A signal detection circuit

Abstract

The present invention provides a signal detection circuit, which includes an input power supply, a first switch, a second switch, a first resistor, a TVS tube, a diode, a second resistor, a third resistor, a first capacitor, an optocoupler, a second capacitor, a voltage-dividing power supply, a fourth resistor, and a NOT gate. The signal detection circuit of the present invention can simultaneously detect passive node signals, active node signals with wide voltage, and active node signals with wide current, and has a simple structure and strong practicability.

Description

Technical Field

[0001] The present invention relates to the technical field of signal detection, and particularly to a signal detection circuit. Background Art

[0002] Active node signals and passive node signals, also known as active switch signals and passive switch signals, respectively represent two types of switch signals. In all walks of life, the detection of switch signals is very important. In particular, in the field of industrial automation, there are a rich variety and a large number of switches in the industrial site. Therefore, the detection of switch signals in the industrial site is directly related to the operation status of the automation site. According to the fundamental attributes of the switch, it can be divided into two types: active and passive. Among them, the active switch (active node) signal refers to a switch signal with an electrical quantity (voltage or current) input; the passive switch (node) signal refers to a switch signal without an electrical quantity input and without node polarity.

[0003] In the prior art, the detection of switch signals usually relies on some specific sensors or integrated circuits, which are costly, the solutions are relatively complex, and often can only detect one of the passive node signal and the active node signal, resulting in poor practicability. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a signal detection circuit that can simultaneously detect passive node signals, active node signals with a wide voltage range, and active node signals with a wide current range, with a simple structure and strong practicability.

[0005] To achieve the above and other related objectives, the present invention provides a signal detection circuit, including an input power supply, a first switch, a second switch, a first resistor, a TVS tube, a diode, a second resistor, a third resistor, a first capacitor, an optocoupler, a second capacitor, a voltage-dividing power supply, a fourth resistor, and a NOT gate; one end of the first switch is connected to the positive pole of the input power supply, and the other end is connected to a first signal input terminal; one end of the second switch is connected to a second signal input terminal, and the other end is connected to one end of the first resistor; the other end of the first resistor is connected to the negative pole of the input power supply; one end of the TVS tube is connected to the second signal input terminal, and the other end is connected to the negative pole of the input power supply; one end of the second resistor is connected to the second signal input terminal, and the other end is connected to the negative pole of the diode, and the positive pole of the diode is connected to the negative pole of the input power supply; the third resistor, the first capacitor, and the optocoupler are connected in parallel across the two ends of the diode; one end of the second capacitor is connected to the voltage-dividing power supply, and the other end is grounded; one end of the fourth resistor is connected to the voltage-dividing power supply, and the other end is connected to the positive output terminal of the optocoupler, and the negative output terminal of the optocoupler is grounded; the input terminal of the NOT gate is connected to the positive output terminal of the optocoupler, and the output terminal outputs the detected node signal.

[0006] In an embodiment of the present invention, it further includes a third switch, a fifth resistor, and an LED. One end of the third switch is connected to the output terminal of the NOT gate, and the other end is grounded after being connected in series with the fifth resistor and the LED.

[0007] In an embodiment of the present invention, the first switch, the second switch, and the third switch are implemented by push-button switches or toggle switches.

[0008] In an embodiment of the present invention, when detecting a passive node signal, the first switch is closed, the second switch is opened, the passive node is connected to the first signal input terminal and the second signal input terminal, and the ground of the passive node signal is connected to the negative pole of the input power supply. Based on this, the passive node signal is output from the output terminal of the NOT gate.

[0009] In an embodiment of the present invention, when detecting an active node signal with a wide voltage range, the first switch and the second switch are opened, the active node with a wide voltage range is connected to the second signal input terminal, and the ground of the passive node signal is connected to the negative pole of the input power supply. Based on the output signal of the NOT gate, the active node signal with a wide voltage range is output.

[0010] In an embodiment of the present invention, when detecting an active node signal with a wide current, the second switch is closed, the first switch is opened, the active node with the wide current is connected to the second signal input terminal, and the ground of the passive node signal is connected to the negative pole of the input power supply, and the active node signal with the wide current is output based on the output signal of the NOT gate. In an embodiment of the present invention, when detecting a node signal, the third switch is closed to indicate the node signal based on the LED.

[0011] As described above, the signal detection circuit of the present invention has the following beneficial effects:

[0012] (1) It can detect passive node signals, active node signals with a wide voltage, and active node signals with a wide current simultaneously;

[0013] (2) The circuit has few components, low cost and is easy to implement, and has certain value for use in industrial fields;

[0014] (3) It includes sufficient electrostatic protection, current limiting protection, filtering and other circuits, can face harsh industrial environments, and has strong practicability. Description of the Drawings

[0015] Figure 1 It shows a schematic structural diagram of the signal detection circuit of the present invention in an embodiment. Detailed Embodiments

[0016] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0017] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the limited conditions for the implementation of the present invention. Therefore, they do not have technical essential meanings. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that the technical content disclosed by the present invention can cover. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of clear narration, rather than used to limit the scope for the implementation of the present invention. The change or adjustment of their relative relationships, without substantial change of the technical content, should also be regarded as the scope for the implementation of the present invention.

[0018] The signal detection circuit of the present invention can detect three types of node signals, namely passive node signals, active node signals with a wide voltage, and active node signals with a wide current, simultaneously. The circuit has few components, low cost and is easy to implement, and has strong practicability.

[0019] As Figure 1 shown, in one embodiment, the signal detection circuit of the present invention includes an input power supply (24V), a first switch S1, a second switch S2, a first resistor R1, a TVS diode VZ1, a diode D1, a second resistor R2, a third resistor R3, a first capacitor C1, an optocoupler U1, a second capacitor C2, a voltage-dividing power supply (3.3V), a fourth resistor R4, and a NOT gate U2.

[0020] One end of the first resistor R1 is connected to the positive electrode (24V) of the input power supply, and the other end is connected to the first signal input terminal (A); one end of the second switch S2 is connected to the second signal input terminal (B), and the other end is connected to one end of the first resistor R1; the other end of the first resistor R1 is connected to the negative electrode (GND) of the input power supply. Among them, the first resistor R1 is a precision resistor. When an input current-type active switch signal is applied, the first resistor R1 can function to convert current into voltage.

[0021] One end of the TVS diode VZ1 is connected to the second signal input terminal (B), and the other end is connected to the negative electrode (GND) of the input power supply. Among them, the TVS diode VZ1 is used for electrostatic protection.

[0022] One end of the second resistor R2 is connected to the second signal input terminal (B), and the other end is connected to the negative electrode of the diode D1. The positive electrode of the diode D1 is connected to the negative electrode (GND) of the input power supply; the third resistor R3, the first capacitor C1, and the optocoupler U1 are connected in parallel across the diode D1. Among them, the second resistor R2 and the third resistor R3 are used in cooperation to divide the input voltage so that a suitable divided voltage exists across the third resistor R3, thereby turning on the optocoupler U1 connected in parallel with the third resistor R3. The diode D1 is used to prevent circuit failures caused by reverse power connection and functions to protect the circuit. The first capacitor C1 is used to filter out some noise of the power supply. The optocoupler U1 can effectively isolate the introduced node signal from the subsequent signal processing circuit, thereby protecting the processing circuit.

[0023] One end of the second capacitor C2 is connected to the voltage-dividing power supply (3.3V), and the other end is grounded (DGND). One end of the fourth resistor R4 is connected to the voltage-dividing power supply (3.3V), and the other end is connected to the positive output terminal of the optocoupler U1. The negative output terminal of the optocoupler U1 is grounded (DGND); the input terminal of the NOT gate U2 is connected to the positive output terminal of the optocoupler U1, and the output terminal outputs the detected node signal. The second capacitor C2 is used to filter out some noise of the power supply. The fourth resistor R4 is a pull-up resistor, which is used to forcibly pull up the input of the NOT gate U2 to a high level in the initial state and when no node signal is input, so that the output of the NOT gate U2 is at a low level. Since the logic of the input node signal is opposite to that of the signal processed by the optocoupler U1, the logic before and after optocoupling is made consistent through the NOT gate U2; at the same time, the driving ability of the signal is increased, so that subsequent loads such as LEDs can be driven.

[0024] In an embodiment of the present invention, the signal detection circuit of the present invention further includes a third switch S3, a fifth resistor R5, and an LED. One end of the third switch S3 is connected to the output terminal of the NOT gate U2, and the other end is grounded (DGND) after being connected in series with the fifth resistor R5 and the LED. Among them, the fifth resistor R5 is a current-limiting resistor for protecting the circuit. The LED is used for indication when the switch signal is connected and the third switch S3 is closed.

[0025] In an embodiment of the present invention, the first switch S1, the second switch S2, and the third switch S3 are implemented by push-button switches or toggle switches.

[0026] The signal detection circuit of the present invention can detect three types of signals, namely passive node signals, active node signals with wide voltage, and active node signals with wide current. Among them, by simply changing the resistance values of the second resistor R2 and the third resistor R3, the detection of active node signals with wide voltage can be achieved. The basic requirement is that as long as the condition for the optocoupler to conduct is satisfied; by simply changing the value of the first resistor R1, the detection of active nodes with wide current can be achieved. By changing the value of the first resistor R1, the voltage converted from the input current can conduct the optocoupler after being divided by the second resistor R2 and the third resistor R3.

[0027] When detecting the passive node signal, close the first switch, open the second switch, connect the passive node to the first signal input terminal and the second signal input terminal, and connect the ground of the passive node signal to the negative electrode (GND) of the input power supply. Output the passive node signal based on the output terminal of the NOT gate. Specifically, connect the first switch S1, disconnect the second switch S2 and the third switch S3, and connect the passive node in the industrial field to the circuit through the two ports of the first signal input terminal A and the second signal input terminal B, and connect the ground of the passive node signal to the negative electrode of the input power supply. Since there is no electrical quantity input in the passive node signal, closing the first switch S1 can provide a 24V voltage to the circuit. When the passive node signal arrives, the first signal input terminal A and the second signal input terminal B are connected, and the entire circuit path is turned on. The second resistor R2 and the third resistor R3 divide the 24V voltage to make the optocoupler U1 turn on. After the optocoupler U1 turns on, the input signal of the NOT gate U2 changes from high level to low level, and the output signal of the NOT gate U2 changes from low level to high level. At this time, the output signal of the NOT gate U2 can be connected to the MCU for data processing and analysis, or the third switch S3 can be closed in advance to indicate the passive node signal on-site based on the LED.

[0028] When detecting the active node signal with a wide voltage, disconnect the first switch and the second switch, connect the active node with a wide voltage to the second signal input terminal (B), and connect the ground of the passive node signal to the negative electrode (GND) of the input power supply. Output the active node signal with a wide voltage based on the output signal of the NOT gate. Specifically, first, disconnect the first switch S1, the second switch S2, and the third switch S3, connect the second signal input terminal B to the active node in the field, and connect the ground of the passive node signal to the negative electrode of the input power supply. Since there is electrical quantity input in the active node, it is not necessary to turn on the first switch S1. When an active node signal with a wide voltage is input from the second signal input terminal B, it directly passes through the second resistor R2 and the third resistor R3 for resistance voltage division to make the optocoupler U1 turn on. After the optocoupler U1 turns on, the input signal of the NOT gate U2 changes from high level to low level, and the output signal changes from low level to high level. At this time, the output signal of the NOT gate U2 can be connected to the MCU for data processing and analysis, or the third switch S3 can be closed in advance to indicate the active node signal with a wide voltage on-site based on the LED.

[0029] When detecting the active node signal of wide current, close the second switch, open the first switch, connect the active node of wide current to the second signal input terminal (B), and connect the ground of the passive node signal to the negative electrode (GND) of the input power supply. Output the active node signal of wide current based on the output signal of the NOT gate. Specifically, connect the second switch S2, disconnect the first switch S1 and the third switch S3, connect the second signal input terminal B to the active node on-site, and connect the ground of the passive node signal to the negative electrode (GND) of the input power supply. Since there is an electrical quantity input to the active node, it is not necessary to turn on the first switch S1. When the active node signal of wide current is input from the second signal input terminal B, first convert the current into a voltage through the first resistor R1, and then perform resistor voltage division through the second resistor R2 and the third resistor R3 to turn on the optocoupler U1. After the optocoupler U1 is turned on, the input signal of the NOT gate U2 changes from high level to low level, and the output signal changes from low level to high level. At this time, the output signal of the NOT gate U2 can be connected to the MCU for data processing and analysis, or the third switch S3 can be closed in advance to indicate the active node signal of wide current on-site based on the LED.

[0030] Preferably, since the output signal of the NOT gate U2 can directly enter the MCU for data analysis and processing, if this circuit is replicated into N pieces, the simultaneous detection of N node signals can be achieved, meeting the requirements of a large number of switches in the industrial field, and the circuit is easy to replicate. At the same time, the output signal of the NOT gate U2 can be connected to an LED through a switch to directly light up the LED for display. When N channels are detected simultaneously, the corresponding switch can be quickly located according to the status of the LED lights of each channel, facilitating the staff to quickly locate and repair faults.

[0031] In summary, the signal detection circuit of the present invention can simultaneously detect passive node signals, active node signals of wide voltage, and active node signals of wide current; has few circuit components, low cost, and is easy to implement, with certain value for use in the industrial field; includes sufficient electrostatic protection, current limiting protection, filtering and other circuits, and can face harsh industrial environments, with strong practicability. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0032] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A signal detection circuit, characterized in that: It includes an input power supply, a first switch, a second switch, a first resistor, a TVS tube, a diode, a second resistor, a third resistor, a first capacitor, an optocoupler, a second capacitor, a voltage-dividing power supply, a fourth resistor, and a NOT gate; One end of the first switch is connected to the positive pole of the input power supply, and the other end is connected to a first signal input terminal; one end of the second switch is connected to a second signal input terminal, and the other end is connected to one end of the first resistor; the other end of the first resistor is connected to the negative pole of the input power supply; One end of the TVS tube is connected to the second signal input terminal, and the other end is connected to the negative pole of the input power supply; One end of the second resistor is connected to the second signal input terminal, and the other end is connected to the negative pole of the diode. The positive pole of the diode is connected to the negative pole of the input power supply; The third resistor, the first capacitor, and the optocoupler are connected in parallel across the two ends of the diode; One end of the second capacitor is connected to the voltage-dividing power supply, and the other end is grounded; One end of the fourth resistor is connected to the voltage-dividing power supply, and the other end is connected to the positive output terminal of the optocoupler. The negative output terminal of the optocoupler is grounded; The input terminal of the NOT gate is connected to the positive output terminal of the optocoupler, and the output terminal outputs the detected node signal; When detecting a passive node signal, close the first switch, open the second switch, connect the passive node to the first signal input terminal and the second signal input terminal, and connect the ground of the passive node signal to the negative pole of the input power supply, and output the passive node signal based on the output terminal of the NOT gate; when detecting an active node signal with a wide voltage, open the first switch and the second switch, connect the active node with a wide voltage to the second signal input terminal, and connect the ground of the passive node signal to the negative pole of the input power supply, and output the active node signal with a wide voltage based on the output signal of the NOT gate; when detecting an active node signal with a wide current, close the second switch, open the first switch, connect the active node with a wide current to the second signal input terminal, and connect the ground of the passive node signal to the negative pole of the input power supply, and output the active node signal with a wide current based on the output signal of the NOT gate.

2. The signal detection circuit according to claim 1, characterized in that: It further includes a third switch, a fifth resistor, and an LED. One end of the third switch is connected to the output terminal of the NOT gate, and the other end is grounded after being connected in series with the fifth resistor and the LED.

3. The signal detection circuit according to claim 2, wherein: The first switch, the second switch, and the third switch are implemented using a push-button switch or a toggle switch.

4. The signal detection circuit according to claim 2, characterized in that: When detecting a node signal, close the third switch to indicate the node signal based on the LED.

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