Improved RS-485 communication module circuit

Abstract

The utility model relates to an improved RS-485 communication module circuit. The modular circuit is used for a train auxiliary inverter system and comprises a transmit-receive driving chip and a PC410L isolation optocoupler unit, the transmit-receive driving chip is connected with the PC410L isolation optocoupler unit, the PC410L isolation optocoupler unit comprises an LED anode pin, the LED anode pin is connected with a power supply through a current-limiting resistor, and the resistance value of the current-limiting resistor is 520 ohms. Compared with the prior art, the utility model has the advantages that the stability of the RS-485 communication module is improved, the failure rate of the RS-485 communication module in the train auxiliary inverter system is reduced, and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of inverters, and in particular to an improved RS-485 communication module circuit. Background Art

[0002] The main functions of the auxiliary inverter system of rail transit trains include: obtaining DC voltage (generally 1500VDC and 750VDC) from the power grid, and converting and outputting 380VAC through an auxiliary inverter (also called a static inverter) to supply power to the auxiliary equipment on the train. During actual maintenance, it is found that the main fault of the vehicle auxiliary inverter system is the RS-485 communication module fault, and the communication module cannot work properly, resulting in the failure of the entire system.

[0003] The role of the RS-485 communication module in the train auxiliary inverter system is to connect to the train bus MVB through internal communication, and can manage the operation of the train auxiliary inverter system in real time and detect the status of each module of the system. The signal is converted through the RS-485 module and the train MVB bus, and transmitted to the train HMI human-machine interface, which is convenient for monitoring and managing the train auxiliary inverter system. During the maintenance of this module, it is found that its main fault is caused by RS-485 communication, and the isolation optocoupler PC410L in the RS-485 communication part is damaged more frequently. The RS-485 communication module uses the optocoupler PC410L to achieve signal isolation, but the voltage fluctuation of the power supply may break down the optocoupler PC410L, resulting in RS-485 communication failure. As Figure 1 shown, through actual maintenance summary and judgment, since the VCC voltage of the traditional RS-485 module communication circuit is DC5.2V during actual operation, the current-limiting resistors R1 = R2 = R3 = R4 = 390R, and the actual working current is about In = VCC / R1 = 13.3mA, and the optocoupler PC410L works under a state greater than the rated current (IF = 10mA), resulting in damage. Therefore, in order to ensure the normal operation of the vehicle auxiliary inverter system as much as possible, how to reduce the failure rate of the RS-485 communication module has become a problem to be solved in this field. Summary of the Utility Model

[0004] The purpose of the present utility model is to provide an improved RS-485 communication module circuit to overcome the defects of the existing RS-485 communication module that has failed.

[0005] The purpose of the present utility model can be achieved by the following technical solutions:

[0006] The present utility model provides an improved RS-485 communication module circuit for a train auxiliary inverter system, which includes a transceiver driver chip and a PC410L isolation optocoupler unit. The transceiver driver chip is connected to the PC410L isolation optocoupler unit. The PC410L isolation optocoupler unit includes an LED anode pin, and the LED anode pin is connected to a power supply through a current-limiting resistor, and the resistance value of the current-limiting resistor is 520 Ω.

[0007] As a preferred technical solution, the transceiver driver chip includes an ADM1485 chip.

[0008] As a preferred technical solution, the ADM1485 chip includes a receive output pin, a receive enable pin, a driver enable pin, and a driver input pin, which are respectively connected to the PC410L isolation optocoupler unit.

[0009] As a preferred technical solution, the ADM1485 chip further includes a first ground pin and a first power supply pin. The first ground pin is grounded, and the first power supply pin is connected to a power supply.

[0010] As a preferred technical solution, the ADM1485 chip further includes a first differential pin and a second differential pin, which are respectively connected to an external differential line.

[0011] As a preferred technical solution, the external differential line is connected to the train bus MVB.

[0012] As a preferred technical solution, the PC410L isolation optocoupler unit includes a plurality of PC410L isolation optocouplers. Each PC410L isolation optocoupler includes an LED anode pin, an LED cathode pin, and an optocoupler output pin. The receive output pin is connected to the LED cathode pin of one of the PC410L isolation optocouplers, and the receive enable pin, the driver enable pin, and the driver input pin are respectively connected to the optocoupler output pins of the remaining PC410L isolation optocouplers.

[0013] As a preferred technical solution, each PC410L isolation optocoupler further includes a second ground pin and a second power supply pin. The second ground pin is grounded, and the second power supply pin is connected to a power supply.

[0014] As a preferred technical solution, the LED cathode pins of the remaining PC410L isolation optocouplers are respectively connected to a 74HC14 chip.

[0015] As a preferred technical solution, the operating current of the PC410L isolation optocoupler unit is 10 mA.

[0016] Compared with the prior art, the present utility model has the following beneficial effects:

[0017] 1. By changing the resistance value of the current-limiting resistor of the isolation optocoupler PC410L in the RS-485 communication module of the train auxiliary inverter system, the present utility model enables the RS-485 communication module to operate stably, thereby reducing the occurrence of faults in the train auxiliary inverter system as a whole.

[0018] 2. In the RS-485 communication module circuit proposed by the present utility model, the PC410L isolation optocoupler unit is connected to the power supply through a current-limiting resistor, and the resistance value of the current-limiting resistor is 520 Ω, which can enable the optocoupler to operate in a current state of 10 mA, improve the stability of the RS-485 communication module, and thus reduce the failure rate of the RS-485 communication module in the train auxiliary inverter system. Description of the Drawings

[0019] Figure 1 is the traditional RS-485 communication module circuit;

[0020] Figure 2 is the improved RS-485 communication module circuit in the embodiment of the present utility model;

[0021] Figure 3 is the working block diagram of the RS-485 communication module in the train auxiliary inverter system in the embodiment of the present utility model;

[0022] Among them: 1. ADM1485 chip; 2. First PC410L isolation optocoupler; 3. Second PC410L isolation optocoupler; 4. Third PC410L isolation optocoupler; 5. Fourth PC410L isolation optocoupler; 21. LED anode pin; 22. LED cathode pin; 23. Optocoupler output pin; 24. Second ground pin; 25. Second power supply pin. Detailed Embodiments

[0023] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0024] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present utility model is usually placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0025] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0026] Embodiment:

[0027] As Figure 2 shown, this embodiment provides an improved RS-485 communication module circuit. The circuit uses the ADM1485 chip 1 as the transceiver driver chip and also includes a PC410L isolation optocoupler unit.

[0028] The ADM1485 chip 1 includes a receive output pin RO, a receive enable pin RE (low level effective), a driver enable pin DE (high level effective), a driver input pin DI, a first ground pin, and a first power supply pin VCC, which are respectively connected to the PC410L isolation optocoupler unit. The first ground pin is grounded to GND2, and the first power supply pin VCC is connected to the power supply VCC2. The ADM1485 chip 1 also includes a first differential pin A and a second differential pin B, which are respectively connected to the external differential line. As Figure 3 shown, the external differential line is connected to the RS-485 train bus MVB.

[0029] The PC410L isolation optocoupler unit includes the first PC410L isolation optocoupler 2, the second PC410L isolation optocoupler 3, the third PC410L isolation optocoupler 4, and the fourth PC410L isolation optocoupler 5 with the same structure. Taking the first PC410L isolation optocoupler 2 as an example, this optocoupler includes an LED anode pin 21, an LED cathode pin 22, an optocoupler output pin 23, a second ground pin 24, and a second power pin 25. The second ground pin 24 is grounded to GND2, and the second power pin 25 is connected to the power supply VCC2. Similarly, the ground pins of the second PC410L isolation optocoupler 3 and the third PC410L isolation optocoupler 4 are grounded to GND2 and their power pins are connected to the power supply VCC2, while the ground pin of the fourth PC410L isolation optocoupler 5 is grounded to GND1 and its power pin is connected to the power supply VCC1.

[0030] In the circuit, the receive output pin RO of the ADM1485 chip 1 is connected to the LED cathode pin of the fourth PC410L isolation optocoupler 5, the receive enable pin RE is connected to the optocoupler output pin 23 of the first PC410L isolation optocoupler 2, the driver enable pin DE is connected to the optocoupler output pin of the second PC410L isolation optocoupler 3, and the driver input pin DI is connected to the optocoupler output pin of the third PC410L isolation optocoupler 4.

[0031] For the first PC410L isolation optocoupler 2, the second PC410L isolation optocoupler 3, and the third PC410L isolation optocoupler 4, their respective LED anode pins are connected to the power supply VCC1 through current-limiting resistors R1, R2, and R3 respectively, and the LED anode pin of the fourth PC410L isolation optocoupler 5 is connected to the power supply VCC2 through the current-limiting resistor R4. Among them, the current-limiting resistors R1 = R2 = R3 = R4 = 520R, that is, 520Ω, so that the optocoupler operates at a current In = VCC / R1 = 10mA, (rated current IF = 10mA) state, improving the stability of the RS-485 communication module, thereby reducing the faults of the RS-485 communication module in the train auxiliary inverter system.

[0032] In addition, the LED cathode pins of the first PC410L isolation optocoupler 2, the second PC410L isolation optocoupler 3, and the third PC410L isolation optocoupler 4 are respectively connected to the corresponding 74HC14 chips, and the optocoupler output pin of the fourth PC410L isolation optocoupler 5 is connected to the 74HC14 chip.

[0033] The module circuit provided in this embodiment uses an optocoupler to achieve signal isolation and realizes RS-485 communication through the ADM1485 chip 1. The first PC410L isolation optocoupler 2 to the third PC410L isolation optocoupler 4 control the DE, DI, and RE pins of the ADM1485, and the fourth PC410L isolation optocoupler 5 is connected to the RO pin of the ADM1485. By changing the resistance value of the current-limiting resistor of the isolation optocoupler PC410L in the RS-485 communication module of the train auxiliary inverter system, the RS-485 communication module can work stably, effectively reducing the failure rate of the RS-485 communication module in the train auxiliary inverter system and overall reducing the occurrence of failures in the train auxiliary inverter system.

[0034] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. An improved RS-485 communication module circuit for a train auxiliary inverter system, characterized in that: It includes a transceiver driver chip and a PC410L isolation optocoupler unit, the transceiver driver chip is connected to the PC410L isolation optocoupler unit, the PC410L isolation optocoupler unit includes an LED anode pin, the LED anode pin is connected to a power supply through a current limiting resistor, and the resistance value of the current limiting resistor is 520Ω.

2. The improved RS-485 communication module circuit according to claim 1, characterized in that: The transceiver driver chip includes an ADM1485 chip.

3. The improved RS-485 communication module circuit according to claim 2, characterized in that: The ADM1485 chip includes a receiving output pin, a receiving enable pin, a driver enable pin and a driver input pin, which are respectively connected to the PC410L isolation optical coupling unit.

4. The improved RS-485 communication module circuit according to claim 3, characterized in that: The ADM1485 chip further includes a first ground pin and a first power pin, wherein the first ground pin is connected to ground, and the first power pin is connected to a power supply.

5. The improved RS-485 communication module circuit according to claim 4, characterized in that: The ADM1485 chip also includes a first differential pin and a second differential pin, which are respectively connected to external differential lines.

6. The improved RS-485 communication module circuit according to claim 5, characterized in that: The external differential lines are connected to the train bus MVB.

7. The improved RS-485 communication module circuit according to claim 3, characterized in that: The PC410L isolation optocoupler unit includes multiple PC410L isolation optocouplers, each of the PC410L isolation optocouplers includes an LED anode pin, an LED cathode pin and an optocoupler output pin, the receive output pin is connected to the LED cathode pin of one of the PC410L isolation optocouplers, and the receive enable pin, the driver enable pin, and the driver input pin are respectively connected to the optocoupler output pins of the remaining PC410L isolation optocouplers.

8. The improved RS-485 communication module circuit according to claim 7, characterized in that: Each of the PC410L isolation optocouplers further includes a second ground pin and a second power pin, wherein the second ground pin is connected to ground, and the second power pin is connected to a power source.

9. The improved RS-485 communication module circuit according to claim 7, characterized in that: The LED cathode pins of the remaining PC410L isolation optocouplers are connected to the 74HC14 chips respectively.

10. The improved RS-485 communication module circuit according to claim 1, characterized in that: The operating current of the PC410L isolation optocoupler unit is 10mA.

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