a terminal block board and a docking connector structure to allow the main control board, LCD board, and case to be selectively replaced and repaired, thereby enabling partial repair without disconnecting the entire wiring in the event of a failure. means of solving the problem

[0036] In order to overcome the limitations of a conventional two-wire water level gauge system, the present invention comprises, as illustrated in FIGS. 1 and 2, a water level sensor (not shown) installed inside a storage tank and a controller device comprising a receiver unit that converts analog information of the water level sensor (not shown) into a 4-20mA loop current, receives water level data through a two-wire transmission line, and converts it into a digital signal, wherein the controller device supplies power to a water level measuring device using a DC component through a two-wire transmission line, modulates the DC component to transmit a 4-20mA current loop signal, and is equipped with a field installation unit installed at the site to simultaneously transmit and receive RS-485 digital communication signals using a differential signal line AB, which is an AC component of the same two-wire transmission line, and a control receiving unit capable of receiving and controlling the signal.

[0037] delete

[0038] The above-mentioned field installation unit is equipped with a current loop driving unit that processes a measurement signal from a water level measuring sensor to generate a loop current and supplies it to an external circuit, and

[0039] In addition to the above-mentioned current loop driving unit, an RS-485 communication transmitter is provided to enable the transmission of digital communication signals through the same two-wire transmission line, and

[0040] The above control receiving unit is equipped with a current loop receiver that detects the loop current, converts it into a digital signal, and processes it, and

[0041] In addition to the above-mentioned current loop receiver, an RS-485 communication receiver is provided to receive digital communication signals through the same two-wire transmission line, and

[0042] The above RS-485 communication transmitter and RS-485 communication receiver are connected via differential signal line AB, and the above differential signal line AB is coupled via loop terminals including LOOP+ and LOOP-.

[0043] The above-mentioned loop terminal section is equipped with a resistor, a capacitor, and an inductor for separating and combining the DC and AC components of the loop current, and

[0044] A control receiving unit for connecting the field wiring bundles of the two-wire transmission lines of each water level measuring sensor installed in the field installation unit, and

[0045] The above control receiving unit comprises a terminal block board, and the terminal block board is provided with a docking connector, and a main control board having a detachable docking structure that is electrically connected by providing a connection connector corresponding to the docking connector is stacked thereon, wherein the main control board is provided with a current loop receiver and an RS-485 communication receiver.

[0046] An LCD board for display output is provided on the upper side of the main control board, and a case structure is provided on the upper side in which a plastic case is integrally provided with a terminal block board.

[0047] The above current loop driving unit comprises an MCU that processes a measurement signal from a water level sensor, and

[0048] It may be configured to include a digital-to-analog converter DAC that converts the output signal of the MCU into an analog signal, and a current loop driver that generates a 4-20mA loop current based on the signal of the DAC and supplies it to an external circuit.

[0049] The above current loop receiver may be configured to include a RESENSE that detects a 4-20mA loop current, an MCU that filters the detected signal through a low-pass filter (LPF), converts the filtered signal into a digital signal through an analog-to-digital converter (ADC), and processes the digital signal.

[0050] The above case structure can be configured to integrate communication signal processing and power supply functions, while allowing the main control board, LCD board, and plastic case to be selectively replaced and repaired without disconnecting the entire wiring in the event of a failure.

[0051] The above RS-485 communication transmitter may include an RS-485 transceiver separately from the above current loop driver, and the transceiver may be configured to include an RS-485 communication transmitter comprising an RO terminal that outputs a transmission signal, a DI terminal that receives a reception signal, and a bias circuit.

[0052] The above RS-485 communication receiver is configured separately from the above current loop receiver and includes an RS-485 transceiver, and the transceiver may be equipped with an RS-485 communication receiver including a DI terminal for receiving a reception signal, an RO terminal for outputting received data, and a bias circuit.

[0053] The above transceiver performs digital communication through differential signal line AB, and the bias circuit may be equipped with pull-up and pull-down resistors to maintain a stable voltage level even in an idle state.

[0054] The above controller device is equipped with a noise filtering circuit to suppress electrical noise generated in an external environment, and the noise filtering circuit may be equipped to improve the stability of current loop signals and RS-485 digital communication signals.

[0055] The above plastic case may be equipped with a waterproof and dustproof structure to protect the internal substrate from moisture, dust, and contamination in the external environment.

[0056] The above controller device may be configured to store water level data and communication status in internal memory so as to record and retrieve data logs for a certain period, and

[0057] The above controller device is configured to perform a remote diagnostic function via RS-485 communication to transmit status information of the sensor and whether an error has occurred to an external control system, and is configured to allow changing and monitoring sensor setting values ​​remotely via RS-485 communication.

[0058] delete Effects of the invention

[0059] The controller device of the present invention, which simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication as described above, supplies power with a DC component through the same 2-wire transmission line, transmits a 4-20mA loop signal by modulating the DC component, and simultaneously transmits and receives digital communication signals in the RS-485 format using a differential signal line which is an AC component.

[0060] In addition, it has the advantage of effectively resolving the problem of parallel transmission of analog and digital signals that occurred in the existing two-wire loop method, and

[0061] In addition, by independently providing a current loop driver, a loop receiver, an RS-485 transmitter, and an RS-485 receiver, analog and digital signals can be processed in parallel, which has the advantage of simultaneously ensuring the accuracy of water level data and communication stability.

[0062] In addition, by placing resistors, capacitors, and inductors in the loop terminal section, DC and AC components can be stably separated and combined, which has the advantage of providing effective noise suppression and long-distance transmission.

[0063] In addition, by adopting a docking connector structure that allows the main control board, LCD board, and case to be selectively replaced and repaired, partial repairs can be performed without disconnecting the entire wiring in the event of a failure, thereby offering the advantage of significantly improving on-site maintainability.

[0064] Therefore, it has the advantage of reducing installation and management costs and enhancing the convenience of field workers, and

[0065] In addition, by being equipped with a noise filtering circuit to suppress electrical noise generated in the external environment, there is an advantage of being able to improve the stability of current loop signals and RS-485 digital communication signals, and

[0066] The plastic case includes a waterproof and dustproof structure to protect the internal circuit board from moisture, dust, and contamination, thereby ensuring stable operation even in harsh environments, and

[0067] Furthermore, the controller device has the advantage of being able to store water level data and communication status in internal memory to record and retrieve data logs for a certain period, and to perform remote diagnostic functions via RS-485 communication to transmit sensor status information and whether an error has occurred to an external control system.

[0068] In addition, this invention is expected to have a truly great advantage in that it allows for remote changes and monitoring of sensor settings, enabling system management without the need for access by field workers. Brief explanation of the drawing

[0069] FIG. 1 is a flowchart showing the controller device of the present invention. FIG. 2 is an embodiment diagram of a control receiving unit configured in the controller device of the present invention. Specific details for implementing the invention

[0070] The present invention provides a controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, comprising:

[0071] A controller device (A) comprising a water level sensor (not shown) installed inside a storage tank, and a receiver that converts analog information of the water level sensor (not shown) into a 4-20mA loop current, receives water level data through a two-wire transmission line, and converts it into a digital signal,

[0073] As illustrated in FIGS. 1 and 2, the controller device (A) supplies power to a water level measuring device using a DC component through two-wire transmission lines (L1)(L2), modulates the DC component to transmit a 4-20mA current loop signal (500)(580), and is equipped with a field installation unit (100) installed at the site to simultaneously transmit and receive RS-485 digital communication signals using a differential signal line AB, which is an AC component of the same two-wire transmission lines (L1)(L2), and a control receiving unit (200) capable of receiving and controlling the signal.

[0075] As illustrated in FIG. 1, the field installation unit (100) is,

[0076] A current loop driving unit (110) that processes a measurement signal from a water level measuring sensor to generate a loop current and supplies it to an external circuit, and

[0077] In addition to the above current loop driving unit (110), an RS-485 communication transmitting unit (300) is provided separately to enable the transmission of digital communication signals through the same two-wire transmission line, and

[0079] As illustrated in FIGS. 1 and 2, the control receiving unit (200) is,

[0080] A current loop receiver (210) that detects the loop current, converts it into a digital signal, and processes it, and

[0081] In addition to the above current loop receiver (210), an RS-485 communication receiver (400) is provided separately to receive digital communication signals through the same two-wire transmission line, and

[0083] The above RS-485 communication transmitter (300) and RS-485 communication receiver (400) are connected via differential signal line AB, and the differential signal line AB is coupled via a loop terminal (C) including LOOP+ (500) and LOOP- (580).

[0085] The above loop terminal section (C) is equipped with a resistor (316), a capacitor (550, 590), and an inductor (510) for separating and combining the DC and AC components of the loop current, and

[0087] A control receiving unit (200) for connecting field wiring bundles of 2-wire transmission lines (L1)(L2) of each water level measuring sensor installed in the field installation unit (100), and

[0089] As illustrated in FIG. 1, the control receiving unit (200) is provided with a terminal block board (251), and the terminal block board (251) is provided with a docking connector (252), and a main control board (260) is stacked and arranged to have a detachable docking structure that is electrically connected by providing a connection connector (255) corresponding to the docking connector (252), wherein the main control board (260) is provided with a current loop receiver (210) and an RS-485 communication receiver (400).

[0091] As shown in FIG. 2, the upper side of the main control board (260) is provided with an LCD board (270) for display output, and the upper side is provided with a plastic case (280) that is integrally provided with the terminal block board (251).

[0093] The above current loop driving unit (110) is,

[0094] An MCU (10) that processes a measurement signal from a water level measurement sensor, and

[0095] A digital-to-analog converter DAC (112) that converts the output signal of the above MCU (10) into an analog signal, and

[0096] It may be configured to include a current loop driver that generates a 4-20mA loop current based on the signal of the DAC (112) and supplies it to an external circuit, and

[0098] The above current loop receiver (210) is,

[0099] A RESENSE (211) that detects a 4-20mA loop current, and

[0100] The above-mentioned detected signal is filtered through a low-pass filter LPF (212), and

[0101] The above filtered signal is converted into a digital signal through an analog-to-digital converter (ADC) (213), and

[0102] It may be configured to include an MCU (214) that processes the digital signal, and

[0104] The above plastic case (280) is,

[0105] It can be configured to integrate communication signal processing and power supply functions, while allowing the main control board (260), LCD board (270), and plastic case (280) to be selectively replaced and repaired without disconnecting the entire wiring in the event of a failure.

[0107] The above RS-485 communication transmitter (300) is,

[0108] In addition to the above current loop drive unit (110), an RS-485 transceiver (310) is included separately.

[0109] The above transceiver (310) has an RO terminal (313) that outputs a transmission signal, and

[0110] It may be provided to include an RS-485 communication transmitter (300) including a DI terminal (312) for receiving a signal and a bias circuit (320), and

[0112] The above RS-485 communication receiver (400) is,

[0113] The above-mentioned current loop receiver (210) is configured separately and includes an RS-485 transceiver (410), and

[0114] The above transceiver (410) has a DI terminal (412) that receives a reception signal, and

[0115] An RS-485 communication receiver (400) may be provided, comprising an RO terminal (413) for outputting received data and a bias circuit (420).

[0117] The above transceiver (310)(410) is,

[0118] Digital communication is performed via differential signal line AB, and

[0119] The above bias circuit (320)(420) may be equipped with pull-up and pull-down resistors to maintain a stable voltage level even in an idle state, and

[0121] The above controller device (A) is,

[0122] To suppress electrical noise generated in the external environment, a noise filtering circuit is provided, and

[0123] The above noise filtering circuit can be provided to improve the stability of the current loop signal and the RS-485 digital communication signal, and

[0125] The above plastic case (280) is,

[0126] It can be equipped with a waterproof and dustproof structure to protect the internal substrate from moisture, dust, and contamination in the external environment, and

[0128] The above controller device (A) is,

[0129] It can be equipped to store water level data and communication status in internal memory so that data logs can be recorded and retrieved for a certain period, and

[0131] The above controller device (A) is,

[0132] It is equipped to perform a remote diagnostic function via RS-485 communication to transmit sensor status information and whether an error has occurred to an external control system, and is also equipped to allow remote modification and monitoring of sensor settings via RS-485 communication.

[0133] delete

[0135] Hereinafter, each component of the controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication according to the present invention will be described in more detail as follows.

[0137] As illustrated in FIGS. 1 and 2, the water level measuring device according to the present invention obtains water level information from a water level sensor installed inside a storage tank, and

[0138] The above-mentioned liquid level sensor detects the height of the liquid and outputs an analog signal, and this signal is converted into a 4~20mA loop current through a current loop driver, and

[0139] The converted loop current is transmitted to an external circuit through the same two-wire transmission line (L1, L2), in which case the DC component is used for power supply and the modulated DC component operates to transmit water level data as a loop signal, and

[0140] An AC component also exists on the same two-wire transmission line, which operates as differential signal line AB to transmit and receive RS-485 digital communication signals, and

[0141] It enables simultaneous power supply, analog loop signal transmission, and digital communication through a single 2-wire transmission line.

[0143] As illustrated in FIG. 1, the field installation unit (100) includes a current loop driving unit (110) that processes the analog signal of the water level sensor to generate a loop current, and separately provides an RS-485 communication transmitting unit (300) to transmit a digital signal through the same line.

[0145] On the other hand, the control receiving unit (200) includes a current loop receiver (210) that detects loop current and converts it into a digital signal, and separately provides an RS-485 communication receiving unit (400) to operate to receive a digital signal through the same line,

[0146] The above-mentioned transmitter and receiver are connected via differential signal line AB, and this signal line includes loop terminal section (C) LOOP+(500) and LOOP-(580).

[0147] A resistor (316), capacitors (550, 590), and inductor (510) are arranged to stably separate and combine the DC component and the AC component, thereby enabling stable loop current and RS-485 signals to be transmitted simultaneously without interference.

[0148] The above control receiving unit (200) can accommodate a bundle of two-wire transmission lines of each water level sensor connected to the field installation unit (100), and

[0149] As shown in FIG. 2, a main control board (260) is stacked and arranged through a terminal block board (251) and a docking connector (252), and

[0150] The main control board (260) processes signals including a current loop receiver (210) and an RS-485 receiver (400), and

[0151] An LCD board (270) is positioned on the upper side of the main control board (260) and operates to perform display output, and

[0152] The entire structure described above is integrally formed with a plastic case (280) to protect the internal circuit board, and allows the main control board (260), LCD circuit board (270), and plastic case (280) to be selectively replaced and repaired without disconnecting the entire wiring in the event of a failure.

[0154] As illustrated in FIG. 1, the current loop driving unit (110) in the controller device (A) operates to receive an analog signal transmitted from a water level sensor, convert it into a 4-20mA loop current, and supply it to an external circuit.

[0155] The above MCU (111) receives an analog signal output from a water level sensor and processes it digitally. The MCU (111) interprets the sensor's measurement value and generates a control signal to convert it into a loop current, so that the digital-to-analog converter DAC (112) converts the digital control signal output by the MCU (111) into an analog voltage signal.

[0156] The process of converting the above digital calculation result into an analog form suitable for actual current driving, and enabling the loop driver to operate,

[0157] The current loop driver generates a loop current in the range of 4 to 20 mA based on the analog signal output from the DAC (112) and supplies it to an external circuit to transmit the water level information of the storage tank as a standardized analog current signal, and

[0158] The above current loop driving unit (110) performs the function of converting analog data of the sensor into a stable 4~20mA loop current through a sequential processing process of MCU (111) → DAC (112) → loop driver and outputting it externally.

[0160] The current loop receiver (210) of the above controller device (A) performs the role of stably detecting a 4-20mA loop current transmitted from a water level sensor inside the storage tank and converting it into a digital signal for processing.

[0161] First, when a loop current is input, the RESENSE (211) circuit detects it and accurately determines the magnitude of the loop current to provide basic data for subsequent signal processing, and

[0162] The above-mentioned detected signal is not used as is, but passes through a low-pass filter (LPF) (212) to remove high-frequency noise or unnecessary signal components, and

[0163] This enables the stable extraction of only the low-frequency components that reflect the original meaning of the loop current, and

[0164] The filtered analog signal is transmitted to an analog-to-digital converter (ADC) (213) to be converted into a digital signal, and the converted ADC (213) converts the continuous analog current value into digital data according to a constant sampling period, so that it is provided in a form that can be processed by a microcontroller and then processed by an MCU (214).

[0165] The above MCU (214) calculates water level data and transmits it to an external control system or display device, and, if necessary, can also perform data logging or linkage with a communication module.

[0166] The above current loop receiver (210) enables the analog loop signal transmitted from the sensor to be converted into stable and precise digital data through a series of processes including loop current detection → filtering → digital conversion → MCU (214) processing.

[0168] Therefore, the water level measuring device has a structure capable of acquiring water level information from a water level sensor installed inside a storage tank and simultaneously processing it into an analog loop signal and a digital communication signal through the same two-wire transmission line, and

[0169] Additionally, the analog signal output from the water level sensor is first transmitted to the field installation unit (100). The field installation unit (100) is provided with a current loop driving unit (110), and this driving unit processes the sensor signal digitally through the MCU (10) and then converts it into an analog voltage signal through a digital-to-analog converter DAC (112).

[0170] The above converted signal is generated as a loop current in the range of 4 to 20 mA by a current loop driver and supplied to an external circuit, wherein in this process, the analog data of the sensor is converted into a standardized loop current to ensure stable transmission, and

[0171] At the same time, the same two-wire transmission line (L1)(L2) supplies power through a DC component and transmits a loop current signal through a modulated DC component.

[0172] Furthermore, the AC component utilizes differential signal line AB to enable the transmission and reception of RS-485 digital communication signals, allowing power supply, analog loop signals, and digital communication to be performed simultaneously on a single line.

[0173] In the above external control receiving unit (200), a current loop receiver (210) that detects loop current operates, and the loop receiver detects loop current through RESENSE (211), removes noise by passing through a low-pass filter (LPF) (212), converts it into a digital signal through an analog-to-digital converter (ADC) (213), and the converted signal is processed by an MCU (214) to be used as water level data.

[0175] As illustrated in FIG. 2, the case structure (280) can significantly improve the overall stability and maintainability of the controller device, and

[0176] The above case structure (28) is not limited to merely protecting the internal circuit board, but integrates communication signal processing and power supply functions so that it can operate as a single module.

[0177] In particular, it can prevent the inconvenience of having to disconnect the entire wiring or completely replace the device in the event of a malfunction in existing devices, and

[0178] The above main control board (260), LCD board (270), and plastic case (280) can be independently separated and replaced, allowing only the relevant part to be selectively replaced and repaired without disassembling the entire system even if a problem occurs only in a specific part, thereby greatly improving maintainability.

[0179] In addition, the case structure (280) is integrally formed with the terminal block board (251), so that it is stably connected to the wiring installed at the site, and the communication signal and power supply are processed integrally inside the case structure (280), and interference from the external environment can be minimized.

[0181] As illustrated in FIG. 1, the RS-485 communication transmitter (300) is configured separately from the current loop driver (110) so as to be able to transmit a digital communication signal through the same two-wire transmission line, and

[0182] The above RS-485 transceiver (310) and the transceiver are equipped with various terminals for stably transmitting digital signals, and the RO terminal (313) has the role of outputting a transmission signal and transmitting digital data to an external circuit or receiver.

[0183] The above DI terminal (312) receives a received signal input from the outside and allows it to be processed inside the transceiver, and

[0184] The above transceiver (310) includes a bias circuit (320) to maintain a stable voltage level even when the communication line is idle, and

[0185] It prevents signal instability or noise issues that commonly occur in the above RS-485 communication and enables stable data transmission even in long-distance communication environments.

[0187] As illustrated in FIG. 1, the RS-485 communication receiver (400) is configured separately from the current loop receiver (210) and performs the role of reliably receiving RS-485 digital communication signals transmitted through the same two-wire transmission line, and

[0188] The above RS-485 transceiver (410) and the transceiver can receive and process digital signals input from the outside, and the DI terminal (412) receives the signal received from the outside and transmits it into the transceiver.

[0189] The above transceiver (410) stably converts the input signal and outputs the received data through the RO terminal (413), and

[0190] The above output data is transmitted to an MCU (214) or other processing module inside the controller so that it can be used for actual control and monitoring, and

[0191] Additionally, the transceiver (410) includes a bias circuit (420) to maintain a stable voltage level even when the communication line is idle, prevent signal instability or line floating that can commonly occur in RS-485 communication, and enable stable data reception even in long-distance and multi-node environments.

[0193] As illustrated in FIG. 1, the RS-485 transceiver (310) (410) enables digital communication through differential signal line AB by utilizing the AC component of the same two-wire transmission line, and

[0194] The above RS-485 method enables stable communication in long-distance transmission and multi-node environments, and in the present invention, by combining this with a loop-based structure, analog loop signals and digital signals can be processed simultaneously.

[0195] The above transceivers (310) (410) are respectively placed in the transmitting unit (300) and the receiving unit (400) and are connected to each other through differential signal line AB.

[0196] Since this differential signal line transmits data using the voltage difference between two lines, it is resistant to noise or interference from the external environment, enabling stable digital communication through the same wiring network.

[0197] Additionally, the transceiver (310)(410) includes a bias circuit (320)(420) equipped with a pull-up resistor and a pull-down resistor to maintain a stable voltage level even when the communication line is idle, thereby preventing the line floating phenomenon that commonly occurs in RS-485 communication and ensuring signal stability by ensuring the line maintains a constant reference voltage even when there is no data.

[0199] As illustrated in FIG. 1, the controller device (A) is equipped with a noise filtering circuit to suppress electrical noise generated in the external environment, and is designed to take into account that various electrical interferences may occur in industrial sites such as storage tanks, thereby ensuring that loop current signals and RS-485 digital communication signals are stably transmitted.

[0200] The noise filtering circuit operates to eliminate high-frequency noise or unnecessary interference that may occur during the transmission of the loop current signal, ensuring that the 4~20mA analog signal is transmitted to the controller while maintaining its original meaning.

[0201] At the same time, it suppresses external electromagnetic interference or line noise in RS-485 communication signals, enabling stable data transmission and reception even in long-distance communication environments.

[0203] As shown in FIG. 2, the plastic case (280) is not merely a structure that accommodates an internal substrate, but operates to protect the device from the external environment and ensure stable operation, and

[0204] The above plastic case (280) is designed to include a waterproof and dustproof structure,

[0205] Since industrial sites such as storage tanks are environments where moisture, dust, and pollutants frequently occur, circuit damage or signal errors can be suppressed when the main control board (260), LCD board (270), terminal block board (251), etc. inside are stably and directly exposed.

[0207] As illustrated in FIG. 1, the controller device (A) is equipped with internal memory to store water level data and communication status so that it can record and manage data in a long-term operating environment, going beyond the function of simply processing water level data in real time, and can record and retrieve data logs for a certain period.

[0209] As illustrated in FIG. 1, the controller device (A) can perform remote diagnosis and control functions beyond simply collecting and displaying water level data, and

[0210] It is possible to exchange data bidirectionally with an external control system using RS-485 communication, and

[0211] The above controller device (A) can transmit status information of the sensor to an external control system via RS-485 communication, so that whether the sensor is operating normally, the occurrence of an error, or the abnormality of a specific part can be checked in real time from a remote location.

[0212] The ability to remotely change or monitor sensor settings can be utilized, allowing an administrator to adjust the sensor's measurement range, correction values, or communication parameters through an external control system. Explanation of the symbols

[0213] A: Controller device C: Loop terminal section L1,L2: Transmission line 10: MCU 100: Field Installation Unit 110: Current Loop Driver 112: DAC 200: Control receiving unit 210: Current Loop Receiver 211: RESENSE 212: LPF 213: ADC 214: MCU 251: Terminal block board 252: Docking connector 255: Connection connector 260: Main control board 270: LCD board 280: Plastic case 300: RS-485 communication transmitter 313: RO terminal 312: DI terminal 320: Bias circuit 316: Resistor 400: RS-485 communication receiver 410: Transceiver 412: DI terminal 413: RO terminal 420: Bias circuit 500, 580: Current loop signal 510: Inductor 550, 590: Capacitor

Claims

Claim 1 A controller device (A) comprising a water level sensor installed inside a storage tank and a receiver that converts analog information of the water level sensor into a 4-20mA loop current, receives water level data through a two-wire transmission line, and converts it into a digital signal, wherein the controller device (A) comprises a field installation unit (100) installed at the site to supply power to a water level measuring device using a DC component through two-wire transmission lines (L1)(L2), modulates the DC component to transmit a 4-20mA current loop signal (500)(580), and simultaneously transmits and receives an RS-485 digital communication signal using a differential signal line AB, which is an AC component of the same two-wire transmission lines (L1)(L2), and a control receiving unit (200) capable of receiving and controlling the same, and wherein the field installation unit (100) comprises a current loop driving unit (110) that processes a measurement signal from the water level measuring sensor to generate a loop current and supplies it to an external circuit. The current loop driving unit (110) is provided with an RS-485 communication transmitting unit (300) separately from the current loop driving unit (110) to transmit a digital communication signal through the same two-wire transmission line, the control receiving unit (200) is provided with a current loop receiver (210) that detects the loop current, converts it into a digital signal, and processes it, and the current loop receiver (210) is provided with an RS-485 communication receiving unit (400) separately from the current loop receiver (210) to receive a digital communication signal through the same two-wire transmission line, the RS-485 communication transmitting unit (300) and the RS-485 communication receiving unit (400) are connected via a differential signal line AB, and the differential signal line AB is coupled via a loop terminal unit (C) including LOOP+ (500) and LOOP- (580), and the loop terminal unit (C) includes a resistor (316), capacitors (550, 590), and a DC component of the loop current and It is equipped with an inductor (510) for separating and combining alternating current components, andA control receiving unit (200) for connecting field wiring bundles of 2-wire transmission lines (L1) and (L2) of each water level measuring sensor installed in the field installation unit (100) is provided, and a main control board (260) having a detachable docking structure is stacked and arranged such that the control receiving unit (200) has a terminal block board (251), the terminal block board (251) has a docking connector (252), and a connection connector (255) corresponding to the docking connector (252) is provided to be electrically connected, and the main control board (260) has a current loop receiver (210) and an RS-485 communication receiver (400), and an LCD board (270) for display output is provided on the upper side of the main control board (260), and a plastic case (280) is provided on the upper side integrally with the terminal block board (251). A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, characterized by having a case (280). Claim 2 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, wherein, in claim 1, the current loop driving unit (110) is configured to include an MCU (10) that processes a measurement signal from a water level measuring sensor, a digital-to-analog converter DAC (112) that converts the output signal of the MCU (10) into an analog signal, and a current loop driver that generates a 4-20mA loop current based on the signal of the DAC (112) and supplies it to an external circuit. Claim 3 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, wherein, in claim 1, the current loop receiver (210) is configured to include a RESENSE (211) that detects a 4-20mA loop current, an MCU (214) that filters the detected signal through a low-pass filter (LPF) (212), converts the filtered signal into a digital signal through an analog-to-digital converter (ADC) (213), and processes the digital signal. Claim 4 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, wherein, in claim 1, the plastic case (280) is configured to integrate communication signal processing and power supply functions, and allows for the selective replacement and repair of the main control board (260), LCD board (270), and plastic case (280) without disconnecting the entire wiring in the event of a failure. Claim 5 In claim 1, the RS-485 communication transmitter (300) is configured to include an RS-485 transceiver (310) separately from the current loop driver (110), and the transceiver (310) is configured to include an RS-485 communication transmitter (300) comprising an RO terminal (313) for outputting a transmission signal, a DI terminal (312) for receiving a reception signal, and a bias circuit (320); and the RS-485 communication receiver (400) is configured separately from the current loop receiver (210) and includes an RS-485 transceiver (410), and the transceiver (410) is configured to include an RS-485 communication receiver (400) comprising a DI terminal (412) for receiving a reception signal, an RO terminal (413) for outputting received data, and a bias circuit (420). Controller device that simultaneously supports RS-485 communication Claim 6 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, characterized in that, in claim 5, the transceiver (310) performs digital communication through differential signal line AB, and the bias circuit (320) is equipped with pull-up and pull-down resistors to maintain a stable voltage level even in an idle state. Claim 7 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, characterized in that, in claim 5, the transceiver (410) performs digital communication through differential signal line AB, and the bias circuit (420) is equipped with pull-up and pull-down resistors to maintain a stable voltage level even in an idle state. Claim 8 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, characterized in that, in claim 1, the controller device is equipped with a noise filtering circuit to suppress electrical noise generated in an external environment, and the noise filtering circuit is equipped to improve the stability of a current loop signal and an RS-485 digital communication signal. Claim 9 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, wherein, in claim 1, the plastic case (280) is provided to protect the internal substrate from moisture, dust, and contamination of the external environment by including a waterproof and dustproof structure. Claim 10 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, characterized in that, in claim 1, the controller device stores water level data and communication status in an internal memory and is configured to record and retrieve data logs for a certain period. Claim 11 A controller device that simultaneously supports a 2-wire current loop-based 4-20mA signal and RS-485 communication, characterized in that, in claim 1, the controller device is configured to perform a remote diagnostic function via RS-485 communication to transmit status information of the sensor and whether an error has occurred to an external control system, and is configured to change and monitor sensor setting values ​​remotely via RS-485 communication.

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