Passive 4-20mA signal wireless acquisition device

Abstract

The invention relates to a passive 4-20mA signal wireless acquisition device, and belongs to the technical field of signal wireless acquisition. The system comprises a main control unit, an energy storage unit and a wireless communication unit. The main control unit is used for stealing energy from an input current signal to enable an internal circuit to work normally, converting the input current signal into a corresponding digital value, and then sending the digital value to target equipment through the wireless communication unit; the energy storage unit is used for collecting idle energy for the wireless communication module to use when the wireless communication module needs large current. The passive 4-20mA signal wireless acquisition device does not need an independent power supply, can work normally after being connected into a current loop in series, is quick and convenient to install, does not need independent wiring, and saves labor and time.

Description

Technical Field

[0001] It relates to the field of signal acquisition and transmission, and specifically to a passive 4~20mA signal wireless acquisition device; Background Art

[0002] At present, many industrial sites and laboratories involve the collection of 4~20mA DC current signals, which will cause the following problems, and the following problems are currently common: Limitations of wired methods: Wired methods are commonly used for signal acquisition, and the installation and wiring process is cumbersome, which not only increases costs but also limits the flexibility and scalability of the equipment.

[0003] Power supply problem: Existing wireless collectors require additional power supply, which also involves the problem of power routing, which not only increases the complexity of the system, but also reduces the reliability and maintainability of the system. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention proposes a passive 4~20mA signal wireless acquisition device that can be realized using common low-cost components. The device can work normally by being directly connected in series to the existing current loop, without any extra wiring, and is compact and very easy to install.

[0005] In order to achieve the above object, the present invention adopts Figure 1 , Figure 2 The technical solution shown is described in detail as follows: A passive 4~20mA signal wireless acquisition device comprises a main control unit, an energy storage unit and a wireless communication unit.

[0006] Main control unit: responsible for stealing energy from the 4~20mA signal output terminal of the source device and collecting the current signal. Through precise circuit design, this unit converts the input current signal into the corresponding voltage signal, performs AD conversion, and finally obtains a digital signal.

[0007] Energy storage unit: responsible for storing a certain amount of energy to supply the intermittent large energy demand of the wireless communication unit. This unit uses energy storage components such as large-capacity capacitors to ensure a stable energy supply during wireless communication.

[0008] Wireless communication unit: responsible for communicating with the wireless host to transmit the collected current value to the target device. This unit supports a variety of wireless communication protocols, such as LoRa, Zigbee, etc., which can be selected according to actual needs.

[0009] The target device should have wireless communication capability, and the wireless communication mode and related parameter settings should be consistent with the passive 4~20mA signal wireless acquisition device described in the present invention.

[0010] Low cost and easy miniaturization: The components used in the passive 4~20mA signal wireless acquisition device described in the present invention are low-priced, small in number, and all have small packaging forms, which greatly saves cost and space and is easy to miniaturize and integrate.

[0011] Seamless access to existing systems: The voltage drop on the current side of the passive 4~20mA signal wireless acquisition device described in the present invention can be as low as 2.5V or less, which is equivalent to inserting a resistor of about 125 ohms in series in the 4~20mA loop of the signal output device. The load capacity of most 4~20mA output devices can reach more than 350 ohms, and the input resistance of 4~20mA signal input devices will not be greater than 200 ohms. This allows the passive 4~20mA signal wireless acquisition device described in the present invention to be connected in series to the original 4~20mA signal communication loop without any wiring, thereby saving installation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 : It is the principle block diagram and application description block diagram of the passive 4~20mA signal wireless acquisition device described in the present invention; Figure 2 : It is the circuit principle diagram of the passive 4~20mA signal wireless acquisition device of the present invention; DETAILED DESCRIPTION

[0013] The detailed contents and technical description of the present invention are further described with reference to embodiments. However, it should be understood that these embodiments are only used for illustrative purposes and should not be construed as limitations on the implementation of the present invention.

[0014] refer to Figure 1 The schematic diagram and application block diagram of a passive 4~20mA signal wireless acquisition device include a main control unit, an energy storage unit and a wireless communication unit.

[0015] like Figure 1As shown, the 4-20mA current signal IAI output by the source device flows in through the input current inflow port of the main control unit and flows out from the input current outflow port, thereby forming a current loop, which does not affect the operation of the source device and the accuracy of the data carried by the IAI signal output by it. After passing through the main control unit, the current IAI will generate a fixed voltage UO, which is used to maintain the operation of the entire circuit, and its size must meet the operating voltage requirements of the main control unit and the wireless communication unit; the energy storage unit works based on the voltage UO and provides energy supply for the wireless communication unit; after collecting the current signal, the main control unit converts it into the corresponding digital value DA0, and performs temperature drift correction and linear correction on DA0 according to the temperature collected by the internal temperature sensor and the set linear calibration curve, and obtains the corrected digital value DA and sends it to the target device through the wireless communication unit in the form of a digital signal.

[0016] refer to Figure 2 The circuit schematic diagram of the passive 4~20mA signal wireless acquisition device shown includes a main control unit, an energy storage unit and a wireless communication unit.

[0017] The main control unit includes: a microcontroller U1, a three-terminal parallel voltage regulator U2, an amplifier U3, an inductor L1, resistors R1-R5 and capacitors C1-C9; The energy storage unit includes: an inductor L2 and a large-capacity capacitor C10; The wireless communication unit includes: a wireless communication module U4, a capacitor C11 and an antenna E1.

[0018] The connection relationship of each device is as follows: The cathode of the three-terminal parallel voltage-stabilizing source U2 is connected to the current output + port of the source device, and the anode is grounded; the resistor R1 and the capacitor C3 are connected in parallel and connected between the anode of U2 and the current output - port of the source device; the capacitor C1 is connected between the anode and the cathode of U2; the resistor R4 and the capacitor C9 are connected in parallel and connected between the 3rd and 4th pins of the amplifier U3; the 1st and 2nd pins of the amplifier U3 are grounded, the 3rd pin is connected to the current output - port of the source device through the resistor R3, the 4th pin is connected to the 17th pin of the microcontroller U1 through the resistor R2, the 5th pin is connected to the 6th pin of the microcontroller and then connected to the cathode of the three-terminal parallel voltage-stabilizing source U2 through the inductor L1; the capacitor C7 is connected in parallel between the 5th pin of the amplifier and the ground; the capacitor C8 is connected in parallel to the microcontroller. The capacitor C2 is connected to the positive port VS+ of the power supply; the capacitors C2 and C4 are connected in parallel and connected between the 5th pin of the microcontroller U1 and the ground; the capacitors C5 and C6 are connected in parallel and connected between the 6th pin of the microcontroller U1 and the ground; the pins 2, 3, 8-11, 16 and 20 of the microcontroller U1 are respectively connected to the 3rd pin, 13th pin, 14th pin, 11th pin, 12th pin, 10th pin and 4th pin of the wireless communication module U4, and the 4th pin is grounded; the 5th and 15th pins of the wireless communication module U4 are grounded, the 6th pin is connected to the cathode of the three-terminal parallel voltage regulator U2 through the inductor L2, and the 16th pin is connected to the antenna E1; the large-capacity capacitor C10 and the capacitor C11 are connected in parallel between the 6th pin of the wireless communication module U4 and the ground; The microprocessor U1 of the present invention should have AD sampling function, SPI communication function, power supply voltage monitoring function and parameter storage function, and its control logic should have the function of detecting whether the power supply voltage meets the wireless communication conditions;

[0019] Signal acquisition: The 4~20mA current signal IAI output by the source device flows into the input current inflow port of the main control unit to form a current loop. The amplifier U3 in the main control unit amplifies the current signal into a corresponding voltage signal UA.

[0020] AD conversion: The microcontroller U1 performs AD conversion on the voltage signal UA to obtain a digital signal DA0.

[0021] Signal correction: The microcontroller U1 performs temperature drift correction and linear correction on DA0 according to the temperature collected by the internal temperature sensor and the set linear calibration curve to obtain the corrected digital value DA.

[0022] Wireless communication: The corrected digital value DA is sent to the target device via the wireless communication unit. During the data transmission process of the wireless communication module U4, the large-capacity capacitor C10 in the energy storage unit provides the necessary energy support.

[0023] Through the above technical scheme, the present invention realizes a passive 420mA signal wireless acquisition device, which is low-cost, easy to install and maintain, and can be seamlessly connected to the existing 420mA signal communication loop, providing a more convenient and efficient solution for signal acquisition in industrial sites and laboratories.

Claims

1. A passive 4~20mA signal wireless acquisition device, characterized in that: include: 1) The main control unit is used to steal energy from the 4~20mA signal output terminal of the source device and collect current signals; 2) an energy storage unit, connected to the main control unit, for storing energy to supply the intermittent large energy demand of the wireless communication unit; 3) a wireless communication unit, connected to the main control unit, for communicating with the target device to transmit the collected current value to the target device; Among them, the target device has wireless communication capability, and the wireless communication method and related parameter settings are consistent with the passive 4~20mA signal wireless acquisition device.

2. The passive 4~20mA signal wireless acquisition device according to claim 1, characterized in that: The device can be directly connected in series to an existing 4-20mA current loop to work normally without the need for additional electrical connections.

3. The wireless data acquisition device according to claim 2, characterized in that: The voltage drop generated on the current side of the device is no more than 2.6V, and is suitable for use with a variety of 4~20mA output devices.

4. The wireless data acquisition device according to any one of claims 1 to 3, characterized in that: The device uses a large-capacity capacitor for energy storage.

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