RS232-to-RS485 passive and active converter

Abstract

The utility model provides an RS232 to RS485 passive and active converter, which relates to the technical field of industrial serial port data communication products and comprises an RS232 signal interface, an RS232 to TTL (transistor-transistor logic) signal chip, a TTL to RS485 chip, an RS485 enable processing chip, an RS485 signal interface, an RS232 circuit electricity stealing chip and a DC-DC (direct current-direct current) power supply step-down chip. The converter has a signal mutual conversion function in a scene of RS232 and RS485 signal conversion, achieves a use effect without power supply by using a charge pump principle, ensures smooth communication, is provided with a DC step-down circuit, and prevents conditions of low RS232 signal level and passive use failure.

Description

Technical Field

[0001] This utility model relates to the technical field of industrial serial port data communication products, specifically an RS232 to RS485 passive and active converter. Background Technology

[0002] Currently, RS232 to RS485 converters are widely used, mainly because RS485 signals can transmit up to 1 kilometer, while RS232 signals can only transmit about 10 meters. Since the host is far from the device, RS232 transmission can be unstable or result in packet loss. Therefore, RS232 to RS485 converters are widely used. However, the power supply to the converter becomes more complicated due to the large number of controlled devices, requiring a separate power adapter. Furthermore, existing converters often use non-standard signal conversion, directly converting RS232 levels to RS485 levels. This results in significant differences in signal amplitude, causing compatibility issues for some devices. Additionally, the power supply range is limited. Therefore, these converters can only meet a portion of the market demand. Utility Model Content

[0003] This invention aims to address the shortcomings of existing technologies by providing a passive-active RS232 to RS485 converter. In scenarios requiring RS232 to RS485 signal conversion, it offers signal conversion functionality. Furthermore, utilizing a charge pump principle, it achieves power-free operation, ensuring smooth communication. It also incorporates a DC step-down circuit to prevent passive failure due to low RS232 signal levels. The passive functionality reduces overall circuit losses, as well as lower costs and material resources.

[0004] To achieve the above objectives, this utility model provides the following technical solution: an RS232 to RS485 passive and active converter, comprising:

[0005] RS232 signal interface, RS232 to TTL signal chip, TTL to RS485 chip and RS485 enable processing chip, RS485 signal interface, RS232 circuit power theft chip, DC-DC power supply step-down chip;

[0006] The RS232 signal interface is connected to the RS232 to TTL signal chip circuit;

[0007] The RS232 to TTL signal chip is connected to the TTL to RS485 chip and the RS485 enable processing chip circuit.

[0008] The TTL to RS485 chip is connected to the RS485 signal interface circuit.

[0009] The RS232 signal interface is connected to the RS232 circuit power theft chip circuit;

[0010] The DC-DC power supply step-down chip is connected to the RS232 signal interface;

[0011] The DC-DC power supply step-down chip is connected to the power supply circuit of the RS232 circuit power theft chip.

[0012] Preferably, the RS232 signal interface is a terminal block. Pin 1 of the RS232 signal interface is input from the interface by an external RS232 receive signal RX2_IN, and pin 2 of the RS232 signal interface is the RS232 transmit signal TX2_OUT, which is an RS232 level signal.

[0013] Preferably, the RS232 to TTL signal chip is a level conversion chip, and pin 13 of the RS232 to TTL signal chip is connected to pin 1 of the RS232 signal interface, RX2_IN signal, through a diode. This signal is an RS232 level signal.

[0014] Preferably, the TTL to RS485 chip is a TTL to RS485 signal conversion chip, the RS485 enable processing chip is a logic gate switch processing chip, and pin 1 of the TTL to RS485 chip is a TTL signal input pin, namely the RX_TTL_OUT signal.

[0015] Preferably, pins 1 and 2 of the RS485 signal interface are RS485_A and RS485_B, and the transmission of this signal is output by pins 6 and 7 of the TTL to RS485 chip.

[0016] Preferably, the RS232 circuit power-stealing chip is a charge pump chip.

[0017] Preferably, the DC-DC power supply step-down chip is a backup power supply circuit.

[0018] This utility model provides a passive-to-active RS232 to RS485 converter, which has the following advantages:

[0019] The advantages of this invention are improved signal integrity and product compatibility: It addresses the shortcomings of existing market technologies. Commonly used RS485 converters typically output a high level, around ±5V. However, because RS232 is directly converted to RS485, the RS485 level is very high, around ±15V. This causes compatibility issues with some RS485 devices due to the excessive amplitude. Conversely, when RS485 is used as an input, it is 5V as a standard signal. When converted to RS232, the RS232 level becomes very low, around 5V, while a ±15V signal is required. This 5V level can cause weak or poor signals in some devices due to insufficient RS232 amplitude, preventing normal communication. Therefore, a standard conversion method is adopted: RS232 is first converted to TTL level using a dedicated level conversion chip circuit. This converts the ±15V RS232 level to the 5V TTL level, and simultaneously converts the TTL level... The 5V level is converted to RS232 ±15V, and after being converted to TTL 5V, it needs to be converted to RS485 level. This uses a dedicated TTL to RS485 level conversion chip circuit, including an enable signal switching circuit. Through these standard conversion circuits, the product has a slight advantage in compatibility and can meet the conversion needs of various devices.

[0020] Secondly, the passive and active multi-functional power supply circuit: Signal conversion circuits all require power. This circuit offers two power supply methods: a self-stolen power supply and an external power supply. While some power supply methods on the market also offer self-stolen power, their voltage range is relatively low, requiring ±7V or higher to obtain voltage. This limits the operation of some RS232 signals, preventing normal self-stolen power and rendering the product unusable. Since there are few external power supply circuits available, the self-stolen power supply circuit can meet the requirements of RS232 signals above ±4V. This allows many RS232 devices to be used directly without external power, saving resources. Simultaneously, a wide-voltage external power supply circuit is designed, supporting 4.5-36V external power. When encountering very low RS232 levels, suitable power supply loops can be found readily. Therefore, in terms of both signal quality and power supply application, this circuit is more valuable than existing converters. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall process of this utility model.

[0022] Figure 2 This is a schematic diagram of the overall circuit of this utility model.

[0023] Figure 3This is a schematic diagram of the RS232 to TTL circuit of this utility model.

[0024] Figure 4 This is a schematic diagram of the RS232 signal input circuit of this utility model.

[0025] Figure 5 This is a schematic diagram of the TTL to RS485 converter circuit of this utility model.

[0026] Figure 6 This is a schematic diagram of the DC-DC power supply circuit of this utility model.

[0027] Figure 7 This is a schematic diagram of the RS485 signal output of this utility model.

[0028] Figure 1-7 In the middle: J1, RS232 signal interface; J2, RS485 signal interface; U1, TTL to RS485 chip; U2, RS485 enable processing chip; U3, RS232 to TTL signal chip; U4, DC-DC power supply step-down chip; U5, RS232 circuit power theft chip. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0031] This application provides an RS232 to RS485 passive and active converter, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments.

[0032] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0033] Please see Figure 1-7 The present embodiment provides an RS232 to RS485 passive and active converter, including: an RS232 signal interface J1, an RS232 to TTL signal chip U3, a TTL to RS485 chip U1 and an RS485 enable processing chip U2, an RS485 signal interface J2, an RS232 circuit power theft chip U5, and a DC-DC power supply step-down chip U4;

[0034] Among them, the RS232 signal interface J1 is connected to the RS232 to TTL signal chip U3. The RS232 interface of the external device inputs an RS232 signal to interface J1. The data of the RS232 signal to interface J1 is connected to the RS232 to TTL signal chip U3. The RS232 to TTL signal chip U3 will convert the RS232 signal level into a TTL level signal. The TTL level signal will be connected to the TTL to RS485 chip U1.

[0035] Among them, the RS232 to TTL signal chip U3 is connected to the TTL to RS485 chip U1 and the RS485 enable processing chip U2. After being converted into a TTL signal by the RS232 to TTL signal chip U3, it will be connected to the TTL to RS485 chip U1. At the same time, the TXTTL IN signal will be connected to the RS485 enable processing chip U2. This enable signal will control the signal transmission and reception switch of the TTL to RS485 chip U1. The TTL to RS485 chip U1 converts the TTL signal level to the RS485 signal level. This RS485 signal is connected to the J2 circuit.

[0036] Among them, the TTL to RS485 chip U1 is connected to the RS485 signal interface J2 circuit. The TTL to RS485 chip U1 outputs RS485_A and RS485_B signals, which are output to the RS485 signal interface J2 interface. The interface can be connected to an external RS485 signal.

[0037] Among them, RS232 signal interface J1 is connected to RS232 circuit power stealing chip U5 circuit. RS232 signal interface J1 transmits RS232 signal RX2_IN from external devices. The RX2_IN signal will be connected to RS232 circuit power stealing chip U5. RS232 circuit power stealing chip U5 is a charge pump chip. It obtains negative voltage from RX2_IN and converts it into positive 5V DC voltage for power supply of RS232 to TTL signal chip U3, TTL to RS485 chip U1, and RS485 enable processing chip U2.

[0038] Among them, the DC-DC power supply step-down chip U4 is connected to the RS232 signal interface J1. It is powered by an external DC_IN DC power supply through the RS232 signal interface J1. The power input is 5-24V DC to the DC-DC power supply step-down chip U4 for step-down processing. The voltage after step-down is 5V DC, which is used to power the RS232 to TTL signal chip U3, the TTL to RS485 chip U1, and the RS485 enable processing chip U2.

[0039] The DC-DC power supply step-down chip U4 is connected to the power supply circuit of the RS232 circuit power theft chip U5. The DC-DC power supply step-down chip U4 outputs a DC voltage of 5V through a diode and is connected to the RS232 circuit power theft chip U5. When the RS232 circuit power theft chip U5 obtains a level from the serial port RX2_IN, it does not need DC_IN power supply on the RS232 signal interface J1. If the RS232 circuit power theft chip U5 cannot obtain a level from the serial port RX2_IN, it will need DC_IN power supply on the RS232 signal interface J1.

[0040] Furthermore, RS232 signal interface J1 is a terminal block. Pin 1 of RS232 signal interface J1 receives the external RS232 receive signal RX2_IN from the interface. Pin 2 of RS232 signal interface J1 transmits the RS232 signal TX2_OUT. This signal is an RS232 level signal, normally a peak voltage of -15V. When RS485 signal interface J2 receives an RS485 signal, pin 2 of RS232 signal interface J1 will transmit an RS232 signal to the external RS232 device.

[0041] Furthermore, the RS232 to TTL signal chip U3 is a level conversion chip. Pin 13 of the RS232 to TTL signal chip U3 is connected to pin 1 of the RS232 signal interface J1 via a diode to the RX2_IN signal. This signal is an RS232 level signal. After being processed by the RS232 to TTL signal chip U3, this signal is converted into a TTL signal, namely RX_TTL_OUT. This signal is divided into two paths: one output is used to light up the LED3 indicator, and the other is used by the RS232 to TTL signal chip U3 to convert the TTL level to RS485_A and RS485_B half-duplex signals. When the RS485 signal interface J2 returns an RS485 signal, pin 12 of the RS232 to TTL signal chip U3 will have a TTL signal TX_TTL_IN input, which will also light up the LED2 indicator. At the same time, pin 14 of the RS232 to TTL signal chip U3 will output the RS232 transmit signal TX2_OUT.

[0042] Furthermore, the TTL to RS485 chip U1 is a TTL to RS485 signal conversion chip, and the RS485 enable processing chip U2 is a logic gate switch processing chip. Pin 1 of the TTL to RS485 chip U1 is the TTL signal input pin, namely the RX_TTL_OUT signal. When an input signal is received, pins 6 and 7 of the TTL to RS485 chip U1 will output RS485_A and RS485_B. When an RS485 signal returns from the RS485 signal interface J2, pins 6 and 7 of the TTL to RS485 chip U1 will input RS485_A and RS485_B. At this time, pin 4 of the TTL to RS485 chip U1 will output a TTL signal, namely TX_TTL_IN. This signal is split into two paths: one output is given to pin 12 of the RS232 to TTL signal chip U3, and the other output is given to the RS485 chip U2. Pin 2 of the RS485 enable chip U2 is used for logic gate control signals. This signal is output from pin 4 of the RS485 enable chip U2 and connected to pins 2 and 3 of the TTL to RS485 chip U1. During one cycle of signal communication, when TX_TTL_IN outputs a high level, pin 4 of the RS485 enable chip U2 outputs a low level to pins 2 and 3 of the TTL to RS485 chip U1. At this time, pin 1 of the TTL to RS485 chip U1 will be turned off, and no signal can be input from pin 1. When TX_TTL_IN outputs a low level, pin 4 of the RS485 enable chip U2 outputs a high level to pins 2 and 3 of the TTL to RS485 chip U1. At this time, pin 1 of the TTL to RS485 chip U1 will be turned on, and RS485 signals can continue to be output. This cycle repeats to achieve the data transmission and reception state.

[0043] Furthermore, pins 1 and 2 of the RS485 signal interface J2 are RS485_A and RS485_B, respectively. The transmission of this signal is output by pins 6 and 7 of the TTL to RS485 chip U1. When data is returned from an external device, pins 1 and 2 of the RS485 signal interface J2 transmit RS485 signals to pins 6 and 7 of the TTL to RS485 chip U1 for communication.

[0044] Furthermore, the RS232 circuit power-stealing chip U5 is a charge pump chip. When an RX2_IN signal is input to pin 1 of the RS232 signal interface J1, it is input through pin 3 of the bidirectional diode D9 and output through pin 1. The output is then supplied to pin 5 of the RS232 circuit power-stealing chip U5. Through the internal charge pump principle of the RS232 circuit power-stealing chip U5, a positive voltage is output from pin 2 of the RS232 circuit power-stealing chip U5. This voltage is input through pin 3 of the bidirectional diode D10 and output through pin 2 to the 5V_TTL power supply circuit, thereby enabling the RS232 to TTL signal chip U3, the TTL to RS485 chip U1, and the RS485 enable processing chip U2 to work normally.

[0045] Furthermore, the DC-DC power supply step-down chip U4 serves as a backup power supply circuit. When the RS232 signal level input to the RS232 signal interface J1 is not very high, such as below 4.5V, the RS232 circuit power-stealing chip U5 cannot meet the power supply requirements. In this case, the DC-DC power supply step-down chip U4 is needed to provide power. Pin 4 of the RS232 signal interface J1 is the DC voltage input terminal. This voltage is supplied to pin 5 of the DC-DC power supply step-down chip U4. After the internal step-down processing of the DC-DC power supply step-down chip U4, the output 5V flows out to 5V_TTL through the negative terminal of diode D2, thereby enabling the RS232 to TTL signal chip U3, the TTL to RS485 chip U1, and the RS485 enable chip U2 to work normally.

[0046] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0047] The foregoing has provided a detailed description of an RS232 to RS485 passive and active converter according to the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A passive-active converter from RS232 to RS485, characterized in that, include: RS232 signal interface (J1), RS232 to TTL signal chip (U3), TTL to RS485 chip (U1) and RS485 enable processing chip (U2), RS485 signal interface (J2), RS232 circuit power theft chip (U5), DC-DC power supply step-down chip (U4); The RS232 signal interface (J1) is connected to the RS232 to TTL signal chip (U3) circuit; The RS232 to TTL signal chip (U3) is connected to the TTL to RS485 chip (U1) and the RS485 enable processing chip (U2) in a circuit. The TTL to RS485 chip (U1) is connected to the RS485 signal interface (J2) circuit; The RS232 signal interface (J1) is connected to the RS232 circuit power theft chip (U5) circuit; The DC-DC power supply step-down chip (U4) is connected to the RS232 signal interface (J1); The DC-DC power supply step-down chip (U4) is connected to the power supply circuit of the RS232 circuit power theft chip (U5).

2. The RS232 to RS485 passive plus active converter of claim 1, wherein, The RS232 signal interface (J1) is a terminal block. Pin 1 of the RS232 signal interface (J1) is input from the interface by the external RS232 receive signal RX2_IN. Pin 2 of the RS232 signal interface (J1) is the RS232 transmit signal TX2_OUT, which is an RS232 level signal.

3. The RS232 to RS485 passive plus active converter of claim 1, wherein, The RS232 to TTL signal chip (U3) is a level conversion chip. Pin 13 of the RS232 to TTL signal chip (U3) is connected to pin 1 of the RS232 signal interface (J1) RX2_IN signal through a diode. This signal is an RS232 level signal.

4. The RS232 to RS485 passive plus active converter of claim 1, wherein, The TTL to RS485 chip (U1) is a TTL to RS485 signal conversion chip, the RS485 enable processing chip (U2) is a logic gate switch processing chip, and pin 1 of the TTL to RS485 chip (U1) is a TTL signal input pin, namely the RX_TTL_OUT signal.

5. The RS232 to RS485 passive plus active converter of claim 1, wherein, Pins 1 and 2 of the RS485 signal interface (J2) are RS485_A and RS485_B, respectively. The transmission of this signal is output from pins 6 and 7 of the TTL to RS485 chip (U1).

6. The RS232 to RS485 passive plus active converter of claim 1, wherein, The RS232 circuit power theft chip (U5) is a charge pump chip.

7. The RS232 to RS485 passive plus active converter of claim 1, wherein, The DC-DC power supply step-down chip (U4) is a backup power supply circuit.

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