A daisy chain type CAN bus cascade end resistance adaptive matching system

Abstract

The utility model discloses a daisy chain type CAN bus cascade terminal resistance adaptive matching system, include: host computer and adopt daisy chain type type in proper order series connection several same or different module, be equipped with terminal resistance matching circuit in each module, the host computer is connected with each module communication through CAN communication bus, terminal resistance matching circuit includes CAN transceiver unit, terminal resistance switching unit, drive unit and terminal resistance unit, CAN transceiver unit is connected with host computer and terminal resistance switching unit electric property respectively, terminal resistance switching unit is connected with drive unit and terminal resistance unit electric property respectively, the utility model solves the limitation of existing daisy chain type CAN bus cascade, can not realize the technical problem of equipment arbitrary position deployment.

Description

Technical Field

[0001] This utility model relates to the field of power system technology, and in particular to a daisy-chain type CAN bus cascade end resistor adaptive matching system. Background Technology

[0002] CAN is a serial bus that uses a multi-master contention architecture. The CAN bus consists of two communication lines: CAN_H and CAN_L. CAN bus communication is stable and has strong anti-interference capabilities, making it a commonly used communication bus in industrial fields. When using the CAN bus, 120Ω terminating resistors need to be inserted at both ends of the bus to suppress signal reflection. Terminating resistors are only required at the beginning and end points; intermediate nodes do not need to be equipped with them. Neglecting terminating resistors or installing them at intermediate nodes will affect the stability of CAN bus communication.

[0003] A daisy-chain topology connects devices or components one by one in a linear sequence. This connection method has low wiring costs and is easy to expand, so it is widely used in modular design products. A daisy-chain connection forms a serial link: device A → device B → device C → ... → device N. The CAN bus is simple in structure (only two communication lines), provides stable communication, and has strong anti-interference capabilities. In daisy-chain cascading scenarios, the CAN bus is usually chosen as the communication bus. When using CAN bus communication in a daisy-chain cascade connection, the CAN bus requires terminating resistors at both ends, while intermediate nodes cannot. This necessitates fixing the devices at both ends of the daisy-chain connection; the two devices at the beginning and end are mandatory and can only be installed at the ends, not arbitrarily. This severely limits the flexibility of the daisy-chain connection and increases equipment production management, requiring the determination of which devices are at the ends and which are configured with terminating resistors, as well as the determination of whether intermediate nodes are configured with terminating resistors. It also increases the difficulty of on-site installation, requiring a clear identification of which devices are configured with terminating resistors and which are not, strictly adhering to the rule of installing devices with terminating resistors at the ends and devices without terminating resistors in the middle. Therefore, to solve the above technical problems, there is an urgent need to propose a daisy-chain CAN bus cascade end resistor adaptive matching system. Utility Model Content

[0004] The main purpose of this invention is to propose a daisy-chain CAN bus cascade end resistor adaptive matching system, which aims to solve the limitations of existing daisy-chain CAN bus cascades and the technical problem that it cannot achieve arbitrary deployment of devices.

[0005] To achieve the above objectives, this utility model provides a daisy-chain CAN bus cascade end resistance adaptive matching system, wherein the daisy-chain CAN bus cascade end resistance adaptive matching system includes:

[0006] The system comprises a host and several identical or different modules connected in a daisy-chain configuration; each module has a terminating resistor matching circuit; the host communicates with each module via a CAN communication bus; the terminating resistor matching circuit includes a CAN transceiver unit, a terminating resistor switching unit, a driver unit, and a terminating resistor unit; the CAN transceiver unit is electrically connected to the host and the terminating resistor switching unit respectively, and the terminating resistor switching unit is electrically connected to the driver unit and the terminating resistor unit respectively.

[0007] In one preferred embodiment, the CAN transceiver unit includes a CAN transceiver D1, a common-mode inductor L1, and a first filter circuit; pin 3 of the CAN transceiver D1 is connected to the first filter circuit and the power supply terminal respectively; pins 6 and 7 of the CAN transceiver D1 are connected to pins 1 and 2 of the common-mode inductor L1 respectively; pins 3 and 4 of the common-mode inductor L1 are connected to the terminating resistor switching unit and the host; and pins 2 and 8 of the CAN transceiver D1 and the other end of the first filter circuit are grounded.

[0008] In one preferred embodiment, the first filter circuit includes capacitor C2 and capacitor C3; one end of capacitor C2 and capacitor C3 is connected to pin 3 of CAN transceiver D1, and the other end of capacitor C2 and capacitor C3 is grounded.

[0009] In one preferred embodiment, the terminating resistor switching unit includes an analog switch U1, a resistor R2, and a second filter circuit. Pin 1 of the analog switch U1 is connected to the resistor R2, the other end of the resistor R2 is connected to the second filter circuit and the power supply, the other end of the second filter circuit is grounded, pin 6 of the analog switch U1 is grounded, pin 3 of the analog switch U1 is connected to the CAN transceiver unit and the CAN_H communication bus, pin 9 of the analog switch U1 is connected to the CAN transceiver unit and the CAN_L communication bus, pins 5 and 7 of the analog switch U1 are connected to the terminating resistor unit, and pins 4 and 8 of the analog switch U1 are connected to the driving unit.

[0010] In one preferred embodiment, the second filter circuit includes a capacitor C1; one end of the capacitor C1 is connected to a resistor R2 and a power supply terminal, and the other end of the capacitor C1 is grounded.

[0011] In one preferred embodiment, the analog switch U1 is a double-pole double-throw analog switch.

[0012] In one preferred embodiment, the terminating resistor unit includes a resistor R1, a resistor R3, and a capacitor C4; one end of the resistor R1 is connected to the terminating resistor switching unit, the other end of the resistor R1 is connected to both the resistor R3 and the capacitor C4, the other end of the capacitor C4 is grounded, and the other end of the resistor R3 is connected to the terminating resistor switching unit.

[0013] In one preferred embodiment, the driving unit includes a resistor R4, a resistor R5, a transistor V1, and a current limiting circuit; the collector of the transistor V1 is connected to the resistor R4 and the terminating resistor switching unit, the other end of the resistor R4 is connected to the power supply terminal and the resistor R5, the other end of the resistor R5 is connected to the current limiting circuit, the other end of the current limiting circuit is connected to the base of the transistor V1, and the emitter of the transistor V1 is grounded.

[0014] In one preferred embodiment, the current limiting circuit includes a resistor R6; one end of the resistor R6 is connected to a resistor R5, and the other end of the resistor R6 is connected to the base of the transistor V1.

[0015] In the above technical solution of this utility model, the daisy-chain CAN bus cascaded end-resistance adaptive matching system includes: a host and several identical or different modules connected in series in a daisy-chain configuration; each module is equipped with a terminating resistor matching circuit; the host is communicatively connected to each module via a CAN communication bus; the terminating resistor matching circuit includes a CAN transceiver unit, a terminating resistor switching unit, a driver unit, and a terminating resistor unit; the CAN transceiver unit is electrically connected to the host and the terminating resistor switching unit respectively, and the terminating resistor switching unit is electrically connected to the driver unit and the terminating resistor unit respectively. This utility model solves the limitations of existing daisy-chain CAN bus cascades, which cannot achieve arbitrary deployment of equipment.

[0016] In this invention, the combination of hardware signal detection and analog switch control enables adaptive matching of daisy-chain CAN bus resistors. This eliminates the need for manual or algorithmic determination of terminal node positions for terminal resistor matching. The hardware approach allows for flexible deployment and plug-and-play functionality, resulting in low cost and high reliability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1This is a schematic diagram of a daisy-chain CAN bus cascade end resistor adaptive matching system according to an embodiment of the present invention;

[0019] Figure 2 This is a first schematic diagram of the terminal resistor matching circuit according to an embodiment of the present invention;

[0020] Figure 3 This is a second schematic diagram of the terminal resistor matching circuit in an embodiment of the present invention.

[0021] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of this utility model 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.

[0024] Furthermore, in this utility model, descriptions involving "first," "second," etc., are 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 with "first" or "second" may explicitly or implicitly include at least one of those features.

[0025] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0026] See Figures 1-3According to one aspect of this utility model, this utility model provides a daisy-chain CAN bus cascaded terminal resistor adaptive matching system, wherein the daisy-chain CAN bus cascaded terminal resistor adaptive matching system includes: a host and several identical or different modules connected in series in a daisy-chain pattern; each module is provided with a terminal resistor matching circuit; the host is communicatively connected to each module through a CAN communication bus; the terminal resistor matching circuit includes a CAN transceiver unit, a terminal resistor switching unit, a driver unit, and a terminal resistor unit; the CAN transceiver unit is electrically connected to the host and the terminal resistor switching unit respectively, and the terminal resistor switching unit is electrically connected to the driver unit and the terminal resistor unit respectively.

[0027] Specifically, in this embodiment, the host and modules are connected in a daisy chain and communicate via a CAN communication bus. Each module has a standard interface with the host and with other modules. In addition to the CAN communication bus, the interface also includes signals such as power supply and insertion status monitoring. Each module is connected to the host and with other modules using a pin and socket method, which meets the plug-and-play feature. Each module integrates an independent terminating resistor matching circuit, which achieves automatic matching when daisy chained through a standardized structure. The module installation position is not restricted.

[0028] Specifically, in this embodiment, the CAN transceiver unit includes a CAN transceiver D1, a common-mode inductor L1, and a first filter circuit; pin 3 of the CAN transceiver D1 is connected to the first filter circuit and the power supply terminal, pins 6 and 7 of the CAN transceiver D1 are connected to pins 1 and 2 of the common-mode inductor L1, pins 3 and 4 of the common-mode inductor L1 are connected to the terminating resistor switching unit and the host, and pins 2 and 8 of the CAN transceiver D1 and the other end of the first filter circuit are grounded.

[0029] Specifically, in this embodiment, the first filter circuit includes capacitor C2 and capacitor C3; one end of capacitor C2 and capacitor C3 is connected to pin 3 of CAN transceiver D1, and the other end of capacitor C2 and capacitor C3 is grounded.

[0030] Specifically, in this embodiment, the terminal resistor switching unit includes an analog switch U1, a resistor R2, and a second filter circuit; pin 1 of the analog switch U1 is connected to the resistor R2, the other end of the resistor R2 is connected to the second filter circuit and the power supply terminal respectively, the other end of the second filter circuit is grounded, pin 6 of the analog switch U1 is grounded, pin 3 of the analog switch U1 is connected to the CAN transceiver unit and the CAN_H communication bus respectively, and pin 9 of the analog switch U1 is connected to the CAN transceiver unit and the CAN_L communication bus respectively; pins 5 and 7 of the analog switch U1 are connected to the terminal resistor unit, and pins 4 and 8 of the analog switch U1 are connected to the drive unit; pins 3 and 9 of the analog switch U1 are common terminals, pins 5 and 7 of the analog switch U1 are normally closed terminals, pins 2 and 10 of the analog switch U1 are normally open terminals, and pin 4 of the analog switch U1 is the first channel module... The analog switch control pins are configured such that when pin 4 of analog switch U1 is low, pins 3 and 5 of analog switch U1 are on; when pin 4 of analog switch U1 is high, pins 3 and 2 of analog switch U1 are on. Pin 8 of analog switch U1 is the second analog switch control pin; when pin 8 of analog switch U1 is low, pins 9 and 7 of analog switch U1 are on; when pin 8 of analog switch U1 is high, pins 9 and 10 of analog switch U1 are on. Matching resistors R1 and R3 are connected to normally closed terminals. When INSERT_DET is high, meaning no module is connected to the next stage, the matching resistors are connected to the CAN communication bus. When INSERT_DET is low, meaning a module is connected to the next stage, the matching resistors are disconnected from the CAN communication bus, thus enabling automatic switching of the matching resistors according to the product's on-site configuration.

[0031] Specifically, in this embodiment, the second filter circuit includes a capacitor C1; one end of the capacitor C1 is connected to a resistor R2 and a power supply terminal, and the other end of the capacitor C1 is grounded.

[0032] Specifically, in this embodiment, the analog switch U1 is a double-pole double-throw analog switch.

[0033] Specifically, in this embodiment, the analog switch U1 can be replaced by a relay, that is, the function of the terminal resistor switching unit can also be realized by replacing the analog switch U1 with a relay.

[0034] Specifically, in this embodiment, the terminating resistor unit includes resistor R1, resistor R3, and capacitor C4; one end of resistor R1 is connected to the terminating resistor switching unit, the other end of resistor R1 is connected to resistor R3 and capacitor C4 respectively, the other end of capacitor C4 is grounded, and the other end of resistor R3 is connected to the terminating resistor switching unit; resistors R1 and R3 are matching resistors.

[0035] Specifically, in this embodiment, the driving unit includes resistor R4, resistor R5, transistor V1, and a current limiting circuit; the collector of transistor V1 is connected to resistor R4 and the terminating resistor switching unit, the other end of resistor R4 is connected to the power supply terminal and resistor R5, the other end of resistor R5 is connected to the current limiting circuit, the other end of the current limiting circuit is connected to the base of transistor V1, and the emitter of transistor V1 is grounded; resistors R4 and R5 are pull-up resistors; INSERT_DET is an insertion detection signal, which can be replaced by a mechanical switch and is connected to resistors R6 and R5 respectively. When a next-level module is connected, this signal will be pulled low; when no next-level module is connected, this signal will be high.

[0036] Specifically, in this embodiment, the current limiting circuit includes a resistor R6; one end of the resistor R6 is connected to the resistor R5, and the other end of the resistor R6 is connected to the base of the transistor V1.

[0037] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the inventive concept of this utility model and the contents of this utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

Claims

1. A daisy-chain CAN bus cascade end resistor adaptive matching system, characterized in that, include: The host and several identical or different modules connected in a daisy chain. Each module is equipped with a terminating resistor matching circuit; The host is connected to each module via a CAN communication bus; the terminating resistor matching circuit includes a CAN transceiver unit, a terminating resistor switching unit, a driving unit, and a terminating resistor unit; the CAN transceiver unit is electrically connected to the host and the terminating resistor switching unit respectively, and the terminating resistor switching unit is electrically connected to the driving unit and the terminating resistor unit respectively.

2. The daisy-chain CAN bus cascade end resistor adaptive matching system according to claim 1, characterized in that, The CAN transceiver unit includes a CAN transceiver D1, a common-mode inductor L1, and a first filter circuit. Pin 3 of the CAN transceiver D1 is connected to the first filter circuit and the power supply terminal, pins 6 and 7 of the CAN transceiver D1 are connected to pins 1 and 2 of the common-mode inductor L1, pins 3 and 4 of the common-mode inductor L1 are connected to the terminating resistor switching unit and the host, and pins 2 and 8 of the CAN transceiver D1 and the other end of the first filter circuit are grounded.

3. The daisy-chain CAN bus cascade end resistor adaptive matching system according to claim 2, characterized in that, The first filter circuit includes capacitor C2 and capacitor C3; one end of capacitor C2 and capacitor C3 is connected to pin 3 of CAN transceiver D1, and the other end of capacitor C2 and capacitor C3 is grounded.

4. A daisy-chain CAN bus cascade end resistor adaptive matching system according to any one of claims 1-3, characterized in that, The terminal resistor switching unit includes an analog switch U1, a resistor R2, and a second filter circuit. Pin 1 of the analog switch U1 is connected to the resistor R2, the other end of the resistor R2 is connected to the second filter circuit and the power supply, the other end of the second filter circuit is grounded, pin 6 of the analog switch U1 is grounded, pin 3 of the analog switch U1 is connected to the CAN transceiver unit and the CAN_H communication bus, pin 9 of the analog switch U1 is connected to the CAN transceiver unit and the CAN_L communication bus, pins 5 and 7 of the analog switch U1 are connected to the terminal resistor unit, and pins 4 and 8 of the analog switch U1 are connected to the drive unit.

5. The daisy-chain CAN bus cascade end resistor adaptive matching system according to claim 4, characterized in that, The second filter circuit includes a capacitor C1; one end of the capacitor C1 is connected to a resistor R2 and a power supply terminal, and the other end of the capacitor C1 is grounded.

6. The daisy-chain CAN bus cascade end resistor adaptive matching system according to claim 4, characterized in that, The analog switch U1 is a double-pole double-throw analog switch.

7. A daisy-chain CAN bus cascade end resistor adaptive matching system according to any one of claims 1-3, characterized in that, The terminating resistor unit includes resistor R1, resistor R3, and capacitor C4; one end of resistor R1 is connected to the terminating resistor switching unit, the other end of resistor R1 is connected to resistor R3 and capacitor C4 respectively, the other end of capacitor C4 is grounded, and the other end of resistor R3 is connected to the terminating resistor switching unit.

8. A daisy-chain CAN bus cascade end resistor adaptive matching system according to any one of claims 1-3, characterized in that, The driving unit includes resistor R4, resistor R5, transistor V1, and a current limiting circuit. The collector of transistor V1 is connected to resistor R4 and the terminal resistor switching unit, the other end of resistor R4 is connected to the power supply terminal and resistor R5, the other end of resistor R5 is connected to the current limiting circuit, the other end of the current limiting circuit is connected to the base of transistor V1, and the emitter of transistor V1 is grounded.

9. A daisy-chain CAN bus cascade end resistor adaptive matching system according to claim 8, characterized in that, The current limiting circuit includes a resistor R6; one end of the resistor R6 is connected to a resistor R5, and the other end of the resistor R6 is connected to the base of a transistor V1.

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