RS485 interface circuit used on ultrasonic sensor

Abstract

The utility model discloses an RS485 interface circuit used on an ultrasonic sensor, and relates to the technical field of sensors, the RS485 interface circuit comprises an RS485 transceiver chip U8 and a protection circuit connected with the RS485 transceiver chip U8, the RS485 transceiver chip U8 is provided with a receiving end RO used for receiving converted external data, the receiving end RO is connected with a signal output end of the ultrasonic sensor, and the protection circuit is connected with the signal output end of the ultrasonic sensor. The transmitting end DI is used for receiving signals from an ultrasonic sensor, the enabling end RE and the enabling end DE are used for controlling the data receiving and transmitting state of a chip, the protection circuit comprises a transient suppression diode D6, and the two ends of the transient suppression diode D6 are connected to the A end and the B end of the RS485 transceiver chip U8 respectively. The data transmission distance between the ultrasonic sensor and external equipment is obviously prolonged, the application range of the ultrasonic sensor is effectively expanded, and a powerful guarantee is provided for reliable work of the ultrasonic sensor.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, and more specifically, to an RS485 interface circuit used in an ultrasonic sensor. Background Technology

[0002] Ultrasonic sensors are widely used in many fields such as modern industrial production and intelligent monitoring systems for critical tasks such as distance measurement and liquid level detection.

[0003] However, traditional sensor interface circuits have many shortcomings in data transmission. For example, they have limited transmission distances, making it difficult to meet the needs of long-distance data transmission in large factories or complex environments; their anti-interference capabilities are poor, and in environments with strong electromagnetic interference, such as near electrical equipment in industrial workshops or around power transmission lines, the accuracy and stability of data transmission are severely affected, leading to large deviations in measurement results or even malfunction. Furthermore, they are vulnerable to sudden events such as electrostatic discharge, lightning surges, and line overcurrent.

[0004] Therefore, traditional circuits lack effective protection mechanisms, making the chips and other electronic components in the circuit extremely vulnerable to damage. This increases equipment maintenance costs and system downtime, severely impacting production efficiency and system reliability. In light of this, we propose an RS485 interface circuit for use in ultrasonic sensors. Utility Model Content

[0005] The purpose of this utility model is to overcome the shortcomings of the existing technology, adapt to the needs of reality, and provide an RS485 interface circuit for ultrasonic sensors. The purpose is to provide an RS485 interface circuit for ultrasonic sensors that, through unique circuit design and component selection, achieves long-distance, high-reliability data transmission and effectively protects the circuit from damage caused by various abnormal conditions.

[0006] To solve the above technical problems, this utility model provides the following technical solution: an RS485 interface circuit for use in an ultrasonic sensor, including an RS485 transceiver chip U8 and a protection circuit connected to the RS485 transceiver chip U8.

[0007] The RS485 transceiver chip U8 has a receiver terminal RO for receiving converted external data, a transmitter terminal DI connected to the signal output terminal of the ultrasonic sensor to receive signals from the ultrasonic sensor, and an enable terminal RE and an enable terminal DE for controlling the data transmission and reception status of the chip.

[0008] The protection circuit includes a transient suppression diode D6, with its two ends connected to terminals A and B of the RS485 transceiver chip U8, respectively. A resettable fuse F4 and a transient suppression diode D5 are connected in parallel to terminal A of the RS485 transceiver chip U8, and a resettable fuse F5 and a transient suppression diode D5 are connected in parallel to terminal B of the RS485 transceiver chip U8.

[0009] This invention utilizes the differential transmission characteristics of the RS485 interface to significantly extend the data transmission distance between the ultrasonic sensor and external devices, meeting the needs of long-distance data transmission in large industrial scenarios and complex environments. Compared with traditional interface circuits, it can increase the transmission distance under the same environmental conditions, effectively expanding the application range of ultrasonic sensors. By employing twisted-pair connections and a reasonable component layout in the circuit design, the circuit's anti-interference capability is greatly enhanced. In environments with strong electromagnetic interference, the data transmission error rate of the interface circuit of this invention is significantly reduced compared to traditional circuits, ensuring the accuracy and stability of data transmission and providing a strong guarantee for the reliable operation of ultrasonic sensors.

[0010] Preferably, the GND terminal of the RS485 transceiver chip U8 is grounded, and a +5V power supply and a capacitor C1 are connected in parallel to the VCC terminal of the RS485 transceiver chip U8, with the other end of the capacitor C1 grounded.

[0011] Preferably, the protection circuit includes resistors R1 and R3. One end of resistor R1 is connected to terminal A of the RS485 transceiver chip U8, and the other end is connected to terminal VCC of the RS485 transceiver chip U8.

[0012] Preferably, one end of the resistor R3 is connected to terminal B of the RS485 transceiver chip U8, and the other end of the resistor R3 is grounded.

[0013] Preferably, the other ends of the two transient suppression diodes D5 are grounded, and the other ends of the self-resetting fuse F4 and the self-resetting fuse F5 are connected to the A and B ends of the RS485 interface of the external device respectively via twisted pair cables.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] 1. This invention utilizes the differential transmission characteristics of the RS485 interface to significantly extend the data transmission distance between the ultrasonic sensor and external devices, meeting the needs of long-distance data transmission in large industrial scenarios and complex environments. Compared with traditional interface circuits, it can increase the transmission distance under the same environmental conditions, effectively expanding the application range of ultrasonic sensors. By adopting twisted-pair connections and a reasonable component layout in the circuit design, the circuit's anti-interference capability is greatly enhanced. In environments with strong electromagnetic interference, the data transmission error rate of the interface circuit of this invention is significantly reduced compared to traditional circuits, ensuring the accuracy and stability of data transmission and providing a strong guarantee for the reliable operation of ultrasonic sensors.

[0016] 2. This utility model also features a well-designed protection circuit, including two transient suppression diodes D5 and one transient suppression diode D6, as well as self-resetting fuses F4 and F5. This effectively addresses electrostatic discharge, lightning surges, and overcurrent conditions, significantly improving circuit stability and reliability, reducing equipment maintenance costs and system downtime. Furthermore, the use of self-resetting fuses F4 and F5 allows the circuit to automatically recover after overcurrent protection without manual intervention, further enhancing circuit maintenance convenience and system continuous operation capability. In applications requiring high continuity of equipment operation, the circuit of this invention can effectively prevent prolonged downtime due to overcurrent faults, ensuring efficient production. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit connection of this utility model. Detailed Implementation

[0018] like Figure 1 As shown, this utility model relates to an RS485 interface circuit used in an ultrasonic sensor, including an RS485 transceiver chip U8 and a protection circuit connected to the RS485 transceiver chip U8.

[0019] The RS485 transceiver chip U8 has a receiver terminal RO for receiving converted external data, a transmitter terminal DI connected to the signal output terminal of the ultrasonic sensor to receive signals from the ultrasonic sensor, and an enable terminal RE and an enable terminal DE for controlling the data transmission and reception status of the chip.

[0020] The protection circuit includes a transient suppression diode D6, with its two ends connected to terminals A and B of the RS485 transceiver chip U8, respectively. A resettable fuse F4 and a transient suppression diode D5 are connected in parallel to terminal A of the RS485 transceiver chip U8, and a resettable fuse F5 and a transient suppression diode D5 are connected in parallel to terminal B of the RS485 transceiver chip U8.

[0021] This invention utilizes the differential transmission characteristics of the RS485 interface to significantly extend the data transmission distance between the ultrasonic sensor and external devices, meeting the needs of long-distance data transmission in large industrial scenarios and complex environments. Compared with traditional interface circuits, it can increase the transmission distance under the same environmental conditions, effectively expanding the application range of ultrasonic sensors. By employing twisted-pair connections and a reasonable component layout in the circuit design, the circuit's anti-interference capability is greatly enhanced. In environments with strong electromagnetic interference, the data transmission error rate of the interface circuit of this invention is significantly reduced compared to traditional circuits, ensuring the accuracy and stability of data transmission and providing a strong guarantee for the reliable operation of ultrasonic sensors.

[0022] In an embodiment of this utility model, the GND terminal of the RS485 transceiver chip U8 is grounded, and a +5V power supply and a capacitor C1 are connected in parallel to the VCC terminal of the RS485 transceiver chip U8, with the other end of the capacitor C1 grounded.

[0023] In an embodiment of this utility model, the protection circuit includes resistors R1 and R3. One end of resistor R1 is connected to terminal A of the RS485 transceiver chip U8, and the other end is connected to terminal VCC of the RS485 transceiver chip U8.

[0024] In an embodiment of this utility model, one end of the resistor R3 is connected to the B terminal of the RS485 transceiver chip U8, and the other end of the resistor R3 is grounded.

[0025] In an embodiment of this utility model, the other ends of the two transient suppression diodes D5 are grounded, and the other ends of the self-resetting fuse F4 and the self-resetting fuse F5 are connected to the A and B ends of the RS485 interface of the external device respectively via twisted pair cables.

[0026] In the embodiments of this utility model, the RS485 transceiver chip U8 is model WS3080EESA, the transient suppression diode D6 is model SMBJ6.5CA, the resettable fuses F4 and F5 are model JK-NSMD010 / 60V, the transient suppression diode D5 is model PSM712-LF-T7, the resistors R1 and R3 are both 10KΩ, and the capacitor C1 has a capacitance of 100nF and a rated operating voltage of 50V.

[0027] This invention also features a sophisticated protection circuit design, including two transient suppression diodes D5 and one transient suppression diode D6, as well as self-resetting fuses F4 and F5. This effectively addresses electrostatic discharge, lightning surges, and overcurrent conditions, significantly improving circuit stability and reliability, reducing equipment maintenance costs and system downtime. Furthermore, the use of self-resetting fuses F4 and F5 allows the circuit to automatically recover after overcurrent protection without manual intervention, further enhancing maintenance convenience and continuous system operation. In applications requiring high continuity of equipment operation, this invention's circuit effectively prevents prolonged downtime due to overcurrent faults, ensuring efficient production.

[0028] Working Principle: This embodiment provides an RS485 interface circuit for use on an ultrasonic sensor. In use, the data or status information acquired by the ultrasonic sensor is output as an electrical signal from its signal output terminal. This signal is connected to the transmitting terminal DI of the RS485 transceiver chip U8. Under the control of the enable terminals RE and DE, the chip U8 converts the TTL level signal from the DI terminal into an RS485 level signal. When the enable terminal is set to transmit mode, the internal drive circuit of the chip processes and amplifies the input signal to meet the differential signal requirements of the RS485 standard, and then outputs it to the RS485 interface of the external device through pins A and B. During this process, resistors R1 and R3 play a certain biasing and current-limiting role, ensuring that the signal is transmitted under appropriate electrical parameters and avoiding signal distortion or chip overload. For example, resistor R1 limits the sudden change in current at terminal A, which helps stabilize the output signal level and ensures that data can be accurately transmitted to the external device, realizing data transmission between the ultrasonic sensor and the external device.

[0029] Data sent by external devices is transmitted via RS485 differential signals to pins A and B of chip U8 through a twisted pair cable. Chip U8's receiver RO is in receive mode under the control of the enable pin RE. At this time, the chip's internal receiving circuit processes the input differential signal, converting it into a TTL level signal. The converted signal can be read and processed by subsequent circuits (such as a connected microcontroller). If feedback is needed to control the ultrasonic sensor's operating status, signal transmission can be achieved through the corresponding control pin (if present). During reception, capacitor C1 filters the power supply, removing power noise and interference that may be introduced by external devices, ensuring stable operation of the chip's receiving circuit, ensuring the accuracy of received data, preventing data errors or loss due to interference, and thus maintaining the reliability of the entire communication link.

[0030] When the circuit encounters instantaneous high voltage conditions such as electrostatic discharge or lightning surges, the voltage across the transient voltage suppressor diode D6 will rise sharply. Once the voltage exceeds its breakdown voltage, D6 quickly conducts, clamping the excessive voltage within a relatively low and safe level range, thereby protecting the transceiver chip U8 and other connected circuit components from damage caused by the instantaneous high voltage. For example, during a lightning surge, a transient voltage pulse of several kilovolts or even higher may appear in the circuit. D6 can respond and conduct within an extremely short time (typically picoseconds to nanoseconds), limiting the voltage below its rated protection level, ensuring that the voltage difference between pins A and B of chip U8 remains within a safe range, and maintaining the chip's normal operating condition.

[0031] Transient voltage suppressor diode D5 is connected in parallel with resettable fuses F4 and F5 at terminals A and B of chip U8, respectively. Its function is similar to that of D6, further enhancing the overvoltage protection capability at terminals A and B. While D6 provides primary high-voltage clamping protection, D5 acts as an auxiliary protection element, offering secondary protection against residual high-voltage pulses that may originate from other paths or be not fully suppressed by D6. This forms a redundant overvoltage protection mechanism, improving the circuit's overall protection capability against transient high voltages and reducing the risk of circuit damage due to overvoltage.

[0032] Furthermore, under normal circuit conditions, the resistance values ​​of resettable fuses F4 and F5 are low, having minimal impact on the circuit current and ensuring normal data transmission and power supply. However, when an abnormal situation occurs in the circuit causing excessive current, such as a short circuit or a component failure leading to a sharp increase in local current, the current through F4 and F5 will exceed their rated operating current. At this time, the resistance value of the resettable fuse will rapidly increase, limiting further current increase and protecting other components in the circuit from damage due to excessive current. After the fault is cleared, the resettable fuse will automatically cool down and return to a low-resistance state, eliminating the need for manual fuse replacement. This allows the circuit to quickly resume normal operation, reducing equipment downtime and improving system availability and maintenance convenience. This characteristic gives the circuit excellent self-protection and recovery capabilities in the face of potential overcurrent faults, enhancing the reliability and stability of the entire system.

[0033] The embodiments disclosed herein are preferred embodiments, but are not limited thereto. Those skilled in the art can readily grasp the spirit of this utility model based on the above embodiments and make different extensions and variations. However, as long as they do not depart from the spirit of this utility model, they are all within the protection scope of this utility model.

Claims

1. An RS485 interface circuit used in an ultrasonic sensor, characterized in that, Includes RS485 transceiver chip U8 and protection circuit connected to RS485 transceiver chip U8; The RS485 transceiver chip U8 has a receiver terminal RO for receiving converted external data, a transmitter terminal DI connected to the signal output terminal of the ultrasonic sensor to receive signals from the ultrasonic sensor, and an enable terminal RE and an enable terminal DE for controlling the data transmission and reception status of the chip. The protection circuit includes a transient suppression diode D6, with its two ends connected to terminals A and B of the RS485 transceiver chip U8, respectively. A resettable fuse F4 and a transient suppression diode D5 are connected in parallel to terminal A of the RS485 transceiver chip U8, and a resettable fuse F5 and a transient suppression diode D5 are connected in parallel to terminal B of the RS485 transceiver chip U8. The other ends of the resettable fuse F4 and the resettable fuse F5 are connected to terminals A and B of the RS485 interface of an external device, respectively, via twisted-pair cables.

2. The RS485 interface circuit for use in an ultrasonic sensor according to claim 1, characterized in that, The GND terminal of the RS485 transceiver chip U8 is grounded, and a +5V power supply and a capacitor C1 are connected in parallel to the VCC terminal of the RS485 transceiver chip U8, with the other end of the capacitor C1 grounded.

3. The RS485 interface circuit for use in an ultrasonic sensor according to claim 2, characterized in that, The protection circuit includes resistors R1 and R3. One end of resistor R1 is connected to terminal A of the RS485 transceiver chip U8, and the other end is connected to terminal VCC of the RS485 transceiver chip U8.

4. The RS485 interface circuit for use in an ultrasonic sensor according to claim 3, characterized in that, One end of the resistor R3 is connected to terminal B of the RS485 transceiver chip U8, and the other end of the resistor R3 is grounded.

5. The RS485 interface circuit for use in an ultrasonic sensor according to claim 1, characterized in that, The other end of the two transient suppression diodes D5 is grounded.

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