An RS-485 communication module for a bidirectional converter with electrical isolation function

Abstract

This utility model discloses an RS-485 communication module for a bidirectional converter with electrical isolation, including differential bus transceiver U3, differential bus transceiver U6, isolated power supply module U4, isolated power supply module U2, high-speed optocoupler U1, and high-speed optocoupler U5. When the 485 master station requests data, the received input data is converted into a UART level signal by differential bus transceiver U3 and output from pin 1 (RO). This signal is transmitted to high-speed optocoupler U5, and then transmitted to the INA port of isolated power supply module U2 through the VO pin of high-speed optocoupler U5. When the 485 slave station returns data, the received output data is converted into a UART level signal by differential bus transceiver U6 and output from pin 1 (RO). This 485 isolation module circuit demonstrates significant advantages in achieving stable and reliable RS-485 communication due to its excellent electrical isolation performance, efficient power management, precise component selection, and strong anti-interference capability.

Description

Technical Field

[0001] This utility model relates to the technical field of RS-485 communication modules, specifically to an RS-485 communication module for a bidirectional converter with electrical isolation function. Background Technology

[0002] With the rapid development of automatic control technology, various industrial control systems are becoming increasingly complex, intelligent, and networked, with ever-increasing information transmission volumes. To meet the communication and control needs of various control systems, data communication bus protocols such as RS-485, I2C, and CAN have been rapidly developed and applied. RS-485 uses two-wire differential balanced transmission technology and has advantages such as simple structure and strong anti-interference capability. I2C is a simple and effective bidirectional two-wire synchronous serial bus. The CAN bus protocol adopts many new technologies, and compared with general communication buses, its data communication has outstanding reliability, real-time performance, and flexibility.

[0003] Regarding the technical problems existing in the prior art, such as the public announcement (CN213659213U) of an isolated RS-485, I2C and CAN communication module, there are common-mode interference and ground potential difference effects, resulting in poor reliability of module signal transmission and significant communication interference problems, causing technical problems such as unreliability and instability of RS-485 communication; at the same time, it does not provide power isolation anti-interference capability.

[0004] Therefore, there is a need to provide an RS-485 communication module for bidirectional converters with electrical isolation function. Utility Model Content

[0005] To address the problems existing in the prior art, this utility model provides an RS-485 communication module for a bidirectional converter with electrical isolation function, aiming to improve and solve the aforementioned technical problems.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution: an RS-485 communication module for a bidirectional converter with electrical isolation function, including a differential bus transceiver U3, a differential bus transceiver U6, an isolation power supply module U4, an isolation power supply module U2, a high-speed optical coupler U1, and a high-speed optical coupler U5. BUCK buck converter: The BUCK buck converter stably reduces the input 24V voltage to 5V, providing reliable power support for the entire circuit. Pin A of differential bus transceiver U3 is set as the positive terminal of the differential signal, and pin B is set as the negative terminal of the differential signal. Pins A and B of differential bus transceiver U3 are equipped with fuses, and pin A is equipped with an input resistor INR. When transmitting data, differential bus transceiver U3 is connected from pin RO to pin VO of high-speed optocoupler U5, and the data is transmitted to the INA port of isolated power module U2 through the VO pin of high-speed optocoupler U5. When receiving data, differential bus transceiver U6 is connected from pin RO to high-speed optocoupler U1, and the data is transmitted to the INA port of isolated power module U4 through the VO pin of high-speed optocoupler U1. Pin A of differential bus transceiver U6 is set as the positive terminal of the differential signal output, and pin B of differential bus transceiver U6 is set as the negative terminal of the differential signal.

[0007] Furthermore, it also includes an isolated power supply module U8. The INA port of the isolated power supply module U4 is connected to a resistor R10. The resistor R10 is connected to pin 2 (+Vin) of the isolated power supply module U8. Pin 5 (GND) of the isolated power supply module U4 is connected to pin 1 (-Vin) of U8 through a ground wire.

[0008] Furthermore, the isolated power supply module U8 also includes C15 and C16 filters. Pin 4 (+Vout) of the isolated power supply module U8 provides isolated +5V OUT_VCC, while pin 3 (-Vout) is connected to OUTGND. The C15 and C16 filters are used to filter and smooth the output voltage to ensure a stable power supply.

[0009] Furthermore, pin 2 of the high-speed optocoupler U5 is connected to resistor R17 and the positive terminal of 5V in sequence, and pin 5 of the high-speed optocoupler U5 is connected to the negative terminal. Pin RO of the differential bus transceiver U3 is connected to resistor R12 and the positive terminal of 5V in sequence, and pin 5 of the differential bus transceiver U3 is connected to the negative terminal.

[0010] Furthermore, pin 6 of the high-speed optocoupler U5 is connected to pin 4 of the differential bus transceiver U6 through resistor R22, pin 5 of the differential bus transceiver U6 is the negative input, pin 1 of the isolated power supply module U4 is connected to the positive terminal (5V) through resistor R10, and pin 3 is the negative input.

[0011] Furthermore, pin 8 of the high-speed optocoupler U1 is connected to the positive terminal 5V through the C2 filter, and the negative terminal is input through pin 5. The signal is transmitted to the INA port of the isolation power module U2 through the VO pin of the high-speed optocoupler U5, and pin 3 of the isolation power module U2 is grounded.

[0012] In summary, this utility model provides an RS-485 communication module for a bidirectional converter with electrical isolation function. Compared with the prior art, the technical advantages of this utility model patent are as follows: 1. Electrical isolation: Electrical isolation of the signals is achieved by using optocouplers (such as U1 and U5), effectively protecting both communicating parties from voltage spikes, ground potential differences, and other electrical interference. This isolation helps improve the reliability and stability of the system.

[0013] 2. Power Management and Buck Design: A high-efficiency BUCK buck converter (e.g., TPS5430DDAG4) is used to stably reduce the input 24V voltage to 5V, providing reliable power support for the entire circuit. This not only ensures the normal operation of each component but also improves energy efficiency and reduces heat loss.

[0014] 3. Precise component selection: High-precision resistors (such as R26 10KΩ 0.1%, R27 3.24KΩ 0.1%) are used in the circuit to ensure the accuracy of circuit parameters, which is crucial for maintaining signal integrity and system reliability.

[0015] 4. Enhanced anti-interference capability: In addition to electrical isolation, filter capacitors (such as C9 100nF / 50V, C7 10nF / 50V, etc.) are used to reduce the impact of electromagnetic interference (EMI) on signal transmission, further enhancing the anti-interference performance of the system.

[0016] 5. Flexible data transmission mode: The design supports bidirectional data transmission and can automatically switch between receiving and transmitting modes according to the signal status, making the module more flexible and adaptable to different communication needs in practical applications.

[0017] 6. Suitable for industrial environments: Given its strong anti-interference capabilities and electrical isolation characteristics, this module is very suitable for applications such as industrial automation and remote monitoring that require long-distance, stable and reliable communication.

[0018] In summary, this RS-485 isolation module circuit demonstrates significant advantages in achieving stable and reliable RS-485 communication due to its excellent electrical isolation performance, efficient power management, precise component selection, and strong anti-interference capabilities. Attached Figure Description

[0019] Figure 1 This is a circuit design diagram of an RS-485 communication module for a bidirectional converter with electrical isolation function according to this utility model. Figure 2 This is the design diagram of the BUCK step-down circuit of this utility model; Figure 3 This is the circuit design diagram of the U8 isolated power supply module of this utility model; Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] like Figures 1 to 3 As shown:

[0022] 1. Isolated power supply module U8 (B0505S-1WR3) U8 (B0505S-1WR3) Pin Connections: • Pin 1 (-Vin): Connect to the negative input (GND).

[0023] • Pin 2 (+Vin): Connected to the positive input terminal (+5V) to provide the input voltage.

[0024] • Pin 3 (-Vout): Output negative terminal, connected to output ground (OUTGND).

[0025] • Pin 4 (+Vout): Output positive, providing isolated output voltage (+5V OUT_VCC).

[0026] 2. Connection of capacitor and test point: • C13, C14: Connected in parallel between +Vin and -Vin for input filtering and voltage smoothing.

[0027] • C16: Connected in parallel between +Vout and -Vout for output filtering and voltage smoothing.

[0028] • C15: Connected between +Vout and -Vout to enhance the stability of the output voltage.

[0029] • 4.7uF capacitor: Connected between +Vout and -Vout to further improve the quality of the output voltage.

[0030] • TP2: Connected to +Vout for monitoring the output voltage.

[0031] • TP3: Connected to -Vout, usually connected to ground, used to reference ground potential.

[0032] 3. BUCK step-down circuit (TPS5430DDAG4) and its related component connections BUCK step-down circuit (TPS5430DDAG4) pin connections: • Pin 8 (PH): Phase node, connected to one end of inductor L1.

[0033] • Pin 1 (BOOT): The other end of the bootstrap capacitor C7 is connected to the PH pin.

[0034] • Pin 3 (VIN): Input voltage, connected to a 24V power supply.

[0035] • Pin 4 (ENA / VSENSE): Enable / feedback voltage sensing, connected to the output voltage via resistor divider R26 and R27.

[0036] • Pins 5, 6, 9: Ground (GND).

[0037] • Pin 7 (NC): Unused pin.

[0038] • Pin 8 (EP): The chip exposes a pad, which is typically grounded to enhance heat dissipation.

[0039] 4. Connection of other components: • C7: Bootstrap capacitor, connected between the BOOT and PH pins.

[0040] • C11: Output filter capacitor, connected between the output voltage and ground.

[0041] • L1: Inductor, connected between the PH pin and the output voltage.

[0042] • D7, D8: Rectifier diodes, connected between the input voltage and ground, respectively.

[0043] • R26, R27: Voltage divider resistors used to set the output voltage feedback.

[0044] RS-485 communication module and related component connections: 5. Differential bus transceiver U3 and U6 (SN75176BDR) pin connections: • Pin 1 (RO): Receive output, connected to the input of optocoupler U1 or U5.

[0045] • Pin 2 (DI): Transmit input, connected to the control signal source.

[0046] • Pin 3 (DE): Data enable, high level to transmit data, low level to receive data.

[0047] • Pin 4 (RE#): Receive enable, active low.

[0048] • Pin 5 (GND): Ground, connected to system ground.

[0049] • Pin 6 (A): Differential signal A, connected to the RS-485 bus.

[0050] • Pin 7 (B): Differential signal B, connected to the RS-485 bus.

[0051] • Pin 8 (VCC): Positive power supply, connected to +5V power supply.

[0052] 6. Pin connections for high-speed optocouplers U1 and U5: • Pin 1 (VO): Output, connected to the input of the next cascaded circuit.

[0053] • Pin 2 (INA): Positive input terminal, connected to the signal source.

[0054] • Pin 3 (INB): Negative input terminal, usually grounded.

[0055] • Pin 4 (GND): Ground, connected to system ground.

[0056] 1. Input and Isolation Power Supply Module (U8, B0505S-1WR3) • Input voltage: +5V is connected to pin 2 (+Vin) of U8 via R10, and GND is connected to pin 1 (-Vin) of U8 via ground. This provides the necessary input voltage for the isolated power supply module.

[0057] • Output Voltage: Pin 4 (+Vout) of U8 provides isolated +5V OUT_VCC, while pin 3 (-Vout) is connected to OUTGND. C16 and C15 are used to filter and smooth the output voltage, ensuring a stable power supply.

[0058] 2. Data transmission and high-speed optical couplers (U1, U5 - HCPL-0600-500E) • Data transmission process: When the 485 master station requests data, the received data will be converted into a UART level signal through the differential bus transceiver U3 and output from pin 1 RO.

[0059] This signal will be transmitted to the high-speed optocoupler U5, and then transmitted to the INA port of the isolated power module U2 through the VO pin of the high-speed optocoupler U5.

[0060] If the transmission signal is 1, then OUT_DIR is still 0, which means it is in read mode, the AB differential line is relaxed, and 1 is sent; if the transmission signal is 0, then OUT_DIR becomes 1, 0 is sent from the DI pin, and data is sent to the slave device through OUT485 in sequence.

[0061] Data receiving process: When the 485 slave returns data, the received data is converted into a UART level signal by the differential bus transceiver U6 and output from pin 1, RO.

[0062] This signal is then transmitted to the high-speed optocoupler U1, and then from the VO pin of the high-speed optocoupler U1 to the INA port of the isolated power supply module U4.

[0063] If the transmission signal is 1, then DE RE# of U3 remains low, indicating read mode, the AB differential lines are relaxed, and 1 is sent; if the transmission signal is 0, then DE RE# of U3 becomes 1, 0 is sent from the DI pin, and data is received back to the host through 485A in sequence.

[0064] 3. RS-485 transceiver (U3, U6 - SN75176BDR) • Transmit mode: When the DE pin is high, data is transmitted via the A and B differential lines; when the RE# pin is low, the receive mode is disabled.

[0065] • Receive mode: When the DE pin is low, the A and B differential lines are relaxed, ready to receive data; when the RE# pin is high, the receive mode is enabled, and the RO pin outputs the received data.

[0066] 4. Power Management (TPS5430DDAG4) • Buck converter: The TPS5430DDAG4 steps the 24V input voltage down to 5V output, providing a stable power supply for the entire system. C9 and C7 are used for filtering and smoothing the input and output voltages to ensure system stability.

[0067] • Feedback control: The voltage divider network consisting of resistors R26 and R27 is connected to the ENA / VSENSE pin to regulate the output voltage to maintain stability.

[0068] 1. Electrical isolation • Problems with existing solutions: Traditional RS-485 communication lacks effective electrical isolation and is susceptible to common-mode interference and ground potential differences, which can lead to communication failures or equipment damage.

[0069] • Advantages of this design: Signal isolation is achieved by using an optocoupler (HCPL-0600-500E), and power isolation is achieved by using an isolated power supply module (B0505S-1WR3), which effectively prevents external interference from affecting the communication system.

[0070] 2. Efficient power management • Problems with existing solutions: Many existing solutions rely on a single power source and cannot provide a stable power supply, especially in environments with large voltage fluctuations.

[0071] • Advantages of this design: The integrated BUCK step-down circuit (TPS5430DDAG4) can stably reduce the 24V voltage to 5V, providing reliable power support for the system, reducing heat loss, and improving energy efficiency.

[0072] 3. Enhanced anti-interference capability • Problems with existing solutions: Traditional RS-485 modules are susceptible to interference in complex electromagnetic environments, affecting communication quality.

[0073] • Advantages of this design: By using filter capacitors (such as C9, C7, etc.) to reduce electromagnetic interference (EMI), the anti-interference performance of the system is further enhanced, ensuring the accuracy of data transmission.

[0074] 4. Flexible data transmission modes • Problems with existing solutions: Some existing solutions require manually switching between receive and transmit modes, which increases operational complexity.

[0075] • Advantages of this design: This module can automatically switch between receiving and transmitting modes according to the signal status without manual intervention, making the module more flexible and adaptable to different communication needs in practical applications.

[0076] 5. Suitable for industrial environments • Problems with existing solutions: Many existing RS-485 modules perform poorly in harsh environments and are prone to failure.

[0077] • Advantages of this design: Due to its strong anti-interference capability and electrical isolation characteristics, this module is very suitable for applications such as industrial automation and remote monitoring that require long-distance, stable and reliable communication.

[0078] Summary: This design significantly improves the reliability and stability of RS-485 communication by introducing electrical isolation, efficient power management, and enhanced anti-interference measures. Compared to existing solutions, it not only solves common communication interference problems but also provides more flexible operation and greater adaptability, making it particularly suitable for applications in complex environments such as industrial automation and remote monitoring.

[0079] The embodiments described in this utility model are for illustrative purposes only and do not constitute a limitation on the scope of the claims. Other substantially equivalent substitutions that can be conceived by those skilled in the art are all within the protection scope of this utility model.

Claims

1. A RS-485 communication module for a bidirectional converter with electrical isolation function, characterized in that, It includes differential bus transceiver U3, differential bus transceiver U6, isolated power supply module U4, isolated power supply module U2, high-speed optocoupler U1, and high-speed optocoupler U5; BUCK buck converter: The BUCK buck converter stably reduces the input 24V voltage to 5V, providing reliable power support for the entire circuit. Pin A of differential bus transceiver U3 is set as the positive terminal of the differential signal, and pin B is set as the negative terminal of the differential signal. Pins A and B of differential bus transceiver U3 are equipped with fuses, and pin A is equipped with an input resistor INR. When transmitting data, differential bus transceiver U3 is connected from pin RO to pin VO of high-speed optocoupler U5, and the data is transmitted to the INA port of isolated power module U2 through the VO pin of high-speed optocoupler U5. When receiving data, differential bus transceiver U6 is connected from pin RO to high-speed optocoupler U1, and the data is transmitted to the INA port of isolated power module U4 through the VO pin of high-speed optocoupler U1. Pin A of differential bus transceiver U6 is set as the positive terminal of the differential signal output, and pin B of differential bus transceiver U6 is set as the negative terminal of the differential signal.

2. The RS-485 communication module with electrical isolation function for bidirectional converter according to claim 1, characterized in that, It also includes an isolated power supply module U8. The INA port of the isolated power supply module U4 is connected to a resistor R10. The resistor R10 is connected to pin 2 (+Vin) of the isolated power supply module U8. Pin 5 (GND) of the isolated power supply module U4 is connected to pin 1 (-Vin) of U8 through a ground wire.

3. The RS-485 communication module for a bidirectional converter with electrical isolation function according to claim 2, characterized in that, The isolated power supply module U8 also includes C15 and C16 filters. Pin 4 (+Vout) of the isolated power supply module U8 provides isolated +5V OUT_VCC, while pin 3 (-Vout) is connected to OUTGND. The C15 and C16 filters are used to filter and smooth the output voltage to ensure a stable power supply.

4. The RS-485 communication module with electrical isolation function for bidirectional converter according to claim 1, characterized in that, Pin 2 of the high-speed optocoupler U5 is connected to resistor R17 and the positive terminal of 5V in sequence, and pin 5 of the high-speed optocoupler U5 is the negative input terminal. Pin RO of the differential bus transceiver U3 is connected to resistor R12 and the positive terminal of 5V in sequence, and pin 5 of the differential bus transceiver U3 is the negative input terminal.

5. The RS-485 communication module with electrical isolation for bidirectional converter according to claim 1, characterized in that, Pin 6 of the high-speed optocoupler U5 is connected to pin 4 of the differential bus transceiver U6 through resistor R22. Pin 5 of the differential bus transceiver U6 is the negative input. Pin 1 of the isolated power supply module U4 is connected to the positive terminal (5V) through resistor R10, and pin 3 is the negative input.

6. The RS-485 communication module with electrical isolation for bidirectional converter according to claim 1, characterized in that, Pin 8 of the high-speed optocoupler U1 is connected to the positive terminal 5V through the C2 filter, and the negative terminal is input through pin 5. The signal is transmitted to the INA port of the isolation power supply module U2 through the VO pin of the high-speed optocoupler U5. Pin 3 of the isolation power supply module U2 is grounded.

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