Compatible circuit based on RS485 interface
By designing a compatible circuit based on the RS485 interface, the problem of RS485 main chip IC being incompatible with multiple circuits was solved, achieving product flexibility and supply chain stability, and adapting to the voltage requirements of different RS485 transceivers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-16
- Publication Date
- 2026-03-10
AI Technical Summary
Existing RS485 main chip ICs cannot be designed to be compatible with multiple circuits, resulting in insufficient product flexibility and supply chain stability, which affects production planning and customer experience.
Design a compatible circuit based on the RS485 interface, including a main control board, a MOS level conversion circuit, a signal selection circuit, and a trigger circuit. The level conversion and signal selection are achieved through a combination of resistors and MOS transistors to adapt to the voltage requirements of different RS485 transceivers.
It enables compatible designs for various circuits, expands the product's adaptability to different scenarios, reduces circuit change time and costs, and ensures product flexibility and supply chain stability.
Smart Images
Figure CN223986323U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to data communication technology field, concretely relates to a compatible circuit based on RS485 interface. BACKGROUND
[0002] In the product with RS485 function interface, the existing RS485 main chip IC cannot be multiple circuit compatible design, so that the flexibility of product and the stability of supply chain cannot be ensured. Due to the influence of multiple factors such as the extension of supply cycle, price fluctuation and customer specific requirements of a kind of RS485 master control chip IC, it cannot be purchased in place in time, seriously delays the production plan and product delivery schedule of factory, and then causes the remarkable negative influence to customer experience, so a compatible circuit based on RS485 interface is needed to be designed. SUMMARY
[0003] The utility model discloses to solve the defects and the insufficient handling of prior art, provide a kind of compatible circuit based on RS485 interface of multiple circuit compatible design.
[0004] To achieve the above object, the technical scheme that the utility model takes is a compatible circuit based on RS485 interface, including main control circuit board, first MOS level conversion circuit, second MOS level conversion circuit, signal selection circuit and flip-flop circuit;The input end of the main control circuit board is electrically connected with the first MOS level conversion circuit, second MOS level conversion circuit, the output end of the first MOS level conversion circuit, second MOS level conversion circuit is electrically connected signal selection circuit, and the signal selection circuit is electrically connected with the flip-flop circuit.
[0005] Further;The first MOS level conversion circuit includes first resistance, second resistance and first MOS tube;The first resistance and second resistance are connected in series, one end is connected to the gate of the first MOS tube, and the other end is electrically connected to the drain of the first MOS tube;The drain of the first MOS tube is electrically connected with signal selection circuit, and the source of the first MOS tube is electrically connected with first resistance;The common end of the first resistance and second resistance is electrically connected with the main control circuit board, and the gate of the first MOS tube is connected with 3.3V voltage.
[0006] Further, the second MOS level conversion circuit comprises a third resistor, a fourth resistor, a fifth resistor and a second MOS transistor; one end of the third resistor is connected with a 5V voltage, and the other end is electrically connected to the drain of the second MOS transistor; the fourth resistor and the fifth resistor are connected in series, one end is connected to the gate of the second MOS transistor, and the other end is electrically connected to the drain of the second MOS transistor; the drain of the second MOS transistor is electrically connected to the signal selection circuit, and the source of the second MOS transistor is electrically connected to the fourth resistor; the common end of the fourth resistor and the fifth resistor is electrically connected to the main control circuit board, and the gate of the second MOS transistor is connected with a 3.3V voltage.
[0007] Further, the signal selection circuit comprises an RS485 transceiver, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor and a first capacitor; one end of the sixth resistor is electrically connected to the first pin of the RS485 transceiver, and the other end is connected to the drain of the first MOS transistor; the seventh resistor and the eighth resistor are connected in series, one end is connected to the third pin of the RS485 transceiver, and the other end is connected to the first pin of the RS485 transceiver; the second pin of the RS485 transceiver is electrically connected to the seventh resistor, one end of the ninth resistor is electrically connected to the drain of the second MOS transistor and the flip-flop circuit, and the other end is electrically connected to the fourth pin of the RS485 transceiver; the fifth pin of the RS485 transceiver is grounded, the tenth resistor, the eleventh resistor and the twelfth resistor are connected in series, one end is grounded, and the other end is electrically connected to the eighth pin of the RS485 transceiver; the seventh pin of the RS485 transceiver is electrically connected to the common end of the eleventh resistor and the twelfth resistor, and the sixth pin of the RS485 transceiver is electrically connected to the common end of the eleventh resistor and the tenth resistor; one end of the first capacitor is grounded, and the other end is electrically connected to the eighth pin of the RS485 transceiver.
[0008] Further, the trigger circuit includes a monostable multivibrator, a diode, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a second capacitor, and a third capacitor; one end of the thirteenth resistor is electrically connected to the ninth resistor, and the other end is electrically connected to the first pin of the monostable multivibrator; one end of the fourteenth resistor is electrically connected to the second pin of the monostable multivibrator, and the other end is connected to a 3.3V voltage; one end of the fifteenth resistor is electrically connected to the third pin of the monostable multivibrator, and the other end is electrically connected to the fourteenth resistor; the eighth pin of the monostable multivibrator is grounded; one end of the second capacitor is grounded, and the other end is electrically connected to the sixteenth pin of the monostable multivibrator; the third capacitor and the sixteenth resistor are connected in series, one end of which is electrically connected to the second capacitor, and the other end is grounded; the fifteenth pin of the monostable multivibrator is connected to the common terminal of the third capacitor and the sixteenth resistor, and the fourteenth pin of the monostable multivibrator is electrically connected to the third capacitor; one end of the diode is electrically connected to the sixteenth resistor, and the other end is connected to the common terminal of the third capacitor and the sixteenth resistor.
[0009] The utility model discloses a beneficial effect has:
[0010] This utility model provides a compatible circuit based on the RS485 interface. By designing the compatibility of various RS485 circuit schemes according to the actual interface application environment, it can expand the product's adaptability to various scenarios and adapt to unified management, reduce the time and cost of circuit changes, and ensure product flexibility and supply chain stability. At the same time, this application is not only simple in structure but also has low manufacturing cost. Attached Figure Description
[0011] Figure 1 This is a schematic diagram illustrating the working principle of a compatible circuit based on an RS485 interface according to this utility model.
[0012] Figure 2 This is a schematic diagram of the first MOS level conversion circuit and the second MOS level conversion circuit in a compatible circuit based on an RS485 interface according to this utility model.
[0013] Figure 3 This is a schematic diagram of the signal selection circuit in a compatible circuit based on an RS485 interface according to this utility model.
[0014] Figure 4 This is a schematic diagram of the trigger circuit in a compatible circuit based on an RS485 interface according to this utility model. Detailed Implementation
[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0016] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0017] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.
[0018] This invention proposes a compatible circuit based on an RS485 interface.
[0019] In the embodiments of this utility model, such as Figure 1 As shown, this RS485 interface-based compatible circuit includes a main control circuit board, a first MOS level conversion circuit, a second MOS level conversion circuit, a signal selection circuit, and a trigger circuit. The main control circuit board is electrically connected to the input terminals of the first MOS level conversion circuit and the second MOS level conversion circuit, the output terminals of the first MOS level conversion circuit and the second MOS level conversion circuit are electrically connected to the signal selection circuit, and the signal selection circuit is electrically connected to the trigger circuit.
[0020] In this embodiment, the first MOS level conversion circuit includes a first resistor, a second resistor, and a first MOS transistor; the first resistor and the second resistor are connected in series, with one end connected to the gate of the first MOS transistor and the other end electrically connected to the drain of the first MOS transistor; the drain of the first MOS transistor is electrically connected to the signal selection circuit, and the source of the first MOS transistor is electrically connected to the first resistor; the common terminal of the first resistor and the second resistor is electrically connected to the main control circuit board, and the gate of the first MOS transistor is connected to a 3.3V voltage.
[0021] In this embodiment, the second MOS level conversion circuit includes a third resistor, a fourth resistor, a fifth resistor, and a second MOS transistor. One end of the third resistor is connected to a 5V voltage, and the other end is electrically connected to the drain of the second MOS transistor. The fourth and fifth resistors are connected in series, with one end connected to the gate of the second MOS transistor and the other end electrically connected to the drain of the second MOS transistor. The drain of the second MOS transistor is electrically connected to a signal selection circuit, and the source of the second MOS transistor is electrically connected to the fourth resistor. The common terminal of the fourth and fifth resistors is electrically connected to the main control circuit board, and the gate of the second MOS transistor is connected to a 3.3V voltage.
[0022] In this embodiment, the signal selection circuit includes an RS485 transceiver, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a first capacitor; one end of the sixth resistor is electrically connected to the first pin of the RS485 transceiver, and the other end is connected to the drain of the first MOSFET; the seventh and eighth resistors are connected in series, with one end connected to the third pin of the RS485 transceiver and the other end connected to the first pin of the RS485 transceiver; the second pin of the RS485 transceiver is electrically connected to the seventh resistor, and one end of the ninth resistor is connected to the second MOSFET. The drain of the transistor and the trigger circuit are electrically connected, and the other end is electrically connected to the fourth pin of the RS485 transceiver; the fifth pin of the RS485 transceiver is grounded; the tenth, eleventh, and twelfth resistors are connected in series, with one end grounded and the other end electrically connected to the eighth pin of the RS485 transceiver; the seventh pin of the RS485 transceiver is electrically connected to the common terminal of the eleventh and twelfth resistors; the sixth pin of the RS485 transceiver is electrically connected to the common terminal of the eleventh and tenth resistors; one end of the first capacitor is grounded, and the other end is electrically connected to the eighth pin of the RS485 transceiver.
[0023] In this embodiment, the trigger circuit includes a monostable multivibrator, a diode, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a second capacitor, and a third capacitor. One end of the thirteenth resistor is electrically connected to the ninth resistor, and the other end is electrically connected to the first pin of the monostable multivibrator. One end of the fourteenth resistor is electrically connected to the second pin of the monostable multivibrator, and the other end is connected to a 3.3V voltage. One end of the fifteenth resistor is electrically connected to the third pin of the monostable multivibrator, and the other end is electrically connected to the fourteenth resistor. The eighth pin of the monostable multivibrator is grounded. One end of the second capacitor is grounded, and the other end is electrically connected to the sixteenth pin of the monostable multivibrator. The third capacitor and the sixteenth resistor are connected in series, with one end electrically connected to the second capacitor and the other end grounded. The fifteenth pin of the monostable multivibrator is connected to the common terminal of the third capacitor and the sixteenth resistor, and the fourteenth pin of the monostable multivibrator is electrically connected to the third capacitor. One end of the diode is electrically connected to the sixteenth resistor, and the other end is connected to the common terminal of the third capacitor and the sixteenth resistor.
[0024] This application designs a circuit that allows for flexible replacement of the RS485 transceiver IC, such as... Figure 2 When the RS485 transceiver model MAX13487EESA+T is selected in the signal selection circuit, its operating voltage is 5V. Therefore, VCC_485 should be connected to the system's 5V power rail (VCC_5V0). This is achieved by setting R8 to 0Ω, while R9 is not connected (NC).
[0025] Because the RS485 transceiver MAX13487E operates at 5V, while the isolated U1_RX and U1_TX signals operate at 3.3V, there is a level mismatch. Therefore, it is necessary to use... Figure 2 The first MOS level conversion circuit shown performs level conversion with the second MOS level conversion circuit to ensure a correct conversion from 3.3V to 5V. Here, the second resistor R4 and the fifth resistor R6 should be empty or not connected (NC) because they do not function in the first and second MOS level conversion circuits.
[0026] When the RS485 transceiver model ADM3485E is selected in the signal selection circuit, its operating voltage is 3.3V, so VCC_485 should be connected to the 3.3V power rail (VCC_3V3). This can be achieved by setting R9 to 0Ω and leaving R8 unconnected (NC).
[0027] If the U1_RX and U1_TX signals of the RS485 transceiver ADM3485E are both at 3.3V after isolation from the front end, no additional level conversion is required. Therefore, the first and second MOS level conversion circuits can be omitted, and the second resistor R4 and the fifth resistor R6 can be directly shorted to 0Ω.
[0028] like Figure 4 As shown, when selecting the RS485 transceiver ADM3485E, it must be used in conjunction with the trigger circuit for triggering and timing control. It is particularly important to note that the monostable multivibrator model is CD74HC123PWR, and its external sixteenth resistor R15 and third capacitor C8 are used to adjust the output pulse width (Tw). Using the provided formula Tw=0.45*R15*C8, appropriate resistor and capacitor values can be calculated to ensure that the generated pulse width is slightly larger than the single bit time (e.g., approximately 86.8μs at a baud rate of 115200bps). In practical applications, it is recommended to verify these parameters through actual testing to ensure communication reliability.
[0029] For different baud rate settings, the values of the sixteenth resistor R15 and the third capacitor C8 can be adjusted according to the calculation method mentioned above to meet specific communication requirements. Ensure that Tw is always slightly larger than a single bit period determined by the baud rate to avoid data transmission errors.
[0030] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.
Claims
1. A compatible circuit based on RS485 interface, characterized in that, The application relates to a signal selection circuit and a trigger circuit; the main control circuit board is electrically connected with the input ends of the first MOS level conversion circuit and the second MOS level conversion circuit; the output ends of the first MOS level conversion circuit and the second MOS level conversion circuit are electrically connected with the signal selection circuit; the signal selection circuit is electrically connected with the trigger circuit; The first MOS level conversion circuit comprises a first resistor, a second resistor and a first MOS tube; one end of the first resistor and the second resistor is connected with the gate of the first MOS tube, and the other end is electrically connected with the drain of the first MOS tube; the drain of the first MOS tube is electrically connected with the signal selection circuit; the source of the first MOS tube is electrically connected with the first resistor; the common end of the first resistor and the second resistor is electrically connected with the main control circuit board; the gate of the first MOS tube is connected with a 3.3V voltage; The second MOS level conversion circuit comprises a third resistor, a fourth resistor, a fifth resistor and a second MOS tube; one end of the third resistor is connected with a 5V voltage, and the other end is electrically connected with the drain of the second MOS tube; one end of the fourth resistor and the fifth resistor is connected with the gate of the second MOS tube, and the other end is electrically connected with the drain of the second MOS tube; the drain of the second MOS tube is electrically connected with the signal selection circuit; the source of the second MOS tube is electrically connected with the fourth resistor; the common end of the fourth resistor and the fifth resistor is electrically connected with the main control circuit board; the gate of the second MOS tube is connected with a 3.3V voltage; The signal selection circuit comprises an RS485 transceiver, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor and a first capacitor; one end of the sixth resistor is electrically connected with the first pin of the RS485 transceiver, and the other end is connected with the drain of the first MOS tube; one end of the seventh resistor and the eighth resistor is connected with the third pin of the RS485 transceiver, and the other end is connected with the first pin of the RS485 transceiver; the second pin of the RS485 transceiver is electrically connected with the seventh resistor; one end of the ninth resistor is electrically connected with the drain of the second MOS tube and the trigger circuit, and the other end is electrically connected with the fourth pin of the RS485 transceiver; the fifth pin of the RS485 transceiver is grounded; one end of the tenth resistor, the eleventh resistor and the twelfth resistor is grounded, and the other end is electrically connected with the eighth pin of the RS485 transceiver; the seventh pin of the RS485 transceiver is electrically connected with the common end of the eleventh resistor and the twelfth resistor; the sixth pin of the RS485 transceiver is electrically connected with the common end of the eleventh resistor and the tenth resistor; one end of the first capacitor is grounded, and the other end is electrically connected with the eighth pin of the RS485 transceiver.
2. The RS485 interface based compatible circuit of claim 1, wherein, The trigger circuit includes a monostable trigger, a diode, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a second capacitor and a third capacitor; one end of the thirteenth resistor is electrically connected with the ninth resistor, and the other end is electrically connected with a first pin of the monostable trigger; one end of the fourteenth resistor is electrically connected with a second pin of the monostable trigger, and the other end is connected with a 3.3V voltage; one end of the fifteenth resistor is electrically connected with a third pin of the monostable trigger, and the other end is electrically connected with the fourteenth resistor; an eighth pin of the monostable trigger is grounded; one end of the second capacitor is grounded, and the other end is electrically connected with a sixteenth pin of the monostable trigger; the third capacitor and the sixteenth resistor are connected in series, one end of which is electrically connected with the second capacitor, and the other end is grounded; a fifteenth pin of the monostable trigger is connected to a common end of the third capacitor and the sixteenth resistor; a fourteenth pin of the monostable trigger is electrically connected with the third capacitor; one end of the diode is electrically connected with the sixteenth resistor, and the other end is connected to the common end of the third capacitor and the sixteenth resistor.