Access circuit for NPN type and PNP type elements

Abstract

The utility model provides an NPN type and PNP type element access circuit, which relates to the technical field of circuit design and comprises a first port CN8-I and a second port CN8-J. One side of the first port CN8-I is sequentially connected in series with a first resistor R32, a second resistor R31 and a photoelectric coupler U8. One end of the second resistor R31 is connected with the first input end of the photoelectric coupler U8, and the second input end of the photoelectric coupler U8 is connected with the second port CN8-J. A signal path can be formed at the two ports of the NPN type or PNP type element, and signals are output to an external control unit through the photoelectric coupler. Therefore, different access circuits do not need to be arranged for the NPN type element and the PNP type element, so that the circuit structure is simplified, the cost is reduced, and the implementation is easy.

Description

Technical Field

[0001] The utility model relates to an access circuit, in particular to an access circuit for NPN and PNP components, belonging to the technical field of circuit design. Background Art

[0002] In the field of industrial automation, components connected to PLCs or MCUs (such as sensors and encoders) are typically NPN and PNP types. For example, both NPN and PNP sensors utilize the saturation and cutoff states of transistors to produce two output states. Their outputs are diametrically opposed. When a signal triggers a PNP sensor, its output line is connected to the power line, equivalent to a high output level. When a signal triggers an NPN sensor, its output line is connected to the 0V line, equivalent to a low output level. This characteristic of NPN and PNP sensors requires two completely different back-end matching circuits. This means that when NPN and PNP sensors are used in microcontroller systems, customized circuit interfaces must be developed for each switching sensor. This complicates the circuit structure and, once a sensor model is determined, cannot be changed, compromising ease of use. Therefore, designing an interface circuit that can accommodate both NPN and PNP electronic components could address these issues. Utility Model Content

[0003] The utility model is implemented by the following technical solutions: an NPN and PNP type component access circuit, including a first port CN8-I and a second port CN8-J connected to an NPN type component or a PNP type component, a first resistor R32, a second resistor R31 and a photoelectric coupler U8 are sequentially connected in series on one side of the first port CN8-I, one end of the second resistor R31 is connected to the first input end of the photoelectric coupler U8, the second input end of the photoelectric coupler U8 is connected to the second port CN8-J, and one end of the second resistor R31 connected to the photoelectric coupler U8 is connected to the second A first capacitor C29 is also connected between ports CN8-J. The photoelectric coupler U8 includes two light-emitting diodes connected in parallel and in reverse. The two light-emitting diodes are respectively connected to the first input terminal and the second input terminal of the photoelectric coupler U8. The first output terminal of the photoelectric coupler U8 is connected to the power supply through a third resistor R44, and the fourth resistor R45 is connected to the external control unit. One end of the fourth resistor R45 is connected to the ground through a second capacitor C30. The access ends of the second port CN8-J of the NPN type component access circuit and the PNP type component access circuit include the power supply and the ground.

[0004] Preferably, a noise filtering circuit is provided between one end of the second resistor R31 and the first input end of the photoelectric coupler U8.

[0005] Preferably, the noise filtering circuit includes a Zener diode D15 and a Zener diode D1 , and the Zener diode D15 and the Zener diode D1 are connected in reverse series.

[0006] Preferably, a signal conditioning circuit is provided between the fourth resistor R45 and the external control unit.

[0007] Preferably, the signal conditioning circuit is a Smith trigger U10-A.

[0008] The utility model provides a circuit for connecting NPN and PNP components, which has the following beneficial effects:

[0009] The utility model can selectively connect the second port of the circuit accessing the NPN or PNP type components to a power supply or ground, depending on the connected NPN or PNP type components. A signal path can be formed between the two ports of the NPN or PNP type components through two reversely connected parallel photodiodes of the photoelectric coupler, and the signal can be output to an external control unit through the photoelectric coupler. In this way, there is no need to set up different access circuits for the NPN and PNP type components, thereby simplifying the circuit structure, reducing costs, and facilitating implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG2 is a schematic diagram of the circuit structure of the first embodiment of the present utility model.

[0011] Figure 2 FIG2 is a schematic diagram of the circuit structure of the second embodiment of the present invention. DETAILED DESCRIPTION

[0012] The embodiment of the utility model provides a circuit for accessing NPN and PNP components.

[0013] See also Figure 1 and Figure 2As shown, the NPN and PNP element access circuit of the present invention includes a first port CN8-I and a second port CN8-J connected to the NPN element or the PNP element, and a first resistor R32, a second resistor R31 and a photocoupler U8 are sequentially connected in series on one side of the first port CN8-I, one end of the second resistor R32 is connected to the first input end of the photocoupler U8, and the second input end of the photocoupler U8 is connected to the second port CN8-J, and a first capacitor C is further connected between the end of the second resistor R32 connected to the photocoupler U8 and the second port CN8-J. 29. The photocoupler U8 includes two light-emitting diodes connected in parallel and in reverse order. The two light-emitting diodes are connected to the first input terminal and the second input terminal of the photocoupler U8. The first output terminal of the photocoupler U8 is connected to the power supply through the third resistor R44. The first output terminal of the photocoupler U8 is connected to the external control unit MCU through the fourth resistor R45. One end of the fourth resistor R45 is connected to the ground through the second capacitor C30. In this process, the second port CN8-J of the circuit connected to the NPN and PNP components is selectively connected to the power supply or the ground according to the connected NPN or PNP components.

[0014] In a specific implementation, a noise filtering circuit is provided between one end of the second resistor R31 and the first input terminal of the photocoupler U8. This noise filtering circuit comprises two Zener diodes D15 and D16, which are connected in series and arranged in opposite directions. Zener diodes D15 and D16 conduct only when the voltage exceeds 5.1V. Noise signals below 5.1V are not conducted. Thus, the Zener diodes can filter out noise signals with voltages below 5.1V.

[0015] In addition, in a specific implementation, a signal conditioning circuit is provided between the fourth resistor R45 and the external control unit. The signal conditioning circuit is a Smith trigger U10-A, which uses the Smith trigger to shape the sine wave signal into a clear, jitter-free square wave signal, making it easier for the external control unit to receive and process it.

[0016] See also Figure 1 As shown, it is a schematic diagram of the circuit structure of the NPN and PNP type components connected to the circuit and the NPN type component of the present invention. When the NPN type component (such as an NPN type sensor) is connected, the second port CN8-J is connected to the power supply (such as 24V), wherein Figure 1One side of the circuit model is an NPN type element, that is, its internal structure can be equivalent to a switching circuit. The switch S3 is connected between the output port and the ground port. When there is a trigger signal, the switch S3 is closed. At this time, the second port CN8-J is at a high potential. In this way, a closed loop is formed through the photoelectric coupler U8, the diode D16, the second resistor R31, the first resistor R32 and the first port CN8-I. In this way, the sensor signal is output to the external control unit through the photoelectric coupler U8.

[0017] See also Figure 2 As shown, it is a schematic diagram of the circuit structure of the NPN and PNP type components connected to the circuit and the PNP type components of the present invention. When the PNP type component (such as a PNP type sensor) is connected, the second port CN8-J is connected to the ground, wherein Figure 1 One side of the circuit model is a PNP type element, that is, its internal structure can be equivalent to a switching circuit. The switch S3 is connected between the external power supply and the output port. When there is a trigger signal, the switch S3 is closed. At this time, the first port CN8-I is at a high potential. In this way, a closed loop is formed through the first resistor R32, the second resistor R31, the diode D15, the photocoupler U8 and the second port CN8-J. In this way, the sensor signal is output to the external control unit through the photocoupler U8.

[0018] In a specific implementation, the above-mentioned photoelectric coupler U8 is the SFH6206-3 photoelectric coupler produced by Infineon, and the Smith trigger is the SN74LV14 logic gate chip produced by Texas Instruments.

[0019] In addition, the first port CN8-I and the second port CN8-J of the NPN and PNP type components access circuit of the present invention are terminal blocks in specific implementations, which can be connected to the power supply (+24V) or ground of the system (such as PLC or cabinet) through cables.

[0020] In summary, the NPN and PNP component access circuits of the present invention selectively connect the second port of the NPN and PNP component access circuits to a power supply or ground depending on the connected NPN or PNP component, and form a signal path between the two ports of the NPN or PNP component through two reversely connected parallel photodiodes of the optocoupler, and output the signal to an external control unit through the optocoupler. This eliminates the need to set up different access circuits for the NPN and PNP components, thereby simplifying the circuit structure, reducing costs, and facilitating implementation.

[0021] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in this invention is defined by the appended claims and their equivalents.

Claims

1. A circuit for connecting NPN and PNP components, comprising a first port CN8-I and a second port CN8-J connected to an NPN component or a PNP component, characterized in that: A first resistor R32, a second resistor R31 and a photoelectric coupler U8 are connected in series on one side of the first port CN8-I in sequence, one end of the second resistor R31 is connected to the first input end of the photoelectric coupler U8, and the second input end of the photoelectric coupler U8 is connected to the second port CN8-J. A first capacitor C29 is also connected between one end of the second resistor R31 connected to the photoelectric coupler U8 and the second port CN8-J. The photoelectric coupler U8 includes two light-emitting diodes connected in parallel and in reverse, and the two light-emitting diodes are respectively connected to the first input end and the second input end of the photoelectric coupler U8. The first output end of the photoelectric coupler U8 is connected to the power supply through a third resistor R44, and the fourth resistor R45 is connected to the external control unit. One end of the fourth resistor R45 is connected to the ground through a second capacitor C30, and the access ends of the second port CN8-J of the NPN type component access circuit and the PNP type component access circuit include the power supply and the ground.

2. The circuit for connecting NPN and PNP components according to claim 1, characterized in that: A noise filtering circuit is provided between one end of the second resistor R31 and the first input end of the photocoupler U8.

3. The NPN and PNP component access circuit according to claim 2, characterized in that: The noise filtering circuit includes a Zener diode D15 and a Zener diode D1 , and the Zener diode D15 and the Zener diode D1 are connected in reverse series.

4. The NPN and PNP component access circuit according to claim 1, characterized in that: A signal conditioning circuit is provided between the fourth resistor R45 and the external control unit.

5. The NPN and PNP component access circuit according to claim 4, characterized in that: The signal conditioning circuit is a Smith trigger U10-A.

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