Multi-protocol communication circuit and device

Abstract

The utility model provides a multi-protocol communication circuit and equipment, which utilizes the characteristics that a CAN protocol transceiver and an RS485 protocol transceiver both transmit differential signals and can mutually tolerate the differential signals of each other, one ends of the CAN protocol transceiver and the RS485 protocol transceiver with the same signal polarity are connected together, and then the transceivers which do not communicate with each other are set to be in a receiving mode through software. According to the embodiment of the utility model, the transceiver which does not participate in communication is not damaged, and the transceiving process of the transceiver which participates in communication is not influenced, so that the two communication protocols can share one communication interface, and compared with the condition that a plurality of interfaces are required to be adopted or a gating switch is additionally arranged, the circuit disclosed by the embodiment of the invention is simpler in structure, small in size and low in cost.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to a multi-protocol communication circuit and device. Background Art

[0002] Common bus communication technologies in industry include CAN communication protocol, RS485 communication protocol, Ethernet communication protocol, etc. Most products on the existing market can only support one of these protocols. To implement communication between CAN communication protocol and RS485 communication protocol, different models of communication products need to be purchased, and limited by hardware, the protocol type cannot be switched through software configuration during use. In this regard, some products can support both CAN communication protocol and RS485 communication protocol at the same time. However, due to the communication differences between the protocols, each protocol requires an independent physical interface. For example, RS485 uses a DB9 interface and CAN uses a 3-pin pluggable terminal, etc. This type of product has many interfaces, which will result in a large product size and inconvenient wiring. And some products can use the same physical interface, but an additional signal gating switch needs to be set inside to select one of the protocols for communication, increasing the cost. Summary of the Utility Model

[0003] This application provides a multi-protocol communication circuit and device with a small size and low cost.

[0004] A multi-protocol communication circuit includes an RS485 protocol transceiver and a CAN protocol transceiver. The first communication end of the RS485 protocol transceiver is commonly connected to the first communication end of the CAN protocol transceiver and serves as a first common communication end; the second communication end of the RS485 protocol transceiver is commonly connected to the second communication end of the CAN protocol transceiver and serves as a second common communication end;

[0005] Both the RS485 protocol transceiver and the CAN protocol transceiver are connected to an external communication circuit through the first common communication end and the second common communication end; among them, in the RS485 protocol transceiver and the CAN protocol transceiver, when one of them communicates with the external communication circuit, the other is set to the receive mode.

[0006] In one embodiment, the multi-protocol communication circuit further includes a communication interface; the first common communication end is connected to the first end of the communication interface; the second common communication end is connected to the second end of the communication interface.

[0007] In one embodiment, the multi-protocol communication circuit further includes:

[0008] An electrostatic protection circuit, which is respectively connected to the first common communication end, the second common communication end, the first end and the second end of the communication interface.

[0009] In one embodiment, the multi - protocol communication circuit further includes:

[0010] An impedance matching circuit, respectively connected to the first common communication terminal and the second common communication terminal, for performing impedance matching between the signal source end and the load end.

[0011] In one embodiment, the impedance matching circuit includes a resistor R1 and a switching element SW. One end of the resistor R1 is connected to the first common communication terminal, the other end of the resistor R1 is connected to one end of the switching element SW, and the other end of the switching element SW is connected to the second common communication terminal.

[0012] In one embodiment, the multi - protocol communication circuit further includes:

[0013] A first filtering circuit, including capacitors C1, C2, and C3 connected in sequence. One end of the capacitor C1 that is not connected to the capacitor C2 is used to connect to a first reference terminal, and one end of the capacitor C3 that is not connected to the capacitor C2 is used to connect to a second reference terminal; the common connection end of the capacitor C1 and the capacitor C2 is connected to the first common communication terminal, and the common connection end of the capacitor C2 and the capacitor C3 is connected to the second common communication terminal; wherein, one of the first reference terminal and the second reference terminal is a power supply terminal, and the other is a ground terminal.

[0014] In one embodiment, the multi - protocol communication circuit further includes:

[0015] A second filtering circuit, including a common - mode inductor, which is respectively connected to the first common communication terminal, the second common communication terminal, the first end and the second end of the communication interface.

[0016] In one embodiment, a resistor R2 is connected in series between the first communication terminal of the RS485 protocol transceiver and the first common communication terminal, and a resistor R3 is connected in series between the second communication terminal of the RS485 protocol transceiver and the second common communication terminal.

[0017] In one embodiment, a resistor R4 is connected in series between the first communication terminal of the CAN protocol transceiver and the first common communication terminal, and a resistor R5 is connected in series between the second communication terminal of the CAN protocol transceiver and the second common communication terminal.

[0018] A multi - protocol communication device, the multi - protocol communication device includes an Ethernet communication circuit and the above - mentioned multi - protocol communication circuit;

[0019] Wherein, when the multi-protocol communication circuit includes the communication interface, the communication interface and the RJ45 interface in the Ethernet communication circuit are the same interface, and the first end and the second end of the communication interface are respectively two idle terminals of the RJ45 interface.

[0020] The above multi-protocol communication circuit uses both the CAN protocol transceiver and the RS485 protocol transceiver to transmit differential signals, and due to the characteristic that they can tolerate each other's differential signals, the ends with the same signal polarity are respectively connected together, and then the transceivers that do not communicate are set to the receiving mode through software. This will neither damage the transceivers that do not participate in communication nor affect the transceiver process of the transceivers that participate in communication. In this way, two communication protocols can share one communication interface. Compared with the need to use multiple interfaces or additionally set up a gating switch, the circuit structure of this embodiment is simpler, smaller in size and lower in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural block diagram of a multi-protocol communication circuit according to an embodiment of the present application;

[0022] Figure 2 is a structural diagram of a multi-protocol communication circuit according to another embodiment of the present application;

[0023] Figure 3 is a structural diagram of a multi-protocol communication circuit according to another embodiment of the present application;

[0024] Figure 4 is a structural diagram of a multi-protocol communication circuit according to another embodiment of the present application;

[0025] Figure 5 is a structural diagram of a multi-protocol communication circuit according to another embodiment of the present application;

[0026] Figure 6 is a schematic circuit structure diagram of a multi-protocol communication circuit according to another embodiment of the present application;

[0027] Figure 7 is a schematic structural diagram of an RJ45 terminal according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0030] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of this application are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture (as shown in the drawings). If this specific posture changes, the directional indications will also change accordingly. The connection mentioned above can be a direct connection or an indirect connection.

[0031] In addition, in this application, descriptions such as "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0032] The present utility model provides a multi - protocol communication circuit. Referring to Figure 1 as shown, the multi - protocol communication circuit includes an RS485 protocol transceiver 120 and a CAN protocol transceiver 110. The first communication terminal of the RS485 protocol transceiver 120 and the first communication terminal of the CAN protocol transceiver 110 are commonly connected and serve as the first common communication terminal (denoted as a in the figure); the second communication terminal of the RS485 protocol transceiver 120 and the second communication terminal of the CAN protocol transceiver 110 are commonly connected and serve as the second common communication terminal (denoted as b in the figure); both the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 are connected to an external communication circuit through the first common communication terminal and the second common communication terminal; among them, in the RS485 protocol transceiver 120 and the CAN protocol transceiver 110, when one of them communicates with the external communication circuit, the other is set to the receiving mode.

[0033] It can be understood that both the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 are differential communication protocols. Their first communication terminals are both used to transmit one of the differential signals, and their second communication terminals are both used to transmit the other differential signal. The differential signals transmitted by the first communication terminal of the RS485 protocol transceiver 120 and the first communication terminal of the CAN protocol transceiver 110 have the same polarity, and their common connection terminal serves as the first common communication terminal. The differential signals transmitted by the second communication terminal of the RS485 protocol transceiver 120 and the second communication terminal of the CAN protocol transceiver 110 have the same polarity, and their common connection terminal serves as the second common communication terminal. In this way, the communication terminals for transmitting signals with the same polarity in the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 are commonly connected, so that only one set of communication interfaces is required to enable the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 to communicate with an external communication circuit.

[0034] Among them, when using one of the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 to communicate with an external communication circuit, the other transceiver needs to be set to the receive mode. Since the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 can withstand the differential signals transmitted during the operation of the other party, this differential signal will not cause damage to the transceiver set to the receive mode, and the transceiver set to the receive mode will not affect the normal communication between the other transceiver and the external communication circuit. In addition, although the transceiver in the receive mode will receive the differential signal and transmit it back to the subsequent data processing unit, the processing of the signal transmitted by this transceiver by the data transmission unit can be turned off, so as to further avoid this transceiver affecting normal communication. The receive modes of the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 can be set by software. For example, when the RS485 protocol transceiver 120 communicates with an external communication circuit, the CAN protocol transceiver 110 is set to the receive mode. At this time, the CAN protocol transceiver 110 will not affect the normal communication between the RS485 protocol transceiver 120 and the external communication circuit, and the transmitted differential signal will not damage the CAN protocol transceiver 110. In some embodiments, the RS485 protocol transceiver 120 may include a CS48520D chip, and the two communication terminals of the RS485 protocol transceiver 120 are respectively terminal A and terminal B; the CAN protocol transceiver 110 may include a CA-IF1044VD chip, and the two communication terminals of the CAN protocol transceiver 110 are respectively terminal CANH and terminal CANL, as shown in Figure 6 shown.

[0035] The above multi - protocol communication circuit utilizes the characteristics that both the CAN protocol transceiver 110 and the RS485 protocol transceiver 120 transmit differential signals and can tolerate each other's differential signals. The ends with the same signal polarity are commonly connected respectively, and then the transceiver that is not in communication is set to the receiving mode through software, which will neither damage the transceiver that does not participate in communication nor affect the transceiver process of the transceiver that participates in communication. In this way, two communication protocols can share the same communication interface. Compared with the need to use multiple interfaces or additionally set a gating switch, the circuit structure of this embodiment is simpler, smaller in size and lower in cost.

[0036] In one embodiment, the multi - protocol communication circuit further includes a communication interface (not shown); the first common communication end is connected to the first end of the communication interface; the second common communication end is connected to the second end of the communication interface.

[0037] It can be understood that the communication interface is used to realize the connection between the multi - protocol communication circuit and the external communication circuit. The communication interface includes at least two ends, and its specific type can be selected according to needs. One end of the communication interface is connected to the first common communication end, and the other end is connected to the second common communication end. The external communication circuit is connected to the communication interface, and thus is respectively connected to the first common communication end and the second common communication end, and then communicates with one of the RS485 protocol transceiver 120 and the CAN protocol transceiver 110 through the first common communication end and the second common communication end.

[0038] In one embodiment, the multi - protocol communication circuit further includes an electrostatic protection circuit, and the electrostatic protection circuit is respectively connected to the first common communication end, the second common communication end, the first end and the second end of the communication interface.

[0039] It can be understood that for any one of the two - path transmissions of the differential signal, the electrostatic protection circuit can be connected between the common communication end and the communication interface to prevent the transmission of this path of signal from being interfered by static electricity. The electrostatic protection circuit can adopt components with electrostatic protection such as capacitors, bipolar transistors, rectifiers, etc.; in one embodiment, the electrostatic protection circuit can include an electrostatic diode D1. As shown in Figure 2 , its first end is connected to the first common communication end, its second end is connected to the second common communication end, and its third end is connected to the ground end. The electrostatic diode has a simple structure and strong protection ability, which can improve the accuracy of signal transmission and is especially suitable for sensitive electronic components.

[0040] In one embodiment, the multi - protocol communication circuit further includes an impedance matching circuit 130, and the impedance matching circuit 130 is respectively connected to the first common communication end and the second common communication end for impedance matching between the signal source end and the load end.

[0041] Among them, the signal source end is the end that outputs differential signals, and the load end is the end that receives differential signals. Through impedance matching, the differential signals can achieve the best transmission efficiency and improve the accuracy of signal transmission.

[0042] It can be understood that based on the connection relationship between the two common communication ends and the communication interface, one end of the impedance matching circuit 130 connected to the first common communication end is also connected to the first end of the communication interface, and one end of the impedance matching circuit 130 connected to the second common communication end is also connected to the second end of the communication interface.

[0043] In one embodiment, as Figure 3 shown, the impedance matching circuit 130 may include a resistor R1 and a switching element SW. One end of the resistor R1 is connected to the first common communication end, the other end of the resistor R1 is connected to one end of the switching element SW, and the other end of the switching element SW is connected to the second common communication end.

[0044] It can be understood that the closing and opening of the switching element SW can be controlled according to whether there is a need for impedance matching, so as to control the access or disconnection of the resistor R1. The resistor R1 can be a fixed resistor or an adjustable resistor; in one embodiment, the resistance value of the resistor R1 can be 120Ω. The impedance matching circuit 130 has a simple structure, occupies a small space, and has a low cost.

[0045] In one embodiment, as Figure 4 shown, the multi-protocol communication circuit further includes a first filter circuit 140. The first filter circuit 140 includes a capacitor C1, a capacitor C2, and a capacitor C3 connected in sequence. One end of the capacitor C1 that is not connected to the capacitor C2 is used to connect to the first reference end, and one end of the capacitor C3 that is not connected to the capacitor C2 is used to connect to the second reference end; the common connection end of the capacitor C1 and the capacitor C2 is connected to the first common communication end, and the common connection end of the capacitor C2 and the capacitor C3 is connected to the second common communication end; among them, one of the first reference end and the second reference end is a power supply end, and the other is a ground end.

[0046] Among them, if the differential signal transmitted by the first common communication end is a high level and the differential signal transmitted by the second common communication end is a low level, then the first reference end is the power supply end and the second reference end is the ground end; conversely, the first reference end is the ground end and the second reference end is the power supply end. Only the connection situation of the capacitor C1 and the capacitor C3 with the two reference ends is schematically shown in the figure when the differential signal transmitted by the first common communication end is a high level and the differential signal transmitted by the second common communication end is a low level as an example.

[0047] It can be understood that based on the connection relationship between the two common communication ends and the communication interface, the common connection end of the capacitor C1 and the capacitor C2 is also connected to the first end of the communication interface, and the common connection end of the capacitor C2 and the capacitor C3 is also connected to the second end of the communication interface.

[0048] The first filtering circuit 140 can filter the differential signals input to the transceiver, eliminate the noise on the bus, and thus improve the accuracy of signal transmission.

[0049] In one embodiment, as Figure 5 shown, the multi-protocol communication circuit further includes a second filtering circuit 150. The second filtering circuit 150 includes a common-mode inductor, and the common-mode inductor is respectively connected to the first common communication terminal, the second common communication terminal, the first end and the second end of the communication interface.

[0050] Among them, the impedance value of the common-mode inductor can be 1000 Ω. It can be understood that the filtering inductor can filter out the electromagnetic interference signals received by the differential signals output by the transceiver, thereby improving the accuracy of data transmission.

[0051] In one embodiment, as Figure 6 shown, a resistor R2 is connected in series between the first communication terminal of the RS485 protocol transceiver 120 and the first common communication terminal, and a resistor R3 is connected in series between the second communication terminal of the RS485 protocol transceiver 120 and the second common communication terminal.

[0052] It can be understood that in order to protect the input and output of the RS485 protocol transceiver 120, a resistor can be set at each of its two data transceiver terminals.

[0053] In one embodiment, as Figure 6 shown, a resistor R4 is connected in series between the first communication terminal of the CAN protocol transceiver 110 and the first common communication terminal, and a resistor R5 is connected in series between the second communication terminal of the CAN protocol transceiver 110 and the second common communication terminal.

[0054] Similarly, similar to the above, in order to protect the input and output of the CAN protocol transceiver 110, a resistor can be set at each of its two data transceiver terminals.

[0055] An embodiment of the present invention further provides a multi-protocol communication circuit, as Figure 6 shown, including an RS485 protocol transceiver 120, a CAN protocol transceiver 110, a communication interface, an electrostatic protection circuit, an impedance matching circuit 130, a first filtering circuit 140, a second filtering circuit 150, a resistor R2, a resistor R3, a resistor R4, and a resistor R5. The impedance matching circuit 130 includes a resistor R1 and a switching element SW. The first filtering circuit 140 includes capacitors C1, C2, and C3. The second filtering circuit 150 includes a common-mode inductor. The RS485 protocol transceiver 120 may include a CS48520D chip, and the CAN protocol transceiver 110 may include a CA-IF1044VD chip. The connection relationship and working process of each component can be referred to Figure 6 and the above embodiments, and will not be elaborated here.

[0056] The embodiment of the present utility model further provides a multi - protocol communication device. The multi - protocol communication device includes an Ethernet communication circuit and the multi - protocol communication circuit of any of the above embodiments. Wherein, when the multi - protocol communication circuit includes a communication interface, the communication interface and the RJ45 interface in the Ethernet communication circuit are the same interface, and the first end and the second end of the communication interface are respectively two idle terminals of the RJ45 interface.

[0057] It can be understood that the multi - protocol communication circuit and the Ethernet communication circuit can jointly form a multi - protocol communication device through an integrated manner, so as to realize RS485 protocol communication, CAN protocol communication, and Ethernet communication, and thus can be applied to more scenarios. Wherein, when the multi - protocol communication circuit is provided with a communication interface for connecting to an external communication circuit, the RJ45 interface in the Ethernet communication circuit can be adopted, and the first common communication end and the second common communication end in the multi - protocol communication circuit are respectively connected to two idle ends of the RJ45 interface. In this way, there is no need to additionally set a communication interface, saving cost and space.

[0058] For example, when the RJ45 interface is applied to the Ethernet communication circuit, among the terminals of the RJ45 interface, in addition to the terminals used for Ethernet communication, there are at least two idle terminals. For example, with reference to Figure 7 As shown, the structure of the RJ45 interface is as shown in the reference figure. In Ethernet communication, the RJ45 interface uses terminals J1 and J2 as the terminals for receiving a pair of differential signals, and uses terminals J3 and J6 as the terminals for outputting a pair of differential signals. Therefore, there are still four idle terminals J4, J5, J7, and J8 left. The idle terminals J4 and J5 can be used to connect to the first common communication end and the second common communication end in a one - to - one correspondence. In addition, the terminals J7 and J8 of the RJ45 interface can be used to provide an external common ground connection for the multi - protocol communication circuit. Wherein, when the multi - protocol communication circuit is provided with an electrostatic protection circuit, the idle terminals J4 and J5 are connected to the two common communication ends through the electrostatic protection circuit.

[0059] In this way, by making full use of the RJ45 interface applied in Ethernet communication, the cost is reduced while ensuring the normal function of the multi - protocol communication circuit.

[0060] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present application by the same token.

Claims

1. A multi-protocol communication circuit, characterized in that: It comprises an RS485 protocol transceiver and a CAN protocol transceiver, wherein a first communication end of the RS485 protocol transceiver is connected to a first communication end of the CAN protocol transceiver and serves as a first common communication end; a second communication end of the RS485 protocol transceiver is connected to a second communication end of the CAN protocol transceiver and serves as a second common communication end; The RS485 protocol transceiver and the CAN protocol transceiver are both connected to an external communication circuit via the first common communication terminal and the second common communication terminal; wherein, when one of the RS485 protocol transceiver and the CAN protocol transceiver communicates with the external communication circuit, the other is set to a receiving mode.

2. The multi-protocol communication circuit according to claim 1, characterized in that: The multi-protocol communication circuit also includes a communication interface; the first common communication end is connected to a first end of the communication interface; and the second common communication end is connected to a second end of the communication interface.

3. The multi-protocol communication circuit according to claim 2, characterized in that: The multi-protocol communication circuit also includes: An electrostatic protection circuit is connected to the first common communication end, the second common communication end, the first end and the second end of the communication interface respectively.

4. The multi-protocol communication circuit according to claim 2, characterized in that: The multi-protocol communication circuit also includes: The impedance matching circuit is connected to the first common communication end and the second common communication end respectively, and is used for performing impedance matching between a signal source end and a load end.

5. The multi-protocol communication circuit according to claim 4, characterized in that: The impedance matching circuit includes a resistor R1 and a switch element SW, one end of the resistor R1 is connected to the first common communication end, the other end of the resistor R1 is connected to one end of the switch element SW, and the other end of the switch element SW is connected to the second common communication end.

6. The multi-protocol communication circuit according to claim 2, characterized in that: The multi-protocol communication circuit also includes: The first filtering circuit includes a capacitor C1, a capacitor C2 and a capacitor C3 connected in sequence, wherein the end of the capacitor C1 not connected to the capacitor C2 is used to be connected to a first reference end, and the end of the capacitor C3 not connected to the capacitor C2 is used to be connected to a second reference end; the common connection end of the capacitor C1 and the capacitor C2 is connected to the first common communication end, and the common connection end of the capacitor C2 and the capacitor C3 is connected to the second common communication end; wherein one of the first reference end and the second reference end is a power supply end, and the other is a ground end.

7. The multi-protocol communication circuit according to claim 2, characterized in that: The multi-protocol communication circuit also includes: The second filtering circuit includes a common-mode inductor, and the common-mode inductor is respectively connected to the first common communication end, the second common communication end, the first end and the second end of the communication interface.

8. The multi-protocol communication circuit according to claim 2, characterized in that: A resistor R2 is connected in series between the first communication terminal and the first common communication terminal of the RS485 protocol transceiver, and a resistor R3 is connected in series between the second communication terminal and the second common communication terminal of the RS485 protocol transceiver.

9. The multi-protocol communication circuit according to claim 2, characterized in that: A resistor R4 is connected in series between the first communication terminal and the first common communication terminal of the CAN protocol transceiver, and a resistor R5 is connected in series between the second communication terminal and the second common communication terminal of the CAN protocol transceiver.

10. A multi-protocol communication device, characterized in that: The multi-protocol communication device comprises an Ethernet communication circuit and a multi-protocol communication circuit as claimed in any one of claims 1 to 9; Wherein, when the multi-protocol communication circuit includes the communication interface, the communication interface is the same interface as the RJ45 interface in the Ethernet communication circuit, and the first end and the second end of the communication interface are respectively two idle terminals of the RJ45 interface.

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